Delta Arae

Delta Arae
δ Arae (circled) in the Ara Constellation
Observation data
Epoch J2000      Equinox ICRS
Constellation Ara
Right ascension 17h 31m 05.91272s
Declination −60° 41′ 01.8522″
Apparent magnitude (V) 3.62
Characteristics
Spectral type B8 Vn + G8 V
U−B color index −0.31
B−V color index −0.10
Astrometry
Radial velocity (Rv)+10 km/s
Proper motion (μ) RA: −54.01 mas/yr
Dec.: −99.25 mas/yr
Parallax (π)16.48±0.34 mas
Distance198 ± 4 ly
(61 ± 1 pc)
Absolute magnitude (MV)−0.31
Orbit
PrimaryA
SecondaryB
Period (P)2.46697±0.00500 yr
Semi-major axis (a)48.7±0.2 mas
Eccentricity (e)0.7380±0.0264
Inclination (i)90.32±0.97°
Longitude of the node (Ω)127.13±0.91°
Argument of periastron (ω)
(secondary)		347.80±1.05°
Details
δ Ara A
Mass3.56 M☉
Radius3.12±0.15 R☉
Luminosity214 L☉
Surface gravity (log g)3.81±0.06 cgs
Temperature13,882 K
Rotational velocity (v sin i)255 km/s
Age125 Myr
δ Ara B
Temperature4,129 K
Other designations
δ Ara, CPD−60°6842, FK5 648, GC 23681, HD 158094, HIP 85727, HR 6500, SAO 253945, PPM 362756, WDS J17311-6041A
Database references
SIMBADdata

Delta Arae is a binary star in the southern constellation Ara. Its name is a Bayer designation that is Latinized from δ Arae, and abbreviated Delta Ara or δ Ara. This system has an apparent visual magnitude of 3.62 and is visible to the naked eye as a point of light. Based upon an annual parallax of 16.48 mas, it is about 198 light-years (61 parsecs) distant from the Earth.

Characteristics

This is an astrometric binary system, identified using data from the Gaia spacecraft. The components have an orbital period of about 2.47 years and a high orbital eccentricity of 0.7380. The orbit is nearly edge-on relative to Earth.

The brighter component is an intermediate-mass B-type main sequence star with a stellar classification of B8 Vn. The 'n' suffix indicates the absorption lines are spread out broadly because the star is spinning rapidly. It has a projected rotational velocity of 255 km/s, resulting in an equatorial bulge with a radius 13% larger than the polar radius. The star has 3.56 times the mass and 3.1 times the radius of the Sun. It is radiating 214 times the luminosity of the Sun from its photosphere at an effective temperature of 13,882 K.

The secondary is 1.27 times fainter than the primary at Gaia's G-band, it has 2.03 times the mass of the Sun and an effective temperature of 9,161 K.

There is a magnitude 9.5 companion G-type main sequence star that may (17% chance) form a gravitationally bound system with Delta Arae. A 12th magnitude optical companion is located 47.4 arcseconds away along a position angle of 313°.

Etymology

Delta Arae was known as 龜三 (meaning: "the 3rd (star) of Guī") in traditional Chinese astronomy.

Allen erroneously called both Delta and Zeta Arae "Tseen Yin" (天陰). He probably confused the constellation "Ara" with "Ari", as 天陰 is actually in Aries.

See also

References

  1. 1 2 3 4 5 6 7 van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600.
  2. 1 2 3 4 Nicolet, B. (1978), "Photoelectric photometric Catalogue of homogeneous measurements in the UBV System", Astronomy and Astrophysics Supplement Series, 34: 1–49, Bibcode:1978A&AS...34....1N.
  3. 1 2 Houk, Nancy (1979), "Michigan catalogue of two-dimensional spectral types for the HD stars", Ann Arbor: Dept. Of Astronomy, 1, Ann Arbor, Michigan: Dept. of Astronomy, University of Michigan, Bibcode:1978mcts.book.....H.
  4. 1 2 3 Shaya, Ed J.; Olling, Rob P. (January 2011), "Very Wide Binaries and Other Comoving Stellar Companions: A Bayesian Analysis of the Hipparcos Catalogue", The Astrophysical Journal Supplement, 192 (1): 2, arXiv:1007.0425, Bibcode:2011ApJS..192....2S, doi:10.1088/0067-0049/192/1/2, S2CID 119226823.
  5. ↑ Evans, D. 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.
  6. 1 2 3 Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID 119257644.
  7. 1 2 3 4 5 6 7 8 Pérez-Couto, X.; Docobo, J. Á.; Campo, P. P. (2024-01-29), "Methodology for obtaining the relative orbit and individual masses of Gaia astrometric binaries", Astronomy & Astrophysics, 682: A12, arXiv:2306.16867, Bibcode:2024A&A...682A..12P, doi:10.1051/0004-6361/202348125, ISSN 0004-6361.
  8. 1 2 3 Fitzpatrick, E. L.; Massa, D. (March 2005), "Determining the Physical Properties of the B Stars. II. Calibration of Synthetic Photometry", The Astronomical Journal, 129 (3): 1642–1662, arXiv:astro-ph/0412542, Bibcode:2005AJ....129.1642F, doi:10.1086/427855, S2CID 119512018.
  9. 1 2 van Belle, Gerard T. (March 2012), "Interferometric observations of rapidly rotating stars", The Astronomy and Astrophysics Review, 20 (1): 51, arXiv:1204.2572, Bibcode:2012A&ARv..20...51V, doi:10.1007/s00159-012-0051-2, S2CID 119273474.
  10. 1 2 Ehrenreich, D.; et al. (November 2010), "Deep infrared imaging of close companions to austral A- and F-type stars", Astronomy and Astrophysics, 523: A73, arXiv:1007.0002, Bibcode:2010A&A...523A..73E, doi:10.1051/0004-6361/201014763, S2CID 54913363.
  11. ↑ "del Ara". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2012-07-27.{{cite web}}: CS1 maint: postscript (link)
  12. 1 2 Chevalier, S., and Tsuchihashi, P., (1911): "Catalogue d'Étoiles fixes, observés a Pekin sous l'Empereur Kien Long (Qianlong (Chien-Lung)), XVIIIe siecle", Annales de l'Observatoire Astronomique de Zô-Sé.
  13. 1 2 伊世同 (Yi Shi Tong) (1981): 『中西対照恒星図表』科学出版社.(in Chinese)
  14. ↑ Allen, Richard Hinckley (1936) [1899]. Star Names and Their Meanings. New York: G. E. Stechert. p. 64. OCLC 9825499.