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HD 42618

HD 42618
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Orion
Right ascension 06h 12m 00.567s[1]
Declination +06° 46′ 59.06″[1]
Apparent magnitude (V) 6.85[2]
Characteristics
Evolutionary stage Main sequence
Spectral type G4V[3]
B−V color index 0.642±0.007[2]
Astrometry
Radial velocity (Rv)−53.52±0.14[4] km/s
Proper motion (μ) RA: 197.247 mas/yr[1]
Dec.: −254.867 mas/yr[1]
Parallax (π)40.9764 ± 0.0240 mas[1]
Distance79.60 ± 0.05 ly
(24.40 ± 0.01 pc)
Absolute magnitude (MV)5.03±0.06[3]
Details
Mass0.92±0.02[5] M☉
Radius0.94[5] R☉
Luminosity0.918±0.012[5] L☉
Surface gravity (log g)4.44±0.01[6] cgs
Temperature5,758±5 K[6]
5,765±17[5] K
Metallicity [Fe/H]−0.096±0.005 dex[6]
−0.10±0.02[5] dex
Rotation16.9 d[7]
Rotational velocity (v sin i)1.83±0.11[6] km/s
Age5.51±0.71 Gyr[6]
5.5±0.2[5] Gyr
Other designations
BD+06 1155, GC 7897, GJ 3387, HD 42618, HIP 29432, SAO 113580, LTT 11802[8]
Database references
SIMBADdata

HD 42618 is a well-studied[7] star with an exoplanetary companion in the equatorial constellation of Orion. With an apparent visual magnitude of 6.85[2] it is too faint to be readily visible to the naked eye. This system is located at a distance of 79.6 light years from the Sun based on parallax measurements. It has a relatively high proper motion, traversing the celestial sphere at an angular rate of 0.321″ per year.[9] HD 42618 is drifting closer with a radial velocity of −53.5[4] km/s and is predicted to come as near as 42.6 light-years in around 297,000 years.[2]

The stellar classification of HD 42618 is G4V,[3] which shows it to be an ordinary G-type main-sequence star. It is considered a close solar analog, which means the physical properties of the star are particularly similar to those of the Sun.[10] Seismic model indicates the star is older and more evolved than the Sun with an age of about 5.5 billion years.[5] It is spinning with a low projected rotational velocity of 1.8 km/s,[6] with the rotation rate being consistent with the star's low activity level.[11] The star has 92% of the mass of the Sun and 94% of the Sun's radius. The surface metallicity is lower than in the Sun,[5] with the abundance patterns being consistent with a solar-type star.[11] HD 42618 is radiating 92% of the luminosity of the Sun from its photosphere at an effective temperature of 5,765 K.[5]

In 2016, the discovery of a candidate exoplanet companion orbiting HD 42618 was announced. Designated HD 42618 b, it was found using the radial velocity method which showed a periodicity of 149.6 days. The orbital elements have the planet orbiting at a distance of 0.55 AU from the host star with an orbital eccentricity (ovalness) of 0.2 and a Neptune-like mass. A second signal with a period of 388 days was detected, but this is unconfirmed and may be false. A 4,850 day signal is likely the result of star's magnetic activity cycle.[7]

The planetary system[7]
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(days) 		Eccentricity Inclination Radius
b ≥ 14.4+2.5
−2.4 M🜨 		0.554±0.011 149.61+0.37
−0.34 		0.19+0.15
−0.12 		— —

References

  1. ^ a b c d Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 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 c Medhi, B. J.; et al. (July 2007), "Results from a spectroscopic survey in the CoRoT fields. I. Search for chromospherically active stars", Astronomy and Astrophysics, 469 (2): 713–719, Bibcode:2007A&A...469..713M, doi:10.1051/0004-6361:20054173.
  4. ^ a b 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.
  5. ^ a b c d e f g h i Castro, M.; et al. (August 2021), "Modeling of two CoRoT solar analogues constrained by seismic and spectroscopic analysis", Monthly Notices of the Royal Astronomical Society, 505 (2): 2151–2158, arXiv:2008.01163, Bibcode:2021MNRAS.505.2151C, doi:10.1093/mnras/stab1410.
  6. ^ a b c d e f dos Santos, Leonardo A.; et al. (August 2016), "The Solar Twin Planet Search. IV. The Sun as a typical rotator and evidence for a new rotational braking law for Sun-like stars", Astronomy & Astrophysics, 592: 8, arXiv:1606.06214, Bibcode:2016A&A...592A.156D, doi:10.1051/0004-6361/201628558, S2CID 53533614, A156.
  7. ^ a b c d Fulton, Benjamin J.; et al. (October 2016), "Three Temperate Neptunes Orbiting Nearby Stars", The Astrophysical Journal, 830 (1): 19, arXiv:1607.00007, Bibcode:2016ApJ...830...46F, doi:10.3847/0004-637X/830/1/46, S2CID 36666883, 46.
  8. ^ "HD 42618", SIMBAD, Centre de données astronomiques de Strasbourg, retrieved 2022-02-17.
  9. ^ Lépine, Sébastien; Shara, Michael M. (March 2005), "A Catalog of Northern Stars with Annual Proper Motions Larger than 0.15" (LSPM-NORTH Catalog)", The Astronomical Journal, 129 (3): 1483–1522, arXiv:astro-ph/0412070, Bibcode:2005AJ....129.1483L, doi:10.1086/427854, S2CID 2603568.
  10. ^ Soubiran, C.; Triaud, A. (May 2004), "The Top Ten solar analogs in the ELODIE library", Astronomy and Astrophysics, 418 (3): 1089–1100, arXiv:astro-ph/0402094, Bibcode:2004A&A...418.1089S, doi:10.1051/0004-6361:20035708.
  11. ^ a b Morel, T.; et al. (April 2013), "Abundance study of the two solar-analogue CoRoT targets HD 42618 and HD 43587 from HARPS spectroscopy", Astronomy & Astrophysics, 552: 10, arXiv:1302.3172, Bibcode:2013A&A...552A..42M, doi:10.1051/0004-6361/201220883, S2CID 53686102, A42.

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