GP Comae Berenices
 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 | |
| Gaia DR2 3938156295111047680, G 61-29, LTT 18284, WD 1303+18, 2MASS J13054243+1801039[6] | |
| 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]
In 1971, Brian Warner discovered that the star, then known as G61-29, is a variable star.[10][11] it was given its variable star designation, GP Comae Berenices, in 1975.[12]
Planetary system
[edit | edit source]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.[13] 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.[14]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (seconds) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | 10.5±1.5 MJ | 0.0014[14] | 2794 | 0 | 59.5±14.5[9]° | ≤ 0.420±0.020 RJ |
References
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