Over the past two weeks, several astrobites authors have been attending the 28th General Assembly of the International Astronomical Union in Beijing, China. Like the semi-annual AAS meetings in the United States, the IAU General Assemblies are large meetings covering a range of topics in astronomy. Each meeting is subdivided into symposia, special sessions, and joint discussions covering specific research areas. You can view the full list of 34(!) topics here, but the list includes sessions like “Science with Large Solar Telescopes, “Calibration of Star Formation Rate Measurements Across the Electromagnetic Spectrum”, “Astrophysics in Antarctica,” and “The Intriguing Life of Massive Galaxies.” Each of the sessions could stand alone as a complete conference, so the IAU General Assembly is a very busy meeting.
For today’s astrobite, I decided to feature five of the hundreds of fantastic posters on display at the conference. I had an incredibly hard time narrowing down the sample of posters and I highly encourage anyone currently attending the IAU to rush to the poster hall to view the posters that I wasn’t able to include in this post. If you presented a poster at the IAU and you’d like your poster to be featured on astrobites, please comment on this post with a short blurb about your research.
Poster 1: Gas Velocity Dispersions and Star Formation
- Authors: K. M. Mogotsi, W. J. G. de Blok, and the HERACLES team
- First Author’s Affiliation: University of Cape Town Astronomy Department/ACGC
- Blurb: Mogotsi et al. combine measurements of the velocity dispersion of neutral hydrogen and carbon monoxide in nearby galaxies in order to test the common assumption that the distribution of neutral hydrogen can be inferred from the distribution of carbon monoxide. They obtain their neutral hydrogen data from The HI Nearby Galaxy Survey (THINGS) and their carbon monoxide data from the HERA (Heterodyne Receiver Array) CO Line Extragalactic Survey (HERACLES). They find that neutral hydrogen has a wider velocity dispersion than carbon monoxide and that the dispersions of both gases are correlated with the star formation rate.
Poster 2: The Infrared Extinction Law in Different Interstellar Environments
- Authors: Shu Wang, Jian Gao, & B. W. Jiang
- First Author’s Affiliation: Department of Astronomy, Beijing Normal University
- Blurb: Wang et al. address the question of how extinction varies along different lines of sight by observing red giant stars along nine different paths and using the observed near-infrared colors of the stars to determine the level of extinction. They discover that the relative extinction (extinction at visible wavelengths divided by extinction at near-infrared wavelengths) is highest when they look toward diffuse regions and lowest when they observe through dense regions and they attribute the decreased relative extinction in dense regions to the growth of dust grains.
Poster 3: Observation and Modelling of Transits and Starspots in the WASP-19 Planetary System
- Authors: Jeremy Tregloan-Reed & John Southworth
- First Author’s Affiliation: Keele University, Staffordshire, UK
- Blurb: Tregloan-Reed & Southworth present a new procedure to simultaneously determine planet and starspot properties from transit light curves. They fit three light curves of the hot Jupiter WASP-19b and find that the host star has a rotation period of 10.4 days. Their analysis also suggests that the planet’s orbit is aligned with the stellar spin axis, which agrees well with previous measurements using another method to measure the orientation between the stellar spin axis and the planet orbit.
Poster 4: Importance of the Cooling Parameters in the Dynamical Evolution of Sgr A*
- Authors: Salome Dibi, S. Drappeau, S. Merkoff, & C. Fragile
- First Author’s Affiliation: University of Amsterdam
- Blurb: Dibi and her collaborators conduct general relativistic magneto-hydrodynamic numerical simulations of the accretion disk surrounding the black hole at the center of the Milky Way galaxy (Sgr A*). They find that the initial magnetic field configuration and the accretion rate strongly influence the behavior of the accretion disk. As part of their study, Dibi et al. find that self-consistent modeling of radiative cooling is crucial for modeling black holes with higher accretion rates than Sgr A*.
Poster 5: Discovery of Super-Lithium-Rich Red Giants in Dwarf Spheroidal Galaxies
- Authors: Xiaoting Fu, Evan N Kirby, Licai Deng, & Puragra Guhathakurta
- First Author’s Affiliation: National Astronomical Observatories, Chinese Academy of Sciences
- Blurb: Lithium should be destroyed in the convective envelopes of red giant stars, but Fu et al. present a sample of 15 lithium-rich red giants. These stars have lithium abundances higher than the primordial abundance of lithium, which means that the stars must have created the additional lithium. Lu et al. theorize that all red giant stars undergo a lithium enrichment phase and that lithium-rich red giants seem rare only because the lithium-enrichment phase lasts for a very short amount of time.