HD 28254

HD 28254
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Dorado
Right ascension 04h 24m 50.705s[1]
Declination −50° 37′ 19.88″[1]
Apparent magnitude (V) 7.69[2]
Characteristics
Spectral type G1IV/V[2]
Apparent magnitude (B) 8.412[3]
Apparent magnitude (R) 7.70[3]
Apparent magnitude (J) 6.395±0.026[3]
Apparent magnitude (H) 6.133±0.031[3]
Apparent magnitude (K) 6.006±0.029[3]
B−V color index 0.722[2]
V−R color index 0.01[3]
Astrometry
Radial velocity (Rv)−9.315±0.002[2] km/s
Proper motion (μ) RA: −67.277[1] mas/yr
Dec.: −143.680[1] mas/yr
Parallax (π)18.1242 ± 0.0247 mas[1]
Distance180.0 ± 0.2 ly
(55.17 ± 0.08 pc)
Absolute magnitude (MV)4.001[2]
Details
Mass1.11±0.01[4] M☉
Radius1.57±0.02[4] R☉
Luminosity2.19±0.01[4] L☉
Surface gravity (log g)4.08±0.02[4] cgs
Temperature5,607±37[4] K
Metallicity [Fe/H]0.36±0.03[2] dex
Rotational velocity (v sin i)2.50±1.0[2] km/s
Age7.8±0.4[4] Gyr
Other designations
CD–50°1385, GC 5376, HD 28254, HIP 20606, SAO 233508, PPM 333464[5]
Database references
SIMBADA
B
Exoplanet Archivedata

HD 28254 is a binary star system located 180 light-years away in the constellation Dorado. The primary component is an 8th magnitude G-type main-sequence star. This star is larger, cooler, brighter, and more massive than the Sun, and its metal content is 2.3 times as much as the Sun. In 2009, a gas giant exoplanet was found in orbit around the star.

Properties

HD 28254 is a G-type star with a spectral type G1IV/V,[2] indicating that it has begun its evolution off the main sequence. It is estimated to have a mass 11% larger than the Sun's, a radius 57% larger, and an age around 7.8 billion years. It has a luminosity of 1.57 times the solar luminosity and an effective temperature of about 5,600 K.[4] HD 28254 has a low activity level and a larger metallicity than the Sun, with 2.3 times the solar iron abundance.[2]

HD 28254 is the brighter component of a visual binary. Its companion, HD 28254 B, has a visual apparent magnitude of 13.8 and is located at a separation of 4.3 arcseconds. The two stars have maintained the same separation through time, indicating that they form a physical binary system.[6] Furthermore, the radial velocity of the primary shows signs of orbital motion. From its brightness, the companion star is probably a red dwarf with spectral type between M0V and M2V, with about 48% the solar mass. The projected separation between the stars is 235 AU, corresponding to an orbital period of more than 1,000 years.[2]

Planetary system

In 2010, the discovery of an exoplanet orbiting HD 28254 was published. It was detected by Doppler spectroscopy from observations with the HARPS spectrograph between October 2003 and April 2009. The best fit model for the 32 radial velocity data obtained consists of a planet in an eccentric 1116 days orbit, plus a quadratic trend that is probably caused by the star HD 28254 B.[2]

The planet is a gas giant with a minimum mass of 1.16 times the mass of Jupiter. It is at a mean distance of 2.15 AU from the star, and takes 1116 days to complete an orbit. Its orbit has a very high eccentricity of 0.81, carrying the planet between 0.41 and 3.90 AU from the star. This can be the result of gravitational interactions with the secondary star via the Kozai mechanism.[2] In 2023, the inclination and true mass of HD 28254 b were measured via astrometry, though the mass remains uncertain - it is between about 1.6 and 6.8 times the mass of Jupiter.[7]

The HD 28254 planetary system[7]
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(days) 		Eccentricity Inclination Radius
b 3.8+3.0
−2.2 MJ 		2.45+0.03
−0.04 		1333±4 0.95+0.03
−0.04 		21+38
−11 or 162+7
−27° 		—

See also

References

  1. ^ 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.
  2. ^ a b c d e f g h i j k l Naef, Dominique; et al. (2010). "The HARPS Search for Southern Extrasolar Planets XXIII. 8 Planetary Companions to Low-activity Solar-type Stars". Astronomy and Astrophysics. 523: A15. arXiv:1008.4600. Bibcode:2010A&A...523A..15N. doi:10.1051/0004-6361/200913616. S2CID 118845989.
  3. ^ a b c d e f 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.
  4. ^ a b c d e f g Bonfanti, A.; Ortolani, S.; Nascimbeni, V. (2016). "Age consistency between exoplanet hosts and field stars". Astronomy & Astrophysics. 585: A5, 14 pp. arXiv:1511.01744. Bibcode:2016A&A...585A...5B. doi:10.1051/0004-6361/201527297. S2CID 53971692.
  5. ^ "HD 28254". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2023-12-14.
  6. ^ Tokovinin, Andrei (2014). "From Binaries to Multiples. I. Data on F and G Dwarfs within 67 pc of the Sun". The Astronomical Journal. 147 (4): article 86, 14 pp. arXiv:1401.6825. Bibcode:2014AJ....147...86T. doi:10.1088/0004-6256/147/4/86. S2CID 53965918.
  7. ^ a b Philipot, F.; Lagrange, A.-M.; et al. (October 2023). "A multi-technique approach to identifying and/or constraining radial-velocity substellar companions". Astronomy & Astrophysics. 678: A107. arXiv:2308.05417. Bibcode:2023A&A...678A.107P. doi:10.1051/0004-6361/202346612. S2CID 260775968.