Hogg_WD_BD_final.pdf (1.82 MB)
Confirming new white dwarf-ultracool dwarf binary candidates
journal contributionposted on 2020-09-08, 16:11 authored by Miriam Hogg, Sarah Casewell, Graham Wynn, Emma Longstaff, Ian Braker, Matthew Burleigh, Rosanna Tilbrook, Stephan Geier, Detlev Koester, John Debes, Nicolas Lodieu
We present the results of a study to discover prospective new white dwarf-L dwarf binaries as identified by their near-infrared excesses in the UKIDSS catalogue. We obtained optical spectra to validate the white dwarf nature for 22 of the candidate primary stars, confirming ten as white dwarfs and determining their effective temperatures and gravities. For all 10 white dwarfs, we determined that the near-infrared excess was indeed indicative of a cool companion. Six of these are suggestive of late M dwarf companions, and three are candidate L dwarf companions, with one straddling the M−L boundary. We also present near-infrared spectra of eight additional candidate white dwarf-ultracool dwarf binaries, where the white dwarf primary had been previously confirmed. These spectra indicate one candidate at the M−L boundary, three potential L dwarf companions, and one suspected M dwarf, which showed photometric variability on a ∼6 h period, suggesting the system may be close. Radial velocity follow-up is required to confirm whether these systems are close, or widely separated.
CitationMonthly Notices of the Royal Astronomical Society, Volume 498, Issue 1, October 2020, Pages 12–24, https://doi.org/10.1093/mnras/staa2233
Author affiliationDepartment of Physics and Astronomy
- AM (Accepted Manuscript)