Paul Abell, NASA Johnson Flight Center
I will present the current status of NASA’s Asteroid Redirect Mission (ARM) that is planned for launch in December 2021. Specifically I will discuss how a solar-electric powered robotic spacecraft will visit a large near-Earth asteroid (NEA), collect a multi-ton boulder from its surface, perform a planetary defense technique at the NEA, and return with the boulder into a stable orbit around the Moon. I will also discuss how astronauts aboard an Orion spacecraft will subsequently explore the boulder, conduct investigations during their extravehicular activities, and return samples to Earth. I will demonstrate how the ARM is part of NASA’s plan to advance technologies, capabilities, and spaceflight experience needed for a human mission to the Martian system in the 2030s. Finally I will discuss how the ARM and subsequent availability of the asteroidal material in cis-lunar space, provide significant opportunities to advance our knowledge of small bodies in terms of science, planetary defense, and in-situ resource utilization (ISRU).
Extinction mapping with LEGUS
The study of star formation and galaxy evolution in nearby galaxies depends on obtaining accurate stellar photometry in those galaxies. However, dust in the galaxies hinders our ability to obtain accurate stellar photometry, particularly in star-forming galaxies that have the highest concentrations of dust. This proposal presents a thesis project to develop a method for generating extragalactic extinction maps using photometry of massive stars from the Hubble Space Telescope. This photometry spans nearly 50 galaxies observed by the Legacy Extragalactic Ultraviolet Survey (LEGUS). The derived extinction maps can be used to correct other stars and Halpha maps (from the Halpha LEGUS) for extinction, and will be used to constrain changes in the dust-to-gas ratio across the galaxy sample and in different star formation rate, metallicity and morphological environments. Previous studies have found links between galaxy metallicty and the dust-to-gas mass ratio. The relationship between these two quantities can be used to constrain chemical evolution models.
Selected galaxies will also be compared to IR-derived dust maps for comparison to recent M31 results from Dalcanton et al. (2015) which found a minimum factor of 2 inconsistency between their extinction-derived maps and emission-derived maps from Draine et al. (2014).
A Faint Flux-Limited LAE Sample at z = 0.3
Isak Wold, UT Austin
Observational surveys of Lya emitters (LAEs) have proven to be an efficient method to identify and study large numbers of galaxies over a wide redshift range. To understand what types of galaxies are selected in LAE surveys – and how this evolves with redshift – it is important to establish a low-redshift reference sample that can be directly compared to high-redshift samples. The lowest redshift where a direct Lya survey is currently possible is at a redshift of z~0.3 via the Galaxy Evolution Explorer (GALEX ) FUV grism data. Using the z~0.3 GALEX sample as an anchor point, it has been suggested that at low redshifts high equivalent width (EW) LAEs become less prevalent and that the amount of escaping Lya emission declines rapidly. A number of explanations for these trends have been suggested including increasing dust content, increasing neutral column density, and/or increasing metallicity of star-forming galaxies at lower redshifts. However, the published z~0.3 GALEX sample is pre-selected from bright NUV objects. Thus, objects with strong Lya emission but faint continuum (high-EW LAEs) could be missed. In this talk, I will present my efforts to re-reduce the deepest archival GALEX FUV grism data and obtain a sample that is not biased against high-EW LAEs. I will discuss the implications of this new sample on the evolutionary trends listed above.