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HD 19467

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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
SIMBADdata

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

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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

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  • Scholz's Star – a star with a brown dwarf companion of similar mass to HD 19467 B[3]

References

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  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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