Astronomy:HD 212771

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Short description: Star located in the constellation Aquarius
HD 212771 / Lionrock
Observation data
Epoch J2000.0   Equinox (celestial coordinates)
Constellation Aquarius
Right ascension  22h 27m 03.072s[1]
Declination −17° 15′ 49.164″[1]
Apparent magnitude (V) 7.6±0.01[2]
Characteristics
Spectral type G8 IV[3]
U−B color index +0.54[4]
B−V color index +0.88[2]
Astrometry
Radial velocity (Rv)14.9±0.03[5] km/s
Proper motion (μ) RA: −85.892[1] mas/yr
Dec.: −104.042[1] mas/yr
Parallax (π)8.9648 ± 0.0314[1] mas
Distance364 ± 1 ly
(111.5 ± 0.4 pc)
Absolute magnitude (MV)2.04[6]
Details
Mass1.56[7] M☉
Radius5.27[7] R☉
Luminosity11.55±0.08[8] L☉
Surface gravity (log g)3.31[7] cgs
Temperature5,003[7] K
Metallicity [Fe/H]−0.09±0.01[9] dex
Age1.676±0.287[9] Gyr
Other designations
Database references
SIMBADdata
Exoplanet Archivedata
Extrasolar Planets
Encyclopaedia		data

HD 212771, also named Lionrock, is a solitary star in the southern zodiac constellation Aquarius. It has an apparent magnitude of 7.60,[2] making it readily visible with binoculars but not the naked eye. Parallax measurements place the object at a distance of 364 light years,[1] and is currently receding with a radial velocity of 15 km/s.[5]

HD 212771 has a stellar classification of G8 IV,[3] indicating that it is a subgiant evolving towards the red giant branch after being an F-type main-sequence star for 1.7 billion years.[9] It has 156% the mass of the Sun and 5 times its radius.[7] It radiates at 11 solar luminosities[8] from its slightly enlarged photosphere at an effective temperature of 5,003 K,[7] giving it a yellow-hue. Unlike most planetary hosts, HD 212771 is slightly metal deficient, and spins with a projected rotational velocity of about 2 km/s.[9]

Planetary system

In 2010, a group of astronomers at the Keck Observatory surveyed several subgiant stars for extrasolar planets via Doppler spectroscopy They happened to find a massive Jupiter-like planet orbiting HD 212771.[10]

HD 212771 is named Lionrock. The name was selected in the NameExoWorlds campaign by Hong Kong, during the 100th anniversary of the IAU. It is named after the Lion Rock. The planet is named Victoriapeak, after the Victoria Peak.[11][12]

The HD 212771 planetary system[7]
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(days) 		Eccentricity Inclination Radius
b / Victoriapeak ≥2.39±0.27 MJ 1.19±0.13 381±1 0.076±0.051 — —

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 Brown, A. G. A. (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics 649: A1. doi:10.1051/0004-6361/202039657. Bibcode: 2021A&A...649A...1G.  Gaia EDR3 record for this source at VizieR.
  2. ↑ 2.0 2.1 2.2 Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P. et al. (March 2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics 355: L27–L30. ISSN 0004-6361. Bibcode: 2000A&A...355L..27H. 
  3. ↑ 3.0 3.1 Houk, N.; Smith-Moore, M. (1988). Michigan Catalogue of Two-dimensional Spectral Types for the HD Stars. Volume 4, Declinations -26°.0 to -12°.0.. 4. Bibcode: 1988mcts.book.....H. 
  4. ↑ Paunzen, E. (May 2022). "Catalogue of stars measured in the Geneva seven-colour photometric system". Astronomy & Astrophysics 661: A89. doi:10.1051/0004-6361/202142355. ISSN 0004-6361. Bibcode: 2022A&A...661A..89P. 
  5. ↑ 5.0 5.1 Jofré, E.; Petrucci, R.; Saffe, C.; Saker, L.; Artur de la Villarmois, E.; Chavero, C.; Gómez, M.; Mauas, P. J. D. (26 January 2015). "Stellar parameters and chemical abundances of 223 evolved stars with and without planets". Astronomy & Astrophysics 574: A50. doi:10.1051/0004-6361/201424474. ISSN 0004-6361. Bibcode: 2015A&A...574A..50J. 
  6. ↑ Anderson, E.; Francis, Ch. (May 2012). "XHIP: An extended hipparcos compilation" (in en). Astronomy Letters 38 (5): 331–346. doi:10.1134/S1063773712050015. ISSN 1063-7737. Bibcode: 2012AstL...38..331A. 
  7. ↑ 7.0 7.1 7.2 7.3 7.4 7.5 7.6 Luhn, Jacob K.; Bastien, Fabienne A.; Wright, Jason T.; Johnson, John A.; Howard, Andrew W.; Isaacson, Howard (20 March 2019). "Retired A Stars and Their Companions. VIII. 15 New Planetary Signals around Subgiants and Transit Parameters for California Planet Search Planets with Subgiant Hosts". The Astronomical Journal 157 (4): 149. doi:10.3847/1538-3881/aaf5d0. Bibcode: 2019AJ....157..149L. 
  8. ↑ 8.0 8.1 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode: 2018A&A...616A...1G.  Gaia DR2 record for this source at VizieR.
  9. ↑ 9.0 9.1 9.2 9.3 Ghezzi, L. (June 2018), "Retired A Stars Revisited: An Updated Giant Planet Occurrence Rate as a Function of Stellar Metallicity and Mass", The Astrophysical Journal 860 (2): 18, doi:10.3847/1538-4357/aac37c, Bibcode: 2018ApJ...860..109G 
  10. ↑ Johnson, John Asher; Howard, Andrew W.; Bowler, Brendan P.; Henry, Gregory W.; Marcy, Geoffrey W.; Wright, Jason T.; Fischer, Debra A.; Isaacson, Howard (June 2010). "Retired A Stars and Their Companions. IV. Seven Jovian Exoplanets from Keck Observatory1". Publications of the Astronomical Society of the Pacific 122 (892): 701–711. doi:10.1086/653809. ISSN 0004-6280. Bibcode: 2010PASP..122..701J. 
  11. ↑ "Approved names" (in en). http://www.nameexoworlds.iau.org/final-results. 
  12. ↑ "International Astronomical Union | IAU". https://www.iau.org/news/pressreleases/detail/iau1912/. 



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