HD 86226
Star in the constellation Hydra
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HD 86226 is a star with a pair of orbiting exoplanet companions, found in the constellation of Hydra. With an apparent visual magnitude of 7.93,[1] it is too dim to be visible with the naked eye. The distance to this system has been determined by the parallax method, yielding a range of 149 light years. It is receding with a heliocentric radial velocity of +19.6 km/s.[4] A survey in 2015 has ruled out the existence of any stellar companions at projected distances above 12 astronomical units.[8]
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Hydra[1] |
| Right ascension | 09h 56m 29.844s[2] |
| Declination | −24° 05′ 57.80″[2] |
| Apparent magnitude (V) | 7.93[1] |
| Characteristics | |
| Evolutionary stage | main sequence[2] |
| Spectral type | G2V[3] |
| Apparent magnitude (B) | 8.577[1] |
| Apparent magnitude (R) | 7.71[1] |
| Apparent magnitude (J) | 6.839±0.019[1] |
| Apparent magnitude (H) | 6.577±0.034[1] |
| Apparent magnitude (K) | 6.463±0.023[1] |
| B−V color index | 0.647±0.014[1] |
| V−R color index | 0.22[4] |
| Astrometry | |
| Radial velocity (Rv) | +19.56±0.19[4] km/s |
| Proper motion (μ) | RA: −177.127 mas/yr[2] Dec.: +47.099 mas/yr[2] |
| Parallax (π) | 21.9301±0.0267 mas[2] |
| Distance | 148.7 ± 0.2 ly (45.60 ± 0.06 pc) |
| Absolute magnitude (MV) | 4.66[1] |
| Details[5] | |
| Mass | 1.08±0.05 M☉ |
| Radius | 1.03±0.02 R☉ |
| Luminosity | 1.24+0.09 −0.07 L☉ |
| Surface gravity (log g) | 4.41±0.02 cgs |
| Temperature | 6,007+75 −71 K |
| Metallicity [Fe/H] | −0.015±0.041 dex |
| Rotation | 22.8±3.0 days |
| Rotational velocity (v sin i) | 3.6[6] km/s |
| Age | 3.8±1.8 Gyr |
| Other designations | |
| CD−23°8866, HD 86226, HIP 48739, SAO 178205, PPM 256971[7] | |
| Database references | |
| SIMBAD | data |
| Exoplanet Archive | data |
Description
This is an ordinary G-type main-sequence star with a stellar classification of G2V.[3] It is similar in size, mass, and composition to the Sun,[9] although it is not considered a solar twin.[10] The age is about 3.8 billion years old. The star is radiating 18% greater luminosity (compared to the Sun) from its photosphere at an effective temperature of 5,863 K.[9] It is spinning with a projected rotational velocity of 3.6 km/s.[6]
As of 2014[update], Radio emission at a frequency of 150 MHz has been tentatively detected from the proximity of this system, although it is not clear whether the star or a satellite orbiting a rapidly rotating planet is the source.[11]
Planetary system
Due to the periodic spectrum shifts when it had when placed under a Doppler test, 13 Magellan Doppler Velocity observations were made of an object found near the star. The object discovered in 2010 had a Keplerian orbit, was declared an exoplanet and dubbed HD 86226 b.[12] A hot Super-Earth planet called HD 86226 c was discovered in 2020.[9] It may be undergoing considerable atmospheric mass loss.[13]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| c | 7.25+1.19 −1.12[9] M🜨 |
0.049±0.001[9] | 3.984436±0.000217[5] | 0.06±0.08[5] | 86.45+0.26 −0.16[9]° |
2.16±0.08[9] R🜨 |
| b | 0.46±0.04[5] MJ | 2.73±0.06[14] | 1,609.5±19.4[5] | 0.04±0.07[5] | — | — |
See also
- HD 129445
- HD 152079
- HD 164604
- HD 175167
- List of exoplanets discovered in 2010 - HD 86226 b
- List of exoplanets discovered in 2020 - HD 86226 c