4329 - WEBB - discovers habitable plane

 

-    4329  -  WEBB  -  discovers habitable planet?  -    The James Webb Telescope detected the coldest ice in the known universe and it contains the building blocks of life.  The latest observations of icy molecules will help scientists understand how habitable planets form.

-------------------------  4329  -  WEBB  -  discovers habitable plane

-   The James Webb Telescope is orbiting in the gravity well between Earth and the Moon.  It can see into deep space by collecting photons that have traveled over 14 billion years.

-

-  Scientists using JWST have observed and measured the coldest ice in the deepest reaches of an interstellar molecular cloud to date. The frozen molecules measured minus 440 degrees Fahrenheit.

-

-    Molecular clouds, made up of frozen molecules, gasses and dust particles, serve as the birthplace of stars and planets, including habitable planets. Scientists used the JWST’s infrared camera to investigate a molecular cloud, “Chameleon I”, about 500 light-years from Earth.

-

-   Within the dark, cold cloud, they identified frozen molecules like carbonyl sulfur, ammonia, methane, methanol and more. These molecules will someday be a part of the hot core of a growing star, and possibly part of future exoplanets. They also hold the building blocks of habitable worlds: carbon, oxygen, hydrogen, nitrogen and sulfur, a molecular cocktail known as “COHNS”.

-

-    This is the initial, dark chemistry stage of the formation of ice on the interstellar dust grains that will grow into the centimeter-sized pebbles from which planets form.

-

-    Stars and planets form within molecular clouds like Chameleon I. Over millions of years, the gases, ices and dust collapse into more massive structures. Some of these structures heat up to become the cores of young stars. As the stars grow, they sweep up more and more material and get hotter and hotter. Once a star forms, the leftover gas and dust around it form a disk.  This matter starts to collide, sticking together and eventually forming larger bodies.   These clumps  become planets. Even habitable ones like ours.

-

-    The JWST sent back its first images in July 2022, and scientists are currently using the $10 billion telescope's instruments to demonstrate what kinds of measurements are possible. To identify molecules within Chameleon I, researchers used light from stars lying beyond the molecular cloud. As the light shines towards us, it is absorbed in characteristic ways by the dust and molecules inside the cloud. These absorption patterns can then be compared to known patterns determined in the lab.

-

-    The team also found more complex molecules they can't specifically identify. But the finding proves that complex molecules do form in molecular clouds before they're used up by growing stars.

-

-    Complex organic molecules, like methanol and potentially ethanol, also suggests that the many star and planetary systems developing in this particular cloud will inherit molecules in a fairly advanced chemical state. 

-

-    How a habitable world like ours got its icy COHNS is still a major question among astronomers. One theory is that COHNS were delivered to Earth via collisions with icy comets and asteroids.

-

-     James Webb Telescope has spotted other galaxies from the dawn of time that are so massive they 'shouldn't exist.   It spotted six gigantic galaxies, each roughly the size of our own Milky Way, that formed at a very fast pace, taking shape just 500 million years after the Big Bang.

-

-    The six gargantuan galaxies, which contain almost as many stars as the Milky Way despite forming only 500 to 700 million years after the Big Bang, have been dubbed "universe breakers".   The discovery calls our entire understanding of galaxy formation into question.

-

-    Scientists don't know exactly when the first clumps of stars began to merge into the beginnings of the galaxies we see today, but cosmologists previously estimated that the process began slowly taking shape within the first few hundred million years after the Big Bang.

-

-    Currently accepted theories suggest that 1 to 2 billion years into the universe's life before these early protogalaxies reached adolescence forming into dwarf galaxies that began devouring each other to grow into ones like our own.

-

-    Because light travels at a fixed speed through the vacuum of space, the deeper we look into the universe, the more remote light we intercept and the further back in time we see. By using the JWST to peer 13.5 billion years into the past, the astronomers found that enormous galaxies had already burst into life very quickly after the Big Bang, when the universe was just 3% of its current age.

-

-    The researchers say the galaxies are so massive, they are in tension with 99 percent of the models for cosmology. This means that either the models need to be altered, or scientific understanding of galaxy formation requires a rethink.

-

-    The Milky Way forms about one to two new stars every year.   Some of these galaxies would have to be forming hundreds of new stars a year for the entire history of the universe. If these galaxies are real, it will push against the limits of our understanding of cosmology.

-

-    Right now, all evidence points to these celestial objects being galaxies, but the astronomers haven't ruled out that some of them could be enormous quasars or supermassive black holes.

-

-   The amount of mass discovered means that the known mass in stars at this period of our universe is up to 100 times greater than we had previously thought.

Previous imaging of the early universe by the Hubble Space Telescope didn't detect the giant galaxies, but JWST is about 100 times more powerful than Hubble.

-

-   The $10 billion JWST launched to a gravitationally stable location beyond the moon's orbit in December 2021. The space observatory was designed to read the earliest chapters of the universe's history in its faintest glimmers of light which have been stretched to infrared frequencies from billions of years of travel across the expanding fabric of space-time.

-

-    The astronomers say their next step will be to take a spectrum image of the giant galaxies providing them with accurate distances and a better idea of the chemical makeup of the monsters hiding at the beginning of the universe.

-

-

January 25, 2023         WEBB  -  discovers habitable planet?               4329

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

--------  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, January 27, 2024  ---------------------------------

 

 

 

 

 

           

 

 

4328 - COMETS - support life?

 

-    4328  -  COMETS  -  support life?     By incorporate physics, biology, and chemistry into studying panspermia as the origin of life is rare to have such a diverse range of topics in one research area.   Future astrobiology studies may use these findings to build on our research on panspermia.

-------------------------  4328 -  COMETS  -  support life?

-     On October 19, 2017, astronomers with the “Pan-STARRS survey” detected an “interstellar object” (ISO) passing through our Solar System for the first time. The object, known as “1I/2017 U1 Oumuamua”, stimulated significant scientific debate and is still controversial today.

-

-    One thing that all could agree on was that the detection of this object indicated that ISOs regularly enter our Solar System.  Subsequent research has revealed that, on occasion, some of these objects come to Earth as meteorites and impact the surface.

-

-    If “ISOs” have been coming to Earth for billions of years, could it be that they brought the ingredients for life.   “Panspermia” is the theory that the seeds of life exist throughout the Universe and are distributed by asteroids, comets, and other celestial objects. ISOs can potentially seed hundreds of thousands of Earth-like planets throughout the Milky Way.

-

-     “Panspermia” is the theory that life was introduced to Earth by objects from the interstellar medium (ISM).   This life took the form of “extremophile” bacteria capable of surviving the harsh conditions of space. Through this process, life is distributed throughout the cosmos as objects pass through the ISM until they reach and impact potentially habitable planets.

-

-    This makes panspermia substantially different from competing theories of how life on Earth began  (abiogenesis), the most widely accepted of which is the “RNA World Hypothesis”.

-

-    This hypothesis states that RNA preceded DNA and proteins in evolution, eventually leading to the first life on Earth.    We must consider the physics behind panspermia (how many objects collided with Earth prior to the earliest fossilized evidence for life?), biological factors (can extremophiles endure supernova gamma radiation?).

-

-    The detection of ‘Oumuamua” in 2017 constituted a major turning point for astronomy, as it was the first time an ISO was observed. The fact that it was detected at all indicated that such objects were statistically significant in the Universe and that ISOs likely passed through the Solar System regularly.

-

-    Two years later, a second ISO was detected entering the Solar System (2I/Borisov), except there was no mystery about its nature this time. As it neared our Sun, 2I/Borisov formed a tail, indicating it was a comet.

-

-   Some of these objects become meteorites that impact on Earth’s surface, and a few have even been identified. This includes “CNEOS 2014-01-08”, a meteor that crashed into the Pacific Ocean in 2014.

-

-    “Oumuamua” serves as a novel data point for panspermia models, as we can use its physical properties, particularly its mass, size (spherical radius), and implied ISM number density, to model the number density and mass density of objects in the interstellar medium.

-

-    These models allow us to estimate the flux density and mass flux of objects in the interstellar medium and, with these models, we can approximate the total number of objects that impacted Earth over 0.8 billion years which is the hypothesized period of time between Earth’s formation and the earliest evidence for life.

-

-    Knowing the total number of collision events on Earth over that 0.8 billion-year period is vital for panspermia, as a greater number of collision events with interstellar objects over that period would imply a higher probability for panspermia.    The physical properties of the interstellar Oumuamua allow for the creation of mathematical models that determine the plausibility of panspermia.

-

-    These considerations ultimately affect the number of objects that will impact Earth (that were not sterilized by astrophysical sources) and the plausibility of panspermia.   Based on their combined physical and biological models, the astronomers derived estimates for the number of ejecta that struck Earth before life emerged. According to the oldest fossilized evidence found in western Australia (from rocks dating to the Archaean Eon), the earliest life forms emerged ca. 3.5 billion years ago.

-

-    We conclude that the maximum probability that panspermia sparked life on Earth is on the order of magnitude of 10-5, or 0.001%. Although this probability appears low, under the most optimistic conditions, potentially 4×10^9 total habitable zone exoplanets exist in our Galaxy, which could indicate a total of 10^4 habitable worlds, 10,000 harboring life.

-

-     A final result of about 100,000 habitable planets that could harbor life in our galaxy with estimates based on the most optimistic projections regarding planetary habitability. It assumes that all Earth-sized rocky planets orbiting within habitable zones are capable of supporting life, meaning they have thick atmospheres, magnetic fields, liquid water on their surfaces, and all life-bearing ejecta that survive entering our atmosphere are capable of depositing microbes on the surface.

-

-

January 25, 2023             COMETS  -  support life?                            4328

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

--------  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, January 27, 2024  ---------------------------------

 

 

 

 

 

           

 

 

4329 - WEBB - discovers habitable planet?

 

-    4329  -  WEBB  -  discovers habitable planet?  -    The James Webb Telescope detected the coldest ice in the known universe and it contains the building blocks of life.  The latest observations of icy molecules will help scientists understand how habitable planets form.

-------------------------  4329  -  WEBB  -  discovers habitable planet?

-   The James Webb Telescope is orbiting in the gravity well between Earth and the Moon.  It can see into deep space by collecting photons that have traveled over 14 billion years.

-

-  Scientists using JWST have observed and measured the coldest ice in the deepest reaches of an interstellar molecular cloud to date. The frozen molecules measured minus 440 degrees Fahrenheit.

-

-    Molecular clouds, made up of frozen molecules, gasses and dust particles, serve as the birthplace of stars and planets, including habitable planets. Scientists used the JWST’s infrared camera to investigate a molecular cloud, “Chameleon I”, about 500 light-years from Earth.

-

-   Within the dark, cold cloud, they identified frozen molecules like carbonyl sulfur, ammonia, methane, methanol and more. These molecules will someday be a part of the hot core of a growing star, and possibly part of future exoplanets. They also hold the building blocks of habitable worlds: carbon, oxygen, hydrogen, nitrogen and sulfur, a molecular cocktail known as “COHNS”.

-

-    This is the initial, dark chemistry stage of the formation of ice on the interstellar dust grains that will grow into the centimeter-sized pebbles from which planets form.

-

-    Stars and planets form within molecular clouds like Chameleon I. Over millions of years, the gases, ices and dust collapse into more massive structures. Some of these structures heat up to become the cores of young stars. As the stars grow, they sweep up more and more material and get hotter and hotter. Once a star forms, the leftover gas and dust around it form a disk.  This matter starts to collide, sticking together and eventually forming larger bodies.   These clumps  become planets. Even habitable ones like ours.

-

-    The JWST sent back its first images in July 2022, and scientists are currently using the $10 billion telescope's instruments to demonstrate what kinds of measurements are possible. To identify molecules within Chameleon I, researchers used light from stars lying beyond the molecular cloud. As the light shines towards us, it is absorbed in characteristic ways by the dust and molecules inside the cloud. These absorption patterns can then be compared to known patterns determined in the lab.

-

-    The team also found more complex molecules they can't specifically identify. But the finding proves that complex molecules do form in molecular clouds before they're used up by growing stars.

-

-    Complex organic molecules, like methanol and potentially ethanol, also suggests that the many star and planetary systems developing in this particular cloud will inherit molecules in a fairly advanced chemical state. 

-

-    How a habitable world like ours got its icy COHNS is still a major question among astronomers. One theory is that COHNS were delivered to Earth via collisions with icy comets and asteroids.

-

-     James Webb Telescope has spotted other galaxies from the dawn of time that are so massive they 'shouldn't exist.   It spotted six gigantic galaxies, each roughly the size of our own Milky Way, that formed at a very fast pace, taking shape just 500 million years after the Big Bang.

-

-    The six gargantuan galaxies, which contain almost as many stars as the Milky Way despite forming only 500 to 700 million years after the Big Bang, have been dubbed "universe breakers".   The discovery calls our entire understanding of galaxy formation into question.

-

-    Scientists don't know exactly when the first clumps of stars began to merge into the beginnings of the galaxies we see today, but cosmologists previously estimated that the process began slowly taking shape within the first few hundred million years after the Big Bang.

-

-    Currently accepted theories suggest that 1 to 2 billion years into the universe's life before these early protogalaxies reached adolescence forming into dwarf galaxies that began devouring each other to grow into ones like our own.

-

-    Because light travels at a fixed speed through the vacuum of space, the deeper we look into the universe, the more remote light we intercept and the further back in time we see. By using the JWST to peer 13.5 billion years into the past, the astronomers found that enormous galaxies had already burst into life very quickly after the Big Bang, when the universe was just 3% of its current age.

-

-    The researchers say the galaxies are so massive, they are in tension with 99 percent of the models for cosmology. This means that either the models need to be altered, or scientific understanding of galaxy formation requires a rethink.

-

-    The Milky Way forms about one to two new stars every year.   Some of these galaxies would have to be forming hundreds of new stars a year for the entire history of the universe. If these galaxies are real, it will push against the limits of our understanding of cosmology.

-

-    Right now, all evidence points to these celestial objects being galaxies, but the astronomers haven't ruled out that some of them could be enormous quasars or supermassive black holes.

-

-   The amount of mass discovered means that the known mass in stars at this period of our universe is up to 100 times greater than we had previously thought.

Previous imaging of the early universe by the Hubble Space Telescope didn't detect the giant galaxies, but JWST is about 100 times more powerful than Hubble.

-

-   The $10 billion JWST launched to a gravitationally stable location beyond the moon's orbit in December 2021. The space observatory was designed to read the earliest chapters of the universe's history in its faintest glimmers of light which have been stretched to infrared frequencies from billions of years of travel across the expanding fabric of space-time.

-

-    The astronomers say their next step will be to take a spectrum image of the giant galaxies providing them with accurate distances and a better idea of the chemical makeup of the monsters hiding at the beginning of the universe.

-

-

January 25, 2023         WEBB  -  discovers habitable planet?               4329

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

--------  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”  -----------

--------------------- ---  Thursday, January 25, 2024  ---------------------------------

 

 

 

 

 

           

 

 

4325 - COSMOLOGY CHANGED ?

 

-    4325  -   COSMOLOGY  CHANGED ? -    Studying the universe involved mapping galaxies and their larger structures, catching catastrophic stellar explosions called supernovas, calculating distances to variable stars, measuring the residual cosmic glow from the early universe.

-------------------------  4325 -  COSMOLOGY  CHANGED ?

-    The glue that held the cosmology stories together had been discovered a few years earlier, in 1998 called “dark energy”.  This mysterious force rather than gluing the cosmos together, is somehow causing it to expand ever more speedily instead of slowing down over time.

-

-    When scientists included this “cosmic something” in their models of the universe, theories and observations meshed. They drafted what is now known as the standard model of cosmology, called “Lambda-CDM”

-

-     In this model dark energy makes up nearly 70% of the universe, while another mysterious dark entity, a type of invisible mass that seems to interact with normal matter only through gravity, makes up about 25%. The remaining 5% is everything we can see: the stars, planets and galaxies that astronomers have studied for millennia.

-

-    As astronomers made more precise observations of the universe across the sweep of cosmic time, cracks began to appear in this standard model. Some of the first signs of trouble came from measurements of variable stars and supernovas in a handful of nearby galaxies.

-

-    Observations that, when compared with the residual cosmic glow, suggested that our universe plays by different rules than we thought, and that a crucial cosmological parameter that defines how fast the universe is flying apart changes when you measure it with different yardsticks.

-

-    Cosmologists had a problem, something they called a “tension”, or, in their more dramatic moments, a crisis.   Discordant measurements have only become more distinct in the decade or so since the first cracks emerged. And this discrepancy isn’t the only challenge to cosmology’s standard model.

-

-    Observations of galaxies suggest that the way in which cosmic structures have clumped together over time may differ from our best understanding of how today’s universe should have grown from seeds embedded in the early universe. And even more subtle mismatches come from detailed studies of the universe’s earliest light.

-

-    To alleviate these tensions, cosmologists are taking two complementary approaches. First, they’re continuing to make more precise observations of the cosmos, in the hope that better data will reveal clues as to how to proceed. In addition, they are finding ways to subtly tweak the standard model to accommodate the unexpected results.

-

-    To characterize our universe, scientists use a handful of numbers, which cosmologists call parameters.    One of those parameters relates to how strongly mass clumps together. That, in turn, tells us something about how dark energy operates, as its accelerating outward push conflicts with the gravitational pull of cosmic mass.

-

-    To quantify “clumpiness”, scientists use a variable called “S8”. If the value is zero, then the universe has no variation and no structure. It’s like a flat, featureless prairie, with not even an anthill to break up the landscape.

-

-    But if S8 is closer to 1, the universe is like a huge, jagged mountain range, with massive clumps of dense matter separated by valleys of nothingness. Observations made by the Planck spacecraft of the very early universe, where the first seeds of structure took hold, find a value of “0.83”.

-

-    To compare the clumpiness in today’s universe with measurements of the infant cosmos, researchers survey how matter is distributed over large swaths of sky.  Accounting for visible galaxies is one thing. But mapping the invisible network upon which those galaxies lie is another. To do that, cosmologists look at tiny distortions in the galaxies’ light, because the path light takes as it weaves through the cosmos is warped as the light is deflected by the gravitational heft of invisible matter.

-

-   By studying these distortions (known as weak gravitational lensing), researchers can trace the distribution of dark matter along the paths the light took. They can also estimate where the galaxies are.   Astronomers create 3D maps of the universe’s visible and invisible mass, which lets them measure how the landscape of cosmic structure changes and grows over time.

-

-    Over the past few years, three weak-lensing surveys have mapped large patches of the sky: the Dark Energy Survey (DES), which uses a telescope in Chile’s Atacama desert; the Kilo-Degree Survey (KIDS), also in Chile; and most recently, a five-year survey from the Subaru Telescope’s Hyper Suprime-Cam (HSC) in Hawai‘i.

-

-    A few years ago, the DES and KIDS surveys produced S8 values lower than Planck’s implying smaller mountain ranges and lower peaks than what the primordial cosmic soup set up.

-

-    The Subaru HSC team surveyed tens of millions of galaxies covering about 416 square degrees on the sky, or the equivalent of 2,000 full moons. In their patch of sky, the team calculated an S8 value of “0.78” in line with the initial results from earlier surveys, and smaller than the measured value from the Planck telescope’s observations of the early universe’s radiation.

-

-   If this S8 tension is really true, there’s something which we do not understand yet.

Cosmologists are now poring over the details of the observations to take out sources of uncertainty.   The Subaru team estimated the distances to most of their galaxies based on their overall color, which could lead to inaccuracies.

-

-    These measurements aren’t easy to make, with subtle complexities in interpretation. And the difference between a galaxy’s warped appearance and its actual shape, the key to identifying invisible mass, is often very small.  Plus, blurring from Earth’s atmosphere can slightly alter the shape of a galaxy, which is one of the reasons why astronomers are  leading a weak-lensing analysis using NASA’s James Webb Space Telescope.

-

-    A dozen years ago, scientists saw the first hints of trouble with measurements of another cosmological parameter. But it took years to accumulate enough data to convince most cosmologists that they were dealing with a full-on crisis.

-

-    Measurements of how fast the universe is expanding today, the “Hubble constant”, don’t match the value you get when extrapolating from the early universe. The conundrum has become known as the “Hubble tension”.

-

-    To calculate the Hubble constant, astronomers need to know how far away things are. In the nearby cosmos, scientists measure distances using stars called Cepheid variables that periodically change in brightness. There’s a well-known relationship between how fast one of these stars swings from brightest to faintest and how much energy it radiates. That relation, which was discovered in the early 20th century, allows astronomers to calculate the star’s intrinsic brightness, and by comparing that to how bright it appears, they can calculate its distance.

-

-    Using these variable stars, scientists can measure the distances to galaxies up to about 100 million light-years from us. But to see a bit farther away, and a bit further back in time, they use a brighter mile marker, a specific type of stellar explosion called a “type Ia supernova”. Astronomers can also calculate the intrinsic brightness of these “standard candles,” which allows them to measure distances to galaxies billions of light-years away.

-

-    These observations have helped astronomers pin a value on how fast the nearby universe is expanding: roughly 73 kilometers per second per megaparsec, which means that as you look further away, for each megaparsec (or 3.26 million light-years) of distance, space is flying away 73 kilometers per second faster.

-

-    If the expansion rate could somehow be increased, just a little bit for a little while in the early universe, you can resolve the Hubble tension.   But that value clashes with one derived from another ruler embedded in the infant universe.

-

-    In the very beginning, the universe was searing plasma, a soup of fundamental particles and energy.  A fraction of a second into cosmic history, some occurrence, perhaps a period of extreme acceleration known as inflation, sent jolts oj pressure waves through the murky plasma.

-

-   Then, as the universe cooled, light that was trapped in the elemental plasma fog finally broke free. That light called the “cosmic microwave background”, or CMB, reveals those early pressure waves, just as the surface of a frozen lake holds onto the overlapping crests of waves frozen in time.

-

-   Cosmologists have measured the most common wavelength of those frozen pressure waves and used it to calculate a value for the Hubble constant of 67.6 km/s/Mpc, with an uncertainty of less than 1%.

-

-    The discordant values, roughly 67 versus 73,  have ignited a fiery debate in cosmology that is still unresolved.

-

-    A type of old, red star that typically lives in the outer portions of galaxies where fewer overlapping bright stars and less dust can lead to clearer measurements. Using those stars astronomers have measured an expansion rate of around 70 km/s/Mpc.

-

-     JWST’s powerful infrared eye is measuring distances to giant red stars in 11 nearby galaxies while simultaneously measuring the distances to Cepheids and a type of pulsating carbon star in those same galaxies.

-

-   As observations continue to constrain these crucial cosmological parameters, scientists are trying to fit the data to their best models of how the universe works. Perhaps more precise measurements will solve their problems, or maybe the tensions are just an artifact of something mundane, like quirks of the instruments being used.

-

-    Data coming in the next year, 2025, may help. First up will be the results from Freedman’s team looking at different probes of the nearby expansion rate. Then in April, researchers will reveal the first data from the largest cosmological sky survey to date, the Dark Energy Spectroscopic Instrument.

-

-     Later in the year, researchers making another primordial background map using the South Pole Telescope will likely release their detailed results of the microwave background at higher resolution. Observations on the more distant horizon will come from the European Space Agency’s Euclid, a space telescope that launched in July, and the Vera C. Rubin Observatory, an all-sky mapping machine being built in Chile that will be fully operational in 2025.

-

-   The universe might be 13.8 billion years old, but our quest to understand it is still in its infancy.  “Now, “Everything has changed”.

-

-

January 21, 2023                   COSMOLOGY  CHANGED ?              4325

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

--------  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, January 24, 2024  ---------------------------------

 

 

 

 

 

           

 

 

ASTEROIDS - how many come close?

 

-    4327  -   ASTEROIDS  -  how many come close?   Last year, 2023,  Earth had more than 100 close encounters with large asteroids. What are the odds of a direct hit in the near future?

--------------  4327 -  ASTEROIDS  -  how many come close?

-   Asteroids are chunks of rock left over from the formation of our Solar System. Approximately half a billion asteroids with sizes greater than four meters in diameter orbit the Sun, traveling through our Solar System at speeds up to about 30 kilometers per second, about the same speed as the Earth.

-

-   Almost every week we see online headlines describing asteroids the size of a "bus", "truck", "vending machine", "half the size of a giraffe" or indeed a whole giraffe. We have also had headlines warning of "city killer", "planet killer" and "God of Chaos" asteroids.

-

-   Of course, the threats asteroids pose are real. Famously, about 65 million years ago, life on Earth was brought to its knees by what was likely the impact of a big asteroid, killing off most dinosaurs. Even a four-meter object traveling at a relative speed of up to 60 kilometres per second is going to pack a punch.

-

-     There are far more small asteroids than large asteroids, and small asteroids cause much less damage than large asteroids.  Asteroid statistics and the threats posed by asteroids of different sizes. NEOs are near-Earth objects, any small body in the Solar System whose orbit brings it close to our planet.

-

-     Earth experiences frequent but low-impact collisions with small asteroids, and rare but high-impact collisions with big asteroids. In most cases, the smallest asteroids largely break up when they hit Earth’s atmosphere, and don’t even make it down to the surface.

-

-   When a small asteroid (or meteoroid, an object smaller than an asteroid) hits Earth’s atmosphere, it produces a spectacular “fireball” , a very long-lasting and bright version of a shooting star, or meteor. If any surviving bits of the object hit the ground, they are called meteorites. Most of the object burns up in the atmosphere.

-

-   Once per year, on average, a four-metre asteroid will intersect the surface of Earth.

If you doubled that surface area, you’d get two per year. Earth’s radius is 6,400km. A sphere with twice the surface area has a radius of 9,000km. So, approximately once per year, a four-meter asteroid will come within 2,600km of the surface of Earth – the difference between 9,000km and 6,400km.

-

-    Double the surface area again and you could expect two per year within 6,400km of Earth’s surface, and so on. This tallies pretty well with recent records of close approaches.

-

-    A few thousand kilometres is a big distance for objects a handful of meters in size, but most of the asteroids covered in the media are passing at much, much larger distances.   Astronomers consider anything passing closer than the Moon,  300,000 km, to be a “close approach”. “Close” for an astronomer is not generally what a member of the public would call “close”.

-

-   In 2022 there were 126 close approaches, and in 2023 we’ve had 50 so far.

-

-   Consider really big asteroids, bigger than one kilometer in diameter. The same highly simplified logic as above can be applied. For every such impact that could threaten civilization, occurring once every half a million years or so, we could expect thousands of near misses (closer than the Moon) in the same period of time.

-

-   Such an event will occur in 2029, when asteroid 153814 (2001 WN5) will pass 248,700km from Earth.

-

-   Approximately 95% of asteroids of size greater than one kilometer are estimated to have already been discovered, and the skies are constantly being searched for the remaining 5%. When a new one is found, astronomers take extensive observations to assess any threat to Earth.

-

-    The “Torino Scale categorizes” predicted threats up to 100 years into the future, the scale being from 0 (no hazard) to 10 (certain collision with big object).   Currently, all known objects have a rating of zero. No known object to date has had a rating above 4 (a close encounter, meriting attention by astronomers).

-

-    Technology has advanced to the point we have a chance to do something if we ever do face a big number on the Torino Scale. Recently, the DART mission collided a spacecraft into an asteroid, changing its trajectory. In the future, it is plausible that such an action, with enough lead time, could help to protect Earth from collision.

-

-    “Centaurs” are small planetary bodies that orbit between Jupiter and Neptune and have baffled astronomers for sharing characteristics with both asteroids and comets.

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-     Centaurs got their name after the mythical half-horse, half-human creatures called centaurs due to their dual characteristics.

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-    James Webb Space Telescope (JWST) has conducted a first-time detection of carbon dioxide in a Centaur, this one designated “39P/Oterma”. A Centaur frequently crosses the orbits of one or more of the gas giant planets within our solar system.

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-        Centaur has been imaged up-close, they typically exhibit a combination of attributes between comets and asteroids.

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-    While carbon monoxide has been detected in two known centaurs, this recent discovery could mark a turning point in how scientists understand the formation, evolution, and composition of not only Centaurs, but of the early solar system, as well.

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-    Centaurs are important to study since they are fairly well-preserved objects in space that can provide insight on the chemical composition and physical processes of the early solar system.

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-   “Centaur 39P/Oterma” was discovered on April 8, 1943.   While 39P/Oterma has long been classified as an inactive comet, it currently exhibits a Centaur-like orbit between Jupiter and Saturn, meaning it doesn’t approach the Sun, and has a radius of approximately 1.37 to 1.55 miles. So, why was 39P/Oterma chosen for this specific study?

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-    “39P/Oterma is what we call an active centaur, a centaur that develops a coma and a tail like a normal comet.   Since it is active, we can use spectroscopy to observe molecules in their coma to gain insights into their composition. 39P was chosen as one of our targets because it would be active during the time of the proposed observations.

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-    JWST’s Near-Infrared Spectrograph (NIRSpec) instrument was used and was supported by ground-based observations from the Gemini North Observatory and Lowell Discovery Telescope to investigate the characteristics of 39P/Oterma while it was orbiting close to its perihelion (closest distance to the Sun) at 5.82 astronomical units (AU) from the Sun in July 2022.

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-    For context, the perihelion of 39P/Oterma has gradually increased since its discovery: 3.39 AU (1958), 5.47 AU (1983), and 5.71 AU (2023), and is projected to reach 5.91 AU and 6.15 AU in 2042 and 2246.

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-    After analyzing the JWST NIRSpec data, the researchers confirmed the first detection of carbon dioxide in any Centaur, and the lowest amount of carbon dioxide ever detected in any Centaur or comet. They also did not detect traces of water or carbon monoxide, which are traditionally detected in Centaurs, specifically 29P/Schwassmann-Wachmann 1 (29P/SW1), another Centaur that shares approximately the same AU distance as 39P/Oterma.

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-     And, though the production rates are low, it shows a different chemical behavior from another Centaur, 29P/SW1, seen at a similar distance (6 AU). This difference in chemical behavior could be from the very different sizes of Centaurs 29P and 39P, or from having different orbital histories, or starting out with different compositions, or possibly a combination of all of these.

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-    The finding of carbon dioxide in a Centaur could be a game changer in terms of understanding the compositions and characteristics of Centaurs, asteroids, and comets throughout the solar system, along with potentially gaining better insight into the formation and evolution of the solar system, overall.

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-    What new discoveries about Centaurs will researchers make in the coming years and decades and how many more Centaurs could possess carbon dioxide throughout the solar system? Only time will tell, and this is why we science!

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January 23, 2023         ASTEROIDS  -  how many come close?         4327

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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, January 24, 2024  ---------------------------------

 

 

 

 

 

           

 

 

4326 - BIGGEST STAR, BIGGEST PLANET?

 

-    4326  -  BIGGEST  STAR,  BIGGEST  PLANET?   -    Though the debate over what "counts" as a planet may seem arbitrary, it highlights big questions about what different planetary systems might look like, particularly those vastly different from ours.   Our own solar system is just one of many innumerable outcomes?

---------------  4326 -  BIGGEST  STAR,  BIGGEST  PLANET?

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-    The biggest star in the universe makes our sun look tiny speck  It is “UY Scuti”, a variable hypergiant with a radius around 1,700 times larger than the radius of the sun.

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-    To put that in perspective, the volume of almost 5 billion suns could fit inside a sphere the size of UY Scuti. 

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-   Our sun is enormous, more than a million Earths could fit inside of it. But on a stellar scale, it could be swallowed up by about half of all stars observed.

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-    In 1860, German astronomers at the Bonn Observatory first cataloged UY Scuti, at the time naming it “BD -12 5055”. During a second observation, astronomers realized it grows brighter and dimmer over a 740-day period, leading to its classification as a variable star.

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-    The star lies near the center of the Milky Way, roughly 9,500 light-years away from Earth. Located within the constellation Scutum, UY Scuti is a hypergiant star. Hypergiants that are larger than supergiants and giants,  are rare stars that shine very brightly. They lose much of their mass through fast-moving stellar winds.

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-    However, all stellar sizes are estimates.  The complication with stars is that they have diffuse edges.   Most stars don't have a rigid surface where the gas ends and vacuum begins, which would have served as a harsh dividing line and easy marker of the end of the star.

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-    Instead, astronomers rely on a star's photosphere to determine its size. The photosphere is where the star becomes transparent to light and the particles of light, or photons, can escape the star.    This is the surface of the star, as this is the point at which photons can leave the star.

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-    If UY Scuti replaced the sun in the center of the solar system, its photosphere would extend just beyond the orbit of Jupiter. The nebula of gas ejected from the star extends far beyond the orbit of Pluto, to 400 times the distance between the Earth and the sun.

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-    UY Scuti's large radius does not make it the most massive, or heaviest, star. That honor goes to “R136a1”, which weighs in at about 300 times the mass of the sun but only about 30 solar radii. UY Scuti, in comparison, is only about 30 times the mass of the sun, but far greater in volume.

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-    Size comparisons are still more complicated because UY Scuti doesn't remain stagnant.   The star varies in brightness as it varies in radius. And the measurement we have now has a margin of error of about 192 solar radii.

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-    The variation or margin of error each could allow other stars to beat out UY Scuti in the race for size. In fact, there are as many as 30 stars whose radii approach or surpass UY Scuti's smallest estimated size.

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-   Which star would take UY Scuti's place if its size were reevaluated? Here are a few that could take the crown from the giant currently measured at 1,700 times the width of the sun:

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-    WOH G64 was once thought to measure a whopping 3,000 times the width of the sun. Newer measurements put it at around 1,504 suns wide.  It is a red hypergiant star in the Large Magellanic Cloud, which is a satellite galaxy of the Milky Way. Like UY

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-   Scuti, WOH G64 varies in brightness.

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-    Westerlund 1-26, which measures more than 1,500 times the width of the sun, according to NASA.

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-    NML Cygni is measured at 1,639 times the width of the sun, according to a 2012 paper in the journal Astronomy and Astrophysics.

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-    KY Cygni measures close to 1,033 times the width of the sun, according to a 2020 paper in the journal Astrophysics of Galaxies.

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-    VY Canis Majoris has been most recently measured to be about 1,420 times the width of the sun. This red hypergiant star was once estimated to be 1,800 to 2,200 times the width of the sun, but new measurements brought it down to size.

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-   What is the biggest planet ever found?   The universe is vast and in the scheme of things, our planet is tiny. Even in our own solar system, Earth is dwarfed by gas giants like Jupiter.

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-   The answer depends on several factors, including how you define a planet. Even so, there are a few candidates for the largest known planet. One of the largest is called “ROXs 42Bb”, a gas giant orbiting a star about 460 light-years from Earth. It is about nine times the mass of Jupiter and has a radius of about 2.5 that of Jupiter.

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-    ROXs 42Bb from data from the Keck Space Telescope.

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-    Two protoplanets both orbit the star PDS 70 about 370 light-years from Earth and have a radius between two and four times that of Jupiter.

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-    Another candidate for the largest planet, HAT-P-67 b, had a radius larger than two times that of Jupiter, which is similar to ROXs 42Bb.

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-     Objects are detected using the transit method, which is when an object appears to cross in front of its host star during its orbit and temporarily dims the star. Exoplanets detected in this way, like HAT-P-67 b, can be directly measured.

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-    The other uncertainty comes from the issue of how to define a planet. Though most people know that stars are very large and planets are much smaller, there's a middle ground, an object called a brown dwarf, which is too small to be a star but is larger than a planet. Though the core of a brown dwarf is not hot enough to fuse regular hydrogen like a star would, it can fuse deuterium, a special form of hydrogen that contains a neutron.

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-   Scientists agree that brown dwarfs are not planets. What's less clear is how to distinguish between the two.   Anything above 13 Jupiter masses is a brown dwarf and anything below is a planet.

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-     Typically, planets like Jupiter form a rocky core, which attracts a disk of dust and gas that gradually becomes a globular planet. ROXs 42Bb may have formed in a different way, where parts of the dust and gas disk were so massive and heavy that they collapsed in on themselves.

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January 23, 2023         BIGGEST  STAR,  BIGGEST  PLANET?             4326

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

--------  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, January 24, 2024  ---------------------------------