Astronomy:HD 201772

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Short description: Star in the constellation Microscopium
HD 201772
Microscopium constellation map.svg
Red circle.svg
HD 201772 is the star circled in red
Observation data
Epoch J2000.0   Equinox (celestial coordinates)
Constellation Microscopium
Right ascension  21h 13m 03.06827s[1]
Declination −39° 25′ 29.7097″[1]
Apparent magnitude (V) 5.26[2]
Characteristics
Spectral type F5 IV-V[3] or F6 V Fe−0.9 CH−0.5[4]
B−V color index +0.44[2]
Astrometry
Radial velocity (Rv)−41±1[5] km/s
Proper motion (μ) RA: +185.855[1] mas/yr
Dec.: −113.449[1] mas/yr
Parallax (π)29.2823 ± 0.0827[1] mas
Distance111.4 ± 0.3 ly
(34.15 ± 0.10 pc)
Absolute magnitude (MV)+2.66[6]
Details
Mass1.5[1] M☉
Radius2.18±0.09[7] R☉
Luminosity7.83±0.04[1] L☉
Surface gravity (log g)3.91±0.09[8] cgs
Temperature6,519±80[9] K
Metallicity [Fe/H]−0.18±0.03[10] dex
Rotational velocity (v sin i)10[11] km/s
Age2.23±0.04 Gyr
Other designations
CD−39°14152, CPD−39°8898, GC 29640, HD 201772, HIP 104738, HR 8104, SAO 212793, LTT 8413[12]
Database references
SIMBADdata

HD 201772, also known as HR 8104, is a yellowish-white hued star located in the southern constellation Microscopium. It has an apparent magnitude of 5.26,[2] making it one of the brighter members of this generally faint constellation. The object is located relatively close at a distance of 111 light-years based on Gaia DR3 parallax measurements[1] but is approaching closer with a heliocentric radial velocity of −41 km/s.[5] At its current distance, HD 201772's brightness is diminished by 0.11 magnitudes due to interstellar dust.[13]

The star has been given multiple stellar classifications over the years. It was given the luminosity class of a subgiant and main sequence star (IV/V; IV-V)[14][3] and a dwarf (V).[15][16] Most sources generally agree that it is a F5 star. Richard O. Gray and colleagues give HD 201772 a class of F6 V Fe−0.9 CH−0.5, which indicates that it is a F-type main-sequence star with an underabundance of iron and CH molecules in its spectrum.[4]

It has 1.47 times the mass of the Sun[17] and an enlarged radius of 2.2 R☉.[7] It radiates 7.8 times the luminosity of the Sun from its photosphere at an effective temperature of 6,519 K.[9] At an age of 2.5 billion years, HD 201722 is currently 1.33 magnitudes above the ZAMS, consistent with a star that is evolving off the main sequence.[11] The star has an iron abundance 66% that of the Sun,[10] making it metal deficient. It spins modestly with a projected rotational velocity of 10 km/s.[11]

HD 201772 is suspected to be a spectroscopic binary consisting of the subgiant described above and an ordinary F6 V star with a mass of 1.31 M☉.[18] However, the stars have no separation or an orbital period.[19] This is because the companion might be a result of spectrum contamination, so HD 201772 is more likely to be a solitary star.[20]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940  Gaia DR3 record for this source at VizieR.
  2. ↑ 2.0 2.1 2.2 Corben, P. M.; Stoy, R. H. (1968). "Photoelectric Magnitudes and Colours for Bright Southern Stars". Monthly Notes of the Astronomical Society of South Africa 27: 11. ISSN 0024-8266. Bibcode: 1968MNSSA..27...11C. 
  3. ↑ 3.0 3.1 Gray, Richard O. (September 1989). "The extension of the MK spectral classification system to the intermediate population II F type stars". The Astronomical Journal 98: 1049. doi:10.1086/115195. ISSN 0004-6256. Bibcode: 1989AJ.....98.1049G. 
  4. ↑ 4.0 4.1 Gray, R. O.; Corbally, C. J.; Garrison, R. F.; McFadden, M. T.; Bubar, E. J.; McGahee, C. E.; O'Donoghue, A. A.; Knox, E. R. (2 June 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. doi:10.1086/504637. ISSN 0004-6256. Bibcode: 2006AJ....132..161G. 
  5. ↑ 5.0 5.1 Gontcharov, G. A. (November 2006). "Pulkovo Compilation of Radial Velocities for 35,495 Hipparcos stars in a common system". Astronomy Letters 32 (11): 759–771. doi:10.1134/S1063773706110065. ISSN 1063-7737. Bibcode: 2006AstL...32..759G. 
  6. ↑ Anderson, E.; Francis, Ch. (May 2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331–346. doi:10.1134/S1063773712050015. ISSN 1063-7737. Bibcode: 2012AstL...38..331A. 
  7. ↑ 7.0 7.1 Masana, E.; Jordi, C.; Ribas, I. (10 April 2006). "Effective temperature scale and bolometric corrections from 2MASS photometry". Astronomy & Astrophysics 450 (2): 735–746. doi:10.1051/0004-6361:20054021. ISSN 0004-6361. Bibcode: 2006A&A...450..735M. 
  8. ↑ Stassun, Keivan G. et al. (9 September 2019). "The Revised TESS Input Catalog and Candidate Target List". The Astronomical Journal 158 (4): 138. doi:10.3847/1538-3881/ab3467. Bibcode: 2019AJ....158..138S. 
  9. ↑ 9.0 9.1 Casagrande, L.; Schönrich, R.; Asplund, M.; Cassisi, S.; Ramírez, I.; Meléndez, J.; Bensby, T.; Feltzing, S. (26 May 2011). "New constraints on the chemical evolution of the solar neighbourhood and Galactic disc(s): Improved astrophysical parameters for the Geneva-Copenhagen Survey⋆". Astronomy & Astrophysics 530: A138. doi:10.1051/0004-6361/201016276. ISSN 0004-6361. Bibcode: 2011A&A...530A.138C. 
  10. ↑ 10.0 10.1 Netopil, Martin (4 May 2017). "Metallicity calibrations for dwarf stars and giants in the Geneva photometric system". Monthly Notices of the Royal Astronomical Society 469 (3): 3042–3055. doi:10.1093/mnras/stx1077. ISSN 0035-8711. Bibcode: 2017MNRAS.469.3042N. 
  11. ↑ 11.0 11.1 11.2 Nordström, B.; Mayor, M.; Andersen, J.; Holmberg, J.; Pont, F.; Jørgensen, B. R.; Olsen, E. H.; Udry, S. et al. (16 April 2004). "The Geneva-Copenhagen survey of the Solar neighbourhood". Astronomy & Astrophysics 418 (3): 989–1019. doi:10.1051/0004-6361:20035959. ISSN 0004-6361. Bibcode: 2004A&A...418..989N. 
  12. ↑ "HD 201772". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+201772. 
  13. ↑ Gontcharov, George A.; Mosenkov, Aleksandr V. (28 September 2017). "Verifying reddening and extinction for Gaia DR1 TGAS main sequence stars". Monthly Notices of the Royal Astronomical Society 472 (4): 3805–3820. doi:10.1093/mnras/stx2219. ISSN 0035-8711. Bibcode: 2017MNRAS.472.3805G. 
  14. ↑ Adams, Walter S.; Joy, Alfred H.; Humason, Milton L.; Brayton, Ada Margaret (April 1935). "The Spectroscopic Absolute Magnitudes and Parallaxes of 4179 Stars". The Astrophysical Journal 81: 187. doi:10.1086/143628. ISSN 0004-637X. Bibcode: 1935ApJ....81..187A. 
  15. ↑ Malaroda, S. (August 1975). "Study of the F-type 1 MK spectral types.". The Astronomical Journal 80: 637. doi:10.1086/111786. ISSN 0004-6256. Bibcode: 1975AJ.....80..637M. 
  16. ↑ Houk, N. (1982). Michigan Catalogue of Two-dimensional Spectral Types for the HD stars. Volume III: Declinations −40° to −26°. Bibcode: 1982mcts.book.....H. 
  17. ↑ Feltzing, S.; Holmberg, J.; Hurley, J. R. (October 2001). "The solar neighbourhood age-metallicity relation - Does it exist?". Astronomy & Astrophysics 377 (3): 911–924. doi:10.1051/0004-6361:20011119. ISSN 0004-6361. Bibcode: 2001A&A...377..911F. 
  18. ↑ Tokovinin, Andrei (14 March 2014). "From Binaries to Multiples. II. Hierarchical Multiplicity of F and G Dwarfs". The Astronomical Journal 147 (4): 87. doi:10.1088/0004-6256/147/4/87. ISSN 0004-6256. Bibcode: 2014AJ....147...87T. 
  19. ↑ Tokovinin, Andrei (14 March 2014). "From Binaries to Multiples. I. Data on F and G Dwarfs within 67 pc of the Sun". The Astronomical Journal 147 (4): 86. doi:10.1088/0004-6256/147/4/86. ISSN 0004-6256. Bibcode: 2014AJ....147...86T. 
  20. ↑ Eggleton, P. P.; Tokovinin, A. A. (11 September 2008). "A catalogue of multiplicity among bright stellar systems". Monthly Notices of the Royal Astronomical Society 389 (2): 869–879. doi:10.1111/j.1365-2966.2008.13596.x. ISSN 0035-8711. Bibcode: 2008MNRAS.389..869E. 
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