HD 220074

HD 220074 is a star located in the northern constellation of Cassiopeia, near the western border with Cepheus. It has a reddish hue and is dimly visible to the naked eye, having an apparent visual magnitude of +6.39.[2] The star is located at a distance of approximately 1,070 light years from the Sun based on parallax, but is drifting closer with a radial velocity of −37 km/s.[3]

HD 220074
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Cassiopeia
Right ascension 23h 20m 14.37869s[1]
Declination +61° 58′ 12.4647″[1]
Apparent magnitude (V) +6.39[2]
Characteristics
Evolutionary stage Giant
Spectral type M2III[3] or K1V[2]
B−V color index 1.678±0.010[2]
Astrometry
Radial velocity (Rv)−36.89±0.21[3] km/s
Proper motion (μ) RA: +7.807[1] mas/yr
Dec.: –5.321[1] mas/yr
Parallax (π)3.0543 ± 0.0595[1] mas
Distance1,070 ± 20 ly
(327 ± 6 pc)
Absolute magnitude (MV)−1.52[3]
Details[3]
Mass1.2±0.3 M☉
Radius59.60+5.85
−6.31[1] R☉
Luminosity782.6±20.1[1] L☉
Surface gravity (log g)1.3±0.5 cgs
Temperature3,935±110 K
Metallicity [Fe/H]−0.25±0.25 dex
Rotational velocity (v sin i)3.0 km/s
Age4.5±2.8 Gyr
Other designations
BD+61° 2427, GC 32499, HD 220074, HIP 115218, HR 8881, SAO 20567[4]
Database references
SIMBADdata
Exoplanet Archivedata
Extrasolar Planets
Encyclopaedia		data

This star was assigned a stellar classification of K1V in the Bright Star Catalogue but is now known to be a red giant with a class of M2III,[5] based on its radius and surface gravity.[3] With the supply of hydrogen at its core exhausted, the star has expanded and cooled off the main sequence. It is around 4.5 billion years old with an estimated mass equal to ~1.2[3] times the mass of the Sun but 60 times the Sun's radius.[1] The star is radiating 783[1] times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 3,935 K.[3]

Planetary system

From September 2008 to June 2012, the team B.-C. Lee, I. Han, and M.-G. Park observed HD 220074 with "the high-resolution spectroscopy of the fiber-fed Bohyunsan Observatory Echelle Spectrograph (BOES) at Bohyunsan Optical Astronomy Observatory (BOAO)".

In 2012, a long-period, wide-orbiting eccentric planet was deduced by radial velocity changes. This finding was published in November, gaining the designation HD 220074 b.[6] Along with HD 208527 b this is one of the first two candidate planets found orbiting red giants.

The HD 220074 planetary system[6]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b ≥11.1±1.8 MJ 1.6±0.1 672.1±3.7 0.14±0.05 — —

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, S2CID 119257644.
  3. Lee, B.-C.; Han, I.; Park, M.-G. (2012). "Planetary companions orbiting M giants HD208527 and HD 220074". Astronomy & Astrophysics. 549: A2. arXiv:1211.2051. Bibcode:2013A&A...549A...2L. doi:10.1051/0004-6361/201220301. S2CID 73522393.
  4. "HD 220074". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2020-11-19.
  5. Hammersley, P. L.; et al. (February 1994). "The use of near-infrared spectroscopy to reclassify HR 8881". Monthly Notices of the Royal Astronomical Society. 266: 678–680. Bibcode:1994MNRAS.266..678H. doi:10.1093/mnras/266.3.678.
  6. "hd_220074_b".
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