Astrobites is again liveblogging AAS! In order to avoid inundating our readers’ RSS feeds, we’ll be updating this post with short paragraphs about the talks we’ve heard and posters we’ve seen. So keep checking back throughout Monday afternoon!
4:30 pm Invited Session: Exploring the Planet Mercury: One Year of MESSENGER Orbital Observations, Sean C. Solomon (Carnegie Institute of Washington)
This fast-paced talk covered the ways in which the MESSENGER spacecraft, which has been orbiting Mercury for a year, has revised our understanding of the magnetic, geological, and tectonic processes on the smallest Solar System planet.
- Composition: Measurements of the surface composition of Mercury answer some questions but unlock new puzzles: the potassium-thorium ratio, for instance, groups Mercury with Earth and Mars rather than Earth’s moon. However, the observed surface elemental abundances rule out the historic assumption that Mercury’s high density is due to a mostly-iron core, forcing us to revise the theory of Mercury’s formation.
- Magnetic Field: The solar wind sculpts Mercury’s magnetic field, pushing the latitude of the magnetic equator to the north by 20% of the planet’s radius and creating “cusps” in the magnetic field. However, the physics of Mercury’s internal magnetic dynamo are still mysterious.
- Presence of Water: Known radar-bright spots on the surface of Mercury are thought to result from reflective water-ice, but how could ice exist on a spinning planet so close to the sun? One postulate suggested that these icy patches lay at the bottoms of craters that were in shadow at all times of the Mercurial day and year. MESSENGER’s altimeter matched the locations of the radar-bright patches to deep craters, giving strength to the water-ice theory.
- Future Prospects: As the sun nears the maximum of the solar activity cycle, we can expect to see increased interaction between the solar wind and the magnetic field of Mercury. Stay tuned!
2:00 pm Press Release: Galaxies Bright, Faint, Near & Far
The afternoon press release centered on extragalactic astronomy from the Local Group to the distant Universe. First, Akos Bogdan from the CfA presented intriguing results on two galaxies that deviate strongly from the Supermassive Black Hole (SMBH) mass – stellar bulge mass relation. His study used the Chandra X-ray satellite to detect very extended emission from hot gas, showing that tidal stripping had not happened in both galaxies, and thus that it was the SMBHs that were unusually bulky, not the galaxies that were unusually wimpy. The second report, from Jay Lockman of NRAO and Spencer Wolfe of West Virginia University, presented the preliminary detection of very faint clumps of neutral hydrogen gas in between local group galaxies M31 (Andromeda) and M33 (Triangulum) using the Green Bank Telescope. The confirmation of such a gaseous bridge suggests previous interactions between our nearest spiral neighbors. Finally, James Rhoads from Arizona State University announced a detailed study of the faintest galaxy ever found at z~7 using narrow-band (redshifted Lyman-alpha) photometry and spectroscopy from the Magellan 6.5 m telescope in Chile. Searches for more such galaxies will help probe the timeline of reionization, Rhoads argues, as the total number detected at a given redshift depends strongly on how ionized the gas is at that time. The reason for this is that Lyman-alpha emission from a galaxy will be highly scattered if the surrounding gas is neutral, rendering the galaxy too extended to detect, while this emission will propagate directly towards us if it is ionized, meaning it will be compact enough to be observed.
12:45 pm: Introduction to Astronomical Bullying
The AAS Committee on the Status of Women in Astronomy (CSWA) organized a town hall session to bring up the idea of “Astronomical Bullying” – what it is and how to handle it. The session also included ample time for audience discussion. Astronomical bullying is behavior in a professional setting in which one individual disparages, disrespectfully attacks, or even teases another, possibly leading to stress that negatively influences the health and/or work of the person that is the subject of the bullying. This is a very subjective definition; just like traditional “playground” bullying, it can take many forms, either overt or covert, verbal or nonverbal, can come from superiors or colleagues, and affects different people in different ways. The speaker, CSWA chair Joan Schmelz, tells us that this phenomenon is real and provides some strategies for dealing with it. The first step for a victim, she implores, is to admit that it is real and not your fault. Next, she suggests avoiding being alone with the bully, and finding other victims or at least witnesses to the behavior. If necessary, filing a collective complaint with these others, and documenting the details (including emails and written transcripts of conversations), are the most effective. Most importantly, she says to talk to someone you trust, particularly if there is someone senior to you. Often their advice – or at least their listening – can solve much of the hardship, if not the cause, of the bullying. “The bully is often the biggest coward in the room,” says psychology, and this thought can often help victims realize they aren’t to blame. The session then opened up for about 30 minutes of discussion, and many interesting ideas were brought up. One of the biggest issues with this type of issue is that it’s often just “preaching to the choir,” and the people that most need to hear it aren’t in the room. One way to address this is by empowering our leaders – department chairs, society council members, and session chairs at conferences – to deal with it. Not just a policy (stating that bullying is not tolerated), but a procedure (for how to handle incidents when they occur) is needed. Incoming AAS president David Halfand drew applause from the audience when he announced that he would bring up the matter at this November’s meeting of the chairs of astronomy departments. The discussion of this important topic will no doubt continue; keep an eye on the CSWA’s website for developments.