02h12m31.4785s, +51° 46′ 43.5621″| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Andromeda |
| Right ascension | 00h52m 00.1876s[1] |
| Declination | +34° 43′ 42.205″[1] |
| Apparent magnitude (V) | 13.03[2] |
| Characteristics | |
| Evolutionary stage | main-sequence star |
| Spectral type | G |
| Astrometry | |
| Radial velocity (Rv) | 48.06[3] km/s |
| Proper motion (μ) | RA: 25.615(14) mas/yr[1] Dec.: 2.712(11) mas/yr[1] |
| Parallax (π) | 2.4728 ± 0.0156 mas[1] |
| Distance | 1,319 ± 8 ly (404 ± 3 pc) |
| Orbit[4] | |
| Primary | HAT-P-28 |
| Companion | HAT-P-28 B |
| Semi-major axis (a) | 0.994±0.002" (404 AU) |
| Details[5] | |
| Mass | 1.02±0.05 M☉ |
| Radius | 1.10+0.09 −0.07 R☉ |
| Luminosity | 1.13+0.23 −0.16[2] L☉ |
| Surface gravity (log g) | 4.36±0.06[2] cgs |
| Temperature | 5680±90[2] K |
| Metallicity [Fe/H] | 0.12±0.08[2] dex |
| Rotational velocity (v sin i) | 0.2+0.5 −0.2[2] km/s |
| Age | 6.1+2.6 −1.9[2] Gyr |
| Other designations | |
Gaia DR2 363702817083391232, GSC 02284-00503, 2MASS J00520018+3443422[3] | |
| Database references | |
| SIMBAD | data |
HAT-P-28 is the primary of a binary star system about 1320 light-years away. It is a G-type main-sequence star. The star's age is older than the Sun's at 6.1+2.6
−1.9 billion years.[2] HAT-P-28 is slightly enriched in heavy elements, having a 130% concentration of iron compared to the Sun. Since 2014, the binary star system is suspected to be surrounded by a debris disk with a 6.1″(2500 AU) radius.[6]
The red dwarf stellar companion was detected in 2015 at a projected separation of 0.972″[7] and confirmed in 2016 to be either bound or comoving.[4]
In 2011 a transiting hot Jupiter planet b was detected on a nearly circular orbit. The planetary equilibrium temperature is 1384±52K.[2] No orbital decay was detected as in 2018, despite the close proximity of the planet to the host star.[5]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | 0.626±0.037 MJ | 0.0434±0.0007 | 3.257215±0.000007 | 0.051±0.033 | 88.0±0.9° | 1.190+0.102 −0.075 RJ |
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