HD 213240
Possible binary star system in the constellation Grus
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HD 213240 is a possible binary star[10] system in the constellation Grus. It has an apparent visual magnitude of 6.81,[2] which lies below the limit of visibility for normal human sight. The system is located at a distance of 133.5 light years from the Sun based on parallax. The primary has an absolute magnitude of 3.77.[2]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Grus |
| Right ascension | 22h 31m 00.36634s[1] |
| Declination | −49° 25′ 59.7690″[1] |
| Apparent magnitude (V) | 6.81[2] |
| Characteristics | |
| Spectral type | G0/G1V[3] + M5-5.5[4] |
| B−V color index | 0.603±0.005[2] |
| Astrometry | |
| Radial velocity (Rv) | −0.37±0.12[1] km/s |
| Proper motion (μ) | RA: −135.912 mas/yr[1] Dec.: −193.844 mas/yr[1] |
| Parallax (π) | 24.4247±0.0208 mas[1] |
| Distance | 133.5 ± 0.1 ly (40.94 ± 0.03 pc) |
| Absolute magnitude (MV) | 3.77[2] |
| Details | |
| Mass | 1.57±0.02[5] M☉ |
| Radius | 1.56+0.03 −0.04[6] R☉ |
| Luminosity | 2.687+0.007 −0.006[6] L☉ |
| Surface gravity (log g) | 4.17±0.02[7] cgs |
| Temperature | 5,921+70 −58[6] K |
| Metallicity [Fe/H] | 0.14±0.01[2] dex |
| Rotational velocity (v sin i) | 3.5[8] km/s |
| Age | 4.6±0.6[7] Gyr |
| Other designations | |
| CD−50° 13701, HD 213240, HIP 111143, SAO 231175, LTT 9047[9] | |
| Database references | |
| SIMBAD | data |
This is an ordinary G-type main-sequence star with a stellar classification of G0/G1V.[3] It is a metal-rich star with an age that has been calculated as being anywhere from 2.7 to 4.6 billion years.[10] The star has 1.6[5] times the mass of the Sun and 1.56[6] times the Sun's radius. It is spinning with a projected rotational velocity of 3.5 km/s.[8] The star is radiating 2.69[6] times the luminosity of the Sun from its photosphere at an effective temperature of 5,921 K.[6]
A red dwarf companion star was detected in 2005 with a projected separation of 3,898 AU.[10]
Planetary system
The Geneva extrasolar planet search team discovered a planet orbiting this star in 2001.[11] Since this planet was discovered by radial velocity, only its minimum mass was initially known, and there was a 5% chance of it being massive enough to be a brown dwarf.[10] In 2023, the inclination and true mass of HD 213240 b were determined via astrometry, confirming its planetary nature.[12]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (years) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | 5.21+1.5 −0.49 MJ |
1.92±0.026 | 2.4071+0.008 −0.0083 |
0.4201+0.01 −0.0093 |
63+17 −20 or 117+20 −17° |
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