| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Hydra |
| Right ascension | 08h 44m 25.70315s[1] |
| Declination | +01° 51′ 36.1055″[1] |
| Apparent magnitude (V) | 10.83 |
| Characteristics | |
| Evolutionary stage | main-sequence star |
| Spectral type | G9V[2] |
| Astrometry | |
| Radial velocity (Rv) | −11.63±0.21[1] km/s |
| Proper motion (μ) | RA: −23.344mas/yr[1] Dec.: −31.570mas/yr[1] |
| Parallax (π) | 9.9636±0.0149 mas[1] |
| Distance | 327.3 ± 0.5 ly (100.4 ± 0.2 pc) |
| Details[3] | |
| Mass | 0.842+0.037 −0.036 M☉ |
| Radius | 0.748±0.015 R☉ |
| Surface gravity (log g) | 4.63±0.06[4] cgs |
| Temperature | 5350±31[4] K |
| Metallicity [Fe/H] | 0.05±0.02[4] dex |
| Rotation | 14.36±0.35d |
| Rotational velocity (v sin i) | 4.10±0.30 km/s |
| Age | 8.5+4.1 −5.5 Gyr |
| Other designations | |
| BD+02 2056,Gaia DR2 3078836109158636928,WASP-84,TYC 211-706-1,GSC 00211-00706,2MASS J08442570+0151361[5] | |
| Database references | |
| SIMBAD | data |
WASP-84, also known asBD+02 2056, is aG-type main-sequence star 327light-years (100parsecs) away in the constellationHydra. Its surface temperature is 5350±31K and is slightly enriched in heavy elements compared to theSun, with ametallicity Fe/H index of 0.05±0.02. It is rich in carbon and depleted of oxygen.[4] WASP-84's age is probably older than theSun at 8.5+4.1
−5.5 billion years.[3] The star appears to have an anomalously small radius, which can be explained by the unusually high helium fraction or by it being very young.[6]
A multiplicity survey did not detect any stellar companions to WASP-84 as of 2015.[7]
In 2013, oneexoplanet, namedWASP-84b, was discovered on a tight, circular orbit.[8] The planet is ahot Jupiter that cannot have formed in its current location and likely migrated from elsewhere. The planetary orbit is well aligned with the equatorial plane of the star, misalignment being equal to 0.3±1.7°. Planetary equilibrium temperature is 832±13K.[2]
In 2023, a second planet was discovered around WASP-84. This appears to be a denserocky planet despite its high mass, comparable toUranus.[9]
| Companion (in order from star) | Mass | Semimajor axis (AU) | Orbital period (days) | Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| c | 15.2+4.5 −4.2 M🜨 | 0.02359±0.00100 | 1.4468849+0.0000022 −0.0000016 | — | 83.20+0.51 −0.49° | 1.95±0.12 R🜨 |
| b | 0.692±0.058 MJ | 0.0778±0.0021 | 8.52349648(60) | <0.077[3] | 88.292+0.045 −0.042° | 0.956±0.024 RJ |
