Astronomy:HD 5608
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Andromeda |
| Right ascension | 00h 58m 14.21894s[1] |
| Declination | +33° 57′ 03.1841″[1] |
| Apparent magnitude (V) | +5.98[2] |
| Characteristics | |
| Evolutionary stage | Red giant branch[3] |
| Spectral type | K0 IV[4] |
| B−V color index | 1.016[2] |
| Astrometry | |
| Radial velocity (Rv) | −23.13±0.12[1] km/s |
| Proper motion (μ) | RA: 36.459[1] mas/yr Dec.: -71.320[1] mas/yr |
| Parallax (π) | 17.0697 ± 0.0302[1] mas |
| Distance | 191.1 ± 0.3 ly (58.6 ± 0.1 pc) |
| Absolute magnitude (MV) | +2.11[4] |
| Orbit[5] | |
| Period (P) | 146+74 −37 yr |
| Semi-major axis (a) | 0.524+0.151 −0.084" (30.7+8.8 −4.9 astronomical unit|AU) |
| Eccentricity (e) | 0.53+0.18 −0.26 |
| Inclination (i) | 147.5+6.6 −13° |
| Longitude of the node (Ω) | 141+56 −48° |
| Periastron epoch (T) | 2,472,895+17,464 −5,098 |
| Argument of periastron (ω) (secondary) | 257+32 −35° |
| Details[6] | |
| HD 5608 A | |
| Mass | 1.50±0.04 M☉ |
| Radius | 5.0±0.1 R☉ |
| Luminosity | 13.1±0.3 L☉ |
| Surface gravity (log g) | 3.20±0.02 cgs |
| Temperature | 4,897±25 K |
| Metallicity [Fe/H] | +0.12±0.03[3] dex |
| Rotational velocity (v sin i) | 1.37[4] km/s |
| Age | 3.0±0.3 Gyr |
| HD 5608 B | |
| Mass | 0.10±0.01[7] M☉ |
| Mass | 121.2+8.3 −7.0[5] MJup |
| Other designations | |
| Database references | |
| SIMBAD | data |
| 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 +5.98.[2] The distance to HD 5608, as estimated from an annual parallax shift of 17.07 mas,[1] is 191 light-years (59 parsecs). 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.[9]
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.[6]
HD 5608 has a co-moving companion, HD 5608 B, at an angular separation of 0.6″, which has been directly imaged. The physical separation of the pair is calculated as 40±1 astronomical unit|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.[7] This companion star has since been characterized by radial velocity and astrometry in addition to imaging.[5]
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 |♃|J}}}}}}, a semimajor axis of 1.9 astronomical unit|AU, and an eccentricity of 0.19.[4] The high eccentricity of this planet could have been induced by the low mass companion star HD 5608 B via the Kozai mechanism.[7]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | ≥1.168+0.062 −0.057 MJ |
1.790+0.007 −0.003 |
768.70+4.72 −1.67 |
0.110+0.029 −0.080 |
— | — |
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940 Gaia DR3 record for this source at VizieR.
- ↑ 2.0 2.1 2.2 Høg, E. et al. (200). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy & Astrophysics 355: L27–L30. Bibcode: 2000A&A...355L..27H.
- ↑ 3.0 3.1 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. doi:10.1051/0004-6361/201833111. A33. Bibcode: 2018A&A...616A..33S.
- ↑ 4.0 4.1 4.2 4.3 4.4 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. doi:10.1093/pasj/64.6.135. Bibcode: 2012PASJ...64..135S.
- ↑ 5.0 5.1 5.2 5.3 Teng, Huan-Yu et al. (December 2023). "Revisiting Planetary Systems in Okayama Planet Search Program: A new long-period planet, RV astrometry joint analysis, and multiplicity-metallicity trend around evolved stars". Publications of the Astronomical Society of Japan 75 (6): 1030–1071. doi:10.1093/pasj/psad056.
- ↑ 6.0 6.1 Bonfanti, A. et al. (2016). "Age consistency between exoplanet hosts and field stars". Astronomy & Astrophysics 585: A5, 14 pp. doi:10.1051/0004-6361/201527297. Bibcode: 2016A&A...585A...5B.
- ↑ 7.0 7.1 7.2 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. doi:10.3847/0004-637X/825/2/127. 127. PMID 32753766. Bibcode: 2016ApJ...825..127R.
- ↑ "HD 5608". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+5608.
- ↑ Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331. doi:10.1134/S1063773712050015. Bibcode: 2012AstL...38..331A.
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