Astronomy:HD 19467

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Short description: Star in the constellation Eridanus
HD 19467
Observation data
Equinox J2000.0]] (ICRS)
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[2] mas/yr
Dec.: −260.642[2] mas/yr
Parallax (π)31.2191 ± 0.024[2] mas
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)319+114
−72 yr
Semi-major axis (a)46.9+11.0
−7.4 astronomical unit|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
Mass0.96±0.02[8] M☉
Radius1.20±0.03[8] R☉
Luminosity1.42±0.06[8] L☉
Surface gravity (log g)4.28±0.04[8] cgs
Temperature5747±40[8] K
Metallicity [Fe/H]−0.11±0.01[7] dex
Rotation29.53±0.16 d[7]
Rotational velocity (v sin i)1.6±0.5[7] km/s
Age9.4±0.9[8] Gyr
HD 19467 B
Mass71.6+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
Temperature1,103+97
−103[6] K
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,[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]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters 38 (5): 331, doi:10.1134/S1063773712050015, Bibcode: 2012AstL...38..331A. 
  2. ↑ 2.0 2.1 2.2 2.3 2.4 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940  Gaia DR3 record for this source at VizieR.
  3. ↑ 3.0 3.1 3.2 3.3 3.4 3.5 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, doi:10.3847/1538-3881/ac273e, Bibcode: 2021AJ....162..301B. 
  4. ↑ 4.0 4.1 Houk, N.; Smith-Moore, M. (1988), Michigan Catalogue of Two-dimensional Spectral Types for the HD Stars. Declinations -26°.0 to -12°.0, 4, University of Michigan, Ann Arbor, MI: Department of Astronomy, Bibcode: 1988mcts.book.....H. 
  5. ↑ 5.0 5.1 Soubiran, C. et al. (2018), "Gaia Data Release 2. The catalogue of radial velocity standard stars", Astronomy and Astrophysics 616: A7, doi:10.1051/0004-6361/201832795, Bibcode: 2018A&A...616A...7S. 
  6. ↑ 6.0 6.1 6.2 6.3 Hoch, Kielan K. W.; Theissen, Christopher A.; Barman, Travis S.; Perrin, Marshall D.; Ruffio, Jean-Baptiste; Rickman, Emily; Konopacky, Quinn M.; Manjavacas, Elena et al. (2024-10-01). "JWST-TST High Contrast: Spectroscopic Characterization of the Benchmark Brown Dwarf HD 19467 B with the NIRSpec Integral Field Spectrograph". The Astronomical Journal 168 (4): 187. doi:10.3847/1538-3881/ad6cd3. ISSN 0004-6256. 
  7. ↑ 7.0 7.1 7.2 7.3 7.4 7.5 7.6 7.7 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, doi:10.1051/0004-6361/202037984, Bibcode: 2020A&A...639A..47M. 
  8. ↑ 8.0 8.1 8.2 8.3 8.4 8.5 Greenbaum, Alexandra Z. et al. (March 2023), "First Observations of the Brown Dwarf HD 19467 B with JWST", The Astrophysical Journal 945 (2): 126, doi:10.3847/1538-4357/acb68b, Bibcode: 2023ApJ...945..126G. 
  9. ↑ 9.0 9.1 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, doi:10.3847/1538-4357/aafe01, Bibcode: 2019ApJ...873...83W. 
  10. ↑ "HD 19467". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+19467. 
  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, doi:10.1088/0004-6256/140/2/293, Bibcode: 2010AJ....140..293B. 
  13. ↑ Ramírez, I. et al. (December 2014), "The Solar Twin Planet Search. I. Fundamental parameters of the stellar sample", Astronomy & Astrophysics 572: id. A48, doi:10.1051/0004-6361/201424244, Bibcode: 2014A&A...572A..48R. 
  14. ↑ Fuhrmann, Klaus; Chini, Rolf (March 2021), "On ancient solar-type stars - II", Monthly Notices of the Royal Astronomical Society 501 (4): 4903–4916, doi:10.1093/mnras/staa3942, Bibcode: 2021MNRAS.501.4903F. 
  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, doi:10.1088/0004-637X/781/1/29, Bibcode: 2014ApJ...781...29C. 
  16. ↑ 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, doi:10.1088/2041-8205/798/2/L43, Bibcode: 2015ApJ...798L..43C. 

Further reading

  • Mesa, D. et al. (July 2020), "Characterizing brown dwarf companions with IRDIS long-slit spectroscopy: HD 1160 B and HD 19467 B", Monthly Notices of the Royal Astronomical Society 495 (4): 4279–4290, doi:10.1093/mnras/staa1444, Bibcode: 2020MNRAS.495.4279M. 
  • Wood, Charlotte et al. (January 2018), "Precise Ages for the Benchmark Brown Dwarfs HD 19467 B and HD 4747 B", American Astronomical Society, AAS Meeting #231 231: id. 450.05, Bibcode: 2018AAS...23145005W. 
  • "Point Source Polarimetry with the Gemini Planet Imager: Sensitivity Characterization with T5.5 Dwarf Companion HD 19467 B", The Astrophysical Journal 820 (2): id. 111, April 2016, doi:10.3847/0004-637X/820/2/111, Bibcode: 2016ApJ...820..111J. 



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