HD 19467
Star in the constellation Eridanus
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HD 19467 is a star with an orbiting brown dwarf companion in the equatorial constellation of Eridanus. It has an apparent visual magnitude of 6.97,[1] which is a challenge to view with the naked eye. The system is located at a distance of 104.5 light years based on parallax measurements,[2] and is drifting further away with a radial velocity of 7 km/s.[5] It has a high proper motion, traversing the celestial sphere at an angular rate of 0.258 arcsec yr−1.[11] Based on the motion and chemical abundances of this star it has been considered a likely member of the Wolf 630 group of co-moving stars, although its age estimate is inconsistent with that assignment.[12]
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Eridanus[1] |
| Right ascension | 03h 07m 18.575s[2] |
| Declination | −13° 45′ 42.42″[2] |
| Apparent magnitude (V) | 6.97[1] |
| Characteristics | |
| Evolutionary stage | main sequence[3] |
| Spectral type | G3 V[4] + T5.5±1.0[3] |
| B−V color index | 0.645±0.010[1] |
| Astrometry | |
| Radial velocity (Rv) | 6.953±0.0003[5] km/s |
| Proper motion (μ) | RA: −8.694 mas/yr[2] Dec.: −260.642 mas/yr[2] |
| Parallax (π) | 31.2191±0.024 mas[2] |
| Distance | 104.47 ± 0.08 ly (32.03 ± 0.02 pc) |
| Absolute magnitude (MV) | 4.52[1] |
| Orbit[6] | |
| Primary | HD 19467 A |
| Name | HD 19467 B |
| Period (P) | 319+114 −72 yr |
| Semi-major axis (a) | 46.9+11.0 −7.4 AU |
| Eccentricity (e) | 0.50+0.10 −0.08 |
| Inclination (i) | 134.7+12.0 −6.9° |
| Longitude of the node (Ω) | 134.8±4.5[7]° |
| Periastron epoch (T) | 2,486,750+1,523 −1,890 BJD |
| Argument of periastron (ω) (secondary) | 280+14 −18° |
| Details | |
| HD 19467 A | |
| Mass | 0.96±0.02[8] M☉ |
| Radius | 1.20±0.03[8] R☉ |
| Luminosity | 1.42±0.06[8] L☉ |
| Surface gravity (log g) | 4.28±0.04[8] cgs |
| Temperature | 5747±40[8] K |
| Metallicity [Fe/H] | −0.11±0.01[7] dex |
| Rotation | 29.53±0.16 d[7] |
| Rotational velocity (v sin i) | 1.6±0.5[7] km/s |
| Age | 9.4±0.9[8] Gyr |
| HD 19467 B | |
| Mass | 71.6+5.3 −4.6[6] MJup |
| Luminosity | (6.49±0.98)×10−6[9] L☉ |
| Surface gravity (log g) | 4.50+0.50 −0.36[6] cgs |
| Temperature | 1,103+97 −103[6] K |
| Metallicity [Fe/H] | −0.15±0.02[9] dex |
| Other designations | |
| BD−14°604, FK5 1087, GJ 3200, HD 19467, HIP 14501, SAO 148780, PPM 212460[10] | |
| Database references | |
| SIMBAD | data |
The spectrum of HD 19467 presents as a G-type main-sequence star with a stellar classification of G3 V.[4] It has been identified as a solar twin based on the similarity of its physical properties to the Sun.[13] This is an older star,[7] with age estimates range from 5.4[3] up to 10.1 billion years,[9] depending on the study. It is considered a thin disk star, which should theoretically limit the age to no more than 8 billion years.[7] The spin rate is correspondingly low with a rotation period of 29.5 days.[7] Based on the abundance of iron, the metallicity is lower than solar.[14][7] The level of magnetic activity in the star's chromosphere as well as X-ray emission are at most below the equivalent level in the Sun.[3]
Brown dwarf
In 2014, a survey team announced the discovery of a brown dwarf in orbit around HD 19467. The presence of an low-mass companion was indicated via an acceleration trend in radial velocity time series data collected between 1996 and 2021. The object was then directly imaged using the NIRC-2 instrument at the Keck Observatory. Designated HD 19467 B, it was located at an angular separation of 1.6″ from the host star. Astrometric observations taken over a 1.1 year period demonstrated that the object is clearly associated with HD 19467 A, having a similar parallax and proper motion. The radial velocity data indicated a minimum mass of 51.9+3.6
−4.3 MJ, with a brightness and colors matching a T-dwarf.[15]
The spectrum of this object was taken at the Palomar Observatory, finding a spectral type of T5.5±1. It was measured as having an effective temperature of 978 K and, like the host star, a sub-solar metallicity.[16] Orbital analysis was used to infer a mass of 65.4 MJ, which is near the substellar mass boundary. It has a highly eccentric orbit with period estimates ranging from 320 to 420 years, depending on the study.[3]
See also
- Scholz's Star – a star with a brown dwarf companion of similar mass to HD 19467 B[3]