HD 45364

HD 45364 is a star in the southern constellation of Canis Major. It is too faint to be visible to the naked eye, having an apparent visual magnitude of 8.08.[2] The distance to this system is 112 light years based on parallax.[1] It is drifting further away from the Sun with a radial velocity of +16.4 km/s,[1] having come within 49 light-years some 1.5 million years ago.[2]

HD 45364
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Canis Major
Right ascension  06h 25m 38.47443s[1]
Declination −31° 28′ 51.4285″[1]
Apparent magnitude (V) 8.08[2]
Characteristics
Spectral type G8V[3]
B−V color index 0.719±0.015[2]
V−R color index 0.01
Astrometry
Radial velocity (Rv)+16.392±0.0004[1] km/s
Proper motion (μ) RA: +52.182[1] mas/yr
Dec.: −11.926[1] mas/yr
Parallax (π)29.0797 ± 0.0316[1] mas
Distance112.2 ± 0.1 ly
(34.39 ± 0.04 pc)
Absolute magnitude (MV)+5.51[2]
Details[4]
Mass0.88±0.02 M☉
Radius0.82±0.01 R☉
Luminosity0.562±0.004 L☉
Surface gravity (log g)4.55±0.03 cgs
Temperature5,540±31 K
Metallicity [Fe/H]−0.14±0.03[2] dex
Rotational velocity (v sin i)1.672±0.665[5] km/s
Age3.4±2.7 Gyr
Other designations
CD−31°3286, HD 30579, HIP 30579, SAO 196806[6]
Database references
SIMBADdata
Exoplanet Archivedata
Extrasolar Planets
Encyclopaedia		data

This object is an ordinary G-type main-sequence star with a stellar classification of G8V,[3] which indicates it is generating energy through core hydrogen fusion. It is around 3.4 billion years old and is spinning with a projected rotational velocity of 1.7 km/s.[5] The star has 88% of the mass of the Sun and 82% of the Sun's radius. It is radiating 56% of the luminosity of the Sun from its photosphere at an effective temperature of 5,540 K. As of August 2008 there are two confirmed extrasolar planets (or exoplanets) orbiting around it.[7]

Planetary system

HD 45364 is one of only a relative few systems that have had more than one exoplanet discovered in its orbit. The two planets, HD 45364 b and HD 45364 c respectively, were both discovered in August 2008 using the radial velocity method. The pair are orbiting the host star with a 3:2 mean motion resonance,[7] which means the inner planet is completing three orbits for every two orbits of the outer planet.

The HD 45364 planetary system[7]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b ≥0.1872 MJ 0.6813 226.93±0.37 0.1684±0.190 — —
c ≥0.6579 MJ 0.8972 342.85±0.28 0.0974±0.012 — —

Formation scenario
Hydrodynamic formation scenario of HD45364

A detailed analysis of the formation scenario revealed that the previously reported orbital configuration might not be correct.[8] The eccentricities are a factor of 4-5 too large to be consistent with standard planet formation theories. This is the first time that planet formation theory was able to predict new orbital parameters of a planetary system. There are other proposed scenario, in which remains the resonant configuration of the planetary system [9]

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References
  1. 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. 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.
  3. Gray, R. O.; et al. (July 2006). "Contributions to the Nearby Stars (NStars) Project: spectroscopy of stars earlier than M0 within 40 pc-The Southern Sample". The Astronomical Journal. 132 (1): 161–170. arXiv:astro-ph/0603770. Bibcode:2006AJ....132..161G. doi:10.1086/504637.
  4. 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.
  5. Soto, M. G.; Jenkins, J. S. (July 2018). "Spectroscopic Parameters and atmosphEric ChemIstriEs of Stars (SPECIES). I. Code description and dwarf stars catalogue". Astronomy & Astrophysics. 615: 28. arXiv:1801.09698. Bibcode:2018A&A...615A..76S. doi:10.1051/0004-6361/201731533. A76.
  6. "HD 45364". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-12-19.
  7. Correia, A. C. M.; et al. (2009). "The HARPS search for southern extra-solar planets XVI. HD 45364, a pair of planets in a 3:2 mean motion resonance". Astronomy and Astrophysics. 496 (2): 521–526. arXiv:0902.0597. Bibcode:2009A&A...496..521C. doi:10.1051/0004-6361:200810774.
  8. Rein, H.; et al. (2010). "The dynamical origin of the multi-planetary system HD 45364" (abstract). Astronomy and Astrophysics. 510 (1). arXiv:0910.5082. Bibcode:2010A&A...510A...4R. doi:10.1051/0004-6361/200913208. (web preprint)
  9. Correa-Otto, J. (2013). "A new scenario for the origin of the 3/2 resonant system HD 45364". Astronomy and Astrophysics. 560 (65): 1–10. arXiv:1307.1822. Bibcode:2013A&A...560A..65C. doi:10.1051/0004-6361/201321917.

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