HD 210277
Star in the constellation Aquarius
From Wikipedia, the free encyclopedia
HD 210277 is a single[11] star in the equatorial constellation of Aquarius. It has an apparent visual magnitude of 6.54,[3] which makes it a challenge to view with the naked eye, but it is easily visible in binoculars. The star is located at a distance of 69.6 light years from the Sun based on parallax, but is drifting closer with a radial velocity of −20.9 km/s.[7]
| Observation data Epoch J2000 Equinox ICRS | |
|---|---|
| Constellation | Aquarius[1] |
| Right ascension | 22h 09m 29.8658s[2] |
| Declination | −07° 32′ 55.162″[2] |
| Apparent magnitude (V) | 6.54[3] |
| Characteristics | |
| Evolutionary stage | main sequence[2] |
| Spectral type | G8V[4] or G8/K0V[5] |
| U−B color index | 0.36[6] |
| B−V color index | 0.75[6] |
| Astrometry | |
| Radial velocity (Rv) | −20.855±0.0003[7] km/s |
| Proper motion (μ) | RA: 85.407(29) mas/yr[2] Dec.: −450.617(23) mas/yr[2] |
| Parallax (π) | 46.8515±0.0283 mas[2] |
| Distance | 69.61 ± 0.04 ly (21.34 ± 0.01 pc) |
| Absolute magnitude (MV) | 4.90±0.05[8] |
| Details[9] | |
| Mass | 1.007+0.040 −0.039 M☉ |
| Radius | 1.087+0.015 −0.016 R☉ |
| Luminosity | 1.002[10] L☉ |
| Surface gravity (log g) | 4.369±0.020 cgs |
| Temperature | 5,705±35 K |
| Metallicity [Fe/H] | 0.170±0.097 dex |
| Rotation | 40.8 d[11] |
| Rotational velocity (v sin i) | 1.888±0.158 km/s |
| Age | 6.471+1.744 −1.643[9] Gyr 8.929±2.671[3] Gyr |
| Other designations | |
| BD−08°5818, GJ 848.4, GJ 9769, HD 210277, HIP 109378, SAO 145906, PPM 206033, LTT 8887, NLTT 53073, GCRV 13920, 2MASS J22092985-0732548[12] | |
| Database references | |
| SIMBAD | data |
| ARICNS | data |
Description
An early classification of HD 210277 was a G0 dwarf,[13] and some sources still use this value.[14] More modern classification surveys list it as G8V,[4] matching a late G-type main-sequence star.[11] It is older than the Sun with a very low level of chromospheric activity[4] and is spinning with a projected rotational velocity of 1.9 km/s. The star has a slightly higher mass and larger radius than the Sun.[9]
Planetary system
In 1999 it was announced that a dust disk orbiting HD 210277, similar to that produced by the Kuiper Belt, had been imaged, lying between 30 and 62 AU from the star.[15] However, observations with the Spitzer Space Telescope failed to detect any infrared excess at 70 micrometres or at 24 micrometres wavelengths.[16][17] Subsequent measurements by the Herschel Space Observatory did detect an excess at 100 and 160 micrometres. A model fit to the emission matches a disk orbiting at 160 AU with a mean temperature of 22 K.[18] The disk signal is fairly strong, with S/N equal to 6.6.[10]
The only known exoplanet was discovered using 34 radial velocity measurements taken from 1996 to 1998 at W. M. Keck Observatory. It has a minimum mass greater than Jupiter orbiting the star in 442 days.[11] The high eccentricity (ovalness) of the exoplanet's orbit means it is unlikely that there is a companion planet co-orbiting the star at a trojan point.[14]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination (°) |
Radius |
|---|---|---|---|---|---|---|
| b | >1.29±0.11 MJ | 1.138±0.066 | 442.19±0.50 | 0.476±0.017 | — | — |
| debris disk | 160[18] AU | — | — | |||