Wednesday, May 29, 2024

- 4487 - JAMES WEBB - sees the first stars?

 

-   4487  -  JAMES  WEBB  -  sees the first stars?  -     Using the James Webb Space Telescope, University of Copenhagen researchers have become the first to see the formation of three of the earliest galaxies in the universe, more than 13 billion years ago.

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----------------------------  4487    -    JAMES  WEBB  -  sees the first stars?

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-   Researchers have witnessed the birth of three of the universe's absolute earliest galaxies, somewhere between 13.3 and 13.4 billion years ago.  Through the telescope, researchers were able to see signals from large amounts of gas that accumulate and accrete onto a mini-galaxy in the process of being built. While this is how galaxies are formed according to theories and computer simulations, it had never actually been witnessed.

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-    Whereas the James Webb has previously shown us early galaxies at later stages of evolution, here we witness their very birth, and thus, the construction of the first star systems in the universe

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-    The researchers estimate the birth of the three galaxies to have occurred roughly 400–600 million years after the Big Bang, the explosion that began it all. While that sounds like a long time, it corresponds to galaxies forming during the first 3–4% of the universe's 13.8-billion-year overall lifetime.

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-   Shortly after the Big Bang, the universe was an enormous opaque gas of hydrogen atoms, unlike today, where the night sky is speckled with a blanket of well-defined stars.  The birth of galaxies took place at a time in the history of the universe known as the “Epoch of Reionization”, when the energy and light of some of the first galaxies broke through the mists of hydrogen gas.

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-   It is precisely these large amounts of hydrogen gas that the researchers captured using the James Webb Space Telescope's infrared vision. This is the most distant measurement of the cold, neutral hydrogen gas, which is the building block of the stars and galaxies, discovered by scientific researchers to date.

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-     The research team has already applied for more observation time with the James Webb Space Telescope, with hopes of expanding upon their new result and learning more about the earliest epoch in the formation of galaxies.

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-    One of the most fundamental questions that we humans have always asked is 'Where do we come from?' Here, we piece together a bit more of the answer by shedding light on the moment that some of the universe's first structures were created.

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-   The first set of scientific data captured with the Euclid telescope, shows another exciting glimpse of the universe's distant past.  The telescope, launched in July 2023, is part of the Dark Energy Satellite Mission, which aims to map the dark universe.  The mission seeks to unlock mysteries of dark matter and dark energy, and reveal how and why the universe looks as it does today.

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-    Several new discoveries include:, free-floating new-born planets, newly identified extragalactic star clusters, new low-mass dwarf galaxies in a nearby galaxy cluster, the distribution of dark matter and intracluster light in galaxy clusters, and very distant bright galaxies from the first billion years of the universe.

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-    As the European Space Agency publishes the first findings from its Euclid space telescope, scientists from the University of Surrey are celebrating fresh insights from the data.   Studies show the gravity of the Milky Way pulls clusters of stars apart, creating streams of stars trailing across the galaxy.

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-     Euclid will completely revolutionize our view of the universe. Already these results are revealing important new findings about local galaxies, new unknown dwarf galaxies, extrasolar planets and some of the first galaxies. These results are only the tip of the iceberg in terms of what will come. Soon Euclid will discover yet unknown details of the dark energy and give a full picture of how galaxy formation occurred across all cosmic time.

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-   May we live in interesting times!  A total of 24 hours were allocated to target 17 specific astronomical objects, from nearby clouds of gas and dust to distant clusters of galaxies, producing stunning images that are invaluable for scientific research. In just a single day, Euclid produced a catalog of more than 11 million objects in visible light and five million more in infrared light.

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-   The most distant galaxies can only be discovered using the longer near-infrared wavelengths seen by Euclid.   What is amazing is that these images cover an area of less than 1% of the full deep observations, showing that we expect to detect thousands of early galaxies in the next few years with Euclid, which will be revolutionary in understanding how and when galaxies formed after the Big Bang.

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-    The images obtained by Euclid are at least four times sharper than those that can be taken from ground-based telescopes. They cover large patches of sky at unrivaled depth, looking far into the distant universe using both visible and infrared light.

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-     The Euclid Consortium includes more than 2,600 members, including over 1,000 researchers from more than 300 laboratories in 15 European countries, plus Canada, Japan and United States, covering various fields in astrophysics, cosmology, theoretical physics, and particle physics.

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-    The mission is ambitious and such complex fundamental science is at the very beginning of an exciting journey to map the structure of the universe.  

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May 28, 2024            JAMES  WEBB  -  sees the first stars?                  4487

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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”  -----------

--------------------- ---  Wednesday, May 29, 2024  ---------------------------------

 

 

 

 

 

           

 

 

486 - SUPERNOVAE 1987A - what are the string of pearls?

-    4486  -   SUPERNOVAE  1987A  -  what are the string of pearls?  -      Astronomers finally have an explanation for the “String of Pearls” in Supernova 1987a.  Not long after the explosion of Supernova 1987a, astronomers were making predictions about how it might look in a few years.

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---------------  4486    -      SUPERNOVAE  1987A  -  what are the string of pearls?

-    Astronomers suggested a pulsar would show up soon and many said that the expanding gas cloud would encounter earlier material ejected from the star. The collision would light up the region around the event and sparkle like diamonds.

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-    Today, astronomers look at the site of the stellar catastrophe and see an expanding, glowing ring of light. Over the years, its shape has changed to a clumpy-looking string of pearls.

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-     What’s happening to affect its appearance? The answer lies in something called the “Crow Instability.”  We see this aerodynamical process when vortexes off the wingtips of airplanes interact with the contrails from their engines. The instability breaks up the contrail into a set of vortex “rings”.

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-   This type of instability could explain why Supernova 1987a formed a string of pearls.  The fascinating part about this is that the same mechanism that breaks up airplane wakes could be in play here.

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-    Light and neutrinos from Supernova 1987a reached Earth on February 23, 1987. The original star, “Sanduleak -69 202”, lay about 168,000 light-years away in the Large Magellanic Cloud. It exploded as Type II, the first one in modern times to show astronomers the details of a core-collapse supernova.

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-     Since then, astronomers watched as a ring of ejected material and a shockwave from the explosion itself spread to space. It slammed into the material shed earlier in the star’s life. It does have a neutron star in the center. Astronomers detected it in 2019 and observed it using   X-ray and gamma-ray observatories.

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-    Several months after the explosion, astronomers used the Hubble Space Telescope to image bright rings surrounding the explosion site. That material came from the stellar wind of the progenitor star. Ultraviolet light from the explosion ionized the gases in the cloud. The inner ring lay about 2/3 of a light-year from the original star.

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-    The expanding ejecta from the supernova eventually collided with it in 2001. That heated it further. The shockwave has now expanded beyond the rings, leaving behind pockets of warm dust and glowing clouds of gas. The turbulence of that shockwave and the damage it did to regions of the inner ring is created the “pearls”.

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-    Astronomers have tried to explain the string using something called a Rayleigh-Taylor instability. That occurs when two fluids (or plasmas) of different densities interact with each other. Think of oil and water trying to mix, or a heavy pyroclastic flow streaming out of a volcano. The interaction forms interesting and predictable shapes in the fluids.

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-      For 1978a, the denser “fluid” is the material ejected during the supernova explosion. It is colliding with a less dense cloud of material ejected earlier that has spread out to space.   A simulation shows the shape of the gas cloud on the left and the vortices, or regions of rapidly rotating flow. Each ring represents a later time in the evolution of the cloud. The gas cloud starts as an even ring with no rotation. It becomes a lumpy ring as the vortices develop. Eventually, the gas breaks up into distinct clumps.

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-    The “Rayleigh-Taylor instability” could tell you that there might be clumps, but it would be very difficult to pull a number out of it.  The “Crow Instability” shows jet contrails are a better comparison because the wingtip vortices break up the long smooth line of a jet contrail. The vortices flow into each other, leaving gaps that can be predicted.

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-    The top and bottom of the cloud got pushed out faster than the middle. That caused it to curl in on itself, triggering a Crow Instability that broke the cloud apart into 32 even clumps similar to the string of pearls at 1987a (which has 30-40 clumps). That predictable number of clumps is why the team suggested the Crow Instability as a formation agent for the string.

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-    Astronomers also think it could help predict the formation of more beaded rings around the explosion site or when dust around a star coalesces to form planets. Recent JWST infrared images seem to show even more clumps that have appeared in the ring, and it will be interesting to see if more of them appear in the future.

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May 22, 2024            SUPERNOVAE  1987A  -  what are the string of pearls?          4472

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

--------  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”  -----------

--------------------- ---  Wednesday, May 29, 2024  ---------------------------------

 

 

 

 

 

           

 

  

4485 - SUPERNOVAE - close to home?

 

-  4485   -   SUPERNOVAE  -    close to home?  -   Before exploding, this star puffed out a sun's worth of mass.  The tumultuous massive star, in the final year or so of its life, ejected large amounts of matter into space before going supernova.   The star exploded in the Pinwheel Galaxy in May, 2023.  It unexpectedly lost approximately one sun's worth of ejected mass during the final years of its life before going supernova.


-------------------------------------  4485    -    SUPERNOVAE  -    close to home?

-    On the night of May 19, 2023, Japanese amateur astronomer Kōichi Itagaki was conducting his regular supernova sweep using  telescopes based in three remote observatories dotted around the country. They were located in  Yamagata, Okayama and on the island of Shikoku.

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-    When Itagaki spotted the light of SN 2023ixf he immediately knew he'd found something special. That’s because this star had exploded in the nearby Pinwheel Galaxy (Messier 101), which is just 20 million light-years away in the constellation of Ursa Major, the Great Bear.

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-   Soon enough, amateur astronomers around the world started gazing at “SN 2023ixf” because the Pinwheel in general is a popular galaxy to observe. However, haste is  key when it comes to supernova observations: Astronomers are keen to understand exactly what is happening in the moments immediately after a star goes supernova. Yet all too often, a supernova is spotted several days after the explosion took place, so they don’t get to see its earliest stages.

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-    Considering how close, relatively speaking, SN 2023ixf was to us and how early it was identified, it was a prime candidate for close study.   Alerted to the supernova, astronomers immediately followed-up with several professional telescopes at their disposal including the 6.5-meter Multi Mirror Telescope (MMT) at the Fred Lawrence Whipple Observatory on Mount Hopkins in Arizona.

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-    They measured the supernova's light spectrum, and how that light changed over the coming days and weeks. When plotted on a graph, this kind of data forms a "light curve."  The spectrum from SN 2023ixf showed that it was a type II supernova.  This is a category of supernova explosion involving a star with more than eight times the mass of the sun.

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-    In the case of SN 2023ixf, searches in archival images of the Pinwheel suggested the exploded star  may have had a mass between 8 and 10 times that of our sun. The spectrum was also very red, indicating the presence of lots of dust near the supernova that absorbed bluer wavelengths but let redder wavelengths pass. This was all fairly typical, but what was especially extraordinary was the shape of the light curve.

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-    Normally, a type II supernova experiences what astronomers call a 'shock breakout' very early in the supernova's evolution, as the blast wave expands outwards from the interior of the star and breaks through the star's surface. Yet a bump in the light curve from the usual flash of light stemming from this shock breakout was missing. It  didn’t turn up for several days. Was this a supernova in slow motion, or was something else afoot?

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-    The delayed shock breakout is direct evidence for the presence of dense material from recent mass loss.  A significant and unexpected amount of mass loss, close to the mass of the sun, occured in the final year prior to explosion.

 

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-   An unstable star puffing off huge amounts of material from its surface creates a dusty cloud of ejected stellar material all around the doomed star. The supernova shock wave therefore not only has to break out through the star, blowing it apart, but also has to pass through all this ejected material before it becomes visible.

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-    Massive stars often shed mass.  Betelgeuse’ over late 2019 and early 2020,  belched out a cloud of matter with ten times the mass of Earth’s moon that blocked some of Betelgeuse’s light, causing it to appear dim.

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-    However, Betelgeuse isn’t ready to go supernova just yet, and by the time it does, the ejected cloud will have moved far enough away from the star for the shock breakout to be immediately visible. In the case of “SN 2023ixf”, the ejected material was still very close to the star, meaning that it had only recently been ejected, and astronomers were not expecting that.

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-   Astronomers were able to observe SN 2023ixf with the Submillimeter Array on Mauna Kea in Hawaii, which sees the universe at long wavelengths. They were able to see the collision between the supernova shockwave and the circumstellar cloud.

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-    The only way to understand how massive stars behave in the final years of their lives up to the point of explosion is to discover supernovae when they are very young, and preferably nearby, and then to study them across multiple wavelengths.  Using both optical and millimeter telescopes we effectively turned SN 2023ixf into a time machine to reconstruct what its progenitor star was doing up to the moment of its death.

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-    Astronomers think of an evolved massive star as being like an onion, with different layers. Each layer is made from a different element, produced by sequential nuclear burning in the star's respective layers as the stellar object ages and its core contracts and grows hotter.

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-    The outermost layer is hydrogen, then you get to helium. Then, you go through carbon, oxygen, neon and magnesium in succession until you reach all the way to silicon in the core. That silicon is able to undergo nuclear fusion reactions to form iron, and this is where nuclear fusion in a massive star’s core stops.  Iron requires more energy to be put into the reaction than comes out of it, which is not efficient for the star.

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-   Thus the core switches off, the star collapses onto it and then rebounds and explodes outwards.

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-   One possibility is that the final stages of burning high-mass elements inside the star, such as silicon (which is used up in the space of about a day), is disruptive, causing pulses of energy that shudder through the star and lift material off its surface. 

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May 28, 2024          SUPERNOVAE  -    close to home?                    4485

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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”  -----------

--------------------- ---  Wednesday, May 29, 2024  ---------------------------------

 

 

 

 

 

           

 

 

Monday, May 27, 2024

4484 - EARTH'S MAGNETIC FIELD - what caused it?

 

-  4484   -   EARTH'S  MAGNETIC  FIELD  -  what caused it?  -    The image of an atom, with electrons swarming around a central nucleus bulging with protons and neutrons, is as iconic in our perception of science.   Exploring the fundamental forces that govern our world, posing questions along the way that seek to explain how the delicate balance of positive and negative charges paved the way for gravity to shape our universe.



---------------  4484    -    EARTH'S  MAGNETIC  FIELD  -  what caused it?

-     Magnetism is a manifestation of electricity, and vice versa. Electricity and magnetism were imprinted into our surroundings from the beginning. Five billion years ago when the new-born Earth was a hot plasma of swirling electrical currents, these flows created magnetic fields. As the magma cooled to form what is today the world's solid outer crust, magnetism was locked into minerals containing iron, such as magnetite.

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-   Today, the Earth's liquid core is still a frenzy of electric currents, which generate a magnetic field. This extends into the atmosphere and far beyond, invisible to our normal senses.    It first permeates the Earth's crust. This is where it leaves a tangible imprint, evidence that there exists a force more powerful than gravity at work within the Earth whose influence extends very far.

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-    Way back in the earliest “Precambrian”, four billion years ago, as the surface cooled, atomic elements accumulated in the strata. The most stable of these, iron, is today one of the most abundant elements in the crust.

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-     Igneous rocks formed from volcanic lava. These rocks have the property that in the presence of a magnetic field, their atoms of iron act like soldiers on parade as they themselves become magnetic. This is exploited in popular demonstrations where the magnetic field of a bar magnet can be made visible.  A magnet surrounded by iron filings

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-    A bar magnet induces magnetism in pieces of iron, revealing the presence of its magnetic field spreading from one pole to the other. Small filings of iron are first scattered on the surface of a table and then a magnet is placed carefully among them. Its magnetic field induces magnetism in the iron filings, turning them into thousands of miniature magnets. Each of these duly orients itself in the magnetic field, revealing how the direction of the magnetic force varies from place to place.

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-    Why do magnets have north and south poles?  The bar magnet is a simple model illustrating what happens for the magnetic Earth itself. Earth's north and south magnetic poles are analogous to those of the bar magnet, our planet's magnetic field extending far into space.

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-    There are no iron filings out in space, but there are large amounts of iron ores in the hills, cliffs, and mountains on Earth. In some places, by chance, these magnetic clusters are quite extensive, as on the Isle of Elba and Mount Ida in Asia Minor, where large outcrops retain the magnetic imprint in rocks known historically as “lodestone”, now named “magnetite”.

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-   There are legends how thousands of years ago in ancient Greece, a shepherd wearing leather shoes held in place by iron nails stumbled across magnetite when the powerful magnetism gripped the nails in his footwear. Whether or not a shepherd named Magnes discovered the eponymous rock, and if so whether it was in Magnesia, north of Athens, or on Mount Ida in Asia Minor, or even another Mount Ida in Crete, it is very likely had such experiences.

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-     Certainly, the power of magnetism would have been apparent ever since the Iron Age. Lightning is a flash of electric current which generates intense magnetic fields and magnetizes ferrous rocks. Smelting to retrieve the pure iron metal from these sources would have revealed their magnetic attraction.

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-     So, the phenomenon has probably been known for some 3,000 years. Like the discovery of fire, that of magnetism probably arose in several places independently, all inspired by the natural magnetization of iron in rocks.

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-   For magnetic rocks are ubiquitous. By the sixteenth century travelers recorded the best examples, from East India and the Chinese coast:   Very massive and weighty, the stone will draw or lift up the just weight of itself in iron or steel.

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May 27, 2024      EARTH'S  MAGNETIC  FIELD  -  what caused it?           4484

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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, May 27, 2024  ---------------------------------

 

 

 

 

 

           

 

 

Sunday, May 26, 2024

4483 - PLANETS - 8 or is it now 5,000?

 

-  4483   -    PLANETS  -   8 or is it now 5,000?  -    The hunt for new exoplanets continues. On May 23rd, 2024,  scientists published the NASA TESS-Keck Catalog, an effort to publicly release over 9,000 radial velocity measurements collected by NASA’s space-based Transiting Exoplanet Survey Satellite (TESS).


----------------------------------------  4483    -    PLANETS  -   8 or is it now 5,000?

-      An accompanying analysis of these 9,000 suspected planets validated 32 new planetary candidates and found the masses of 126 confirmed planets and candidates with a wide range of masses and orbits.

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-    Radial velocity (RV) measurements are a backbone of exoplanet hunting. Telescopes collect data on how a star “wobbles” by checking for a red-shift (if it’s moving toward the Earth) or blue-shift (if it’s moving away) based on the gravitational pull of an exoplanet orbiting it. If the data presents a repeating pattern, the scientists know they have a likely exoplanet candidate.

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-    To calculate the planet’s rotational period, scientists use the frequency of the changes in light from the star. They can estimate a planet’s orbital period based on how quickly the star cycles through the red and blue shifts they would expect from a complete planetary orbit. Unfortunately, since telescope time is limited, most of the exoplanets found so far using this method have much shorter orbital periods than the Earth.

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-    Calculating a planet’s mass is also possible using the RV method by simply calculating the planet’s gravitational pull as it is either directly behind or in front of the star. The magnitude of the respective red or blue shift can be directly tied to the planet’s mass, causing the gravitational pull.

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-    A “sub-Neptune” is a category of planet that is a gas giant slightly smaller than Neptune, the smallest gas giant in our solar system. A planet known as TOI-1824 falls into this category but has a unique weight.  It is 19 times as massive as Earth despite being only about 2.6 times its size. That is an extremely dense planet and well outside of the range of other typical sub-Neptunes, which typically vary between 6 and 12 times the mass of our own planet.

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-     A planet in the dataset that is closer in size to our own is TOI-1798c. From the mass perspective, it’s about the same size as Earth. However, it is so close to its parent’s star that it orbits it every 12 hours. This puts it in the category of an “Ultra-short period” (USP) orbit. -

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-     Typically, these planets are tidally locked to their star and blasted with massive amounts of radiation. Estimates put the solar radiation it receives from its host star at 3,000 times that received by the Earth.

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-    Doubtless, other exoplanets are hiding in the trove of data release.   As humanity begins to collect more and more discovered exoplanets, more strange and exciting new worlds will be found. It’s a crazy galaxy out there, and we’re only just starting to explore it.

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May 22, 2024          PLANETS  -   8 or is it now 5,000?                    4472

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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, May 26, 2024  ---------------------------------

 

 

 

 

 

           

 

 

4482 - FREE FLOATING PLANETS - how many are there?

 

-  4482   -    FREE  FLOATING  PLANETS  -   how many are there?  -   Over 5,000 planets have been found orbiting other star systems. One of the satellites hunting for them is “TESS,” the “Transiting Exoplanet Survey Satellite”. Astronomers using TESS think they are made a  surprising discovery; their first free-floating, or rogue, planet.


-------------------------------  4482    -     FREE  FLOATING  PLANETS  -   how many are there?

-    The rogue planet was discovered using “gravitational microlensing” where the planet passed in front of a star, distorting its light and revealing its presence.

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-   We are all familiar with the eight planets in our solar system and perhaps becoming familiar with the concept of exoplanets. But there is another category of planet, the “rogue planets”. These mysterious objects travel through space without being gravitationally bound to any star. Their origin has been cause for much debate but popular theory suggests they were ejected from their host star system during formation, or perhaps later due to gravitational interaction.

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-    Simulations have suggested that these 'free-floating planets' or “FFPs” should be abundant in the galaxy yet until now, not many have been detected. The popular theory of ejection from star systems may not be the full story though.

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-    It is now thought that different formation mechanisms will be responsible for different FFP masses. Those FFPs that are high mass may form in isolation from the collapse of gas while those at the low mass end (comparable to Earth) are likely to have been subjected to gravitational ejection from the system.

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-   Detecting such wandering objects among the stars is rather more of a challenge than you might expect. Their limited emission (or reflection) of electromagnetic radiation makes them pretty much impossible to observe. Enter gravitational microlensing, a technique that relies upon an FFP passing in front of a star, it's gravity then focusing light from the distant star resulting in a brief brightness change as the planet moves along its line of sight. To date, only three FFPs have been detected from Earth using this technique.

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-   A team of astronomers have been using TESS to search for such microlensing events. TESS was launched in April 2018 and while in orbit, scans large chunks of sky to monitor the brightness of tens of thousands of stars. The detection of light changes may reveal the passage of an FFP as it drifts silently in front of the star. It's not an easy hunt though as asteroids in our solar system, exoplanets bound to stars and even stellar flares can all give false indications.

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-     One FFP candidate event associated with the star “”TIC-107150013”  is 3.2 parsec away.

The event lasted 0.074 days +/- 0,002 and revealed a light curve with features expected of a FFP. This marks the first FFP discovered by TESS, an exciting step along the way to start to unravel the mysteries surrounding these strange alien worlds.

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-    There's a population of planets that drifts through space untethered to any stars. Some of these FFPs form as loners, never having enjoyed the company of a star. But most are ejected from solar systems somehow, and there are different ways that can happen.

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-     FFPs are mysterious because they're extremely difficult to detect. But astronomers are getting better at it and are getting better tools for the task. In 2021, astronomers made a determined effort to detect them in Upper Scorpius and Ophiuchus and detected 70 of them, possibly many more.

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-    In broad terms, there are two ways FFPs can form. They can form like most planets do, in protoplanetary disks around young stars. These planets form by accretion of dust and gas. Or they can form like stars do by collapsing in a cloud of gas and dust unrelated to a star.

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-    For planets that form around stars and are eventually kicked out, there are different ejection mechanisms. They can be ejected by interactions with their stars in a binary star system, they can be ejected by a stellar flyby, or they can be ejected by planet-planet scattering.

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-   The locations of 115 potential rogue planets were recently discovered in 2021 by a team of astronomers in a region of the sky occupied by Upper Scorpius and Ophiucus. The exact number of rogue planets found by the team is between 70 and 170, depending on the age assumed for the study region.

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-   Simulations have found that circumbinary systems produce FFPs efficiently. In these simulations, each binary system ejects an average of between two to seven planets with greater than 1 Earth mass. For giant planets greater than 100 Earth masses, the number of ejected planets drops to 0.6 planets ejected per system.

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-    The simulations also showed that most planets are ejected from their circumbinary disks between 0.4 to 4 million years after the beginning of the simulation. At this age, the circumbinary disk hasn't been dissipated and blown away.

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-   The most important result might concern the velocity dispersions of FFPs.  As the planets are ejected from the systems, they retain significant excess velocities, between 8–16 km/s. This is much larger than observed velocity dispersions of stars in local star-forming regions. So this means that the velocity dispersions of FFPs can be used to tell ejected ones from ones that formed as loners.

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-    The velocity dispersions provide another window into the FFP population.   Simulations show that the velocity dispersion of FFPs ejected through interactions with binary stars is about three times larger than the dispersion from planets ejected by planet-planet scattering.

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-    They also found that the level of turbulence in the disk affects planet ejection. The weaker the turbulence is, the more planets are ejected. Turbulence also affects the mass of ejected planets: weaker turbulence ejects less massive planets, where about 96% of ejected planets are less than 100 Earth masses.

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-    We still don't have a strong idea of how many FFPs there are. Some researchers think there could be trillions of them. The upcoming Nancy Grace Roman space telescope will use gravitational lensing to take a census of exoplanets, including a sample of FFPs with masses as small as Mars'.

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-    In future work astronomers intend to determine if there are chemical composition differences between FFPs. That would constrain the types of stars they form around and where in their protoplanetary disks they formed. That would require spectroscopic studies of FFPs.

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-    Astronomers can begin to discern where individual FFPs came from and better understand the population at large.

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May 26, 2024             FREE  FLOATING  PLANETS  -   how many are there?          4482

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

--------  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, May 26, 2024  ---------------------------------

 

 

 

 

 

           

 

 

Saturday, May 25, 2024

4480 - DAYTIME TELESCOPES - really?

 

-  4480   -    DAYTIME  TELESCOPES  -  really?  -    Stargazing in broad daylight using a multi-lens telescope will change how we do astronomy?   Astronomers at Macquarie University have pioneered a new technique for observing celestial objects during the day, potentially allowing around-the-clock astronomy.


---------------------------------------  4480    -    DAYTIME  TELESCOPES  -  really?

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-   Astronomers are using the University's “Huntsman Telescope” which is a unique array of 10 camera lenses working in parallel, originally designed for ultra-sensitive night sky observations. Huntsman has the ability to accurately measure stars, satellites and other targets when the sun is high overhead, despite astronomers traditionally only observing at night.

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-    People have tried observing stars and satellites in optical wavelengths during the day for centuries, but it has been very difficult to do. Our tests show the Huntsman can achieve remarkable results in daylight hours.

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-   The telescope combines an astronomy camera and astro-mechanical focusing equipment with an array of 10 highly sensitive 400mm Canon lenses, oriented to cover the same patch of sky.

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-   Because the sun floods out most light from other celestial objects, astronomers rarely observe during the day, but special "broadband" filters on a test version of the Huntsman telescope to block most daylight while still allowing specific wavelengths from celestial objects to pass through.

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-    The Huntsman's daytime capability allows continual monitoring of certain bright stars that can be unobservable at night for months at a time because they are too close to the sun. One example is the red supergiant Betelgeuse, a nearby star around 650 light-years away in the Orion constellation in our Milky Way galaxy.

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-    Betelgeuse is of great interest to astronomers since the star dimmed substantially from late 2019 through 2020, likely due to a major ejection of gas and dust.  Without this daytime mode, we'd have no idea if one of the brightest stars in the sky has gone supernova until a few months after its explosive light reached Earth.

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-    We know Betelgeuse will blow up 'soon' in astronomical terms this means anytime between now and millions of years into the future, but not exactly when it will happen.   For about four months of the year, it's only observable during the daytime because the sun gets between Betelgeuse and the Earth at this time.

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-    This breakthrough paves the way for uninterrupted, long-term studies of stars like Betelgeuse as they undergo powerful eruptions near their end of life, expelling massive amounts of stellar material in the final stages of the cosmic cycle of rebirth.

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-    Astronomers love when stars in the Milky Way go supernova because it can tell us so much about how elements are created in the universe.   Unfortunately, supernova in the Milky Way are relatively rare, the last time it happened was in 1604.

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-   But when a supernova went off in a mini-galaxy next to our Milky Way galaxy in 1987, this was so useful for astronomers that they still observe the expanding supernova explosion almost 40 years later.

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-    Mastering daytime observation also delivers a big advantage in the rapidly expanding field of “space situational awareness” (SSA), which is the close monitoring of an ever-growing population of satellites, space debris and other artificial objects orbiting Earth.

 

More satellites will be launched in the next 10 years than in the entire history of human space exploration.   With around 10,000 active satellites already circulating the planet and plans to launch a further 50,000 low Earth orbit satellites in the next decade, there's a clear need for dedicated day and night telescope networks to continually detect and track satellites.

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-    Potential satellite collisions have grave implications for communications, GPS, weather monitoring and other critical infrastructure.  Satellite photometry, an astronomy technique using optical telescopes to study changes in the brightness of celestial objects, can reveal valuable information, including the composition, age and condition of orbiting objects.

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-    Opening up to daytime observation of satellites allows us to monitor not just where they are, but also their orientation, and adds to the information we get from radar and other monitoring methods, protecting against potential collisions.

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-   Daytime astronomy is an exciting field, and with advances in camera sensors, filters and other technologies, we saw dramatic improvements in the sensitivity and precision achievable under bright-sky conditions.

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-   The Huntsman has been constructed so the 10 lenses work in parallel, feeding 10 ultra-fast CMOS camera sensors that together can take thousands of short-exposure images per second.

The attached camera can process images and manage very large data streams in an instant, using robotic control to track and capture fast-moving objects, and delivering continuous 24-hour monitoring of objects.

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-   Daytime astronomy will be increasingly critical as we enter the next Space Age.

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May 22, 2024                DAYTIME  TELESCOPES  -  really?             4480

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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”  -----------

--------------------- ---  Saturday, May 25, 2024  ---------------------------------

 

 

 

 

 

           

 

 

4479 - EUCLID TELESCOPE - will it discover Dark Energy?

 

-  4479   -    EUCLID  TELESCOPE -  will it discover Dark Energy?  -     Europe's Euclid space telescope may see into the dark universe and may put Einstein's famous theory of general relativity into question.  There is a problem with our understanding of the universe: It doesn't make sense if we account only for the matter and energy that we can see, measure or detect.


------------------------  4479    -    EUCLID  TELESCOPE -  will it discover Dark Energy?

-    Albert Einstein's famous general theory of relativity, which describes the physical 'rules' of the universe in a series of equations only adds up on cosmic scales if there is five times as much matter dispersed throughout the cosmos than what we can see and detect.

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-    This invisible matter, or “dark matter”, together with another invisible entity, “dark energy”, form the biggest mystery in cosmology, and the origins of the universe. While dark matter pulls stuff together with the force of gravity, the elusive dark energy seems to be doing the exact opposite, pushing things apart and causing the acceleration of the expansion of the universe that was first discovered in 1998.

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-    Solving cosmology's greatest mystery, I'm working on it!.  “Dark matter” is something that gravity works on in the same way as normal matter, but it doesn't interact with any light or any anything so we only know it's there by the effect it has on the movements of galaxies and stars.

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-    Whereas dark energy is something we found out about more recently when we discovered that the expansion of the universe seems to be getting faster with time. That doesn't make any sense if you think there's just gravity there. It should be slowing down.

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-    The new European Euclid telescope, launching on Saturday, July 1,2024, might bring that answer a little closer into view. The spacecraft, fitted with a 3-foot-11 inch telescope, will also help map the distribution of dark matter across spacetime in three dimensions for the first time.

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-    But how exactly is Euclid going to "reveal" the existence of the invisible universe when it cannot see and measure it? The telescope, fitted with sensors capable of detecting visible and infrared light, will join the famed James Webb Space Telescope at “Lagrange Point 2”. In this region some 900,000 miles away from Earth, the gravitational forces of the planet and the sun are equal, keeping the spacecraft in a stable location relative to Earth.

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-    Here, shielded from the glare of the star at the center of our solar system, Euclid will look into the depths of the cosmos, 10 billion years back in time, to map the distribution of galaxies across one third of the sky outside our Milky Way galaxy. It will take over six years for the $660 million telescope to complete its survey.

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-    Euclid's images will also allow astronomers to study how the gravity of invisible dark matter alters the shapes of the galaxies as they appear in those images.   Distortions, also known as the gravitational lensing effect, are minuscule.    So minuscule in fact, that they can't be accurately measured by ground-based telescopes due to the blurring caused by Earth's atmosphere.

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-   The effect is very tiny, less than 1%.   To detect this tiny effect is very difficult. We need to be very, very precise with our image quality and measure many, many galaxies to be able to deduce anything.

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-   By using complicated math, astronomers will be able to use these gravitational lensing measurements to calculate the amount of dark matter between Euclid and each distorted galaxy, allowing them to create the first ever 3D map of the dark matter's distribution in the universe.

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-    Although “dark matter” has never been directly observed, scientists are quite certain of its existence.   There is evidence of dark matter in so many ways that it is quite unlikely that Euclid could find evidence through measuring the gravitational lensing that it does not exist.   There is simply not enough normal matter to grow galaxy structures, to have them assemble the way they are.

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-   The existence of dark energy, on the other hand, is less certain and it's in this area where Euclid scientists expect the biggest surprises. At stake is the ultimate validation of Albert Einstein's famous and widely accepted theory of relativity, which claims to capture what is supposed to be the universal rules of the behavior of all matter and energy in the universe.

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-    It could be simply that general relativity doesn't really work at cosmic scale, and therefore dark energy is not needed.  We need dark energy now if we assume that general relativity works. Dark energy is not needed to grow the cosmic structures, to grow stars and galaxies.

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-    Many experiments and observations made at smaller distances have confirmed the theory of general relativity over the years. If Euclid's measurements were to take this theory into question, it would be "an absolute discovery," .

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-    Astronomers want to find evidence for the existence of dark energy in the distribution of galaxies and galaxy clusters across spacetime. They believe this distribution is not random, but a reflection of soundwaves that bounced around the ancient universe.

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-   In the wake of these soundwaves, regions of denser gas emerged that later gave rise to galaxies.   Astronomers can observe these patterns in the “cosmic microwave background”, the remnants of the first light that spread through the emerging universe in the first hundreds of thousands of years after the Big Bang and that can still be detected today.

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-    In the cosmic microwave background, we can see this pattern as it looked in very early times.   With Euclid, we will be able to measure it much closer to us now in time in the pattern of galaxies in the sky. We will see this imprint in the scale that galaxies like to cluster, in their preferred distance separation.

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-   By comparing the ancient imprints with the newer ones, scientists will be able to see how much the universe has expanded since its earliest days and what role dark energy may have played in this process.

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-    Because the dark energy pushes the universe apart, if there's a lot of dark energy, we'll see that that scale is much larger than we would have otherwise.

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-    It will take years for the telescope to gather enough data to answer the big questions. Today all models point to the existence of dark energy that is constant and spread uniformly throughout the cosmos.

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-     Some evidence suggests that things may not be all that simple. The Hubble constant that describes the rate of the universe's expansion doesn't appear to be the same in the nearby observable cosmos as it is in the early universe, a possible sign that something might not be right with the cosmology models.   Maybe we will have a surprise when we find out.

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May 23, 2024       EUCLID  TELESCOPE -  will it discover Dark Energy?             4479

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

--------  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”  -----------

--------------------- ---  Saturday, May 25, 2024  ---------------------------------