HD 109271
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Virgo
Right ascension 12h 33m 35.555s[1]
Declination −11° 37′ 18.73″[1]
Apparent magnitude (V) 8.05 ± 0.01[2]
Characteristics
Spectral type G5 V[2] + DA[3]
B−V color index +0.658±0.002[2]
Astrometry
Radial velocity (Rv)−4.971±0.0011[4] km/s
Proper motion (μ) RA: −169.971 mas/yr[1]
Dec.: 81.000 mas/yr[1]
Parallax (π)17.9082 ± 0.0379 mas[1]
Distance182.1 ± 0.4 ly
(55.8 ± 0.1 pc)
Absolute magnitude (MV)4.1±0.1[2]
Position (relative to HD 109271 A)[3]
ComponentHD 109271 B
Epoch of observation2018
Angular distance5.425″
Position angle267.354°
Projected separation304 AU
Details[2]
HD 109271 A
Mass1.047±0.024 M☉
Radius1.295+0.023
−0.020[5] R☉
Luminosity1.649±0.008[5] L☉
Surface gravity (log g)4.28±0.10 cgs
Temperature5,783±62 K
Metallicity [Fe/H]0.10±0.05 dex
Rotational velocity (v sin i)2.7 km/s
Age7.3±1.2 Gyr
HD 109271 B
Mass~0.6[3] M☉
Other designations
BD−10° 3494, HD 109271, HIP 61300, SAO 157362, LTT 4770[6]
Database references
SIMBADdata
Exoplanet Archivedata

HD 109271 is a wide binary star system in the constellation of Virgo. The brighter member of the binary has a pair of orbiting exoplanets. With an apparent visual magnitude of 8.05,[2] it cannot be seen with the naked eye. Parallax measurements made by Gaia put the star at a distance of 181 light-years (55 parsecs) away from the Sun, but it is drifting closer with a radial velocity of −5 km/s.[4] The system shows a high proper motion, traversing the celestial sphere at an angular rate of 0.232 arcsec yr−1.[7]

The primary component is an ordinary G-type main-sequence star with a stellar classification of G5 V. It is a much older star than the Sun with an age of about 7.3 billion years, and is spinning with a projected rotational velocity of 2.7 km/s.[2] This star has 7% more mass than the Sun and a 30% greater girth.[5] The abundance of iron, a measure of the star's metallicity, is similar but slightly higher than in the Sun.[2] It is radiating 1.65[5] times the luminosity of the Sun from its photosphere at an effective temperature of around 5,783 K.[2]

In 2020, a white dwarf companion of 0.6 M☉ was found orbiting the primary at an angular separation of 5.4″ along a position angle of 267°. At the distance of this system, this corresponds to a projected separation of 304 AU. That is, they are physically separated by at least this distance. Additional stellar companions are ruled out down to a separation of 0.15″ from the primary.[3]

Planetary system

From 2003 to 2012, the star was under observance from the High Accuracy Radial Velocity Planet Searcher (HARPS).[2] In 2012, two eccentric hot Neptune-mass planets were deduced by radial velocity. They were published in January 2013. These are close to a 1:4 resonance, so the system is similar to HD 69830. A third Neptune in the Venus zone was hypothesised from the data. These planets managed to survive the post main-sequence epoch of the companion star, when it shed much of its original mass.[3]

The HD 109271 planetary system[8][2]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b >0.054 ± 0.004 MJ 0.079 ± 0.001 7.8543 ± 0.0009 0.25 ± 0.08 — —
c >0.076 ± 0.007 MJ 0.196 ± 0.003 30.93 ± 0.02 0.15 ± 0.09 — —
d (unconfirmed) >1.3 neptune MJ 1 430 0.36 — —

References

  1. 1 2 3 4 5 Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  2. 1 2 3 4 5 6 7 8 9 10 11 Lo Curto, G.; et al. (2013). "The HARPS search for southern extrasolar planets: XXXVI. New multi-planet systems in the HARPS volume limited sample: a super-Earth and a Neptune in the habitable zone". Astronomy & Astrophysics. 551: 7. arXiv:1301.2741. Bibcode:2013A&A...551A..59L. doi:10.1051/0004-6361/201220415. S2CID 116916728. A59.
  3. 1 2 3 4 5 Ginski, Christian; et al. (2021). "How many suns are in the sky? A SPHERE multiplicity survey of exoplanet host stars". Astronomy & Astrophysics. 649: A156. arXiv:2009.10363. Bibcode:2021A&A...649A.156G. doi:10.1051/0004-6361/202038964. S2CID 221836281.
  4. 1 2 Soubiran, C.; et al. (2018). "Gaia Data Release 2. The catalogue of radial velocity standard stars". Astronomy and Astrophysics. 616: A7. arXiv:1804.09370. Bibcode:2018A&A...616A...7S. doi:10.1051/0004-6361/201832795. S2CID 52952408.
  5. 1 2 3 4 Johns, Daniel; et al. (November 2018). "Revised Exoplanet Radii and Habitability Using Gaia Data Release 2". The Astrophysical Journal Supplement Series. 239 (1): 14. arXiv:1808.04533. Bibcode:2018ApJS..239...14J. doi:10.3847/1538-4365/aae5fb. 14.
  6. ↑ "HD 109271". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2024-01-09.
  7. ↑ Luyten, W. J. (June 1995). "NLTT Catalogue (Luyten, 1979)". VizieR Online Data Catalog. Bibcode:1995yCat.1098....0L.
  8. ↑ "Planet HD 109271 b". Extrasolar Planets Encyclopaedia. Retrieved 3 September 2017.
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