Astronomy:HD 170773

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Short description: F-type star with a debris disk
HD 170773
The 74 exocomet belts imaged by ALMA’s REASONS survey, showing belts of all shapes, sizes and ages (REASONS comboplot full nonames).jpg
Image of the disk with the REASONS survey[1]
Observation data
Epoch J2000.0   Equinox (celestial coordinates)
Constellation Corona Australis
Right ascension  18h 33m 00.91673s[2]
Declination −39° 53′ 31.2751″[2]
Apparent magnitude (V) 6.22±0.01[3]
Characteristics
Spectral type F5 V[4][5]
B−V color index +0.42[6]
Astrometry
Radial velocity (Rv)−25.2±1.0[7] km/s
Proper motion (μ) RA: +86.353[2] mas/yr
Dec.: −79.927[2] mas/yr
Parallax (π)27.0749 ± 0.03[2] mas
Distance120.5 ± 0.1 ly
(36.93 ± 0.04 pc)
Absolute magnitude (MV)+3.38[8]
Details
Mass1.30[9] M☉
Radius1.43±0.07[10] R☉
Luminosity3.62±0.01[2] L☉
Surface gravity (log g)4.21±0.04[11] cgs
Temperature6,694±126[12] K
Metallicity [Fe/H]−0.02±0.04[13] dex
Rotational velocity (v sin i)67.2±6.2[14] km/s
Age1.50+1.2−0.7[11] Gyr
Other designations
CD−39°12704, CPD−39°8118, FK5 3470, GC 25304, HD 170773, HIP 90936, HR 6948, SAO 210286
Location of HD 170773 on the map (circled)
Database references
SIMBADdata

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,[3] 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[2] and it is drifting closer with a heliocentric radial velocity of −25.2 km/s.[7] 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.[8]

HD 170773 has a stellar classification of F5 V,[4][5] 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[9] and 1.43 times the radius of the Sun.[10] It radiates 3.62 times the luminosity of the Sun[2] from its photosphere at an effective temperature of 6,694 K,[12] giving it the typical yellowish-white hue of a F-type star. HD 170773 has a near solar metallicity of [Fe/H] = −0.02[13] and it is estimated to be 1.5 billion years old.[11] It spins fairly quickly with a projected rotational velocity of 67.2 km/s.[14]

The star has a debris disk located 78 astronomical unit|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

  1. ↑ Matrà, L.; Marino, S.; Wilner, D. J.; Kennedy, G. M.; Booth, M.; Krivov, A. V.; Williams, J. P.; Hughes, A. M. et al. (2025-01-15). "REsolved ALMA and SMA Observations of Nearby Stars (REASONS): A population of 74 resolved planetesimal belts at millimetre wavelengths". Astronomy and Astrophysics 693. doi:10.1051/0004-6361/202451397. Bibcode: 2025A&A...693A.151M. 
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 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.
  3. ↑ 3.0 3.1 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. 
  4. ↑ 4.0 4.1 Houk, N. (1982). Michigan Catalogue of Two-dimensional Spectral Types for the HD stars. Declinations −40° to −26°. 3. Bibcode: 1982mcts.book.....H. 
  5. ↑ 5.0 5.1 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. doi:10.1086/504637. ISSN 0004-6256. Bibcode: 2006AJ....132..161G. 
  6. ↑ Corben, P. M. (1966). "Photoelectric magnitudes and colours for bright southern stars". Monthly Notes of the Astronomical Society of South Africa 25: 44. ISSN 0024-8266. Bibcode: 1966MNSSA..25...44C. 
  7. ↑ 7.0 7.1 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. 
  8. ↑ 8.0 8.1 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. 
  9. ↑ 9.0 9.1 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. 
  10. ↑ 10.0 10.1 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. doi:10.1051/0004-6361:20035930. ISSN 0004-6361. Bibcode: 2004A&A...426..297K. 
  11. ↑ 11.0 11.1 11.2 Sepulveda, Aldo G.; Matrà, Luca; Kennedy, Grant M.; Burgo, Carlos del; Öberg, Karin I.; Wilner, David J.; Marino, Sebastián; Booth, Mark et al. (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. doi:10.3847/1538-4357/ab2b98. ISSN 1538-4357. Bibcode: 2019ApJ...881...84S. 
  12. ↑ 12.0 12.1 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. doi:10.1051/0004-6361/201016276. ISSN 0004-6361. Bibcode: 2011A&A...530A.138C. 
  13. ↑ 13.0 13.1 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. doi:10.1093/mnras/stx1077. ISSN 0035-8711. Bibcode: 2017MNRAS.469.3042N. 
  14. ↑ 14.0 14.1 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. doi:10.1051/0004-6361/201220762. ISSN 0004-6361. Bibcode: 2014A&A...561A.126D. 
  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. 
  16. ↑ 16.0 16.1 Moór, A.; Pascucci, I.; Kóspál, á.; Ábrahám, P.; Csengeri, T.; Kiss, L. L.; Apai, D.; Grady, C. et al. (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. doi:10.1088/0067-0049/193/1/4. ISSN 0067-0049. Bibcode: 2011ApJS..193....4M. 
  17. ↑ Sadakane, K.; Nishida, M. (July 1986). "Twelve additional 'Vega-like' stars". Publications of the Astronomical Society of the Pacific 98: 685. doi:10.1086/131813. ISSN 0004-6280. Bibcode: 1986PASP...98..685S. 
  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. doi:10.1086/381700. ISSN 0004-637X. Bibcode: 2004ApJ...603..738Z. 
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