Astronomy:HD 170642

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Short description: A-type dwarf; Corona Australis
HD 170642
Corona Australis constellation map.svg
Red circle.svg
Location of HD 170642 (circled)
Observation data
Epoch J2000.0   Equinox (celestial coordinates)
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[1] mas/yr
Dec.: −37.47[1] mas/yr
Parallax (π)14.23 ± 0.23[1] mas
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
CD−39°12696, CPD−39°8114, GC 25285, HD 170642, HIP 90887, HR 6942, SAO 210277[14]
Database references
SIMBADdata

HD 170642, also designated as HR 6942 or rarely 13 G. Coronae Australis, is a single star[15] 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.[16] It has an absolute magnitude of +0.93.[7]

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.[17][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

  1. ↑ 1.0 1.1 1.2 1.3 1.4 Template:Cite New HIP red.
  2. ↑ 2.0 2.1 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. (1982). Michigan Catalogue of Two-dimensional Spectral Types for the HD stars. Volume III: Declinations −40° to −26°. Bibcode: 1982mcts.book.....H. 
  4. ↑ 4.0 4.1 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. doi:10.1086/191349. ISSN 0067-0049. Bibcode: 1989ApJS...70..623G. 
  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. ISSN 0024-8266. Bibcode: 1965MNSSA..24...41L. 
  6. ↑ 6.0 6.1 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. 
  7. ↑ 7.0 7.1 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. 
  8. ↑ 8.0 8.1 8.2 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. doi:10.1088/0004-637X/804/2/146. Bibcode: 2015ApJ...804..146D. 
  9. ↑ 9.0 9.1 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. doi:10.1051/0004-6361:20035930. ISSN 0004-6361. Bibcode: 2004A&A...426..297K. 
  10. ↑ 10.0 10.1 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. doi:10.1111/j.1365-2966.2012.21873.x. ISSN 0035-8711. Bibcode: 2012MNRAS.427..343M. 
  11. ↑ 11.0 11.1 11.2 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. doi:10.1051/0004-6361:20021711. ISSN 0004-6361. Bibcode: 2003A&A...398.1121E. 
  12. ↑ 12.0 12.1 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. 
  13. ↑ 13.0 13.1 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. doi:10.1051/0004-6361/201016386. ISSN 0004-6361. Bibcode: 2011A&A...531A.143D. 
  14. ↑ "HD 170642". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+170642. 
  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. doi:10.1111/j.1365-2966.2008.13596.x. ISSN 0035-8711. Bibcode: 2008MNRAS.389..869E. 
  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. doi:10.1093/mnras/stx2219. ISSN 0035-8711. Bibcode: 2017MNRAS.472.3805G. 
  17. ↑ 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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