HD 108874

HD 108874 is a yellow dwarf star (spectral type G5 V) in the constellation of Coma Berenices. It is 195 light years from Earth[1] and has two extrasolar planets that are possibly in a 9:2 orbital resonance.

HD 108874

Orbits around the star HD108874
Observation data
Epoch J2000      Equinox J2000
Constellation Coma Berenices
Right ascension 12h 30m 26.8818s[1]
Declination +22° 52′ 47.3806″[1]
Apparent magnitude (V) 8.76
Characteristics
Spectral type G5 V
B−V color index 0.764
V−R color index 0.4
Variable type ”None”
Astrometry
Radial velocity (Rv)–30.7 km/s
Proper motion (μ) RA: 127.453±0.071[1] mas/yr
Dec.: −90.120±0.061[1] mas/yr
Parallax (π)16.7730 ± 0.0443[1] mas
Distance194.5 ± 0.5 ly
(59.6 ± 0.2 pc)
Absolute magnitude (MV)3.72
Details
Mass0.996±0.032[2] M☉
Radius1.062±0.070[2] R☉
Luminosity1.14 L☉
Surface gravity (log g)4.39±0.12[2] cgs
Temperature5585±20[2] K
Metallicity [Fe/H]0.18[3] dex
Rotation40.20±0.15 days[2]
Rotational velocity (v sin i)1.36±0.26[2] km/s
Age6.48±3.47[2] Gyr
Other designations
BD+23°2466, HIP 61028, SAO 82344[4]
Database references
SIMBADdata
Exoplanet Archivedata

Star

HD 108874 is probably billions of years older than our Sun however the age is not well constrained. The star has a temperature of about 5600 K. Its metallicity is 1.18 times that of the Sun, meaning it has greater iron abundance relative to hydrogen and helium. It has about the same mass as the Sun, but the radius is probably greater.[2][3]

Planetary system

In 2003, the jovian planet HD 108874 b was discovered by the US-based team lead by Paul Butler, Geoffrey Marcy, Steven Vogt, and Debra Fischer. A total of 20 radial velocity observations, obtained at the W. M. Keck Observatory between 1999 and 2002, were used to make the discovery.[5] In 2005, further observations revealed this star has another jovian planet orbiting further out, designated as HD 108874 c.[3] The orbital parameters of both planets were updated in 2009 with additional observations.[6] Those two planets are near, and possibly in a 9:2 orbital resonance. This means if HD 108874 b orbits the star nine times, then HD 108874 c orbits twice, because the orbital period for planet c is four and a half times longer than planet b.[2]

There is an additional radial velocity signal in the data at a period of 40 days however this likely caused by the stellar rotation period.[2]

The HD 108874 planetary system[2]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b >1.25±0.10 MJ 1.05±0.02 395.34±0.19 0.142±0.011 — —
c >1.09±0.16 MJ 2.81±0.06 1732.2±9.8 0.229±0.032 — —

See also
  • List of extrasolar planets

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. Benatti, S.; et al. (2017). "The GAPS Programme with HARPS-N at TNG. XII. Characterization of the planetary system around HD 108874". Astronomy and Astrophysics. 599. A90. arXiv:1611.09873. Bibcode:2017A&A...599A..90B. doi:10.1051/0004-6361/201629484.
  3. Vogt, Steven S.; et al. (2005). "Five New Multicomponent Planetary Systems" (PDF). The Astrophysical Journal. 632 (1): 638–658. Bibcode:2005ApJ...632..638V. doi:10.1086/432901.
  4. "HD 108874". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-10-13.
  5. Butler, R. Paul; et al. (2003). "Seven New Keck Planets Orbiting G and K Dwarfs". The Astrophysical Journal. 582 (1): 455–466. Bibcode:2003ApJ...582..455B. CiteSeerX 10.1.1.7.6988. doi:10.1086/344570.
  6. Wright, J. T.; et al. (2009). "Ten New and Updated Multi-planet Systems, and a Survey of Exoplanetary Systems". The Astrophysical Journal. 693 (2): 1084–1099. arXiv:0812.1582. Bibcode:2009ApJ...693.1084W. doi:10.1088/0004-637X/693/2/1084.

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