HD 117618

HD 117618, named Döfida by the IAU,[8] is a single,[9] yellow-hued star in the southern constellation of Centaurus. With an apparent visual magnitude of 7.17,[2] it is too faint to be visible to the naked eyes of a typical observer. The distance to this star, as determined from its annual parallax shift of 26.34±0.60 mas as seen from Earth's orbit,[1] is about 124 light years. It is moving further away with a heliocentric radial velocity of around +1.6 km/s.[2]

HD 117618

Observation data Epoch J2000      Equinox J2000
Constellation	Centaurus
Right ascension	13^h 32^m 25.55543^s[1]
Declination	–47° 16′ 16.9091″[1]
Apparent magnitude (V)	7.17[2]
Characteristics
Spectral type	G0 V[3]
B−V color index	0.603±0.010[2]
Astrometry
Radial velocity (Rv)	+1.60±0.76[2] km/s
Proper motion (μ)	RA: +24.87[1] mas/yr Dec.: −125.01[1] mas/yr
Parallax (π)	26.34 ± 0.60[1] mas
Distance	124 ± 3 ly (38.0 ± 0.9 pc)
Absolute magnitude (MV)	4.27[2]
Details[4]
Mass	1.10±0.02 M☉
Radius	1.17±0.04 R☉
Luminosity	1.6±0.1 L☉
Surface gravity (log g)	4.34±0.03 cgs
Temperature	6,019±50 K
Metallicity [Fe/H]	+0.03±0.01[5] dex
Rotational velocity (v sin i)	3.67[6] km/s
Age	4.0±1.3 Gyr
Other designations
Dofida, CD−46° 8708, GC 18290, HD 117618, HIP 66047, SAO 224228[7]
Database references
SIMBAD	data
Extrasolar Planets Encyclopaedia	data

This star is similar to the Sun, being a G-type main-sequence star with a stellar classification of G0 V.[3] It is about 10% more massive and 17% larger than the Sun, with an estimated age of roughly four billion years[4] and a projected rotational velocity of 3.67 km/s.[6] The star is radiating 1.6 times the Sun's luminosity from its photosphere at an effective temperature of 6,019 K.[4]

Name

HD 117618, and its planet HD 117618b, were chosen as part of the 2019 NameExoWorlds campaign organised by the International Astronomical Union, which assigned each country a star and planet to be named. HD 117618 was assigned to Indonesia. The winning proposal named the star "Döfida" meaning our star in Nias language, and its planet "Noifasui" meaning revolve around in Nias language (derived from the word ifasui, meaning to revolve around, and no, indicating that the action occurred in the past and continued to the present time).[8]

Planetary system

In 2005, the Anglo-Australian Planet Search program announced the discovery of a low-mass planet in orbit around HD 117618. This object was found through measurements of radial velocity variation, which were larger than those produced by the intrinsic jitter of the host star. The best Keplerian fit to the data gave a periodicity of 25.8 days with an eccentricity of around 0.37 and a semimajor axis of 0.17 AU. The lower bound on the object's mass was estimated to be 0.16 M_J.[10] These values were subsequently refined, as shown in the table below.[11]

The HD 117618 planetary system[11]

Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination	Radius
b	>0.178 ± 0.021 MJ	0.176 ± 0.010	25.827±0.019	0.42 ± 0.17	—	—

See also

• HD 117207
• List of extrasolar planets

References

1. van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357.
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. Gray, R. O.; et al. (July 2006). "Contributions to the Nearby Stars (NStars) Project: spectroscopy of stars earlier than M0 within 40 pc-The Southern Sample". The Astronomical Journal. 132 (1): 161–170. arXiv:astro-ph/0603770. Bibcode:2006AJ....132..161G. doi:10.1086/504637.
4. Bonfanti, A.; Ortolani, S.; Nascimbeni, V. (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.
5. Adibekyan, V.; et al. (August 2016). "Abundance trend with condensation temperature for stars with different Galactic birth places". Astronomy & Astrophysics. 592: 12. arXiv:1606.04714. Bibcode:2016A&A...592A..87A. doi:10.1051/0004-6361/201628883. A87.
6. 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.
7. "HD 114837". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-07-05.
8. "Approved names (§ Indonesia)". Name Exo Worlds. IAU. Retrieved 18 January 2020.
9. Raghavan, Deepak; et al. (July 2006), "Two Suns in The Sky: Stellar Multiplicity in Exoplanet Systems", The Astrophysical Journal, 646 (1): 523–542, arXiv:astro-ph/0603836, Bibcode:2006ApJ...646..523R, doi:10.1086/504823.
10. Tinney, C. G.; et al. (2005). "Three Low-Mass Planets from the Anglo-Australian Planet Search". The Astrophysical Journal. 623 (2): 1171–1179. Bibcode:2005ApJ...623.1171T. CiteSeerX 10.1.1.491.2941. doi:10.1086/428661.
11. Butler, R. P.; et al. (2006). "Catalog of Nearby Exoplanets". The Astrophysical Journal. 646 (1): 505–522. arXiv:astro-ph/0607493. Bibcode:2006ApJ...646..505B. doi:10.1086/504701.