3726 - SUPERNOVAE - how close can it get?

           -  3726  - SUPERNOVAE  -  how close can it get?       Ionizing radiation from supernovae can alter Earth’s atmospheric chemistry. The initial burst of energy from a supernova poses one threat, and so do the cosmic rays that arrive hundreds or thousands of years later.  X-rays can arrive months or years later.              

---------------------  3726  -   SUPERNOVAE  -  how close can it get?                

-  How dangerous are nearby supernovae to life on Earth?  From a distance, supernovae explosions are fascinating. A star more massive than our Sun runs out of hydrogen and becomes unstable.  It explodes and releases so much energy it can outshine its host galaxy for months.

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-  But space is vast and largely empty, and supernovae are relatively rare. And most planets don’t support life, so most supernovae probably explode without affecting any living things.

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-  One type of supernova has a more extended reach than thought.   It could have consequences for planets like ours.  Earth is no stranger to supernovae. One hasn’t been close enough to sterilize Earth, but there’s evidence showing supernovae have affected life on Earth.

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-  A 2018 paper presented evidence of a supernova exploding near Earth about 2.6 million years ago. It was about 160 light-years away. The supernova was tied to the “Pliocene marine megafauna extinction“. In that event, up to a third of Earth’s large marine species were wiped out, but only in shallow coastal waters.

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-  Up to 20 supernovae have showed up in the last 11 million years. Some of these were as close as 130 light-years to Earth.  About 2 million years ago, one of the supernovae exploded close enough to our planet to damage the ozone layer.

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-  There are different types of supernovae. Some of them have a much longer reach and much greater duration. Scientists have long known about the powerful gamma rays that supernova release during the explosion. They also know about the cosmic rays that can arrive hundreds or thousands of years later. If this happens close enough to a planet like Earth, the cosmic rays can deplete the ozone layer and increase muon radiation at the surface.

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-  An X-ray luminous supernova is different from other supernovae. When a supernova explodes, it emits gamma rays and other photons immediately. In an x-ray luminous supernova, gamma rays and photons are emitted, but some of the radiation from the explosion interacts with a dense circumstellar medium surrounding the progenitor star. This creates X-rays that can be lethal up to 160 light-years away.

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-  In a scenario where an supernova exploded close to Earth, it can take months or years following the initial explosion for the X-rays to arrive. Interactions with the circumstellar debris cause a delay. The X-rays can deplete Earth’s ozone layer, allowing harmful ultraviolet radiation from the Sun to reach the planet’s surface.  After the X-rays arrive, the cosmic rays arrive.  Cosmic rays are not really rays they are atomic nuclei, protons and electrons.  

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-  What are the lethal distances for supernovae?  There are many variables, both in the progenitor star and its environment. The progenitor star’s mass loss is especially important. But by characterizing the lethal X-ray dose for Earth’s stratosphere and the energy output of some of the brightest supernova.  The astronomers calculated the lethal distance for some well-known supernovae:

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-   SN 1987A exploded in the Large Magellanic Cloud, and the light reached Earth in 1987. Scientists observed the explosion and confirmed the source of energy for visible light for the first time. It proved that the long-duration glow after an  explosion is radioactive.

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-  SN1987A wasn’t very lethal. They say the supernova was only deadly to a distance of less than one light-year. It was the least dangerous supernova out of the 31 the team characterized.

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-  The most lethal of the 31 was “SN2006jd“  . It exploded in the galaxy NGC 4179, about 57 million light-years away, and the light reached Earth in 2006.  SN2006jd was lethal out to almost 100 light-years.

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-  The five most lethal supernova in this study are all “Type Iin” supernovae, as are seven of the top ten.  The top five are all “Type Iin” x-ray luminous supernovae, and so are seven of the top ten.  Type IIn supernovae also have the greatest range of influence. 

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-   SN 2006jd  has a range of influence that spans from 30 parsecs to 60 parsecs (100 light-years to 200 light-years.).

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-  Our Solar System is inside what’s known as the “Local Bubble“. It’s a cavity carved out of space in the Milky Way’s Orion Arm. Multiple supernovae explosions created the bubble in the last 10 to 20 million years. 

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-  Advances in X-ray astronomy will shed more light on the consequences for terrestrial planets, there’s lots more to uncover.  The interacting X-ray phase of an supernova’s evolution can entail significant consequences for terrestrial planets. The evidence certainly points to this process as capable of imposing lethal consequences for life at formidable distances.

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-  Scientists know that supernovae have had some effect on Earth. The presence of the radioactive isotope 60Fe has a half-life of 2.6 million years. Researchers have found undecayed 60Fe in ocean samples dating from 2 to 3 Million years ago. It should have decayed into nickel long ago. Supernovae can create 60Fe through nucleosynthesis when they explode.

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-  But other things can create 60Fe.  Asymptomatic giant branch stars can make it, too.

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-  Researchers also found 53Mn in the same samples of ferromanganese crust that hold the 60Fe. It’s also a radioactive isotope that should’ve decayed by now. Unlike 60Fe, only supernovae can create 53Mn. Its presence is definite proof of nearby supernovae in the recent geological past.  “Fe” is iron  amd “Mn” is magnesium.

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-   Ionizing radiation from supernovae can alter Earth’s atmospheric chemistry from substantial distances. The initial burst of energy from a supernova poses one threat, and so do the cosmic rays that arrive hundreds or thousands of years later and linger. X-rays can arrive months or years after the initial outburst. 

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-  Supernova outbursts have almost certainly struck our planet.  If the radiation weakened the ozone layer, allowing more UV radiation to reach the Earth’s surface, it would’ve caused mutations. It’s called UV mutagenesis, which may have driven molecular evolution and been critical in the origin of sex. In fact, mutation is evolution’s primary driver.

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-   The Galactic Habitable Zone (GHZ) is a region in a galaxy where habitability is most likely. Since supernovae can be fatal for life if close enough, regions with many stars that can potentially explode as supernovae are less habitable. Supernovae can be lethal at greater distances than thought and can be fatal in the period of a few months or years after the initial outburst due to the X-rays.

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-  October 31, 2022            SUPERNOVAE  -  how close can it get?                   3726                                                                                                                                  

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--------------------- ---  Monday, October 31, 2022  ---------------------------

 

3725 - DARK MATTER - measuring the mass of galaxie

 -  3725 -   DARK  MATTER  -  measuring the mass of galaxies?    Gravitational lensing occurs when a massive object is between the observer and a bright celestial body. The massive object warps space-time and modifies the path of light rays passing through it.

---------------  3725  -   DARK  MATTER  -  measuring the mass of galaxies?

-  Astronomers measured a time delay of 6.73 years, the longest ever detected for a gravitational lens,  between multiple images of a quasar. This result after 14.5 years of observation will improve knowledge about galaxy clusters and the dark matter they contain.

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-  Galaxy clusters are the largest gravitationally bound structures in the universe and can contain thousands of galaxies. In addition to galaxies and gas, the clusters are mostly made up of dark matter, imperceptible by direct detection of light, of a still unknown nature. 

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-  When observing a distant quasar through a galaxy or cluster of galaxies, if the gravitational lensing effect is strong enough, several images of the same celestial body are formed.  The observations were carried out over 14.5 years with the 1.2 meter telescope located at the Fred Lawrence Whipple Observatory (FLWO) of the Harvard-Smithsonian Center for Astrophysics, in collaboration with scientists at The Ohio State University .

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-  The four images of the quasar  correspond to a single quasar whose light is curved on its path towards us by the gravitational field of the galaxy cluster.  Since the trajectory followed by the light rays to form each image is different, we observe them at different instants of time; in this case we have to wait 6.73 years for the signal we observed in the first image to be reproduced in the fourth one.

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-  Measuring these time delays helps to better understand the properties of galaxies and clusters of galaxies, their mass and its distribution, in addition to providing new data for the estimation of the Hubble constant.  

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-  It has been possible to constrain the distribution of dark matter in the inner region of the cluster, since the lensing effect is sensitive not only to ordinary matter but also to dark matter assures that the calculation of the time delay.   This allows astronomers to determine the distribution of stars and other compact objects in the intracluster medium, as well as to calculate the size of the quasar’s accretion disk.

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October 29, 2022      DARK  MATTER  -  measuring the mass of galaxies?        3722                                                                                                                                   

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-----  Comments appreciated and Pass it on to whomever is interested. ---

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--  email feedback, corrections, request for copies or Index of all reviews 

---  to:  ------    jamesdetrick@comcast.net  ------  “Jim Detrick”  -----------

--------------------- ---  Monday, October 31, 2022  ---------------------------

3723 - QUASAR - where did they come from?

  -  3723  -  QUASAR  -  where did they come from?    Quasars are extremely bright and extremely distant objects. Their huge energy output is thought to be due to activity around the central supermassive black hole in young galaxies, near the edge of the observable universe.

---------------------  3723  -   QUASAR  -  where did they come from?

-  In 1979, astronomers spotted two nearly identical quasars that seemed close to each other in the sky. These “Twin Quasars” are actually separate images of the same object.   The light paths that created each image traveled through different parts of the cluster. One path took a little longer than the other.

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-  That meant a flicker in one image of the quasar occurred 14 months later in the other.  The cluster’s mass distribution formed a lens that distorted the light and drastically affected the two paths.

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-  In 2022 astronomers had spent fourteen years measuring an even longer time delay between multiple images of their target quasar. The galaxy cluster “SDSS J1004+4112” plays a role in the delay. The combo of galaxies and dark matter in the cluster is really entangling the quasar light as it passes through. That’s causing the light to travel different trajectories through the gravitational lens. The result is the same strange time-delayed effect.

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-  The four images of the quasar actually correspond to a single quasar whose light is curved on its path towards us by the gravitational field of the galaxy cluster.   Since the trajectory followed by the light rays to form each image is different, we observe them at different instants of time; in this case, we have to wait 6.73 years for the signal we observed in the first image to be reproduced in the fourth one.

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-   Gravitational lensing creates an optical effect as light passes through a region of space with a strong gravitational influence.

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-  Galaxy clusters are astonishingly massive and the largest gravitationally bound structures we know of in the universe. Some contain thousands of galaxies. The combined gravity of the galaxies, plus the intermingled dark matter in the cluster can entangle light from more distant objects as it passes through or near the cluster. The mass  in the cluster is spread out unevenly. That affects each path of light through the cluster.

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-    Measuring these time delays helps to better understand the properties of galaxies and clusters of galaxies, their mass, and its distribution.    This data helps us understand other characteristics of the lensing cluster.  It has been possible to constrain the distribution of dark matter in the inner region of the cluster, since the lensing effect is sensitive not only to ordinary matter but also to dark matter.

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-   Calculating the time delay allows other discoveries, including the distribution of stars and other objects in the area of space between galaxies in the cluster. It will help astronomers to calculate the size of the distant quasar’s accretion disk.

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-   These observations occurred over 14.5 years at the 1.2-meter telescope located at the Fred Lawrence Whipple Observatory.  

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-  The word quasar stands for “quasi-stellar radio source“. Quasars got that name because they looked starlike when astronomers first began to notice them in the late 1950s and early 60s. But quasars aren’t stars. 

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-  Scientists now know they are young galaxies, located at vast distances from us, with their numbers increasing towards the edge of the visible universe.   Quasars are extremely bright, up to 1,000 times brighter than our Milky Way galaxy. They are highly active, emitting staggering amounts of radiation across the entire electromagnetic spectrum.

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-  Because they’re far away, we’re seeing these objects as they were when our universe was young. The oldest quasar is approximately 13.03 billion light-years away, and therefore we see it as it was just 670,000,000 years after the Big Bang.

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-   Quasars are the extremely luminous centers of galaxies in their infancy. A quasar is a type of “active galactic nucleus“.   The intense radiation released by an AGN powers a supermassive black hole at its center. The radiation comes from material in the accretion disk surrounding the black hole when it is superheated to millions of degrees by the intense friction generated by the particles of dust, gas and other matter in the disk colliding countless times with each other.

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-  The inward spiral of matter in a supermassive black hole’s accretion disk at the center of a quasar is the result of particles colliding and bouncing against each other and losing momentum. That material came from the enormous clouds of gas, mainly consisting of molecular hydrogen, which filled the universe in the era shortly after the Big Bang.  In the early universe, quasars had a vast supply of matter to feed on.

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-  As matter in a quasar’s black hole accretion disk heats up, it generates radio waves, X-rays, ultraviolet and visible light. The quasar becomes so bright that it’s able to outshine entire galaxies. They are so far from us that we only observe the active nucleus, or core, of the galaxy in which they reside. We see nothing of the galaxy apart from its bright center. It’s like seeing a distant car headlight at night: you have no idea of which type of car you are looking at, as everything apart from the headlight is in darkness.

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-  “Seyfert galaxies” are not classed as quasars but that still have bright, active centers where we can see the rest of the galaxy.   Seyfert galaxies make up perhaps 10% of all the galaxies in the universe. They are not classed as quasars because they are much younger and have well-defined structures. Quasar-containing galaxies are young and formless.

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-  Consider the amounts of energy required to illuminate an object sufficiently to make it visible in radio waves from the farthest reaches of the universe.  Quasars can emit up to a thousand times the energy of the combined luminosity of the 200 billion or so stars in our own Milky Way galaxy. 

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-  A typical quasar is 27 trillion times brighter than our sun!   Most large galaxies went through a so-called “quasar phase” in their youth, soon after their formation. They subsided in brightness when they ran out of matter to feed the accretion disk surrounding their supermassive black holes.

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-   After this epoch, galaxies settled into “quiescence“, their central black holes starved of material to feed on. The black hole at the center of our own galaxy has been seen to flare up briefly, however, as passing material strays into it, releasing radio waves and X-rays. It’s conceivable that a black hole can tear apart entire stars and consume them as they cross its event horizon, the point of no return.

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-   We know that 3.5 million years ago there was a gigantic explosion known as a Seyfert flare at the center of our galaxy.  It was apparently centered on Sagittarius A*, the Milky Way’s supermassive black hole, producing two huge lobes of superheated plasma extending some 25,000 light years from the north and south galactic poles. These are huge lobes Fermi bubbles and they are visible today at gamma and X-ray wavelengths.

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-  Huge lobes extend above and below the plane of our Milky Way galaxy. They shine in gamma rays and X-rays and thus are invisible to the human eye.  A quasar’s light passed through one of these bubbles. Imprinted on that light is information about the outflow’s speed, composition, and eventually mass. 

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-  Quasars were first discoveries in the late 1950s from astronomers using radio telescopes. They saw starlike objects that radiated radio waves ( “quasi-stellar radio objects“), but which were not visible in optical telescopes. Their resemblance to stars, their brightness and small angular diameters understandably led astronomers of the time to assume they were looking at objects within our own galaxy.

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-  Many early observations of quasars, including those of “3C48” and “3C273“, the first two quasars to be discovered, took place in the early 1960s by British-Australian astronomer John Bolton. He and his colleagues found it puzzling that quasars were not visible in optical telescopes. They wanted to find quasars’ so-called “optical counterparts,” that is, a quasar which would be visible to their eyes in a telescope rather than only being detectable with radio instruments.

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-  Astronomers simply didn’t know at that time that quasars were extremely distant, too distant for their optical counterparts to be visible from Earth at that time, despite being intrinsically brilliant objects.  In 1963, astronomers Allan Sandage and Thomas A. Matthews found what they were looking for, what appeared to be a faint, blue star at the location of a known quasar. 

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-  Then, using the 200-inch Hale telescope, Bolton and his team observed quasar 3C273 as it passed behind the moon. These observations also let them obtain spectra. And again the spectra looked strange, showing unrecognizable emission lines. These lines tell astronomers which chemical elements are present in the object they are examining. But the quasar’s spectral lines were nonsensical, seeming to indicate elements which should not be present.

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-  The hydrogen emission lines fall farther to the right, toward longer wavelengths, compared to where hydrogen emission lines would normally be located on the spectrum. They are “redshifted“, indicating that the quasar is located at an extreme distance from us. 

Astronomer Maarten Schmidt, after examining the strange emission lines in the spectra of quasars, suggested that astronomers were seeing normal emission lines that were highly shifted towards the red end of the electromagnetic spectrum!

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-  The redshift was due to the quasar’s great distance. Light being stretched by the expansion of the universe during its long journey to us from the edge of the visible cosmos appears much redder.

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-  But if it were really true that quasars were as far away as towards the edge of the visible universe, how could they have generated such enormous quantities of energy? In 1964, even the existence of black holes caused hot debate. Many scientists considered them nothing more than mathematical freaks, because surely they could not exist in the real universe.

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-    The debate about the nature of quasars raged on until the 1970s when a new generation of Earth- and space-based telescopes established beyond reasonable doubt that quasars do indeed lie at vast distances, that we are seeing galaxies when they were young, that the quasar stage is a natural phase of their growth. 

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-  With black holes finally being taken seriously too, astronomers could now finally model the identity of the almost incomprehensible powerhouse behind quasars: supermassive black holes consuming stupendous amounts of gas and radiating vast amounts of energy across the spectrum as a result.

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-  This is why quasars sit towards the edge of the visible universe and why we don’t see them closer: because quasars are young galaxies, seen not long after their formation in the early universe.

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-   Quasars are extremely bright and extremely distant objects. Their huge energy output is thought to be due to activity around the central supermassive black hole in young galaxies, near the edge of the observable universe.

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October 29, 2022         QUASAR  -  where did they come from?              3722                                                                                                                                   

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-----  Comments appreciated and Pass it on to whomever is interested. ---

---   Some reviews are at:  --------------     http://jdetrick.blogspot.com -----  

--  email feedback, corrections, request for copies or Index of all reviews 

---  to:  ------    jamesdetrick@comcast.net  ------  “Jim Detrick”  -----------

--------------------- ---  Monday, October 31, 2022  ---------------------------

3722 - DARK MATTER - versus the expanding universe?

  -  3722 -   DARK  MATTER  -  versus the expanding universe?   Dark Matter  and Dark Energy are called “dark” because we do not know what they are.  Astronomers have discovered dark matter around galaxies that existed about 12 billion years ago. This is the earliest detection yet of this mysterious substance that dominates the matter in the universe.

--------------  3722  -   DARK  MATTER  -  versus the expanding universe?

-  Dark matter in the early universe is less 'clumpy' than predicted by many current cosmological models. This understanding of how galaxies evolve suggest that the fundamental rules governing the universe could have been different when the 13.7 billion-year-old universe was just 1.7 billion years old. 

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-  Mapping dark matter in the very early universe is done with the “cosmic microwave background” (CMB), a fossil radiation left over from the Big Bang that is distributed throughout the entire universe.  It is radiation left over from the Big Bang and has stretched put it wavelength to microwave wavelengths and lower energies. 

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-   Because light takes a finite time to travel from distant objects to Earth, astronomers see other galaxies as they existed when the observed light left them. The more distant a galaxy, the longer the light has been traveling to us and thus the further back in time we see them, so we see the most distant galaxies as they were billions of years ago, in the infant universe. 

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-   Dark matter is the mysterious substance that makes up 85% of the total mass of the universe. It doesn't interact with matter and light like the everyday matter that is 15% and made of protons and neutrons that fills stars, planets and us.

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-  To 'see' dark matter astronomers must rely on its interaction with gravity.  According to Einstein's theory of relativity, objects of tremendous mass cause the curvature of space-time.   The larger the cosmic object, the more extreme the warping of space-time it causes.

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-  Massive objects like galaxies cause space-time to curve so strongly that light from sources behind a galaxy is curved, just like the path of a marble rolled across the stretched rubber sheet would deviate. This effect shifts the position of the light source in the sky, a phenomenon called “gravitational lensing“.

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-    Astronomers can observe how light from a source behind that galaxy is changed as it passes the 'lens galaxy.' The more dark matter a lens galaxy contains the greater the distortion of the light passing it. 

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-  Because the earliest and most distant galaxies are very faint, as astronomers look deeper into the universe and further back in time, the lensing effect becomes more subtle and more difficult to see.  Scientists need both a lot of background sources and a lot of early galaxies to spot lensing by dark matter. This problem has limited the mapping of dark matter distribution to galaxies that are around 8 to 10 billion years old. 

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-  But the CMB provides a more ancient light source than any galaxy can provide. The CMB is ubiquitous radiation that was created when the universe cooled enough to allow atoms to form, reducing the number of photon-scattering free electrons in a moment cosmologists call 'the last scattering.'  The reduction in free electrons allowed photons to travel freely, meaning that the universe suddenly stopped being opaque and became transparent to light.

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-  And just like light from other distant sources, the CMB can be distorted by galaxies with dark matter due to gravitational lensing.  The combined lensing distortions of a large sample of ancient galaxies with those of the CMB was used to detect dark matter dating back to when the universe was just 1.7 billion years old. And this ancient dark matter paints a very different cosmic picture.

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-  For the first time, we were measuring dark matter from almost the earliest moments of the universe.  Astronomers can see more galaxies that are in the process of formation than at the present; the first galaxy clusters are starting to form as well.  These clusters can be comprised of between 100 and 1,000 galaxies bound to large amounts of dark matter by gravity.

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-  The widely accepted current theory is the “Lambda-CDM model” that suggests that tiny fluctuations in the CMB should have resulted in gravity creating densely packed pockets of matter. These fluctuations eventually lead matter to collapse to form galaxies, stars and planets, and should also result in dense pockets of dark matter. 

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- The research will continue to collect data to assess whether the Lambda-CDM model conforms to observations of dark matter in the early universe or if the assumptions behind the model need to be revised. 

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-  The Vera C. Rubin Observatory's Legacy Survey of Space and Time (LSST) could allow the researchers to look at dark matter even further back in time.   Another powerful tool is two decades' worth of observations of supernova explosions. This is a powerful new analysis tool has provided the most accurate accounting of dark energy and dark matter.

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-  Dark energy and dark matter are mysterious because despite making up at least 95% of the universe's energy and matter content, they can't be observed directly. The existence of dark energy is inferred from the fact it drives the accelerating expansion of the universe. 

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-   Dark matter, which does not interact with light and is thus "invisible" is indirectly detected due to its gravitational influence, which literally prevents galaxies from flying apart as they rotate. 

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-  Astronomy research confirms that the matter-energy content of the universe is made up by around two-thirds dark energy and one-third matter, most of which is in the form of dark matter. They also  confirm that the universe has been expanding at an accelerating rate for the last few billion years, and leaves a key disagreement in the rate of this expansion still unresolved.

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-   The new study used more than 1,500 supernovas.   Astronomers improved their analysis techniques as well as addressing potential sources of error.   The technique relies on what astronomers call Type 1a supernovas, which are a type of cosmic explosion that occurs when stellar remnants called white dwarfs accumulate matter from a companion star at a rapid rate, triggering runaway thermonuclear reactions.

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-  This variety of cosmic explosions can be so bright that they outshine the light output from every star in their galaxy combined, so astronomers have spotted this type of supernova as much as 10 billion light-years away.

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-   Because light takes a finite time to travel to Earth, astronomers are looking back in time as well, in the case of 10 billion light-years, back to when the universe was just one-quarter of its current age.  Every Type 1a supernova releases the same amount of light, so astronomers call them "standard candles" and use these events to measure cosmic distances and the expansion rate of the universe.

-

-  Distance measurements are possible because the brightness of Type 1a supernova light diminishes as it travels. Calculating the expansion of the universe is more complicated; it relies on determining how much the light has been stretched out, or "redshifted,"  as it travels for billions of years across an expanding universe.

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-   The redshift from supernovas at varying distances and thus at different periods in cosmic history reveals how fast the universe was expanding during its different time periods.  Two separate teams of scientists in 1998 used observations of distant Type 1a supernovas to calculate that the expansion of the universe was in fact accelerating. 

-

-  Acceleration came as a major shock to physicists, who had assumed that whatever had triggered the initial rapid expansion of the universe, "the Big Bang" , had dissipated and the expansion rate of the universe had slowed. 

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-  “Dark Energy” became a placeholder name for the cosmic push that is stretching out the very fabric of the universe faster and faster. Dark matter is almost the flip side of this coin, with its gravitational influence helping to hold galaxies together internally as dark energy pushed them apart from each other.

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-  The expansion of the universe began speeding up when dark energy began to dominate over the influence of matter and began to drive the universe apart at an ever-increasing rate. 

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-  The rate of expansion of the universe is called the “Hubble constant“, which is  calculated at 45.6 miles per second per megaparsec with only 1.3% uncertainty. This means for every megaparsec, which equals 3.26 million light-years, the analysis estimates that in the nearby universe space itself is expanding at more than 160,000 miles per hour.

-

-  Another way of measuring the Hubble constant uses the cosmic microwave background (CMB) radiation, a fossil light left over from an event shortly after the Big Bang. However, this approach and the Type 1a supernova approach suggest different values for the Hubble constant. 

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-   In many ways, this latest “Pantheon+ analysis” is a culmination of more than two decades' worth of diligent efforts by observers and theorists worldwide in deciphering the essence of the expansion of the universe.   I hope this review expanded your mind?

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October 29, 2022        DARK  MATTER  -  versus the expanding universe?         3722                                                                                                                                   

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-----  Comments appreciated and Pass it on to whomever is interested. ---

---   Some reviews are at:  --------------     http://jdetrick.blogspot.com -----  

--  email feedback, corrections, request for copies or Index of all reviews 

---  to:  ------    jamesdetrick@comcast.net  ------  “Jim Detrick”  -----------

--------------------- ---  Sunday, October 30, 2022  ---------------------------

3724 - MARSQUAKES - how they analyze the planet?

  -  3724 -  MARSQUAKES  -   how they analyze the planet?   “Marsquakes” are earthquakes that occur on the planet Mars.  Astronomers can measure them just like we measure earthquakes from our orbiting satellites.  Astronomers have observed seismic waves propagating along the surface of Mars in the same way. 

---------------------  3724  -  MARSQUAKES  -   how they analyze the planet?

-  The “marsquakes” that resulted from two large meteorites that hit Mars were recorded by NASA's ‘InSight lander”.  These recordings provided new insights into the structure of the Martian crust, bringing scientists closer to learning how the planet formed and evolved over time.

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-    After almost three years of detecting only “body waves” which are seismic waves traveling through the body of a planet, on Mars.   The InSight observed surface waves in late December, 2021, when two meteorites collided with the red planet.

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-   Data from the Mars Reconnaissance Orbiter confirmed that both meteorites had hypocenters (the point of origin for a quake) on the surface of Mars.  Before this, all our knowledge of the Martian crust was based on what was right below the InSight lander.

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-   Scientists didn't know if the crust was different in other locations across the planet. With these surface waves, they were finally able to obtain a better understanding of the crust along a big stretch of Mars.

-

-  A planet's crust, or its outermost solid shell, provides important clues about how that planet formed and evolved over time. Most planetary crusts, including those of Earth and Mars, formed through early dynamic processes in the mantle and were later modified by other events such as volcanism, sedimentation, erosion and impact cratering. Crust analysis can allow researchers to gain a better understanding of the land-shaping conditions of a planet from billions of years ago.

-

-  They analyzed the velocity of surface waves coming from the two meteorite impacts. They could determine the relationship between surface wave velocity, frequency and depth to estimate the average properties of the crust 3 to 18.6 miles below the surface.

-

-  On average, the two meteorite impact sites did not vary strongly with depth and had faster seismic velocity than what was previously observed directly below the lander. The faster velocities suggest either compositional differences or reduced porosity in areas traversed by the surface waves.

-

-  The composition of the crust will determine some of the density, but so will factors like porosity; if you have a lot of holes in the crust, it can also decrease the density of the material.

-

-  A volcano, with all its intrusions and magma coming up through the crust beneath it, would have also altered the crust density and composition in that region.  Mars has a very unique feature, which is the very sharp contrast between its Northern and Southern hemispheres. 

-

-  The southern part is really old, has high topography and is very heavily cratered. Meanwhile, the northern region is volcanic, very low-lying and has comparatively few craters. 

-

-  Researchers have been analyzing the measurements made by the NASA InSight mission's seismometer.  The Mars Reconnaissance Orbiter in late December 2021 showed a large impact crater about 3,500 kilometers from InSight.   They were also able to pinpoint a meteorite impact at just under 5,000 miles from InSight as the source of a second atypical quake.

-

-  Because the hypocenter of each earthquake was at the surface, they generated not only seismic body waves similar to previously recorded marsquakes in which the hypocenters were at greater depth, but also waves that propagated along the planet's surface. 

-

-  What makes the seismic surface waves so important to researchers is that they provide information about the structure of the Martian crust. Seismic body waves, which travel through the planet's interior during a quake, have provided insights into Mars's core and mantle, but have revealed little about the crust away from the lander itself.

-

-    On average, the Martian crust between the impact sites and InSight's seismometer has a very uniform structure and high density. Directly below the lander they detected three layers of crust that implied a lower density.

-

-  The new findings are remarkable because a planet's crust provides important clues about how that planet formed and evolved. Since the crust itself is the result of early dynamic processes in the mantle and subsequent magmatic processes, it can tell about conditions billions of years ago and the timeline of impacts, which were particularly common in Mars' early days.

-

-   The speed at which surface waves propagate depends on their frequency, which in turn depends on their depth.  By measuring changes in velocity in the seismic data across different frequencies, it is possible to infer how the velocity changes at different depths, because each frequency is sensitive to different depths. 

-

-  This provides the basis for estimating the average density of the rock.  The seismic velocity also depends on the elastic properties of the material through which the waves travel. This data allowed the researchers to determine the structure of the crust at depths of between roughly 5 and 30 kilometers below the surface of Mars.

-

-    Why then was the average speed of the surface waves recently observed considerably higher than would be expected based on the earlier point measurement under the Mars InSight lander? Is this mainly due to the surface rock, or are other mechanisms in play? 

-

-    Volcanic rocks tend to exhibit higher seismic velocities than sedimentary rocks. Also, the paths between the two meteorite impacts and the measurement site pass through one of the largest volcanic regions in Mars' northern hemisphere.

-

-  Lava flows and the closure of pore spaces from heat created by volcanic processes, can increase the velocity of seismic waves.   The crustal structure beneath InSight's landing site may have been formed in a unique way, perhaps when material was ejected during a large meteoritic impact more than three billion years ago. That would mean the structure of the crust under the lander is probably not representative of the general structure of the Martian crust.

-

-  Ever since the first telescopes were pointed at Mars, it has been known that a sharp contrast exists between the planet's southern and northern hemispheres. While the dominant feature of the southern hemisphere is a plateau covered by meteorite craters, the northern hemisphere consists mostly of flat, volcanic lowlands that may have been covered by oceans in the planet's early history. This division into southern highlands and northern lowlands is called the “Mars dichotomy“.

-

-   The initial results appear to disprove one of the widespread theories for the Mars dichotomy: the crusts in the north and in the south are probably not composed of different materials, as has often been assumed, and their structure may be surprisingly similar at relevant depths.

-

-   In May,  2022, InSight observed the largest marsquake to date, with a magnitude of 5.0 It also recorded seismic surface waves generated by this shallow event. This happened just in time, since the InSight mission will soon be coming to an end now that the lander's solar panels are covered in dust, and it is running out of power.   An initial analysis of the data confirms findings that the researchers obtained from the other two meteorite impacts.

-

-  Astronomers had been waiting for so long for these waves, and now, just months after the meteorite impacts, they observed this big quake that produced extremely rich surface waves. These allow us to see even deeper into the crust, to a depth of about 90 kilometers.

-

October 29, 2022          MARSQUAKES  -   how they analyze the planet?             3722                                                                                                                                   

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--------------------- ---  Sunday, October 30, 2022  ---------------------------

3721 - GRAVITY - how fast does it travel?

  -  3721 -   GRAVITY  -  how fast does it travel?    If the Sun were to disappear in an instant, how long would Earth’s orbit continue before we sped off in a straight line?   With that in mind, a fascinating question to ponder is whether gravity has a speed. It turns out that it does, and scientists have precisely measured it.

---------------------  3721  -  GRAVITY  -  how fast does it travel?  

-  The answer is about 8 minutes before the Earth felt the los of the Sun’s gravity.

-

-   Suppose at this very instant, somehow the Sun was made to disappear not just go dark, but vanish entirely. We know that light travels at a fixed speed,  300,000 kilometers per second, or 186,000 miles per second.  

-

-  From the known distance between the Earth and the Sun, 150 million kilometers, or 93 million miles, we can calculate how long it would take before we here on Earth would know the Sun had disappeared. It would take about eight minutes and 20 seconds before the noon sky would go dark.

-

-   If the sun disappeared, it would not only stop emitting light, but also stop exerting the gravity that holds the planets in orbit  If gravity is infinitely fast, gravity would also disappear as soon as the Sun poofed into nonexistence. We’d still see the Sun for a little over eight minutes, but the Earth would already start wandering off, heading for interstellar space. 

-

-  On the other hand, if gravity traveled at the speed of light, our planet would continue to orbit the Sun as usual for eight minutes and 20 seconds, after which it would stop following its familiar path.

-

-  What is the speed of gravity?  Different answers have been proposed throughout scientific history. Sir Isaac Newton, who invented the first sophisticated theory of gravity, believed the speed of gravity was infinite. He would have predicted that the Earth’s path through space would change before Earth-bound humans noticed that the Sun was gone.

-

-  On the other hand, Albert Einstein believed that gravity traveled at the speed of light.  He would have predicted that humans would simultaneously notice the disappearance of the Sun and the change of Earth’s path through the cosmos. He built this assumption into his theory of general relativity, which is currently the best accepted theory of gravity, and it very precisely predicts the path of the planets around the Sun.

-

-   Einstein’s theory of gravity made several testable predictions. The most important one is that he realized that the familiar gravity we experience can be explained as a distortion of the fabric of space: the greater the distortion space and time, the higher the gravity.

-

-   This idea has significant consequences. It suggests that space is malleable.  Space compresses and relaxes similar to how air transmits sound waves. These spatial distortions are called “gravitational waves” and they will travel at the speed of gravity. 

-

-   If we can detect gravitational waves, we can measure the speed of gravity. But distorting space in ways that scientists can measure is quite difficult and well beyond current technology. Luckily, nature has helped us out.

-

-   In space, planets orbit stars. But sometimes stars orbit other stars. Some of those stars were once massive and have lived their lives and died, leaving a blackhole, the corpse of a dead, massive star. If two such stars have died, then you can have two black holes orbiting one another. 

-

-  As they orbit, they emit tiny amounts of gravitational radiation, which makes them lose energy and draw closer to one another. Eventually, the two black holes get close enough that they merge. This violent process releases enormous amounts of gravitational waves. 

-

-  For the fraction of a second that the two black holes come together, the merging releases more energy in gravitational waves than all of the light emitted by all of the stars in the visible Universe during the same time.

-

-  While gravitational radiation was predicted back in 1916, it took scientists nearly a century to develop the technology to detect it. To detect these distortions, scientists take two tubes, each about 2.5 miles long, and orient them at 90 degrees, so they form an “L.” They then use a combination of mirrors and lasers to measure the length of both of the legs. Gravitational radiation will change the length of the two tubes differently, and if they see the right pattern of changes of length, they have observed gravitational waves.

-

-  The first observation of gravitational waves occurred in 2015, when two black holes located more than 1 billion light years away from Earth merged. While this was a very exciting moment in astronomy, it didn’t answer the question of the speed of gravity. For that, a different observation was needed.

-

-  Although gravitational waves are emitted when two black holes collide, that’s not the only possible cause. Gravitational waves are also emitted when two neutron stars slam together. Neutron stars are also burned-out stars, similar to black holes, but slightly lighter.

-

-   When neutron stars collide, not only do they emit gravitational radiation, they also emit a powerful burst of light that can be seen across the Universe.  To determine the speed of gravity, scientists needed to see the merging of two neutron stars.  In 2017, astronomers got their chance. They detected a gravitational wave and a little over two seconds later, orbital observatories detected gamma radiation, which is a form of light, from the same location in space originating in a galaxy located 130 million light years away. 

-

-  The merging of two neutron stars emits both light and gravitational waves at the same time, so if gravity and light have the same speed, they should be detected on Earth at the same time. Given the distance of the galaxy that housed these two neutron stars, we know that the two types of waves had traveled for about 130,000,000 lightyears and arrived within two seconds of one another.  

-

-  So, gravity and light travel at the same speed, determined by a precise measurement. It validates Einstein once again, and it hints at something profound about the nature of space. Scientists hope one day to fully understand why these two very different phenomena have identical speeds.  I am at a loss to explain it.  

-

October 27, 2022         GRAVITY  -  how fast does it travel?                3721                                                                                                                                   

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--------------------- ---  Friday, October 28, 2022  ---------------------------

3720 - BLACKHOLES - how they create gravity waves?

  -  3720 -  -   BLACKHOLES  -  how they create gravity waves? Countless gravitational wave events have been detected by observatories across the globe.  They have become an almost daily occurrence. This has allowed astronomers to gain insight into some of the most extreme objects in the Universe.

----------------  3720  -   BLACKHOLES  -  how they create gravity waves?

-  Shortly before black holes collide they tangle spacetime up into knots.  In February, 2016, scientists at the “Laser Interferometer Gravitational-Wave Observatory” (LIGO) announced the first-ever detection of gravitational waves (GWs). Originally predicted by Einstein’s Theory of General Relativity, these waves are ripples in spacetime that occur whenever massive objects like when black holes and neutron stars merge. 

-

-  Researchers observed a binary black hole system originally detected in 2020 by the “Advanced LIGO, Virgo, and Kamioki Gravitational Wave Observatory (KAGRA)”. In the process, they noticed a peculiar twisting motion ( a precession) in the orbits of the two colliding black holes that was 10 billion times faster than what was noted with other precessing objects. This is the first time a precession has been observed with binary black holes, which confirms yet another phenomenon predicted by General Relativity .

-

-  Binary black holes are considered a prime candidate for researching gravitational waves since astronomers expect some will consist of precessing binaries. In this scenario, black holes will circle each other in ever-tightening orbits, generating an increasingly strong gravity wave signal until they merge. 

-

-  However, no definitive evidence of orbital precession has been observed from the 84 Binary Black Hole systems detected by Advanced LIGO and Virgo so far. 

-

-  However, the team noticed something different when examining the “GW200129” event detected by LIGO–Virgo–KAGRA collaboration during its third operational run.  One of the black holes in this system (40 solar masses) is considered the fastest-spinning black hole ever detected through gravitational waves. 

-

-  Unlike all previous observations of binary black holes, the system’s rapid rotation has such a profound effect on spacetime that the entire system wobbles back and forth. This form of precession is known as “Frame Dragging” (the “Lense–Thirring effect“), an interpretation of General Relativity where gravitational forces are so strong that they “drag” the very fabric of spacetime with them.

-

-  This same phenomenon is seen when observing Mercury’s orbit, which periodically precesses as it orbits the Sun. In short, Mercury’s path around the Sun is highly eccentric, and the closest point in its orbit (perihelion) also moves over time, rotating about the Sun like a spinning top. 

-

-  These observations are one of the ways General Relativity was tested and confirmed after Einstein formalized it in 1916.  Precession in general relativity is usually such a weak effect that it is almost imperceptible.  It’s a very tricky effect to identify. Gravitational waves are extremely weak and to detect them requires the most sensitive measurement apparatus in history. The precession is an even weaker effect buried inside the already weak signal.

-

-  Previously, the fastest-known example was a binary pulsar that took over 75 years for the orbit to process. In this case, the Binary Black Hole known as GW200129 observed on January 29th, 2020, processes several times a second, an effect 10 billion times as strong as the binary pulsar. 

-

-   Most black holes astronomers have found with gravitational waves have been spinning fairly slowly. The larger black hole in this binary, which was about 40 times more massive than the Sun, was spinning almost as fast as physically possible. Our current models of how binaries form suggest this one was extremely rare, maybe a one-in-a-thousand event. 

-

-  Before black holes merge with the most extreme gravitational event astronomers have ever observed  Binary Black Holes can experience an orbital precession. It is also the latest in a long line of examples that demonstrate how Gravity Wave astronomy allows astronomers to probe the laws of physics under the most extreme conditions imaginable. 

-

-  With a network consisting of Advanced LIGO, Virgo, and KAGRA detectors in the US, Europe, and Japan, it is also one of the most vibrant fields of astronomical research.  This network is currently being upgraded to enhance its sensitivity to Gravity Wave events and will commence its fourth round of observations  in 2023.

-

-   When this happens, it is hoped that several hundred black hole collisions will be detected and added to the Gravity Wave catalog. This will allow astronomers to gain greater insight into the most extreme gravitational phenomenon in the Universe and let them know if GW200129 was an outlier or if such extreme events are a common occurrence.

-

October 27, 2022        BLACKHOLES  -  how they create gravity waves?        3720                                                                                                                                   

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--------------------- ---  Friday, October 28, 2022  ---------------------------

3719 - PILLARS OF CREATION - Organic molecules in space?

  -  3719 -   PILLARS  OF  CREATION  - Organic molecules in space?  For Webb, the Pillars are still just the beginning, providing only a glimpse of what the $10 billion telescope can accomplish.  Everybody in the astronomical community is very excited about what the future holds for Webb. 

---------  3719 -   PILLARS  OF  CREATION  - Organic molecules in space?

-  The James Webb Telescope sees organic molecules in the hearts of galaxies.  When the Webb Telescope (JWST) launched, one of its jobs was studying galactic formation and evolution.  Around the Universe galaxies take the shape of grand spirals like the Whirlpool galaxy and giant ellipticals like M60. But galaxies didn’t always look like this.

-

-  We don’t see these shapes when we look at the most distant and most ancient galaxies. Early galaxies are lumpy and misshapen and lack the structure of modern galaxies.

-

-  The molecules are “polycyclic aromatic hydrocarbons” (PAHs). They’re important building blocks for prebiotic compounds. Those compounds may have played a role in the early formation of life.

-

-   They are not only attractive to scientists because of their connection to life. When PAHs are illuminated with optical and UV radiation from stars, they get excited and are very bright in infrared emission bands. So observing them tells astronomers a lot about conditions inside the galaxy.

-

-  The JWST’s Mid-Infrared Instrument (MIRI) is tuned to observe in the 5 to 28-micron range of the electromagnetic spectrum and can provide wide-field imaging. It can also perform medium-resolution spectroscopy.

-

-   The structural evolution of galaxies is dependent on so many other properties of a galaxy, like star formation, stellar mass, and metallicity.   Throughout the lifetime of a galaxy, it will undergo multiple processes that alter its structure and morphology. These include the formation of galactic bulges and disks, and the end of active star formation. They also include gas inflow, which drives the formation of spiral arms. The main event that drives galaxy evolution is probably mergers with other galaxies.

-

-  Since PAHs are widespread in space in different environments and objects, their ubiquitous nature makes them valuable to scientists because they can compare how different PAHs behave in different places and understand more about the environments they’re in. 

-

-   Because PAHs get excited by stars and become luminous in infrared, astronomers use them to trace activity inside galaxies. They are excellent tracers for star formation in star-forming galaxies. They also trace activity in active galactic nuclei (AGN,) the luminous regions at the center of galaxies where the luminosity doesn’t come from stars. 

-

-  Theory predicts how PAHs should behave. Previous research predicted that PAHs couldn’t survive near the centers of galaxies with active black holes. They should be destroyed in that environment, where energetic photons can shred them.

-

-  But, thanks to the power of the JWST we now know that’s not true. The researchers think the PAHs can survive near the black holes because there might be a large amount of molecular gas near the galactic nucleus.

-

-  Supermassive black holes (SMBH) are enormous strange and powerful objects that literally warp space time. They also emit powerful radiation, sometimes as high energy photons in x-ray and gamma-ray wavebands. So even though PAHs can survive near black hoes, they don’t all survive. Smaller molecules and charged molecules were destroyed in this environment, but larger and more neutral molecules did survive. 

-

-   It is incredible to think that we can observe PAH molecules in the nuclear region of a galaxy and the next step is to analyze a larger sample of active galaxies with different properties. This will enable us to better understand how PAH molecules survive and which are their specific properties in the nuclear region. 

-

-   Floral formations of newborn stars areonly a few hundred thousand years old, the creation inside the “Pillars of Creation“. For Webb's predecessor, the Hubble Telescope, which observes the universe mostly in visible light these pillars were impenetrable, menacing dark formations rising from the Eagle Nebula, a cloudy cluster of stars in the constellation Serpens less than 6,000 light-years away from Earth. But Webb, with its infrared, heat-detecting gaze, peered through the darkness to reveal how light in the universe is being born. 

-

-  Webb's images are providing a unique window into the dark and freezing clouds where stellar embryos are being incubated from a hydrogen-rich dust.  Webb's images will advance our understanding of how stars form and where our own sun came from.

-

-  The red dots visible in Webb's images are protostars, cocoons of dust and gas so dense that they are collapsing together under the weight of their own gravity. As the clouds collapse, they form rotating balls, which will eventually become so dense that the hydrogen atoms in their cores will begin to fuse together in the process of nuclear fusion, which makes stars shine. 

-

-  The protostars that Webb sees are not fully there yet, only beginning to glow in the infrared light as they warm above the coldness of the surrounding cloud, which is no warmer than minus 390 degrees Fahrenheit.

-

-  These young stars that we see are not yet burning hydrogen, but gradually, as more and more material falls in, the middle becomes denser and denser, and then suddenly, it becomes so dense that the hydrogen burning switches on, and then suddenly their temperature jumps up to 35 million degrees Fahrenheit.

-

-    The Pillars of Creation are one of the closest regions of active star formation to Earth.  The site provides the best opportunity to study star-forming processes. 

-

-   The image was taken by NIRCam in six different filters, showing the Pillars in different colors than they would appear to the human eye. The only wavelength in the image that the human eye would detect is that of the color red, which is represented as blue in the image.  The longest wavelengths in this image are six times longer than the human eye could see."

-

-  With each color, a different component of the physical processes taking place in the nebula appears. The bluish wisps of gas and dust that emanate like thin veils out of the nebula's edges are clouds of ionized hydrogen, electrons stripped from the colder atomic hydrogen forming the dark dense clouds by intense ultraviolet light streaming from nearby massive stars. 

-

-  Ionized hydrogen billowing out of the dense clouds of molecular dust that forms the Pillars of Creation.  With Webb's ability to reveal the structure of the dust cloud astronomers will also be able to study the processes that sculpted the towering clouds over millions of years. 

-

-  The material that the pillars are made of is what we call the “interstellar medium“, the medium between the stars.  It becomes more transparent as you go to longer infrared wavelengths. The Hubble images told us only where the material was, but Webb now shows us where it's thicker and where it's thinner. It's almost like making an X-ray of a human.

-

-  Astronomers know that the Pillars are not a stable cosmic sculpture but rather a constantly changing flow of material, similar to the constantly changing surface of a sandy beach. What shapes the pillars are powerful stellar winds emanating from a cluster of large stars.

-

-   Strong cosmic magnetic fields hold the clouds together, protecting them from being dispersed by the stellar winds. Still, within several million years, the Pillars will no longer resemble the iconic images that we see today. 

-

October 26, 2022       PILLARS  OF  CREATION  - Organic molecules in space?    3719                                                                                                                                    

----------------------------------------------------------------------------------------

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--------------------- ---  Thursday, October 27, 2022  ---------------------------

3718 - NATURAL DISASTERS - examples that make you think?

  -  3718 -   -   NATURAL  DISASTERS  -  examples that make you think?   Natural disasters are devastating events that have the potential to cause huge amounts of damage and loss of life. Globally, around 60,000 people die each year as a result of disasters such as droughts, floods, earthquakes and tsunamis, and a further 150 million people are impacted. 

------  3718  -   NATURAL  DISASTERS  -  examples that make you think?

-  Sometimes I am caught complaining about California fires and no rain, then too much rain,.  So I tried to take a look at the bigger scheme of things:

-

-  Over the past decade, global natural disasters have accounted for 0.1% of total deaths. The number of deaths from natural disasters has declined over the past century yet these events continue to cause significant amounts of loss and damage.

-

-  FOR EXAMPLE:

-

-  On September 8, 1900, a storm swept through Galveston, an island off the coast of Texas. At the time, Galveston was one of Texas's biggest port cities, but a hurricane with 140 mph winds swept it off the map. It's estimated that 3,600 houses and 600 businesses were reduced to rubble across 1,900 acres. 

-

-   The final death toll was estimated to be between 6,000 and 8,000 people, one-sixth of the island's population. 

-

-  Another example occurred in 2008.   A deadly 7.9-magnitude earthquake hit several regions of south-central China. It caused multiple landslides and building collapses that killed almost 70,000 people across Sichuan province. 

-

-  The landslides created at least 828 makeshift dams across rivers and streams in the region, which caused widespread flooding. The situation was exacerbated by heavy rainfall before military personnel removed these accidental dams. 

-

-  Between 2019 and 2020, Australia experienced some of the deadliest wildfires in recent history. The official death toll for the wildfires was 33.  A further 445 people died from conditions related to smoke inhalation from the wildfires, and 4,000 people were admitted to hospital. 

-

-  Between September 2019 and March 2020, 46 million acres of forests in southeast Australia were burnt.  The majority of wildfires are believed to have been ignited by lightning; however, according to research conducted by the University of Oxford, the risk of intense fire weather during the bushfire season in southeastern Australia has increased by 30% since 1900 as a result of climate change. 

-

-  On September 20, 2017, Puerto Rico was hit by the deadliest natural disaster in the last 100 years. Hurricane Maria had the highest average rainfall of all 129 storms that have hit Puerto Rico in the past 60 years.

- 

-  The hurricane dropped around 41 inches of rain onto the island, which caused devastating floods.  The total death toll caused by Hurricane Maria was more than 4,600. Hurricane Maria was also the third most costly tropical cyclone in the U.S., causing around $98 billion worth of damage. 

-

-  We go from hurricanes to volcanoes.   When the Mount Tambora volcano in Indonesia blew its top on April 10, 1815, it was the climax of the largest eruption in recorded history. It's estimated that 36 cubic miles of exploded rock blasted into the atmosphere and could be seen from as far as 808 miles away, according. 

-

-  The explosion expelled so much volcanic ash into Earth's atmosphere that it reduced  the amount of sunlight reaching Earth's surface. As a result, the temperature in the Northern Hemisphere at the time, fell by 1 degree Fahrenheit  and 1816 became known as "the year without a summer." 

-

-  The eruption caused 11,000 immediate deaths from pyroclastic flows (fast-moving solid lava, hot gas and ash), and a further 100,00 people died from food shortages over the preceding decade caused by the reduction in sunlight. 

-

-  In 1986, lethal clouds of carbon dioxide (CO2) bubbled up from the depths of Lake Nyos in northwest Cameroon and  caused the deaths of almost 1,800 people and 3,000 livestock.

-

-   Lake Nyos is sat on top of a magma chamber, which leaks CO2 into the water above. In 1986, a sudden eruption of 1.6 million tons of CO2 gas burst from the lake, in an event known as a limnic eruption. 

-

-  The gas cloud rolled down the surrounding hillsides and smothered neighboring villages. Eight hundred and forty-five people survived the event but were taken to hospital, 19% of whom were treated for lesions and bullae (blister-like protrusions on the skin) caused by the CO2. 

-

-  On May 31, 1970, a 7.9-magnitude earthquake caused one of Peru's deadliest landslides. The quake emanated around 22 miles from Mount Huascarán, Peru's highest mountain. The force of the earthquake caused massive landslides that buried surrounding towns, in particular Yungay and Ranrahirca. 

-

-  It's estimated that cascading mountain ice and rocks sped down Huascarán at around 100 mph, including a 772-ton  boulder that crashed into Ranrahirca. A total of 70,000 people lost their lives.

-

-  On October 8 ,2005, Kashmir in Pakistan was hit by a 7.6-magnitude earthquake. Landslides caused by the earthquake buried several towns and villages, including Balakot and Muzaffarabad. 

-

-  Around 90% of all buildings in Balakot were demolished by the quake. In total

 3 million homes were destroyed throughout Kashmir; more than 75,000 people were killed and a further 100,000 were injured. It's believed that the sudden and rapid release of seismic stress between the Indian and Eurasian tectonic plates was the cause of the earthquake. 

-

-  Ok, I’ll quit complaining about California’s fires and rain, and earthquakes.  In the bigger picture this is a cakewalk living adventure.

-

October 25, 2022     NATURAL  DISASTERS  -  examples that make you think?    3718                                                                                                                                    

----------------------------------------------------------------------------------------

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---  to:  ------    jamesdetrick@comcast.net  ------  “Jim Detrick”  -----------

--------------------- ---  Thursday, October 27, 2022  ---------------------------