An ultraviolet band light curve for GP Comae Berenices, adapted from Smak (1975).[1] The error bar shown on the leftmost point applies to all points. | |
Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Coma Berenices |
Right ascension | 13h 05m 42.401s[2] |
Declination | +18° 01′ 03.76″[2] |
Apparent magnitude (V) | 15.69[3] |
Characteristics | |
Evolutionary stage | White dwarf |
Spectral type | DBe[4] |
Apparent magnitude (g) | 15.929[2] |
Variable type | AM CVn |
Astrometry | |
Proper motion (μ) | RA: −344.92±0.06 mas/yr[2] Dec.: 34.85±0.06 mas/yr[2] |
Parallax (π) | 13.7306 ± 0.0452 mas[2] |
Distance | 237.5 ± 0.8 ly (72.8 ± 0.2 pc) |
Details[5] | |
Mass | 0.59±0.09 M☉ |
Temperature | 14,800±500 K |
Other designations | |
Database references | |
SIMBAD | data |
GP Comae Berenices, abbreviated to GP Com and also known as G 61-29, is a star system composed of a white dwarf orbited by a planetary mass object, likely the highly eroded core of another white dwarf star.[7] The white dwarf is slowly accreting material from its satellite at a rate of (3.5±0.5)×10−11 M☉/year and was proven[8] to be a low-activity AM CVn star.[7][5] The star system is showing signs of a high abundance of ionized nitrogen from the accretion disk around the primary.[9]
The material emitted from the planetary mass companion is mostly helium, with a molar ratio of nitrogen up to 1.7%, very low neon levels and other elements not detectable at all.[10] Approximately half of the luminosity of the system comes from the accretion disk.[5] The planetary object is suspected to contain a strange quark matter core due to its unusually high density, which must be above 187.5 g/cm3 to prevent tidal disruption; the theoretical bound for planets composed solely of ordinary matter is on the order of 30 g/cm3. The object's orbit is expected to decay within 100 million years due to gravitational wave emission.[11]
Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (seconds) |
Eccentricity | Inclination | Radius |
---|---|---|---|---|---|---|
b | 10.5±1.5 MJ | 0.0014[11] | 2794 | 0 | 59.5±14.5[9]° | ≤ 0.420±0.020 RJ |