Tuesday, September 04, 2018, 03:30pm - 04:30pm
This repeat is an exception to the normal repeat pattern
Fabiola Campos, The University of Texas at Austin
Outliers in globular clusters: the case of 47 Tucanae
Abstract
We used HST multicolor photometric data of the globular cluster 47 Tucanae to find 25 outliers from the single-star model tracks in the color-magnitude diagram. All these objects are likely members of 47 Tucanae. By comparing those sources with evolutionary models, we were able to show that the majority of those sources are likely binary systems. We have also compared with X-ray source catalogues and found no nearby sources. We concluded that these outliers are most likely formed by a white dwarf and a main-sequence star and a small number of possible double-degenerate systems.
Hope Chen, The University of Texas at Austin
An Updated Story of Structure Formation in Molecular Clouds: What if the Physics Does Not Care About Forming Stars?
Abstract
Dense cores and clumps form in molecular clouds, and stars form in these gravitationally dominated dense cores and clumps. Such a linear story of star formation has dominated the narrative of star formation theory since the 1980s. In this talk, I will present the discovery of a population of coherent structures in nearby molecular clouds, which hint at an updated star formation theory that needs to explain the formation of structures—imminently star forming or not—through the turbulent processes. I will also present a few ongoing projects focusing on implementing statistical and visualization tools that will help us better understand the structure formation in molecular clouds.
Andrew Graus, The University of Texas at Austin
The Timing of Reionization and the Distribution of Milky Way Satellites
Abstract
A standard prediction of galaxy formation theory is that the ionizing background suppresses galaxy formation in haloes with peak circular velocities smaller than Vpeak ~ 20 km/s, rendering the majority of haloes below this scale completely dark. Such a process is believed to be the solution to explaining the lack of satellite galaxies around the Milky Way compared to dark matter substructures. However, the large number of dwarf galaxies discovered in DES, and recent hydrodynamics simulations have called this standard prediction into question. I will re-analyze the question of where dark matter substructure should become dark, and further discuss how the timing of reionization can impact the formation of dwarf galaxies, using state-of-the-art simulations.
David Guszejnov, The University of Texas at Austin
The Origin of Scales and Scaling Laws in Star Formation
Abstract
In the first part of the talk I will focus on the origin of the IMF peak, the characteristic scale of stars. Several popular IMF models argue this mass is set by isothermal turbulence, I will demonstrate that not to be the case, additional physics (e.g. feedback) is required to set the IMF peak. Theories are further constrained by the near universal IMF of the Milky Way that I will explore with simulated galaxies. Finally, I will present analytic arguments (supported by simulations) that a large number of observables (e.g. IMF slope) are the consequences of scale-free structure formation and are (to first order) unsuitable for differentiating between star formation theories.
Location: RLM 15.216B
