The brightest pure-H ultracool white dwarf
We report the identification of LSR J0745+2627 in the United Kingdom InfraRed Telescope Infrared Deep Sky Survey (UKIDSS) Large Area Survey (LAS) as a cool white dwarf with kinematics and age compatible with the thick-disk/halo population. LSR J0745+2627 has a high proper motion (890 mas/yr) and a high reduced proper motion value in the J band (H-J = 21.87). We show how the infrared-reduced proper motion diagram is useful for selecting a sample of cool white dwarfs with low contamination. LSR J0745+2627 is also detected in the Sloan Digital Sky Survey (SDSS) and the Wide-field Infrared Survey Explorer (WISE). We have spectroscopically confirmed this object as a cool white dwarf using X-Shooter on the Very Large Telescope. A detailed analysis of its spectral energy distribution reveals that its atmosphere is compatible with a pure-H composition model with an effective temperature of 3880 +/- 90 K. This object is the brightest pure-H ultracool white dwarf (T-eff <4000 K) ever identified. We have constrained the distance (24-45 pc), space velocities and age considering different surface gravities. The results obtained suggest that LSR J0745+2627 belongs to the thick-disk/halo population and is also one of the closest ultracool white dwarfs.
Item Type | Article |
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Uncontrolled Keywords | white dwarfs; stars: Population II; stars: abundances; stars: individual: ULAS J074509.02+262705.0; stars: individual: SDSS J074509.02+262705.0; stars: fundamental parameters; DIGITAL-SKY-SURVEY; MODEL ATMOSPHERE ANALYSIS; LUMINOSITY FUNCTION; PHOTOMETRIC SYSTEM; SOLAR NEIGHBORHOOD; NORTHERN STARS; 3D KINEMATICS; SPY PROJECT; CATALOG |
Date Deposited | 27 Jul 2024 00:05 |
Last Modified | 27 Jul 2024 00:06 |
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Read more research from the creator(s):
- Catalan, S.
- Tremblay, P. -E.
- Pinfield, D.J.
- Smith, Leigh
- Zhang, Z. H.
- Napiwotzki, R.
- Marocco, F.
- Day-Jones, A. C.
- Gomes, J.
- Forde, K.P.
- Lucas, P.W.
- Jones, H.R.A.
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