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HD 170521
Location of HD 170521 (circled)
Observation data
Epoch J2000.0       Equinox J2000.0 ( ICRS)
Constellation Corona Australis
Right ascension 18h 31m 56.22382s [1]
Declination −43° 30′ 26.5714″ [1]
Apparent magnitude (V) 5.69±0.01 [2]
Characteristics
Spectral type K2 III [3]
B−V color index +1.34 [4]
Astrometry
Radial velocity (Rv)7.2±0.4 [5] km/s
Proper motion (μ) RA: −1.328  mas/ yr [1]
Dec.: −8.795  mas/ yr [1]
Parallax (π)2.1538 ± 0.1596  mas [1]
Distance1,500 ± 100  ly
(460 ± 30  pc)
Absolute magnitude (MV)−1.90 [6]
Details
Mass1.55 [7]  M☉
Radius78.6±4.1 [8]  R☉
Luminosity934 [9]  L☉
Surface gravity (log g)0.96 [10]  cgs
Temperature4,474±122 [11]  K
Metallicity [Fe/H]−0.49 [7]  dex
Rotational velocity (v sin i)6.5±1 [12] km/s
Other designations
12 G. Coronae Australis [13], CD−43°12600, CPD−34°8647, GC 25272, HD 170521, HIP 90842, HR 6937, SAO 229094 [14]
Database references
SIMBAD data

HD 170521, also known as HR 6937 or rarely 12 G. Coronae Australis, is a solitary star [15] located in the southern constellation Corona Australis. It is faintly visible to the naked eye as an orange-hued point of light with an apparent magnitude of 5.69. [2] The object is located relatively far at a distance of approximately 1,500 light years based on Gaia DR3 parallax measurements, [1] and it is receding with a heliocentric radial velocity of 7.2  km/s. [5] At its current distance, HD 170521's brightness is heavily diminished by 0.46 magnitudes due to extinction from interstellar dust [16] and it has an absolute magnitude of −1.90. [6]

HD 170521 has a stellar classification of K2 III, [3] indicating that it is an evolved red giant. It has 1.55 times the mass of the Sun [7] but it has expanded to 78.6 times the Sun's radius. [8] The object radiates 934 times the luminosity of the Sun [9] from its enlarged photosphere at an effective temperature of 4,474  K. [11] HD 170521 is metal deficient with an iron abundance only 32.4% that of the Sun (Fe/H) = −0.49 [7] and it spins modestly with a projected rotational velocity of 6.5  km/s. [12]

References

  1. ^ a b c d e 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. ^ a b Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P.; Wicenec, A. (March 2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27–L30. Bibcode: 2000A&A...355L..27H. ISSN  0004-6361. S2CID  17128864.
  3. ^ a b Houk, Nancy (1978). Michigan catalogue of two-dimensional spectral types for the HD stars: Declinations −53° to −40°. Vol. 2. Bibcode: 1978mcts.book.....H.
  4. ^ 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. Bibcode: 1968MNSSA..27...11C. ISSN  0024-8266.
  5. ^ a b 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. arXiv: 1606.08053. Bibcode: 2006AstL...32..759G. doi: 10.1134/S1063773706110065. eISSN  1562-6873. ISSN  1063-7737. S2CID  119231169.
  6. ^ a b Anderson, E.; Francis, Ch. (May 2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331–346. arXiv: 1108.4971. Bibcode: 2012AstL...38..331A. doi: 10.1134/S1063773712050015. eISSN  1562-6873. ISSN  1063-7737. S2CID  119257644.
  7. ^ a b c d Anders, F.; et al. (August 2019). "Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia DR2 stars brighter than G = 18". Astronomy & Astrophysics. 628: A94. arXiv: 1904.11302. Bibcode: 2019A&A...628A..94A. doi: 10.1051/0004-6361/201935765. eISSN  1432-0746. ISSN  0004-6361. S2CID  131780028.
  8. ^ a b Kervella, P.; Thévenin, F.; Di Folco, E.; Ségransan, D. (October 2004). "The angular sizes of dwarf stars and subgiants". Astronomy & Astrophysics. 426 (1): 297–307. arXiv: astro-ph/0404180. Bibcode: 2004A&A...426..297K. doi: 10.1051/0004-6361:20035930. eISSN  1432-0746. ISSN  0004-6361.
  9. ^ a b McDonald, I.; Zijlstra, A. A.; Boyer, M. L. (21 November 2012). "Fundamental parameters and infrared excesses of Hipparcos stars: Parameters and IR excesses from Hipparcos". Monthly Notices of the Royal Astronomical Society. 427 (1): 343–357. arXiv: 1208.2037. Bibcode: 2012MNRAS.427..343M. doi: 10.1111/j.1365-2966.2012.21873.x. eISSN  1365-2966. ISSN  0035-8711. S2CID  118665352.
  10. ^ McDonald, I.; Zijlstra, A. A.; Watson, R. A. (15 June 2017). "Fundamental parameters and infrared excesses of Tycho–Gaia stars". Monthly Notices of the Royal Astronomical Society. 471 (1): 770–791. arXiv: 1706.02208. Bibcode: 2017MNRAS.471..770M. doi: 10.1093/mnras/stx1433. eISSN  1365-2966. ISSN  0035-8711. S2CID  73594365.
  11. ^ a b Stassun, Keivan G.; et al. (9 September 2019). "The Revised TESS Input Catalog and Candidate Target List". The Astronomical Journal. 158 (4): 138. arXiv: 1905.10694. Bibcode: 2019AJ....158..138S. doi: 10.3847/1538-3881/ab3467. eISSN  1538-3881. hdl: 1721.1/124721. S2CID  166227927.
  12. ^ a b De Medeiros, J. R.; Alves, S.; Udry, S.; Andersen, J.; Nordström, B.; Mayor, M. (January 2014). "A catalog of rotational and radial velocities for evolved stars V: Southern stars *". Astronomy & Astrophysics. 561: A126. arXiv: 1312.3474. Bibcode: 2014A&A...561A.126D. doi: 10.1051/0004-6361/201220762. eISSN  1432-0746. ISSN  0004-6361. S2CID  54046583.
  13. ^ Gould, Benjamin Apthorp (1878). "Uranometria Argentina : brillantez y posicion de las estrellas fijas, hasta la septima magnitud, comprendidas dentro de cien grados del polo austral : con atlas". Resultados del Observatorio Nacional Argentino. 1. Bibcode: 1879RNAO....1.....G.
  14. ^ "HD 170521". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved May 19, 2023.
  15. ^ 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. arXiv: 0806.2878. Bibcode: 2008MNRAS.389..869E. doi: 10.1111/j.1365-2966.2008.13596.x. eISSN  1365-2966. ISSN  0035-8711. S2CID  14878976.
  16. ^ 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. arXiv: 1709.01160. Bibcode: 2017MNRAS.472.3805G. doi: 10.1093/mnras/stx2219. eISSN  1365-2966. ISSN  0035-8711. S2CID  118879856.
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