HD 9578

HD 9578 is a candidate wide binary star system located at a distance of approximately 183[1] light-years from the Sun in the southern constellation of Sculptor. The main star must be viewed with binoculars or a telescope, as its low apparent visual magnitude of 8.35[2] is too faint to be viewed with the naked eye. The system is drifting closer to the Sun with a radial velocity of −4 km/s.[1]

HD 9578
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Sculptor
Right ascension  01h 33m 17.14463s[1]
Declination −38° 14′ 42.0595″[1]
Apparent magnitude (V) 8.35[2]
Characteristics
Spectral type G1V[3] + ~M4[4]
Apparent magnitude (B) 8.788[5]
Apparent magnitude (J) 7.156[6]
Apparent magnitude (H) 6.89[6]
Apparent magnitude (K) 6.798[6]
B−V color index 0.680±0.015[2]
Astrometry
Radial velocity (Rv)−3.9±0.2[1] km/s
Proper motion (μ) RA: –31.415[1] mas/yr
Dec.: –38.109[1] mas/yr
Parallax (π)17.7921 ± 0.0319[1] mas
Distance183.3 ± 0.3 ly
(56.2 ± 0.1 pc)
Absolute magnitude (MV)4.76[2]
Details[7]
A
Mass1.02+0.03
−0.02 M☉
Radius1.11+0.05
−0.08[1] R☉
Luminosity1.4[1] L☉
Surface gravity (log g)4.42±0.05 cgs
Temperature5,798±50 K
Metallicity [Fe/H]0.08±0.04 dex
Rotational velocity (v sin i)2.36[8] km/s
Age5.56+0.65
−3.36 Gyr
B
Mass0.21[4] M☉
Other designations
CD−38°528, CPD−38°128, HD 9578, HIP 7245, SAO 193177, PPM 277127, TYC 7541-00066-1, 2MASS J01331715-3814421[9]
Database references
SIMBADdata
Exoplanet Archivedata
Extrasolar Planets
Encyclopaedia		data

The primary component is an ordinary G-type main-sequence star with a stellar classification of G1V.[3] It is around five and a half billion years old,[7] and is spinning with a projected rotational velocity of 2.4 km/s.[8] The star has nearly the same mass as the Sun[7] but with an 11% greater girth.[1] It is radiating 1.4[1] times the luminosity of the Sun from its photosphere at an effective temperature of 5,798 K.[7]

A faint co-moving companion was detected in 2015, located at an angular separation of 3.245″±0.010″ along a position angle of 251.19°±0.10° from the primary, corresponding to a projected separation of 186 AU. Designated component B, it is a red dwarf with a class of around M4 and has an estimated 0.21 times the mass of the Sun.[4]

The discovery of a candidate extrasolar planetary companion was announced in a press release in October 2009. Designated HD 9578 b, this object has at least 0.62 times the mass of Jupiter. It takes 1.35 years to orbit the primary, with an orbital semimajor axis of 1.27 AU.[10][4]

The HD 9578 planetary system
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b ≥ 0.62 MJ 1.27 494 ? — —

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. Houk, Nancy (1979). "Michigan catalogue of two-dimensional spectral types for the HD stars". 3. Ann Arbor, Michigan: Dept. of Astronomy, University of Michigan. Bibcode:1982mcts.book.....H. Cite journal requires |journal= (help)
  4. Mugrauer, M.; Ginski, C. (July 2015). "High-contrast imaging search for stellar and substellar companions of exoplanet host stars". Monthly Notices of the Royal Astronomical Society. 450 (3): 3127–3136. Bibcode:2015MNRAS.450.3127M. doi:10.1093/mnras/stv771.
  5. Høg, E.; et al. (2000). The Tycho-2 catalogue of the 2.5 million brightest stars. Astronomy and Astrophysics. 355. pp. L27. Bibcode:2000A&A...355L..27H. doi:10.1888/0333750888/2862. ISBN 978-0333750889.
  6. Cutri, R. M.; Skrutskie, M. F.; Van Dyk, S.; Beichman, C. A.; et al. (June 2003). "2MASS All Sky Catalog of point sources". The IRSA 2MASS All-Sky Point Source Catalog, NASA/IPAC Infrared Science Archive. Bibcode:2003tmc..book.....C.
  7. Aguilera-Gómez, Claudia; et al. (2018). "Lithium abundance patterns of late-F stars: An in-depth analysis of the lithium desert". Astronomy and Astrophysics. 614: A55. arXiv:1803.05922. Bibcode:2018A&A...614A..55A. doi:10.1051/0004-6361/201732209.
  8. Delgado Mena, E.; et al. (April 2015). "Li abundances in F stars: planets, rotation, and Galactic evolution". Astronomy & Astrophysics. 576: 24. arXiv:1412.4618. Bibcode:2015A&A...576A..69D. doi:10.1051/0004-6361/201425433. A69.
  9. "HD 9578". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-11-10.
  10. Udry, S.; et al. (2009). Towards Other Earths RV planet search around solar-type stars: The HARPS GTO legacy. Porto, Portugal.

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