HD 2638

This article will address the topic of HD 2638 from a broad and varied perspective, exploring different aspects and points of view related to this topic. From its origin to its relevance today, through its implications in various areas, this article will seek to provide a complete and detailed vision of HD 2638. Through a thorough and rigorous analysis, the aim is to offer the reader a complete overview that allows them to understand the importance and scope of HD 2638 in today's society. In addition, possible challenges and opportunities related to this topic will be addressed, as well as recommendations and perspectives for the future.

HD 2638
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Cetus
Right ascension 00h 29m 59.8721s[1]
Declination −05° 45′ 50.3987″[1]
Apparent magnitude (V) 9.44[2]
Characteristics
Spectral type K1V[3] (G8V + M1V)[4]
B−V color index +0.886±0.003[2]
Astrometry
Radial velocity (Rv)+9.576±0.0010[1] km/s
Proper motion (μ) RA: −107.019±0.094[1] mas/yr
Dec.: −223.039±0.062[1] mas/yr
Parallax (π)18.1656±0.0510 mas[1]
Distance179.5 ± 0.5 ly
(55.0 ± 0.2 pc)
Absolute magnitude (MV)5.96[2]
Orbit[5]
PrimaryHD 2638 A
CompanionHD 2638 BC
Period (P)130 yr
Semi-major axis (a)25.5±1.9 AU
Details[6]
A
Mass0.89±0.02 M☉
Radius0.8±0.01 R☉
Luminosity0.407±0.004 L☉
Surface gravity (log g)4.58±0.02 cgs
Temperature5,160±24 K
Metallicity 0.12±0.05[7] dex
Age1.9±2.6 Gyr
BC
Mass0.425±0.067[4] M☉
Radius0.46±0.02[4] R☉
Luminosity0.030±0.005[4] L☉
Surface gravity (log g)4.80±0.02[4] cgs
Temperature3571±48[4] K
Other designations
BD–06°82, Gaia DR2 2526925389919277056, HD 2638, HIP 2350, WDS J00293-0555BC, NLTT 1594, 2MASS J00295988-0545502[8]
Database references
SIMBADdata
Exoplanet Archivedata

HD 2638 is a ternary star system[9] system in the equatorial constellation of Cetus. The pair have an angular separation of 0.53″ along a position angle of 166.7°, as of 2015.[9] This is system too faint to be visible to the naked eye, having a combined apparent visual magnitude of 9.44;[2] a small telescope is required. The distance to this system is 179.5 light years based on parallax, and it is drifting further away with a radial velocity of +9.6 km/s.[1] The magnitude 7.76 star HD 2567 forms a common proper motion companion to this pair[9] at projected separation 839″.[5]

The HD 2638 members A and BC have a projected separation of about 25.5±1.9 AU and thus an orbital period of around 130 years.[4] They have a combined stellar classification of K1V.[3] The primary component is a G-type main-sequence star with a class of G8V.[4] It is smaller and less massive than the Sun, and has a lower luminosity.[6] The secondary is a binary consisting of who red dwarf stars on close orbit with combined mass less than half the mass of the primary, and a composite spectral class of M1V.[4]

Planetary system

In 2005, the discovery of an extrasolar planet HD 2638 b orbiting the primary was announced by the Geneva Extrasolar Planet Search Team. The planet has a mass 0.48 times that of Jupiter and 152.6 times that of Earth.[10] The planet existence was placed under doubt in 2015 due to discovered additional stellar companions.[5]

The HD 2638 planetary system[10]
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(days) 		Eccentricity Inclination Radius
b >0.48 MJ 0.044 3.4442±0.0002 0.0407 — —

See also

References

  1. ^ a b c d e f g Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  2. ^ a b c d 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.
  3. ^ a b Houk, N.; Swift, C. (1999). "Michigan catalogue of two-dimensional spectral types for the HD Stars". Michigan Spectral Survey. 5. Bibcode:1999MSS...C05....0H.
  4. ^ a b c d e f g h i Wittrock, Justin M.; et al. (November 2016). "Stellar Companions to the Exoplanet Host Stars HD 2638 and HD 164509". The Astronomical Journal. 152 (5): 7. arXiv:1609.00016. Bibcode:2016AJ....152..149W. doi:10.3847/0004-6256/152/5/149. S2CID 45942803. 149.
  5. ^ a b c Roberts Jr, Lewis C.; Tokovinin, Andrei; Mason, Brian D.; Riddle, Reed L.; Hartkopf, William I.; Law, Nicholas M.; Baranec, Christoph (2015), "Know the Star, Know the Planet. III. Discovery of Late-Type Companions to Two Exoplanet Host Stars", The Astronomical Journal, 149 (4): 118, arXiv:1503.01211, Bibcode:2015AJ....149..118R, doi:10.1088/0004-6256/149/4/118, S2CID 30908636
  6. ^ a b Bonfanti, A.; et al. (2015). "Revising the ages of planet-hosting stars". Astronomy and Astrophysics. 575. A18. arXiv:1411.4302. Bibcode:2015A&A...575A..18B. doi:10.1051/0004-6361/201424951. S2CID 54555839.
  7. ^ Tsantaki, M.; Sousa, S. G.; Adibekyan, V. Zh.; Santos, N. C.; Mortier, A.; Israelian, G. (2013). "Deriving precise parameters for cool solar-type stars. Optimizing the iron line list". Astronomy and Astrophysics. 555. arXiv:1304.6639. Bibcode:2013A&A...555A.150T. doi:10.1051/0004-6361/201321103.
  8. ^ "HD 2638". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2011-12-20.
  9. ^ a b c Riddle, Reed L.; et al. (January 2015). "A Survey of the High Order Multiplicity of Nearby Solar-type Binary Stars with Robo-AO". The Astrophysical Journal. 799 (1): 21. arXiv:1411.0682. Bibcode:2015ApJ...799....4R. doi:10.1088/0004-637X/799/1/4. S2CID 5642378. 4.
  10. ^ a b Moutou, C.; et al. (2015). "The HARPS search for southern extra-solar planets IV. Three close-in planets around HD 2638, HD 27894 and HD 63454". Astronomy and Astrophysics. 439 (1): 367–373. arXiv:1411.7048. Bibcode:2005A&A...439..367M. doi:10.1051/0004-6361:20052826.