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Abstract We conducted a search for new ultracool companions to nearby white dwarfs using multiple methods, including the analysis of colors and examination of images in both the optical and the infrared. Through this process, we identified 51 previously unrecognized systems with candidate ultracool companions. 31 of these systems are resolved in at least one catalog, and all but six are confirmed as comoving companions via common proper motion and consistent parallax measurements (when available). We have followed up four comoving companions with near-infrared spectroscopy and confirm their ultracool nature. The remaining twenty candidates are unresolved, but show clear signs of infrared excess which is most likely due to the presence of a cold, low-mass companion or a dusty circumstellar disk. Three of these unresolved systems have existing optical spectra that clearly show the presence of a cool stellar companion to the white dwarf primary via spectral decomposition. These new discoveries, along with our age estimates for the primary white dwarfs, will serve as valuable benchmark systems for future characterization of ultracool dwarfs.
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High Proper Motion Discoveries from the UKIRT Hemisphere Survey
Abstract We used the third data release of the UKIRT Hemisphere Survey to locate previously unrecognized high proper motion objects. We identify a total of 127 new discoveries with total proper motions ≳300 mas yr−1. A significant fraction of these sources with counterparts in the Gaia DR3 catalog are found to be distant (>100 pc) low-mass stars, where their large tangential velocities and placement on color–magnitude diagrams suggest that they are likely low-metallicity M-type subdwarfs. Optical spectroscopy is used to confirm the low mass and low metallicity for two such sources. Using available optical and infrared photometry, we estimate the spectral type for all non-Gaia sources and find 10 likely late-M dwarfs, 15 objects with colors most consistent with L-type dwarfs, and nine possible T-type dwarfs. Follow-up spectroscopy is needed to confirm spectral types and further characterize these new discoveries.
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- Award ID(s):
- 2238468
- PAR ID:
- 10674133
- Author(s) / Creator(s):
- ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; more »
- Publisher / Repository:
- The Astronomical Journal
- Date Published:
- Journal Name:
- The Astronomical Journal
- Volume:
- 170
- Issue:
- 5
- ISSN:
- 0004-6256
- Page Range / eLocation ID:
- 277
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
-
Accepted Manuscript
- Journal Article:
- https://doi.org/10.3847/1538-3881/ae0ad5
