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HD 19467
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]
Distance104.47 ± 0.08  ly
(32.03 ± 0.02  pc)
Absolute magnitude (MV)4.52 [1]
Orbit [6]
PrimaryHD 19467 A
CompanionHD 19467 B
Period (P)398+95
−93 yr
Semi-major axis (a)54±9  AU
Eccentricity (e)0.56±0.09
Inclination (i)129.8+8.1
−5.1°
Longitude of the node (Ω)134.8±4.5°
Periastron epoch (T)2,512,264+12,428
−12,637  BJD
Argument of periastron (ω)
(secondary)		64.2+5.5
−6.3°
Details
HD 19467 A
Mass0.96±0.02 [7]  M☉
Radius1.20±0.03 [7]  R☉
Luminosity1.42±0.06 [7]  L☉
Surface gravity (log g)4.28±0.04 [7]  cgs
Temperature5,747±40 [7]  K
Metallicity [Fe/H]−0.11±0.01 [6]  dex
Rotation29.53±0.16 d [6]
Rotational velocity (v sin i)1.6±0.5 [6] km/s
Age5.4+1.9
−1.3 Gyr [3]
10.06+1.16
−0.82 [8]  Gyr
HD 19467 B
Mass65.4+5.9
−4.6 [3]  MJup
Luminosity(6.49±0.98)×10−6 [8]  L☉
Temperature978+20
−43 [9]  K
Metallicity [Fe/H]−0.15±0.02 [8]  dex
Other designations
BD−14° 604, FK5 1087, GJ 3200, HD 19467, HIP 14501, SAO 148780, PPM 212460 [10]
Database references
SIMBAD data

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]

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, [6] with age estimates range from 5.4 [3] up to 10.1 billion years, [8] depending on the study. It is considered a thin disk star, which should theoretically limit the age to no more than 8 billion years. [6] The spin rate is correspondingly low with a rotation period of 29.5 days. [6] Based on the abundance of iron, the metallicity is lower than solar. [14] [6] 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. [9] 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]

References

  1. ^ a b c d e Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv: 1108.4971, Bibcode: 2012AstL...38..331A, doi: 10.1134/S1063773712050015, S2CID  119257644.
  2. ^ a b c d e Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv: 2208.00211. Bibcode: 2023A&A...674A...1G. doi: 10.1051/0004-6361/202243940. S2CID  244398875. Gaia DR3 record for this source at VizieR.
  3. ^ a b c d e f g h Brandt, G. Mirek; et al. (December 2021), "Improved Dynamical Masses for Six Brown Dwarf Companions Using Hipparcos and Gaia EDR3", The Astronomical Journal, 162 (6), id. 301, arXiv: 2109.07525, Bibcode: 2021AJ....162..301B, doi: 10.3847/1538-3881/ac273e.
  4. ^ a b Houk, N.; Smith-Moore, M. (1988), Michigan Catalogue of Two-dimensional Spectral Types for the HD Stars. Declinations -26°.0 to -12°.0, vol. 4, University of Michigan, Ann Arbor, MI: Department of Astronomy, Bibcode: 1988mcts.book.....H.
  5. ^ a b Soubiran, C.; et al. (2018), "Gaia Data Release 2. The catalogue of radial velocity standard stars", Astronomy and Astrophysics, 616: A7, arXiv: 1804.09370, Bibcode: 2018A&A...616A...7S, doi: 10.1051/0004-6361/201832795, S2CID  52952408.
  6. ^ a b c d e f g h Maire, A. -L.; et al. (July 2020), "Orbital and spectral characterization of the benchmark T-type brown dwarf HD 19467B", Astronomy & Astrophysics, 639, id. A47, arXiv: 2005.10312, Bibcode: 2020A&A...639A..47M, doi: 10.1051/0004-6361/202037984.
  7. ^ a b c d e Greenbaum, Alexandra Z.; et al. (March 2023), "First Observations of the Brown Dwarf HD 19467 B with JWST", The Astrophysical Journal, 945 (2): 126, arXiv: 2301.11455, Bibcode: 2023ApJ...945..126G, doi: 10.3847/1538-4357/acb68b.
  8. ^ a b c d Wood, Charlotte M.; et al. (March 2019), "Benchmarking Substellar Evolutionary Models Using New Age Estimates for HD 4747 B and HD 19467 B", The Astrophysical Journal, 873 (1): 83, arXiv: 1901.03687, Bibcode: 2019ApJ...873...83W, doi: 10.3847/1538-4357/aafe01.
  9. ^ a b Crepp, Justin R.; et al. (January 2015), "Direct Spectrum of the Benchmark T Dwarf HD 19467 B", The Astrophysical Journal Letters, 798 (2), id. L43, arXiv: 1412.6101, Bibcode: 2015ApJ...798L..43C, doi: 10.1088/2041-8205/798/2/L43.
  10. ^ "HD 19467", SIMBAD, Centre de données astronomiques de Strasbourg, retrieved 2024-01-17.
  11. ^ Luyten, W. J. (June 1995), "NLTT Catalogue (Luyten, 1979)", VizieR Online Data Catalog, Bibcode: 1995yCat.1098....0L.
  12. ^ Bubar, Eric J.; King, Jeremy R. (August 2010), "Spectroscopic Abundances and Membership in the Wolf 630 Moving Group", The Astronomical Journal, 140 (2): 293–318, arXiv: 1005.1205, Bibcode: 2010AJ....140..293B, doi: 10.1088/0004-6256/140/2/293.
  13. ^ Ramírez, I.; et al. (December 2014), "The Solar Twin Planet Search. I. Fundamental parameters of the stellar sample", Astronomy & Astrophysics, 572, id. A48, arXiv: 1408.4130, Bibcode: 2014A&A...572A..48R, doi: 10.1051/0004-6361/201424244.
  14. ^ Fuhrmann, Klaus; Chini, Rolf (March 2021), "On ancient solar-type stars - II", Monthly Notices of the Royal Astronomical Society, 501 (4): 4903–4916, Bibcode: 2021MNRAS.501.4903F, doi: 10.1093/mnras/staa3942.
  15. ^ Crepp, Justin R.; et al. (January 2014), "The TRENDS High-contrast Imaging Survey. V. Discovery of an Old and Cold Benchmark T-dwarf Orbiting the Nearby G-star HD 19467", The Astrophysical Journal, 781 (1): 29, arXiv: 1311.0280, Bibcode: 2014ApJ...781...29C, doi: 10.1088/0004-637X/781/1/29.

Further reading

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