Astronomy:HD 170384

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Short description: A-type dwarf; Corona Australis
HD 170384
Corona Australis constellation map.svg
Red circle.svg
Location of HD 170384 (circled)
Observation data
Epoch J2000.0   Equinox (celestial coordinates)
Constellation Corona Australis
Right ascension  18h 31m 02.94877s[1]
Declination −41° 54′ 49.8025″[1]
Apparent magnitude (V) 6.02±0.01[2]
Characteristics
Evolutionary stage main sequence star[3]
Spectral type A3 V[4]
B−V color index +0.14[5]
Astrometry
Radial velocity (Rv)−11.4±0.4[6] km/s
Proper motion (μ) RA: −3.406[1] mas/yr
Dec.: −31.578[1] mas/yr
Parallax (π)14.2387 ± 0.0341[1] mas
Distance229.1 ± 0.5 ly
(70.2 ± 0.2 pc)
Absolute magnitude (MV)+1.86[7]
Details
Mass2.00[8] M☉
Radius1.91±0.10[9] R☉
Luminosity16.7+1.1−1.0[3] L☉
Surface gravity (log g)4.19+0.08−0.07[10] cgs
Temperature8,694[11] K
Metallicity [Fe/H]−0.01[12] dex
Rotation19.2 h[13]
Rotational velocity (v sin i)127±5[13] km/s
Age544[8] Myr
Other designations
CD−41°12871, CPD−41°8697, GC 25249, HD 170384, HIP 90759, HR 6931, SAO 229080[14]
Database references
SIMBADdata

HD 170384, also known as HR 6931 or rarely 11 G. Coronae Australis, is a solitary white-hued star located in the southern constellation Corona Australis. It has an apparent magnitude of 6.02,[2] making it barely visible to the naked eye, even under ideal conditions. The object is located relatively close at a distance of 229.1 light-years based on Gaia DR3 parallax measurements[1] and it is drifting closer with a heliocentric radial velocity of −11.4 km/s.[6] At its current distance, HD 170384's brightness is diminished by interstellar extinction of 0.28 magnitudes[15] and it has an absolute magnitude of +1.86.[7]

This object has a stellar classification of A3 V, indicating that it is an ordinary A-type main-sequence star. It has double the Sun's mass[8] and 1.91 times the radius of the Sun.[9] It radiates 16.7 times the luminosity of the Sun[3] from its photosphere at an effective temperature of 8,694 K.[11] HD 170384 has a near solar metallicity at [Fe/H] = −0.01 (97% solar)[12] and it is estimated to be 544 million years old,[8] having completed 45% of its main sequence lifetime.[3] Like many hot stars HD 170384 spins rapidly, having a projected rotational velocity of 127 km/s and an estimated rotation period of 19.2 hours.[13]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 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 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 3.2 3.3 Zorec, J.; Royer, F. (January 2012). "Rotational velocities of A-type stars IV: Evolution of rotational velocities". Astronomy & Astrophysics 537: A120. doi:10.1051/0004-6361/201117691. ISSN 0004-6361. Bibcode: 2012A&A...537A.120Z. 
  4. ↑ Houk, Nancy (1978). Michigan catalogue of two-dimensional spectral types for the HD stars: Declinations −53° to −40°. 2. Bibcode: 1978mcts.book.....H. 
  5. ↑ Corben, P. M. (April 1971). "Photoelectric Magnitudes and Colours for Bright Southern Stars". Monthly Notes of the Astronomical Society of South Africa 30 (4): 37. ISSN 0024-8266. Bibcode: 1971MNSSA..30...37C. 
  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 8.3 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. ↑ 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. 
  11. ↑ 11.0 11.1 Balona, L. A. (October 7, 2019). "Evidence for spots on hot stars suggests major revision of stellar physics". Monthly Notices of the Royal Astronomical Society (Oxford University Press (OUP)) 490 (2): 2112–2116. doi:10.1093/mnras/stz2808. ISSN 0035-8711. 
  12. ↑ 12.0 12.1 Gontcharov, G. A. (December 2012). "Dependence of kinematics on the age of stars in the solar neighborhood". Astronomy Letters 38 (12): 771–782. doi:10.1134/S1063773712120031. ISSN 1063-7737. Bibcode: 2012AstL...38..771G. 
  13. ↑ 13.0 13.1 13.2 Reiners, A.; Royer, F. (February 2004). "First signatures of strong differential rotation in A-type stars". Astronomy & Astrophysics 415 (1): 325–329. doi:10.1051/0004-6361:20034175. ISSN 0004-6361. Bibcode: 2004A&A...415..325R. 
  14. ↑ "HD 170384". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+170384. 
  15. ↑ 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. 
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