HD 178322
Location of HD 178322 (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Corona Australis
Right ascension 19h 09m 57.65200s[1]
Declination −41° 53′ 32.0836″[1]
Apparent magnitude (V) 5.86±0.01[2]
Characteristics
Spectral type B5 V + B6 V[3]
U−B color index −0.49[4]
B−V color index −0.08[4]
Variable type suspected[5]
Astrometry
Radial velocity (Rv)13.3±2[6] km/s
Proper motion (μ) RA: −0.360 mas/yr[1]
Dec.: −10.096 mas/yr[1]
Parallax (π)2.104 ± 0.1145 mas[1]
Distance1,550 ± 80 ly
(480 ± 30 pc)
Absolute magnitude (MV)−2.31[7] (combined)
Orbit[8]
PrimaryA
CompanionB
Period (P)12.4700 d
Semi-major axis (a)0.235 AU[9]
Eccentricity (e)0.05
Inclination (i)71.19°
Periastron epoch (T)2,438,237.4500 JD
Argument of periastron (ω)
(secondary)		199.1[10]°
Argument of periastron (ω)
(primary)		19.10[10]°
Semi-amplitude (K1)
(primary)		79.70 km/s
Semi-amplitude (K2)
(secondary)		78.90 km/s
Details
Age50.1±8.4[11] Myr
A
Mass4.39[10] M☉
Radius3.26[9] R☉
Luminosity11,749[12] L☉
Temperature15,488[12] K
Rotational velocity (v sin i)45[9] km/s
B
Mass4.35[10] M☉
Radius3.07[9] R☉
Luminosity513[12] L☉
Temperature14,454[12] K
Rotational velocity (v sin i)45±7[9] km/s
Other designations
45 G. Coronae Australis[13], CD−42°13933, CPD−42°8616, GC 26375, HD 178322, HIP 94157, HR 7257, SAO 229531[14]
Database references
SIMBADdata

HD 178322, also known as HR 7257 or rarely 45 G. Coronae Australis, is a double-lined spectroscopic binary located in the southern constellation Corona Australis. It has a combined apparent magnitude of 5.86,[2] making it faintly visible to the naked eye under ideal conditions. The system is located relatively far at a distance of roughly 1,550 light-years based on Gaia DR3 parallax measurements,[1] and it is currently receding with a heliocentric radial velocity of 13.3 km/s.[6] At its current distance, HD 178322's brightness is diminished by an extinction of 0.28 magnitudes[15] and it has an absolute magnitude of −2.31.[7] The system has a high peculiar velocity of 28.9+4.1
−7.9 km/s,[11] indicating that it may be a runaway star system; it is said to be part of the Scorpius-Centaurus Association.[16]

The components of HD 178322 are both B-type main-sequence stars with stellar classifications of B5 V and B6 V respectively.[3] Both stars have roughly 4.4 times the mass of the Sun[10] and they spin moderately with projected rotational velocities of 45 km/s.[9] The primary has 3.26 times the radius of the Sun[9] and it radiates 11,749 times the luminosity of the Sun[12] from its photosphere at an effective temperature of 15,488 K. The companion has 3.07 times the Sun's girth[9] and it radiates 513 times the luminosity of the Sun[12] from its photosphere at an effective temperature of 14,454 K.[12] Both stars take roughly 12 days to complete a relatively circular orbit[8] at a separation of 0.235 AU.[9] The system is estimated to be 50 million years old.[11]

References

  1. 1 2 3 4 5 6 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. 1 2 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. 1 2 Levato, H. (January 1975). "Rotational velocities and spectral types for a sample of binary systems". Astronomy and Astrophysics Supplement Series. 19: 91–99. Bibcode:1975A&AS...19...91L. ISSN 0365-0138. S2CID 118523421.
  4. 1 2 Gutierrez-Moreno, Adelina; Moreno, Hugo (June 1968). "A Photometric Investigation of the SCORPlO-CENTAURUS Association". The Astrophysical Journal Supplement Series. 15: 459. Bibcode:1968ApJS...15..459G. doi:10.1086/190168. eISSN 1538-4365. ISSN 0067-0049. S2CID 123957668.
  5. ↑ Samus’, N. N.; Kazarovets, E. V.; Durlevich, O. V.; Kireeva, N. N.; Pastukhova, E. N. (January 2017). "General catalogue of variable stars: Version GCVS 5.1". Astronomy Reports. 61 (1): 80–88. Bibcode:2017ARep...61...80S. doi:10.1134/S1063772917010085. eISSN 1562-6881. ISSN 1063-7729. S2CID 125853869.
  6. 1 2 Evans, David S. (June 20–24, 1966), "The Revision of the General Catalogue of Radial Velocities", in Batten, Alan Henry; Heard, John Frederick (eds.), Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30, vol. 30, University of Toronto: International Astronomical Union, p. 57, Bibcode:1967IAUS...30...57E, doi:10.1017/S007418090010662X, S2CID 122899856
  7. 1 2 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. 1 2 Thackeray, A. D.; Hutchings, J. B. (1 February 1965). "Orbits of Two Double-lined Binaries HD 140008 and 178322". Monthly Notices of the Royal Astronomical Society. 129 (2): 191–197. Bibcode:1965MNRAS.129..191T. doi:10.1093/mnras/129.2.191. eISSN 1365-2966. ISSN 0035-8711. S2CID 125267464.
  9. 1 2 3 4 5 6 7 8 9 Howe, K. S.; Clarke, C. J. (1 January 2009). "An analysis of v sin (i) correlations in early-type binaries". Monthly Notices of the Royal Astronomical Society. 392 (1): 448–454. Bibcode:2009MNRAS.392..448H. doi:10.1111/j.1365-2966.2008.14073.x. eISSN 1365-2966. ISSN 0035-8711. S2CID 120183969.
  10. 1 2 3 4 5 Kraicheva, Z.; Popova, E.; Tutukov, A.; Yungelson, L. (July 1980). "Catalogue of physical parameters of spectroscopic binary stars". Bull. Inf. Centre Données Stellaires. 19: 71. Bibcode:1980BICDS..19...71K. S2CID 118298938.
  11. 1 2 3 Tetzlaff, N.; Neuhäuser, R.; Hohle, M. M. (October 12, 2010). "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun". Monthly Notices of the Royal Astronomical Society. Oxford University Press (OUP). 410 (1): 190–200. arXiv:1007.4883. Bibcode:2011MNRAS.410..190T. doi:10.1111/j.1365-2966.2010.17434.x. ISSN 0035-8711. S2CID 118629873.
  12. 1 2 3 4 5 6 7 Vansina, F.; De Grève, J. P. (October 1982). "Close binary systems before and after mass transfer". Astrophysics and Space Science. 87 (1–2): 377–401. Bibcode:1982Ap&SS..87..377V. doi:10.1007/BF00648931. eISSN 1572-946X. ISSN 0004-640X. S2CID 123986012.
  13. ↑ 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.
  14. ↑ "HD 178322". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved May 30, 2023.
  15. ↑ Schmidt-Kaler, Th. (October 1982). "Automated spectral classification. A survey". Bulletin d'Information du Centre de Donnees Stellaires. 23: 2. Bibcode:1982BICDS..23....2S. ISSN 1169-8837. S2CID 230958433.
  16. ↑ Buscombe, W.; Morris, P. M. (1 September 1960). "The Scorpio-Centaurus Association: I. Radial Velocities of 120 Bright Stars". Monthly Notices of the Royal Astronomical Society. 121 (3): 263–278. Bibcode:1960MNRAS.121..263B. doi:10.1093/mnras/121.3.263. eISSN 1365-2966. ISSN 0035-8711. S2CID 121858509.
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