Podcaster: Dr. Pamela Gay;
Title: Escape Velocity Space News – EVSN: Cool Worlds, Exploding Stars, & an Asteroid That Missed Earth
Organization: Cosmoquest
Link: http://dailyspace.org/
Description: From October 8, 2020
New images taken with the ALMA Observatory show a young proto-stellar disk with the rings and gaps of planetary formation growing together, once again challenging our preconceptions. And other research into stellar formation adds heavy metals to the mix to match models to observations. Plus, an old, metal-poor galaxy halo.
Bio: Dr. Pamela Gay is a Senior Scientist at Planetary Science Institute and a Director of CosmoQuest.
Today’s sponsor: Big thanks to our Patreon supporters this month: Paul M. Sutter, Chris Nealen, Frank Frankovic, Frank Tippin, Jako Danar, Michael Freedman, Nik Whitehead, Rani Bush, Ron Diehl, Steven Emert, Brett Duane, Don Swartwout, Vladimir Bogdanov, Steven Kluth, Steve Nerlich, Phyllis Foster, Michael W, James K Wood, Katrina Ince, Cherry Wood.
Please consider sponsoring a day or two. Just click on the “Donate” button on the lower left side of this webpage, or contact us at signup@365daysofastronomy.org.
Please visit our Patreon page: https://www.patreon.com/365DaysOfAstronomy
or you can consider to sponsor a day of our podcast : https://cosmoquest.org/x/365daysofastronomy/product/sponsor-an-episode-of-365-days-of-astronomy/
Transcript:
This is The Daily Space for today, Thursday, October 8th, 2020. I am Dr. Pamela Gay and I am here to put science in your brain. And today’s science is largely science that has resisted being understood. It’s the science of how star systems form and change the substance of the universe. At the most basic level, we struggle with questions like, how do stars and planets form and how do stars change the composition of the universe over time?
For the longest time, by which I mean since we really started trying to model what’s going on, we thought stars had to be well on their way to being fully formed a million years old or so, before the disks around them began to form planets. In broad brushstrokes, our story said that a collapsing cloud of gas and possibly dust would fragment into cocoons or proplets in which a star would form. Over time, the core of this knot of material would become dense enough and hot enough, the nuclear reactions would begin and that protostar would light up and begin interacting with the infalling material around it.
Some of the material around the new forming star would eventually collapse into planets and the solar system would be born. The exact details of this story have been unclear, and it seems that each new theory has been undone by the next new observation. Well, today’s newly published observations show that even this level of broad understanding was not entirely correct.
New images from the Atacama Large Millimeter Array show evidence of a dusk ring with gaps circling IRS-63, a protostar less than 500,000 years old. This coexistence of a forming planetary disk and a forming star seems to indicate that stars and planets form side by side and are roughly the same age. This work is published in the latest issue of Nature and is led by Dominique Segarra-Cox, who writes, We used to think that stars entered adulthood first and then were the mothers of planets that came later.
But now we see that protostars and planets grow and evolve together from early times like siblings. Co-author Ian Stevens goes on to say, These rings and gaps suggest that we are seeing the earliest evidence of planet formation and that planets certainly start to form within the first half million years and probably within the first 150,000 years. Planets, especially planets like Jupiter, started their own formation at one of the earliest stages of the star formation process.
Over time, it is my hope that observers using the Atacama Large Millimeter Array and other high-resolution systems that work in the infrared and radio will be able to observe systems spanning the entire planet formation process, eventually putting together essentially a film of star and planet evolution that may catch each stage through a different star system, but that allows us to see the entirety of the process, the same way that walking the halls of a hospital will allow you to see human growth from birth to death in the myriad faces on the different floors. Better telescopes are only one half of the equation for better understanding our solar system.
We also need better computers that allow more flexible and innovative computer models. One common assumption coded into our models of galaxies, for instance, is that we can treat them as though their metal content is constant over time. The thing is, we know the universe was formed with only hydrogen, helium, and trace amounts of lithium and beryllium.
Everything else, by definition, had to come later. With each subsequent supernova and with the breath of each star’s wind, heavy elements have been added into our universe’s mix of elements. But when we’ve modeled galaxies and tried to recreate the generations of stars that we see, we’ve typically told our software to just assume the metallicity of the universe is constant over time, at least on a galaxy-by-galaxy basis.
But it isn’t, which means we can’t actually recreate the universe we see with our simulations. Using new software that allows metallicity and dust content to vary over time, a team from Australia’s ICAR have been able to reproduce 7,000 well-observed galaxies. According to lead researcher Sabine Belstadt, with this tool we can now dissect nearby galaxies to determine the state of the universe and the rate at which stars form and mass grows at any age over the past 13 billion years.
It’s absolutely mind-blowing stuff. This research appears in the journal Monthly Notices of the Royal Astronomical Society. Belstadt goes on to explain further, Most of the stars in the universe were born in extremely massive galaxies early on in cosmic history, around 3 to 4 billion years after the Big Bang.
Today, the universe is almost 14 billion years old, and most new stars are being formed in much smaller galaxies. This research goes to show that we can’t hard-code any variables in our universe. We have to give our code the complexity the universe deserves if we want to understand things.
Finally, we have a story of beautiful galaxy diagnostics. Many things in the universe are hard to see without massive telescopes. When we look at star clusters, we try to understand them by looking at the most massive and easily seen stars.
It turns out, bright stars aren’t the only tool we have to understand what’s going on. In a new study of the elliptical galaxy M105, researchers carefully mapped the population of objects, stars, and planetary nebulae, and found that the planetary nebulae traced a diffused population of metal-poor stars in the halo of the galaxy, while the majority of the galaxy’s material lies within 3 kiloparsecs of the galaxy’s center. This halo spans from 15 to 50 kiloparsecs.
This large halo only produces about 4% of M105’s light, but its large size means the motions of these stars and planetary nebulae can be used to trace the effects of dark matter. M105 is located in the Leo 1 galaxy group, which is just 10 megaparsecs away, and is the closest group to have all the major kinds of galaxies. This research hints at how planetary nebulae can be used as tracers of metal-poor populations in other galaxies.
And that rounds out our show for today. This has been the Daily Space. Today’s episode was written by me, Dr. Pamela Gay. Engineering is provided by Ali 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. We are a production of the Planetary Science Institute, a 501c3 nonprofit dedicated to exploring our solar system and beyond.
We are here thanks to the generous contributions of people like you. This October 24th and 25th, we’re going to be holding a 36-hour-long hangout-a-thon to raise funds to cover our costs during the 2021 fiscal year. To learn more and donate today, please visit our website, cosmoquest.org.
End of podcast:
365 Days of Astronomy
=====================
The 365 Days of Astronomy Podcast is produced by Planetary Science Institute. Audio post production by me, Richard Drumm, project management by Avivah Yamani, and hosting donated by libsyn.com. This content is released under a creative commons Attribution-NonCommercial 4.0 International license. Please share what you love but don’t sell what’s free.
This show is made possible thanks to the generous donations of people like you! Please consider supporting our show on Patreon.com/CosmoQuestX and get access to bonus content. Without your passion and contribution, we won’t be able to share the stories and inspire the worlds. We invite you to join our community of storytellers and share your voice with listeners worldwide.
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!