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Observation data
Epoch J2000      Equinox J2000
Constellation Ursa Minor
Right ascension  15h 02m 09.6297s[1]
Declination +66° 12′ 19.1461″[1]
Apparent magnitude (V) 15.9
Proper motion (μ) RA: −6.055±0.128[1] mas/yr
Dec.: 8.106±0.112[1] mas/yr
Parallax (π)2.0573 ± 0.0591[1] mas
Distance1,590 ± 50 ly
(490 ± 10 pc)
Temperature200,000 K
Other designations
WD 1501+663
Database references

H1504+65 is an enigmatic peculiar star in the constellation Ursa Minor. With a surface temperature of 200,000 K and an atmosphere composed of carbon, oxygen and 2% neon, it is the hottest white dwarf ever discovered. It is thought to be the stellar core of a post AGB star, though its composition is unexplainable by current models of stellar evolution.[2]


  1. ^ a b c d e Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  2. ^ Werner, K.; Rauch, T. (2011). "UV spectroscopy of the hot bare stellar core H1504+65 with the HST Cosmic Origins Spectrograph". Astrophysics and Space Science. 335 (1): 121–24. Bibcode:2011Ap&SS.335..121W. doi:10.1007/s10509-011-0617-x.