2020ApJ...894...53K -
Astrophys. J., 894, 53-53 (2020/May-1)
The ELM Survey south. I. An effective search for extremely low mass white dwarfs.
KOSAKOWSKI A., KILIC M., BROWN W.R. and GIANNINAS A.
Abstract (from CDS):
We begin the search for extremely low mass (M <= 0.3M☉, ELM) white dwarfs (WDs) in the southern sky based on photometry from the VST ATLAS and SkyMapper surveys. We use a similar color selection method as the Hypervelocity star survey. We switched to an astrometric selection once Gaia Data Release 2 became available. We use the previously known sample of ELM white dwarfs to demonstrate that these objects occupy a unique parameter space in parallax and magnitude. We use the SOAR 4.1 m telescope to test the Gaia-based selection, and identify more than two dozen low mass white dwarfs, including six new ELM white dwarf binaries with periods as short as 2 h. The better efficiency of the Gaia-based selection enables us to extend the ELM Survey footprint to the southern sky. We confirm one of our candidates, J0500-0930, to be the brightest (G = 12.6 mag) and closest (d = 72 pc) ELM white dwarf binary currently known. Remarkably, the Transiting Exoplanet Survey Satellite (TESS) full-frame imaging data on this system reveals low-level (<0.1%) but significant variability at the orbital period of this system (P = 9.5 hr), likely from the relativistic beaming effect. TESS data on another system, J0642-5605, reveals ellipsoidal variations due to a tidally distorted ELM WD. These demonstrate the power of TESS full-frame images in confirming the orbital periods of relatively bright compact object binaries.
Abstract Copyright:
© 2020. The American Astronomical Society. All rights reserved.
Journal keyword(s):
White dwarf stars - Spectroscopy - Radial velocity - Compact objects
VizieR on-line data:
<Available at CDS (J/ApJ/894/53): table2.dat table3.dat tableb[1-5].dat>
Simbad objects:
219
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