Wikipedia

HD 170642

HD 170642, also designated as HR 6942 or rarely 13 G. Coronae Australis, is a single star[16] located in the southern constellation Corona Australis. It is faintly visible to the naked eye as a white hued star with an apparent magnitude of 5.16.[2] The object is located relatively close at a distance of 229 light years based on Hipparcos parallax measurements,[1] but it is approaching the Solar System with a somewhat constrained heliocentric radial velocity of −6 km/s.[6] At its current distance, HD 170642's brightness is diminished by 0.28 magnitudes due to interstellar dust.[17] It has an absolute magnitude of +0.93.[7]

HD 170642
Location of HD 170642 (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Corona Australis
Right ascension 18h 32m 21.33140s[1]
Declination −39° 42′ 14.4023″[1]
Apparent magnitude (V) 5.16±0.01[2]
Characteristics
Spectral type A3 V[3] or A3 Van[4]
B−V color index +0.08[5]
Astrometry
Radial velocity (Rv)−6±4.2[6] km/s
Proper motion (μ) RA: +32.47 mas/yr[1]
Dec.: −37.47 mas/yr[1]
Parallax (π)14.23 ± 0.23 mas[1]
Distance229 ± 4 ly
(70 ± 1 pc)
Absolute magnitude (MV)+0.93[7]
Details
Mass2.25[8] M☉
Radius2.59±0.13[9] R☉
Luminosity32.6[10] L☉
Surface gravity (log g)3.96[11] cgs
Temperature8,938±161[12] K
Metallicity [Fe/H]+0.24[11] dex
Rotational velocity (v sin i)177±1[13] km/s
Age480[8] Myr
Other designations
13 G. Coronae Australis[14], CD−39°12696, CPD−39°8114, GC 25285, HD 170642, HIP 90887, HR 6942, SAO 210277[15]
Database references
SIMBADdata

This is an ordinary A-type main-sequence star with a stellar classification of A3 V.[3] Other sources include broad/nebulous absorption lines due to rapid rotation.[18][4] It has 2.25 times the mass of the Sun and is estimated to be 480 million years old.[8] HD 170642 has a radius of 2.59 R☉.[9] When combined with an effective temperature of 8,938 K,[12] it radiates 32.6 times the luminosity of the Sun[10] from its photosphere. The star is metal enriched, having an iron abundance 74% greater than the Sun's.[11] Like many hot stars HD 170642 spins rapidly, having a projected rotational velocity of 177 km/s.[13]

References

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  1. ^ a b c d e van Leeuwen, Floor (13 August 2007). "Validation of the new Hipparcos reduction". Astronomy & Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. eISSN 1432-0746. ISSN 0004-6361. Hipparcos 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.
  3. ^ a b Houk, N. (1982). Michigan Catalogue of Two-dimensional Spectral Types for the HD stars. Volume III: Declinations −40° to −26°. Bibcode:1982mcts.book.....H.
  4. ^ a b Gray, R. O.; Garrison, R. F. (July 1989). "The late A-type stars - Refined MK classification, confrontation with Stromgren photometry, and the effects of rotation". The Astrophysical Journal Supplement Series. 70: 623. Bibcode:1989ApJS...70..623G. doi:10.1086/191349. eISSN 1538-4365. ISSN 0067-0049.
  5. ^ Lake, R. (1965). "Photometric Magnitudes and Colours for Bright Southern Stars (Sixth List)". Monthly Notes of the Astronomical Society of South Africa. 24: 41. Bibcode:1965MNSSA..24...41L. ISSN 0024-8266.
  6. ^ 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.
  7. ^ 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.
  8. ^ a b c David, Trevor J.; Hillenbrand, Lynne A. (12 May 2015). "The Ages of Early-type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets". The Astrophysical Journal. 804 (2): 146. arXiv:1501.03154. Bibcode:2015ApJ...804..146D. doi:10.1088/0004-637X/804/2/146. eISSN 1538-4357.
  9. ^ 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.
  10. ^ 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.
  11. ^ a b c Erspamer, D.; North, P. (28 January 2003). "Automated spectroscopic abundances of A and F-type stars using echelle spectrographs". Astronomy & Astrophysics. 398 (3): 1121–1135. arXiv:astro-ph/0210065. Bibcode:2003A&A...398.1121E. doi:10.1051/0004-6361:20021711. eISSN 1432-0746. ISSN 0004-6361.
  12. ^ 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.
  13. ^ a b Díaz, C. G.; González, J. F.; Levato, H.; Grosso, M. (July 2011). "Accurate stellar rotational velocities using the Fourier transform of the cross correlation maximum". Astronomy & Astrophysics. 531: A143. arXiv:1012.4858. Bibcode:2011A&A...531A.143D. doi:10.1051/0004-6361/201016386. eISSN 1432-0746. ISSN 0004-6361.
  14. ^ 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.
  15. ^ "HD 170642". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved December 25, 2022.
  16. ^ 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.
  17. ^ 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.
  18. ^ Evans, D. S. (1966). "Fundamental data for Southern stars (6th list)". Royal Greenwich Observatory Bulletins. 110: 185. Bibcode:1966RGOB..110..185E.
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