Beyond the Local Volume. I. Surface Densities of Ultracool Dwarfs in Deep HST/WFC3 Parallel Fields
Physics and Astronomy
Ultracool dwarf stars and brown dwarfs provide a unique probe of large-scale Galactic structure and evolution; however, until recently spectroscopic samples of sufficient size, depth, and fidelity have been unavailable. Here, we present the identification of 164 M7-T9 ultracool dwarfs in 0.6 deg2 of deep, low-resolution, near-infrared spectroscopic data obtained with the Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) instrument as part of the WFC3 Infrared Spectroscopic Parallel Survey and the 3D-HST survey. We describe the methodology by which we isolate ultracool dwarf candidates from over 200,000 spectra, and show that selection by machine-learning classification is superior to spectral index-based methods in terms of completeness and contamination. We use the spectra to accurately determine classifications and spectrophotometric distances, the latter reaching to ∼2 kpc for L dwarfs and ∼400 pc for T dwarfs.
Original Publication Information
Christian Aganze et al. "Beyond the Local Volume. I. Surface Densities of Ultracool Dwarfs in Deep HST/WFC3 Parallel Fields." 2022 Astrophysical Journal 924(2): 1-28.
Aganze, Christian; Burgasser, Adam J.; Malkan, Mathew; Theissen, Christopher A.; Arevalo, Roberto A. Tejada; Hsu, Chih-Chun; Gagliuffi, Daniella C. Bardalez; Ryan, Russell E. Jr.; and Holwerda, Benne, "Beyond the Local Volume. I. Surface Densities of Ultracool Dwarfs in Deep HST/WFC3 Parallel Fields" (2022). Faculty Scholarship. 825.
© 2022. The Author(s). Published by the American Astronomical Society.