Today’s news is brief but balanced. Join us to explore new work that looks at how stellar mergers match-up with highly magnetic stars, how gas falling in doesn’t balance with gas blown out of our galaxy, and finally get a brief update on the Hyabusa 2 mission.
This is the Daily Space for today, Thursday, October 10, 2019. I am your host, Dr Pamela Gay, and I am here to put science in your brain.
This week things may sound a bit different. I’m on vacation, and the rest of our team is working on other projects. The news, however, stops for no one, and neither do we.
Today’s news starts with a story where enhancements in computational abilities are starting to make new understanding possible. As an observational astronomer, I’m very much a “seeing is believing” kind of person, but sometimes you can see something but it takes more than just observations to understand what is going on. This is the cause with magnetic fields. There are a number of stars with abnormally strong magnetic fields and until recently we simply haven’t had the computational abilities to understand just what is driving these fields. This has now changed, and in a new paper in the journal Nature, scientists Fabian Schneider and Philipp Podsiadlowski from the University of Oxford have simulated how the star Tau Scorpii may have formed through the merger of two separate stars. In the process, this spun up a powerful massive field as all the angular momentum drove up rotation and other complex effects. When this one star that was two stars dies as a supernova, it is possible that the resulting object may be a magnetar, a kind of stellar remnant with a magnetic field 100 million times stronger than the strongest. Stars that merge like Tau Scorpii are called blue stragglers and appear to make up about 10% of all massive stars and this frequency is consistent with the frequency of highly magnetic stars.
A lot of science includes matching what goes into a situation with what comes out, just as the rate of stellar mergers was matched with the number of magnetic stars. In another case of balancing the equations, astronomers using the Hubble Space Telescope have studied the flow of gas out of galaxy and balanced it with what is coming back and found not everything balances out. Powerful events like supernovae and violent stellar winds blow gas out of the Milky Way’s disk, and then gravity pulls it back, but somewhere between leaving and returning, the gas found some friends to bring home with it. This excess material is likely stolen from the intergalactic medium and from the dwarf galaxies the Milky Way is in the process of consuming. This new gas isn’t exactly surprising, but it is now demonstrably there, and what is amazing is the work that went into this study. This research, now published in the Astrophysical Journal, used 200 past ultraviolet observations of the diffuse halo that surrounds the disk of our galaxy. These observations were taken to study the universe beyond our galaxy and then repurposed. Future work using this kind of a data recycling will replicate this study with the nearby Andromeda Galaxy.
And finally we have a quick update from Hyabusa 2. Until today, it had been hovering at an altitude of 8km above Ryugu as they observed the descent of Minerva-II2. Today, they returned the mission to its normal altitude as Minerva finishes its mission. The next major milestone for Hayabusa will be its November departure to head toward home. In December of next year, the mission will throw its precious cargo of asteroid bits back to Earth, where they will land in Australia.
And that rounds out our show for today.
Thank you all for listening. The Daily Space is produced by Susie Murph, and is a product of the Planetary Science Institute, a 501(c)3 non profit dedicated to exploring our Solar System and beyond. We are made possible through the generous contributions of people like you. If you would like to learn more, please check us out on patreon.com/cosmoquestx
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