KPD 0005+5106

KPD 0005+5106 is a helium-rich white dwarf^[6] located 1,350 light-years from Earth.^[2] As a "pre-white dwarf", it is believed to still be in the helium-burning phase, just before nuclear fusion finally stops. It is one of the hottest known white dwarfs, with a temperature of 200,000 K.^[4]

KPD 0005+5106

Artist impression of KPD 0005+5106 and possible companion object
Observation data Epoch J2000      Equinox J2000
Constellation	Cassiopeia[1]
Right ascension	00h 08m 18.17031s[2]
Declination	+51° 23′ 16.5984″[2]
Apparent magnitude (V)	13.32[3]
Characteristics
Evolutionary stage	Helium-burning pre-white dwarf[4]
Spectral type	DOZ1[5]
Astrometry
Proper motion (μ)	RA: +30.043 mas/yr[2] Dec.: −0.727 mas/yr[2]
Parallax (π)	2.4089±0.0355 mas[2]
Distance	1,350 ± 20 ly (415 ± 6 pc)
Details[4]
Mass	0.64+0.08 −0.04 M☉
Radius	0.059+0.031 −0.018 R☉
Luminosity	5,000 L☉
Surface gravity (log g)	6.7±0.3 cgs
Temperature	200,000±20,000 K
Database references
SIMBAD	data

Possible companion object

KPD 0005+5106 has been observed to emit high-energy X-rays that regularly increase and descrease in luminosity every 4 hours and 42 minutes. This indicates that the star possibly has a companion orbiting it. Simulations show that a Jupiter-mass object can exceed the roche lobe and is the most likely companion for KPD 0005+5106. The white dwarf pulls material from its companion into a disk around itself, before it slams into its north and south poles. The concentration of material at the poles causes the creation of two bright spots emitting high-energy X-rays.^[6][7]