Lambda2 Fornacis

For other stars with this Bayer designation, see λ Fornacis.

Lambda^2 Fornacis

λ^2 Fornacis on the right of the Fornax Dwarf Galaxy Credit: ESO/Digitized Sky Survey 2
Observation data Epoch J2000.0      Equinox J2000.0
Constellation	Fornax
Right ascension	02^h 36^m 58.6079^s[1]
Declination	−34° 34′ 40.714″[1]
Apparent magnitude (V)	5.78[2]
Characteristics
Spectral type	G1V[3]
B−V color index	+0.653±0.005[2]
Astrometry
Radial velocity (Rv)	+11.80±0.65[2] km/s
Proper motion (μ)	RA: −18.507±0.065[1] mas/yr Dec.: −258.869±0.089[1] mas/yr
Parallax (π)	39.3512 ± 0.0543 mas[1]
Distance	82.9 ± 0.1 ly (25.41 ± 0.04 pc)
Absolute magnitude (MV)	3.74±0.04[4]
Details
A
Mass	1.18±0.04[4] M☉
Radius	1.50±0.05[4] R☉
Luminosity	3.03[2] L☉
Surface gravity (log g)	4.12±0.03[4] cgs
Temperature	5,936[4] K
Metallicity [Fe/H]	+0.19[4] dex
Rotational velocity (v sin i)	1.4 or 3.2[5] km/s
Age	4.34±0.82[4] Gyr
B
Mass	0.11[6] M☉
Other designations
λ^2 For, CD–35°903, Gaia DR2 5062172841616745856, GC 3153, GJ 105.1, HD 16417, HIP 12186, HR 772, SAO 193811, PPM 278138, LTT 1280, NLTT 8516, GCRV 1481, 2MASS J02365859-3434404[7]
Database references
SIMBAD	data
Exoplanet Archive	data
ARICNS	data

λ² Fornacis, Latinized as Lambda² Fornacis, is the primary of a binary star system in the southern constellation of Fornax. It is just visible to the naked eye as a dim, yellow-hued point of light with an apparent visual magnitude of 5.78.^[2] It is located 83 light years distant from the Sun, based on stellar parallax,^[1] and is drifting further away with a radial velocity of +12 km/s.^[2]

This object is a G-type main-sequence star with a stellar classification of G1V.^[3] It is considered a solar analog, being photometrically-similar to the Sun.^[8] The star is an estimated 4.3^[4] billion years old with 1.2 times the mass of the Sun and 1.5 times the Sun's radius.^[4] It is radiating three^[2] times the luminosity of the Sun from its photosphere at an effective temperature of 5,936 K.^[4] The abundance of elements with more mass than helium is 55% higher than in the Sun.^[4][9]

There is a faint co-moving companion star located to the east of the main star at an angular separation of 45″. This is most likely an M5–M6 class red dwarf with 0.11 times the Sun's mass. The projected separation between the pair is about 1,000 AU.^[6]

Planetary system

Precision Doppler spectroscopy from an intensive 48 night observing campaign on the Anglo-Australian Telescope has revealed the presence of a low-mass extrasolar planet orbiting the star. This object has an orbital period of 17.24 days and an eccentricity of 0.2. It has a minimum (baseline) mass of 21.9 M_🜨.^[10]

The Lambda^2 Fornacis planetary system^[10]

Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination	Radius
b	≥0.069±0.007 MJ	0.14±0.01	17.24±0.01	0.2±0.09	—	—

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. 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. 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. S2CID 119476992.
4. da Silva, L.; et al. (November 2006). "Basic physical parameters of a selected sample of evolved stars". Astronomy and Astrophysics. 458 (2): 609–623. arXiv:astro-ph/0608160. Bibcode:2006A&A...458..609D. doi:10.1051/0004-6361:20065105. S2CID 9341088.
5. Soto, M. G.; Jenkins, J. S. (July 2018). "Spectroscopic Parameters and atmosphEric ChemIstriEs of Stars (SPECIES). I. Code description and dwarf stars catalogue". Astronomy & Astrophysics. 615: 28. arXiv:1801.09698. Bibcode:2018A&A...615A..76S. doi:10.1051/0004-6361/201731533. S2CID 119107228. A76.
6. Mugrauer, M.; et al. (March 2014). "New wide stellar companions of exoplanet host stars". Monthly Notices of the Royal Astronomical Society. 439 (1): 1063–1070. Bibcode:2014MNRAS.439.1063M. doi:10.1093/mnras/stu044.
7. "lam02 For". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-09-23.
8. Datson, Juliet; et al. (February 2015). "Spectroscopic study of solar twins and analogues". Astronomy & Astrophysics. 574: 12. arXiv:1412.8168. Bibcode:2015A&A...574A.124D. doi:10.1051/0004-6361/201425000. S2CID 53708062. A124.
9. 10^+0.19 = 1.55
10. O’Toole, Simon; et al. (2009). "A Neptune-mass Planet Orbiting the Nearby G Dwarf HD16417". The Astrophysical Journal. 697 (2): 1263–1268. arXiv:0902.4024. Bibcode:2009ApJ...697.1263O. doi:10.1088/0004-637X/697/2/1263. S2CID 16341718.