HD 5608

HD 5608
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Andromeda
Right ascension 00h 58m 14.21900s[1]
Declination +33° 57′ 03.1833″[1]
Apparent magnitude (V) +5.99[2]
Characteristics
Evolutionary stage Red giant branch[3]
Spectral type K0 IV[4]
B−V color index 1.000±0.005[2]
Astrometry
Radial velocity (Rv)−22.80±0.14[1] km/s
Proper motion (μ) RA: 36.419[1] mas/yr
Dec.: -71.265[1] mas/yr
Parallax (π)17.1801 ± 0.0649[1] mas
Distance189.8 ± 0.7 ly
(58.2 ± 0.2 pc)
Absolute magnitude (MV)2.24[2]
Details[5]
HB 5608 A
Mass1.50±0.04 M☉
Radius5.0±0.1 R☉
Luminosity13.1±0.3 L☉
Surface gravity (log g)3.20±0.02 cgs
Temperature4,897±25 K
Metallicity [Fe/H]+0.12±0.03[3] dex
Age3.0±0.3 Gyr
HD 5608 B
Mass0.10±0.01[6] M☉
Other designations
BD+33° 140, FK5 2061, HD 5608, HIP 4552, HR 275, SAO 54306[7]
Database references
SIMBADdata
Extrasolar Planets
Encyclopaedia		data

HD 5608 is an orange-hued star in the northern constellation of Andromeda with one known planet, HD 5608 b.[4] It is a dim star near the lower limit of visibility to the naked eye, having an apparent visual magnitude of +5.99.[2] The distance to HD 5608, as estimated from an annual parallax shift of 17.18 mas,[1] is 190 light years. It is moving closer to the Earth with a heliocentric radial velocity of −23 km/s,[1] and is expected to make its closest approach in 1.285 million years when it comes to within 124 light-years.[2]

This is a K-type subgiant star on the red giant branch track with a stellar classification of K0 IV.[4] It has 1.5 times the mass of the Sun and, at the age of three billion years, has expanded to five times the Sun's radius. It is radiating 13 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,897 K. It has a higher than solar metallicity – a term astronomers use to describe the abundance of elements other than hydrogen and helium.[5]

HD 5608 has a co-moving companion, HD 5608 B, at an angular separation of 0.6″. The physical separation of the pair is calculated as 40±1 AU or 47±3 AU, depending on the assumptions. It has an H band magnitude difference of 9.40 with the primary and an estimated mass of 0.10 M☉. A second companion at a separation of 7.4″ is a background star.[6]

Planetary companion

In 2012, the Okayama Planet Search Program reported the detection of a substellar companion in orbit around HD 5608, based upon Doppler measurements between 2003 and 2011 from the Okayama observatory in Kurashiki. These showed a linear trend indicating the existence of a distant companion. The data showed an additional periodicity of around 766 days. This object shows a minimum mass of 1.4 MJ and a semimajor axis of 1.9 AU.[4]

The HD 5608 planetary system[4]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
HD 5608 b >1.4 MJ 1.9 792.6±7.7 0.190±0.061 — —

References

  1. 1 2 3 4 5 6 7 8 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.
  2. 1 2 3 4 5 Anderson, Natali (June 11, 2017). "HD 3167d: New Super-Earth Discovered around Nearby Star". Science News. Sci-News.com. Retrieved October 7, 2018.
  3. 1 2 Stock, Stephan; et al. (August 2018). "Precise radial velocities of giant stars. X. Bayesian stellar parameters and evolutionary stages for 372 giant stars from the Lick planet search". Astronomy & Astrophysics. 616: 15. Bibcode:2018A&A...616A..33S. doi:10.1051/0004-6361/201833111. A33.
  4. 1 2 3 4 5 Sato, Bun'ei; et al. (2012). "Substellar Companions to Seven Evolved Intermediate-Mass Stars". Publications of the Astronomical Society of Japan. 64 (6). 135. arXiv:1207.3141. Bibcode:2012PASJ...64..135S. doi:10.1093/pasj/64.6.135.
  5. 1 2 Bonfanti, A.; et al. (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.
  6. 1 2 Ryu, Tsuguru; et al. (July 2016), "High-contrast Imaging of Intermediate-mass Giants with Long-term Radial Velocity Trends", The Astrophysical Journal, 825 (2): 13, Bibcode:2016ApJ...825..127R, doi:10.3847/0004-637X/825/2/127, 127
  7. ↑ "HD 5608". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved October 10, 2018.
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