Wikipedia

HD 170773

HD 170773 (HR 6948; 14 G. Coronae Australis) is a solitary star located in the southern constellation Corona Australis. It has an apparent magnitude of 6.22,[2] placing it near the limit for naked eye visibility, even under ideal conditions. The object is located relatively close at a distance of 120 light-years based on Gaia DR3 parallax measurements[1] and it is drifting closer with a heliocentric radial velocity of −25.2 km/s.[6] At its current distance, HD 170773's brightness is diminished by an interstellar extinction of 0.19 magnitudes[15] and it has an absolute magnitude of +3.38.[7]

HD 170773
Location of HD 170773 on the map (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Corona Australis
Right ascension 18h 33m 00.91673s[1]
Declination −39° 53′ 31.2751″[1]
Apparent magnitude (V) 6.22±0.01[2]
Characteristics
Spectral type F5 V[3][4]
B−V color index +0.42[5]
Astrometry
Radial velocity (Rv)−25.2±1.0[6] km/s
Proper motion (μ) RA: +86.353 mas/yr[1]
Dec.: −79.927 mas/yr[1]
Parallax (π)27.0749 ± 0.03 mas[1]
Distance120.5 ± 0.1 ly
(36.93 ± 0.04 pc)
Absolute magnitude (MV)+3.38[7]
Details
Mass1.30[8] M☉
Radius1.43±0.07[9] R☉
Luminosity3.62±0.01[1] L☉
Surface gravity (log g)4.21±0.04[10] cgs
Temperature6,694±126[11] K
Metallicity [Fe/H]−0.02±0.04[12] dex
Rotational velocity (v sin i)67.2±6.2[13] km/s
Age1.50+1.2
−0.7[10] Gyr
Other designations
14 G. Coronae Australis[14], CD−39°12704, CPD−39°8118, FK5 3470, GC 25304, HD 170773, HIP 90936, HR 6948, SAO 210286, TIC 313723578
Database references
SIMBADdata

HD 170773 has a stellar classification of F5 V,[3][4] indicating that it is an ordinary F-type main-sequence star that is generating energy via hydrogen fusion at its core. It has also been given a classification of F5 IV, indicating that it is a slightly evolved subgiant that is ceasing hydrogen fusion at its core. It has 1.30 times the mass of the Sun[8] and 1.43 times the radius of the Sun.[9] It radiates 3.62 times the luminosity of the Sun[1] from its photosphere at an effective temperature of 6,694 K,[11] giving it the typical yellowish-white hue of a F-type star. HD 170773 has a near solar metallicity of [Fe/H] = −0.02[12] and it is estimated to be 1.5 billion years old.[10] It spins fairly quickly with a projected rotational velocity of 67.2 km/s.[13]

The star has a debris disk located 78 AU away and it has a temperature of 43 K.[16] It was first observed in 1986 by astronomers K. Sakadane and M. Nishida in their survey of Vega-like stars due to the star displaying an infrared excess that could suggest the presence of a circumstellar disk.[17] However, the actual disk was not discovered until 2004 using the Spitzer Space Telescope.[18] There might be a second cooler disk surrounding the star, but subsequent observations have not confirmed this.[16]

References

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  1. ^ a b c d e f g 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, N. (1982). Michigan Catalogue of Two-dimensional Spectral Types for the HD stars. Declinations −40° to −26°. Vol. 3. Bibcode:1982mcts.book.....H.
  4. ^ a b 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. arXiv:astro-ph/0603770. Bibcode:2006AJ....132..161G. doi:10.1086/504637. eISSN 1538-3881. ISSN 0004-6256. S2CID 250741593.
  5. ^ Corben, P. M. (1966). "Photoelectric magnitudes and colours for bright southern stars". Monthly Notes of the Astronomical Society of South Africa. 25: 44. Bibcode:1966MNSSA..25...44C. 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 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. S2CID 33401607.
  9. ^ a b Kervella, P.; Thévenin, F.; Di Folco, E.; Ségransan, D. (April 8, 2004). "The angular sizes of dwarf stars and subgiants: Surface brightness relations calibrated by interferometry". 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. S2CID 6077801.
  10. ^ a b c Sepulveda, Aldo G.; Matrà, Luca; Kennedy, Grant M.; Burgo, Carlos del; Öberg, Karin I.; Wilner, David J.; Marino, Sebastián; Booth, Mark; Carpenter, John M.; Davies, Claire L.; Dent, William R. F.; Ertel, Steve; Lestrade, Jean-Francois; Marshall, Jonathan P.; Milli, Julien; Wyatt, Mark C.; MacGregor, Meredith A.; Matthews, Brenda C. (August 14, 2019). "The REASONS Survey: Resolved Millimeter Observations of a Large Debris Disk around the Nearby F Star HD 170773". The Astrophysical Journal. 881 (1): 84. arXiv:1906.08797. Bibcode:2019ApJ...881...84S. doi:10.3847/1538-4357/ab2b98. ISSN 1538-4357. S2CID 195316295.
  11. ^ a b 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. arXiv:1103.4651. Bibcode:2011A&A...530A.138C. doi:10.1051/0004-6361/201016276. eISSN 1432-0746. ISSN 0004-6361. S2CID 56118016.
  12. ^ a b 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. arXiv:1705.00883. Bibcode:2017MNRAS.469.3042N. doi:10.1093/mnras/stx1077. eISSN 1365-2966. ISSN 0035-8711. S2CID 119034918.
  13. ^ 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.
  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. ^ 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.
  16. ^ a b Moór, A.; Pascucci, I.; Kóspál, á.; Ábrahám, P.; Csengeri, T.; Kiss, L. L.; Apai, D.; Grady, C.; Henning, Th.; Kiss, Cs.; Bayliss, D.; Juhász, A.; Kovács, J.; Szalai, T. (March 2011). "Structure and Evolution of Debris Disks Around F-type Stars. I. Observations, Database, and Basic Evolutionary Aspects". The Astrophysical Journal Supplement Series. 193 (1): 4. arXiv:1012.3631. Bibcode:2011ApJS..193....4M. doi:10.1088/0067-0049/193/1/4. ISSN 0067-0049. S2CID 119243287.
  17. ^ Sadakane, K.; Nishida, M. (July 1986). "Twelve additional 'Vega-like' stars". Publications of the Astronomical Society of the Pacific. 98: 685. Bibcode:1986PASP...98..685S. doi:10.1086/131813. ISSN 0004-6280. S2CID 120682699.
  18. ^ Zuckerman, B.; Song, Inseok (March 10, 2004). "Dusty Debris Disks as Signposts of Planets: Implications for Spitzer Space Telescope". The Astrophysical Journal. 603 (2): 738–743. arXiv:astro-ph/0311546. Bibcode:2004ApJ...603..738Z. doi:10.1086/381700. ISSN 0004-637X. S2CID 3456817.
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