Astrobites at AAS 225: Day 1

Welcome to the winter American Astronomical Society (AAS) meeting in Seattle! Several of us are attending the conference this year, and we will report highlights from each day right here on astrobites. If you’d like to see more timely updates during the day, we encourage you to follow @astrobites on twitter or search the #aas225 hashtag.

Things kicked off last night at our undergraduate reception booth. Most of the booths are advertising graduate programs to prospective students, and we were excited to introduce a new cohort of students at AAS for the first time to astrobites.

The next morning, the conference really got started. Between plenary talks, press conferences, parallel sessions, and a myriad of other events, we can’t begin to cover everything, but here are some of our personal favorites from Monday.

Press Conference: Exoplanets & Host Stars I (by Erika Nesvold)

The first press conference focused on new exoplanet results. Soren Meibom (from Harvard CfA) discussed a Kepler study measuring the spin rates of cool stars in clusters to better understand the relationship between spin rate and age. He announced that Kepler has most recently measured stellar spin rates in a 2.5 billion year old cluster.

Astrobiter Courtney Dressing, also at CfA, talked about the recipe for making a rocky exoplanet, and showed a plot of recently discovered exoplanets indicating that planets from about 1-5 Earth masses have roughly the same composition as the Earth and Venus, but planets larger than 6 Earth masses tend to have much lower densities.

Laura Schaefer (CfA again!) announced the results of a model of the “deep water cycle” in exoplanets — the exchange of water between the surface of a planet and its mantle, which is driven by plate tectonics. Small exoplanets (less than one Earth mass) tend to develop deep oceans early in their lifetimes, but the oceans die out quickly. In larger exoplanets, around 5 Earth masses, ocean development is delayed by up to 1 billion years, but the oceans don’t die out, and in fact get deeper with time. The lifetime of surface oceans on rocky exoplanets has implications for the timescale of the development of complex life on these planets.

Finally, Debra Fischer, from Yale, provided some commentary reflecting on the last 20 years of exoplanet discovery. 51 Pegasi b, the first exoplanet discovered orbiting a main-sequence star, was discovered in 1995. Before the discovery, astronomers had been searching for exoplanets for decades, and worried that they might be very rare. Since then, however, we’ve discovered that exoplanets are very common. Debra Fischer laid out three questions for scientists to answer in the coming years and decades: Where are the habitable planets around nearby stars? Do they harbor life? And how do we get there?

Plenary Talk: What Do We Expect of a Space Program? (by Erika Nesvold)

The speaker for this plenary talk, John Logsdon of the Space Policy Institute at George Washington University, has a B.S. in Physics and a Ph.D. in Political Science, and has written books about the space race and Apollo. He pointed out that the question in the title of his talk, “What Do We Expect of a Space Program?” was asked by White House staffers back in 1971, and that we still don’t have a consensus on the answer to that question. The US spends more on space than the rest of the world combined, if you include NOAA and national defense activities in space, but NASA’s budget peaked in 1965 and has dropped significantly since then, if you measure the budget in 2013 dollars or as a percentage of the domestic discretionary spending budget.

Dr. Logsdon is skeptical that activism by space enthusiasts and professionals will lead to any increase in NASA’s budget, but he did point out that the space science funding within NASA’s budget did not experience that sharp peak in 1965, and in fact has risen fairly steadily over the last few decades. Human spaceflight funding is much more , and there is a strictly-enforced “firewall” between the space science and human spaceflight budgets (so money can’t be taken from space science to fund human spaceflight). Logsdon suggested that NASA develop a human spaceflight program that other countries would be willing and able to participate in, to encourage international cooperation.

Press Conference: The Milky Way & Local Group (by Meredith Rawls)

The afternoon press conference featured two visually stunning Hubble images. The first is a new and improved version of the famous “Pillars of Creation,” or Eagle Nebula. What’s really amazing is how this image was taken with the same telescope as 20 years ago… all the improvements in the new version are from better instruments installed during Hubble servicing missions.

The second knock-your-socks-off Hubble image is actually a mosaic of the nearby Andromeda Galaxy. In many ways, it is easier to study than our own Milky Way, because we can see the entire galaxy from an outside vantage point.

 Plenary Talk: Back to the Beginning: The Rosetta Mission at Comet 67P/Churyumov-Gerasimenko (by Meredith Rawls)

In November 2014, the Rosetta orbiter landed Philae on a comet. With this remarkable achievement came loads of new data to analyze, and this talk by Paul Weissman presented many interesting results. The atmosphere in the room was celebratory and nostalgic—so many people put so much work into the Rosetta mission, and it is incredibly heartening to finally see the success of a mission that took more than a decade to arrive at its destination.


On top of this already-full day, there was a huge poster session with bunches of undergraduate research! If you are presenting work from a senior thesis, REU, or other research project at AAS, we’d love to feature your project on astrobites.

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This post was written collectively by multiple members of the Astrobites team. Meet the authors of Astrobites.

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