KELT-2
Star in the constellation Auriga
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KELT-2 (also called HD 42176) is a binary star located about 439 light-years away in the constellation Auriga. The apparent magnitude of the system is 8.68[5], which means it is not visible to the naked eye but can be seen with binoculars. The system is moving towards the Sun at over 40 km/s.[2]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Auriga[1] |
| KELT-2A | |
| Right ascension | 06h 10m 39.345s[2] |
| Declination | +30° 57′ 25.71″[2] |
| Apparent magnitude (V) | 8.77±0.01[3] |
| KELT-2B | |
| Right ascension | 06h 10m 39.258s[4] |
| Declination | +30° 57′ 27.85″[4] |
| Apparent magnitude (V) | 11.9±0.2[3] |
| Characteristics | |
| Spectral type | F7 V[1] + K2 V[3] |
| Apparent magnitude (G) | 8.59[2] + 11.99[4] |
| B−V color index | 0.53[1] |
| Astrometry | |
| A | |
| Radial velocity (Rv) | −47.38[2] km/s |
| Proper motion (μ) | RA: 16.865[2] mas/yr Dec.: −2.155[2] mas/yr |
| Parallax (π) | 7.4327±0.0217 mas[2] |
| Distance | 439 ± 1 ly (134.5 ± 0.4 pc) |
| Absolute magnitude (MV) | 3.27[1] |
| B | |
| Radial velocity (Rv) | −40.93±2.01[4] km/s |
| Proper motion (μ) | RA: 17.864±0.026[4] mas/yr Dec.: −3.589±0.019[4] mas/yr |
| Parallax (π) | 7.2950±0.0255 mas[4] |
| Distance | 447 ± 2 ly (137.1 ± 0.5 pc) |
| Details[5] | |
| A | |
| Mass | 1.314+0.063 −0.060[5] M☉ |
| Radius | 1.84+0.07 −0.05[5] R☉ |
| Luminosity | 3.5[5] L☉ |
| Surface gravity (log g) | 4.03+0.02 −0.03[5] cgs |
| Temperature | 6148±48[5] K |
| Metallicity [Fe/H] | 0.03±0.08[5] dex |
| Rotation | 12.9+0.2 −0.5 d[5] |
| Rotational velocity (v sin i) | 9±2[5] km/s |
| Age | 3.97±0.01[5] Gyr |
| B | |
| Mass | 0.78[3] M☉ |
| Radius | 0.7[3] R☉ |
| Surface gravity (log g) | 4.65[3] cgs |
| Temperature | 4850±150[3] K |
| Other designations | |
| BD+30 1138, HD 42176, HIP 29301, WDS J06107+3057, TYC 2420-899-1, 2MASS J06103935+3057258 | |
| Database references | |
| SIMBAD | HD 42176 |
| HD 42176 B | |
Description
KELT-2A is the primary star in the common-proper-motion binary star system KELT-2 (HD 42176). It is an F-type main sequence star[1] about 1.314 times as massive as the sun[5]. It has about 1.84 times the Sun's radius and radiates 3.5 times the Sun's luminosity at a temperature of about 6148 K.[5] It is 3.97 billion years old and has a rotational velocity of around 9 km/s.[5] KELT-2B is an early K dwarf approximately 295 AU away, which was discovered simultaneously with the planet KELT-2Ab in 2012.[3] It has 78% of the Sun's mass, 70% of its radius, and an effective temperature of 4850±150 K.[3]
Planetary system
This star has one known planet, the extrasolar planet KELT-2Ab, a hot jupiter orbiting the star at an average distance of 0.05504±0.00086 AU with an orbital period of 4.11379±0.00001 days.[3]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination (°) |
Radius |
|---|---|---|---|---|---|---|
| b | 1.524 ± 0.088 MJ | 0.05504 ± 0.00086 | 4.113789 ± 0.000009 | 0 | — | 1.290 ± 0.057 RJ |