Podcaster: Dr. Pamela Gay;
Title: Escape Velocity Space News – EVSN: Star Formation Occurs in Competitive Environment
Organization: Cosmoquest
Link: http://dailyspace.org/
Description:From April 21, 2021.
A survey of the stellar nursery in the Orion Nebula Cluster provides evidence that stars compete for material and their size depends on what they gather rather than their initial core size. Plus, NASA mission updates, fast radio bursts, neutron stars, visible novae, and mountain building in the Andes.
Bio: Dr. Pamela Gay is a Senior Scientist at Planetary Science Institute and a Director of CosmoQuest.
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Transcript:
[Dr. Pamela Gay]
And welcome to the Daily Space. I’m your host, Dr. Pamela Gay, and I am here to put science in your brain. Beth Johnson is off today, taking a well-deserved day of rest, and she will be back on Thursday.
On April 19th at 0734 UTC, which was the middle of the night here in the Northern Hemisphere and was, well, noon where Ingenuity and Percy are on Mars. At that auspicious hour, NASA’s Mars helicopter, Ingenuity, successfully performed the first powered flight from the surface of another planet. It was relatively short, only to a 3-meter altitude and with a flight time of just over 39 seconds.
But it made history. This was the first time something flew in the atmosphere of another planet. And while this flight might not have been all that interesting, we look forward to more interesting flights in the future.
Overcompensating on the interesting side of things, NASA released images of the site on the asteroid Bennu where the OSIRIS-REx mission punched the asteroid. I have to say, every time I read or hear about what happened, new details make the story even more interesting. The intention was to boop the asteroid gently with the mission’s sample arm, hit it with a blast of air from an air canister to launch the material into the sample container, and then fly away after just a couple of seconds.
This is still what is shown in released animations, but what actually happened, I have now learned, includes not just the arm plunging into the asteroid, but, well, after that plunge, that’s when the air canister went off. So, as we now know, the mission stabbed its arm into the surface of Bennu, blasted the air canister well under the surface, and would have kept plunging into the asteroid if it hadn’t used reverse thrusters to escape after its arm was already 0.5 meters into the asteroid. To give you a sense of scale, we have images on our website, dailyspace.org, that shows a region the size of a large parking space that has been completely disrupted by this mission’s intended gentle boop. Spacecraft often make super surprising discoveries. We build them to accomplish one set of science objectives and we give them a lot of flexibility so that hopefully they can handle any random incidents or discoveries that crop up after the mission has launched. Things like what Osiris-Rex had to deal with.
Well, one upcoming mission, the Lucy probe that will do flybys of Trojan asteroids, well, it has already started to make, or at least its team has started to make, discoveries before it even left the ground. Trojan asteroids, these are chunks of rock that share an orbit with Jupiter that are gravitationally clumped up ahead of and behind Jupiter in its orbit around the Sun. This mission is being put on a very elliptical orbit that will allow it to visit first the leading Trojans and then on its next orbit to visit the lagging Trojans.
The orbit was specifically designed to allow the mission to do close flybys of seven known objects and it’s expected newly discovered objects will be added over the course of the mission. One object however has already been added. In January 2020, it was realized one of the targets, it was actually a binary, a large asteroid with a tiny moon of its own.
And in continued observations of the regions that Lucy will be visiting, well, the Atlas system, the asteroid terrestrial impact last alert system based in Hawaii, it’s found that the leading and trailing clouds of asteroids have different average shapes with the leading asteroids tending to be more elongated and smaller. According to research on archive led by Andrew McNeil, the leading cloud also has more objects in it. And this combination of facts seems to indicate that with more objects to collide, more collisions have indeed taken place, each one reshaping the asteroids involved.
Launching in October of this year, Lucy is expected to reach this leading cloud in 2027 and to then visit the trailing cloud in 2033. Expect more discoveries in the years before the encounters as observers here work to make sure Lucy doesn’t encounter any surprises out there. Not all of today’s news comes from within our solar system.
One of our regular topics, fast radio bursts, has a new advancement, very much not in our solar system. First discovered in 2007, these are literally momentary flashes of energy that reach Earth in the radio portion of the electromagnetic spectrum. Often there will be just a single flash from a place in the sky that we can’t link to a single star or other object.
Other times, we see recurring flashes. To try and get a better sense of what might be happening, joint observations were made with the CHIME radio telescope in British Columbia and LOFAR in the Northern Netherlands. CHIME operates at 500 to 800 megahertz while LOFAR sees at longer wavelengths from 10 to 240 megahertz, which extends to either side of the FM radio band.
Working together, these telescopes observed fast radio burst 2018-09-16b. They discovered that the fast radio burst emitted energy at the longer wavelengths and these lower energy photons arrived at LOFAR three days after the higher energy light was seen by CHIME. According to study co-author Danielle Micheli, this systematic delay rules out explanations for the periodic activity that do not allow for the frequency dependence and thus brings us a few steps closer to understanding the origin of these mysterious bursts.
This work appears in the Astrophysical Journal Letters and was led by Ziggy Polennis. While we don’t know what fast radio bursts are, there are hints they’re some kind of neutron star that has a massive magnetic field that periodically rearranges itself and lets off a massive burst of energy. We see other objects including our own Sun with its solar flares exhibiting this kind of energetic magnetic field related behavior.
If fast radio bursts do come from neutron stars, this means that some of the smallest glowing objects in the sky are also responsible for some of the most energetic crackles we detect. Neutron stars are the dead remnants of massive stars that aren’t massive enough to explode a supernovae, but are massive enough that when they are no longer able to produce energy through fusion, will collapse down and crush their atoms into exotic forms of matter. Neutron stars are roughly the size of Manhattan Island and can contain a bit more than two times the Sun’s mass in stuff.
Theories suggest that the outer skin can be fairly normal matter, but inside the dead star, pressure forces protons and electrons to combine into a dense degenerate gas of neutrons. What we didn’t know was if the super dense core was just neutrons or some more compact form of matter like a quark soup. New research from the International Space Station’s NICER X-ray telescope looks at one of the largest mass neutron stars out there, Pulsar J0740 plus 6620, to see if its size can reveal its inner nature.
They also looked at the average mass J0030 plus 0451 for comparison. Early results indicate the higher mass Pulsar is bigger than predicted by quark soup center theories and smaller than predicted by theories with just neutrons and protons. This was not expected and hints at new states of matter.
According to team lead Cole Miller, NICER is not only rewriting the textbooks on neutron stars, but also revolutionizing our confidence in our measurements of objects that are both very distant and very small. According to study co-author Anna Watts, our new measurements of J0740 show that even though it’s almost 50% more massive than J0030, it’s essentially the same size. This challenges some of the more squeezable models of neutron star cores, including versions where the interior is just a sea of quarks.
J0740’s size and mass also pose problems for some less squeezable models containing only neutrons and protons. Understanding what is inside neutron stars may help us understand black holes and allow us to get at new fundamental physics that tells the story of the earliest moments of our universe. Neutron stars and the lower mass white dwarf stars are so dense that they can get closer to any potential companion stars than may be healthy for those companions.
They literally will strip material off of their companions in some cases, and that in-falling material, when it gets dense enough, can explode in myriad different ways referred to as NOVI. Currently, three different NOVI are visible to small telescopes. V1710 Scorpii, V6595 Sagittarius, and V1405 Cassiopeia.
All three systems appear to be classical NOVI, and they are made up of a white dwarf star, an object about the size of the moon with the mass of the Sun, as well as that lower-mass companion star that is getting stripped of material. There is an excellent article on how to find these objects in your backyard with a small telescope on skyandtelescope.org, and we’re going to link to that article in dailyspace.com and encourage any of you morning folks to get out and look up. While all these objects are visible in the Southern Hemisphere, you should be able to get at least two out of three if you’re not too far south in the Southern Hemisphere.
One of the most stunning regions in the sky for amateur astronomers to observe is the Orion star-forming region. From the famous M42 nebula in the sword to the Horsehead Nebula, to cloud after cloud of glowing nebulosity and knots of star formation, this region of the sky is a complex of star formation that allows researchers to see all the short-lived stages of star formation. As we’ve said before and will say again, we don’t fully understand star and planet formation, but we understand the broadest brushstrokes.
At its initial stages, a giant molecular cloud will collapse and fragment into a dense core that will over time continue collapsing into a spinning disk with a protostar in its center. These systems can draw more or less material, growing more or less, depending on what they pull in. Over what times this drawing in of additional material occurs, well, that had been a bit of a mystery, and it was suspected that perhaps large stars were able to continue growing, competitively stealing material, and possibly, well, preventing their neighbors from growing quite so much around them.
In new observations taken with the National Observatories of Astronomy in Japan’s Nobuyama 45 meter radio telescope, well, it’s found that this competition for resources occurs at the earliest stages of star formation, with dense cores already stealing material to reach their size, and those sizes reflect their final masses. This team looked at regions of star formation, both at the earliest dense cores of collapsing material stage, and also at the newly formed stage of star formation, and found that the distribution of masses of these two kinds of systems, dense cores and young stars, are the same mass distribution. Prior to these results, it was thought that stars formed either through a competitive accretion model, where all stars start with roughly the same size dense core, and over time grow more or less successfully, or that stars grow through a core collapse model, where different sized dense cores form and lead to different sized stars.
These results indicate that at least with the Orion Nebula, the core collapse model appears right. These observations are now being extended to other star forming regions to see if this is a universal result, or if, as so often happens, the universe does the same thing in different ways in different places. What I love about this research is that it’s allowing us to really build a model of star formation over time.
Just by looking at the Orion Nebula, we can see clouds fragmenting, we can see dense cores forming, we can watch the stars growing in cocoons of material stellar propletes, and then breaking free and shining with their light. We are building a movie, and someday we will understand the details of star formation. It’s just going to take more observations.
We have to constantly observe things to put together ever more detailed pictures of both the universe around us and the planet beneath us. We talk a lot on this show about climate change, especially what we are undergoing now. The activities of humans have definitely had an impact on the current climate situation, but nature likes to have a hand in everything as well.
And we’re still learning just how some of the larger processes, like mountain building, are affected by climate in the past, and how they are being affected by climate change today. In a recent paper in the journal Tectonics, researchers theorized that a feedback loop existed between tectonic deformation and the climate about 13 to 7 million years ago in the northern Patagonian Andes of South America. The team conducted field observations focusing on an area called the Forland Basin, which is to the east of the Andes and is basically the area behind the mountains that gets pushed back and folded up as the mountains rise.
The Andes began forming when the Nazca Plate began to subduct under the South American Plate. We talked a few episodes ago about how volcanic arcs form, and the Andes are essentially a volcanic arc formed on land instead of as islands. As these volcanoes grew, they deformed that Forland Basin.
The largest period of deformation occurred in that 13 to 7 million years ago window, and then started to decrease. At that point, glaciation began in the mountains themselves. Now, with the glaciers eroding away through warmer temps and increasing rainfall, and not just due to the current climate change, but extending back a couple million years, the Forland Basin deformation has stopped, and fault activity in the mountains has increased.
Researchers now have the numbers to confidently say that climate change can actually affect mountain building processes, and not only the other way around. This is a friendly reminder that the world is bigger than we sometimes realize, and sometimes smaller, and it’s all tied together. Speaking of the Andes, a recent paper published in the journal Latin American Antiquity examined how structures in the ancient city of Karel in Peru were oriented based on astronomy.
The city itself, long since abandoned, dates back to around 3000 BCE, and the society that lived there was the Supe culture, named for the river on which the city was built. And while much of that city is oriented parallel to the river, as one would expect from a predominantly agricultural society, several of the large and clearly important pyramidal buildings have an orientation that aligns with the full moon and the June solstice. First author César González García explains, it is noteworthy that these orientations can be related to the precipitation cycles on the Andean summits, with the consequent beneficial flooding of the river, and thus with the agricultural cycles.
That time also coincided with the end of the fishing season, taking place over a wide area of the nearby coast. Co-author Juan Antonio Belmonte notes, the results of the research in the position and the orientation of the main buildings show that the presence of the river Supe is the main determining influence on the orientation of the buildings because although they are not sited directly at the river, they are systematically parallel to it. It’s a curious phenomenon, convergent with what was occurring at that same time thousands of kilometers away in the Valley of the Nile.
These monuments from the Supe Valley culture from 5,000 years ago are now the first and therefore oldest examples of pre-Columbian American interactions between the landscape and the sky. And that is your daily reminder to look up and observe how astronomy influences your life. This has been The Daily Space.
[Speaker 3]
Today’s episode was written by Dr. Pamela Gay and Beth Johnson. Engineering is provided by Allie Pelfrey and web content is produced by Beth Johnson. You can get a complete transcript, show notes, and see images related to each of our stories at our website dailyspace.org.
The Daily Space is a product of the Planetary Science Institute, a 501c3 non-profit dedicated to exploring our solar system and beyond. We are here thanks to the generous contributions of people like you. The best way you can support us is through patreon.com slash CosmoQuestX. Like us? Please share us! You never know whose life you can change by adding a daily dose of science.
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365 Days of Astronomy
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As we wrap up today’s episode, we are looking forward to unravel more stories from the Universe. With every new discovery from ground-based and space-based observatories, and each milestone in space exploration, we come closer to understanding the cosmos and our place within it.
Until next time let the stars guide your curiosity!