EVSN - Betelgeuse: Smaller & Closer Than Previously Thought… What?

Announcements and upcoming watch party

0:00It's the 365 Days of Astronomy podcast, coming in 3, 2, 1.

0:30This is The Daily Space for today, Monday, October 19th, 2020. I'm your host, Dr. Pamela Gay, and I am here to put science in your brain.

0:47Welcome to Monday. This is going to be a Monday of announcements, so please bear with me for a moment. The news is coming. It's just going to take a bit. First off, I'd like to share that we're going to be standardizing our news segment to 30 minutes. This means more science most days, but there's almost always that, but we're going to be going back to four days a week. So we're going to be coming to you live Tuesday through Friday, bringing you all that is new in space and astronomy. Next, tomorrow we'll be hosting a watch party for

1:21the OSIRIS-REx mission's asteroid boop. Literally, they're going to be booping the asteroid Bennu with their tag instrument, as they commit a grab-and-fly theft of minerals from the asteroid's surface. Join us live at 5 p.m. Eastern, 2 p.m. Pacific on twitch.tv slash CosmoQuestX. We'll have giveaways and rock-counting reminiscing in the CosmoQuest Discord. Finally, and most importantly of all, I'd like to remind everyone that 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,

1:57including the production of this show during the 2021 fiscal year. This is a not-for-profit science program, and your donations are tax-deductible where allowed by law. To learn more and donate today, please visit our website, CosmoQuest.org.

New research on Betelgeuse size

2:14And now, to the news. Today's top story brings back our favorite red giant star, Betelgeuse. A new paper published in the Astrophysical Journal with lead author Meredith Joyce looks at Betelgeuse as a pulsating variable star and uses atmospheric physics to bring us new insights on what the red giant is up to. This paper combines new observations with new computer models to derive the star's mass and size from its outward behavior in much the same way that one might

2:50derive the size of a jug based on what notes can be produced by blowing across its opening. Different sized objects naturally resonate in specific ways. By understanding how Betelgeuse pulsates in the fundamental mode and first overtone mode, those first two pitches you can make with your bottle. They were able to figure out Betelgeuse's physical size. This let them then figure out more accurately the star's distance, because if we know how big something appears in the sky, there's a

3:23simple mathematical relationship between how big something is and how big it appears that gives us the distance. Our current estimates had been based on Hipparchus measurements of how Betelgeuse appears to move relative to background objects when the Earth moves around the Sun. This technique called parallax can be super useful, but trying to measure how much an object shifts when that object is a blobby star like Betelgeuse can be a challenge. Betelgeuse appears to be 42 milli arc seconds across and seems to

3:59shift just 5.95 maybe plus 0.58 maybe less by 0.85 milli arc seconds. This is really hard to measure and Betelgeuse hasn't been looked at yet with the new Gaia space telescope. By working from the theoretical size they got from its pulsation modes and calculating a new distance, this team found that the lower edge of the error bars in the prior measurement by Hipparchus seem to be, well, where Betelgeuse actually is in size.

4:38Their results found that Betelgeuse is just 530 light years away. This is 25% of the distance from the prior estimate, but as I said, it's within the error bars of that measurement. This closer distance makes Betelgeuse a bit smaller. It appears to be 750 times the radius of the Sun. Nevertheless, this is a giant star that probably started out with more than 20 solar masses of material and it will still explode in

5:08about 100,000 years. At this point, they believe the star Betelgeuse is still burning helium in its core and it's nowhere near ready to go boom. It's always cool when completely different techniques can narrow in on more precise values for something. This shows us once again that there is no one way to do science.

Mars Insight mole status update

5:35Returning to another old friend, we have news from the Mars Insight mission that the mole instrument is finally all the way beneath the surface of Mars. This 16-incher, 40-centimeter long sensor was meant to pile drive itself 3 meters or more beneath the Martian surface and measure the heat profile of the soil as it went. I have to admit, more than any other Mars instrument in recent years, this was the instrument

6:05whose results I was most interested in seeing. The Martian soil both retains heat and protects everything beneath it from the harsh radiation of space. There have been myriad models that indicate that depending on the temperature profile of the soil, it may be possible to have salty liquid water very close to Mars surface. Without actual data, however, all we can do is model what might be happening based on best guess estimates of soil composition, density, and thermal behavior.

6:41The Insight mole was going to be the first real measurement of Mars soil at depth that we've ever had. The only problem has been that Mars soil is so different from what was expected that the little probe has been unable to bury itself deep into the surface, or really even into the surface. This cylinder is designed with a pile drive inside that slowly raises within the tube a mass and then sends that mass slamming downward. This should cause the mole to bury itself downward like a shovel thrust

7:18into the ground, and ideally friction should keep it at that new depth. This slow upward movement of the internal mechanism and rapid downward motion was extensively tested on Earth and proved itself excellent at digging through artificial Mars soil that was designed based on the characteristics of soils explored by other Mars missions. But the soil at the Mars Insight position? It appears to be clay, and the pile driver is just bouncing upward instead of burying itself deeper.

7:57To get the mole completely underground, the mission team resorted to using the spacecraft's shovel to push down on the mole while it tried to drive itself downward. Once the mole was close to the surface, they piled dirt on it and pushed with the shovel some more. There's still a glimmer of perhaps dying hope that the mole will break through the clays and enter soil that it can dig through as designed so it can complete

8:27its mission. At this point, almost two years after arriving on Mars, I have to say I'm in awe of the continued patience of this mission team. It's expected to take several months for the team to pile enough dirt on top of the mole that the shovel will be able to effectively push down on it while it tries to dig some more. And they're just gonna rearrange sand for these couple of months and do their best to get the mole to bury itself downward. This is a slow and

9:04study attempt to get the science done. And I really wish the team all the luck and patience in the world as they work to get their sensor buried.

Distant exoplanets and hydrogen gas

9:16Finally, we now have a couple news notes. The new St. X Observatory in Mexico has detected two exoplanets orbiting the red dwarf TOI 1266. This demonstrates that this new telescope can do the job it was designed to do. St. X is an acronym for search and characterization of transiting exoplanets and makes the not intuitive decision to use the I and N in characterization to make the acronym pronounceable, which makes me think

9:50maybe this is a backronym. These test observations were taken just before Mexico's COVID-19 related lockdown began, and the observatory has been closed since then. When the lockdown lifts, this telescope is poised to make planet finding a little bit easier. While we don't normally cover individual new planet discoveries because they are so common, we will make an exception for this scope's first worlds. These two worlds orbit their red dwarf home every 11 and 19 days. The inner planet is just under 2.5

10:25Earth radii and is classified as a sub-Neptune planet. The outer planet is 1.5 times the size of Earth Earth and counts as a super Earth. These worlds and the new scope are described in a new paper in astronomy and astrophysics with the first author, Bryce Olivier de Maury, who says planets between about the radius of TOI 1266 b and c are quite rare, likely because of the effect of strong irradiation from the star, which can erode their atmospheres. Saint-Ex project coordinator and

11:01researcher Yelaine Gomez-Makao Chu adds, being able to study two different types of planets in the same system is a great opportunity to better understand how these different sized planets came to be.

11:16While Saint-Ex has been chasing new planets, the newly upgraded giant meter wave radio telescope has been chasing gas. Specifically, it has been measuring the hydrogen gas content of galaxies so far away that we are seeing them as they appeared 8 billion years ago. According to Aditya Chowdhury, lead author of this study, which appears in the journal Nature, we have for the first time measured the atomic hydrogen gas content of star-forming galaxies, about 8 billion years ago. Using the upgraded GMRT, given the intense star formation in these early

11:53galaxies, their atomic gas would be consumed by star formation in just one or two billion years. And if the galaxies could not acquire more gas, their star formation activity would decline and finally cease. The observed decline in star formation activity can thus be explained by the exhaustion of atomic hydrogen. This newly published work took advantage of upgrades that took place in 2017. Even with these upgrades, however, their measurements were extremely difficult to make,

12:26and instead of looking at just one galaxy to measure its specific hydrogen content, they looked at 8,000 different galaxies and combined their data to get an average measurement. Prior to making the telescope more sensitive, they were unable to measure the weak hydrogen 21-centimeter signal in distant galaxies, even with this stocking technique. Study co-author Jeram Changura states, the new wideband receivers and electronics allowed us to use 10 times more galaxies in the stacking analysis,

12:59giving sufficient sensitivity to detect the weak average 21-centimeter signal. We can't wait for the COVID-19 pandemic to be over for many different reasons. And wanting to see what these two new systems can do with their killer instrumentation are just two of those reasons. When they start producing more science, we'll bring it to you here. Until then, this has been The Daily Space. Today's episode was written by me, Dr. Pamela Gay. Engineering is provided by Ali Pelfry and web

13:32content 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.

14:09To learn more and donate today, please visit our website, CosmoQuest.org. You are listening to the 365 Days of Astronomy Podcast.

14:30Cool.

14:37The 365 Days of Astronomy Podcast is produced by the Planetary Science Institute. Audio post-production is by me, Richard Drumm. Project management is by Aviva Yamani. And hosting is donated by Libsyn.com. This content is released under a Creative Commons Attribution non-commercial 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.

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15:42space exploration, we come closer to understanding the cosmos and our place within it. Until next time, let the stars guide your curiosity.