Chi1 Sagittarii

Chi1 Sagittarii
Diagram showing star positions and boundaries of the Sagittarius constellation and its surroundings
Location of χ1 Sagittari (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Sagittarius
Right ascension 19h 25m 16.49013s[1]
Declination −24° 30′ 30.8599″[1]
Apparent magnitude (V) +5.03[2]
Characteristics
Spectral type A3/5 IV/V[3]
B−V color index +0.23[2]
Astrometry
Radial velocity (Rv)−43.4±1.6[4] km/s
Proper motion (μ) RA: +61.63[1] mas/yr
Dec.: −50.66[1] mas/yr
Parallax (π)12.95 ± 0.50[1] mas
Distance252 ± 10 ly
(77 ± 3 pc)
Absolute magnitude (MV)+0.59[5]
Orbit[6]
Period (P)5.72 yr
Semi-major axis (a)0.069″
Eccentricity (e)0.710
Inclination (i)97.3°
Longitude of the node (Ω)259.0°
Periastron epoch (T)1984.29
Argument of periastron (ω)
(secondary)		10.7°
Details
Chi1 Sgr A
Mass1.64[7] M☉
Luminosity42.9[8] L☉
Surface gravity (log g)4.15[7] cgs
Temperature7,859±267[7] K
Rotational velocity (v sin i)54[9] km/s
Age393[7] Myr
Other designations
Chi1 Sgr, 47 Sgr, CPD−24° 6721, HD 182369, HIP 95477, HR 7362, SAO 188101, WDS J19253-2431[10]
Database references
SIMBADdata

Chi1 Sagittarii (χ1 Sagittarii) is a binary star[6] system in the zodiac constellation of Sagittarius. The pair have a combined apparent visual magnitude of +5.03,[2] which is bright enough to be seen with the naked eye. Based upon an annual parallax shift of 12.95 mas as seen from Earth,[1] it is located around 252 light years from the Sun. It is advancing through space in the general direction of the Earth with a radial velocity of −43.4 km/s.[4]

This is a visual binary with an orbital period of 5.72 years, an eccentricity of 0.710, and an angular semimajor axis of 69 mas. The primary, component A, is an A-type star showing a mixed spectrum that matches a stellar classification of A3/5 IV/V.[3] Helmut Abt classified it as an Am star with a spectral type of kA5hF0VmF0.[11] This notation indicates it has the calcium K-lines of an A5 star, and the hydrogen and metal lines of an F0 star. It is around 393[7] million years old and is spinning with a projected rotational velocity of 54 km/s.[9] The star has an estimated 1.6[7] times the mass of the Sun and is radiating 42.9[8] times the Sun's luminosity from its photosphere at an effective temperature of 7,859 K.[7]

References

  1. 1 2 3 4 5 6 van Leeuwen, F. (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.
  2. 1 2 3 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; Smith-Moore, M. (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, 4, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode:1988mcts.book.....H.
  4. 1 2 Kharchenko, N. V.; et al. (2007), "Astrophysical supplements to the ASCC-2.5: Ia. Radial velocities of ˜55000 stars and mean radial velocities of 516 Galactic open clusters and associations", Astronomische Nachrichten, 328 (9): 889–896, arXiv:0705.0878, Bibcode:2007AN....328..889K, doi:10.1002/asna.200710776.
  5. ↑ 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.
  6. 1 2 "Sixth Catalog of Orbits of Visual Binary Stars". United States Naval Observatory. April 25, 2016. Retrieved 20 June 2017.
  7. 1 2 3 4 5 6 7 David, Trevor J.; Hillenbrand, Lynne A. (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.
  8. 1 2 McDonald, I.; et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society, 427 (1): 343–57, arXiv:1208.2037, Bibcode:2012MNRAS.427..343M, doi:10.1111/j.1365-2966.2012.21873.x.
  9. 1 2 Royer, F.; et al. (February 2007), "Rotational velocities of A-type stars. III. Velocity distributions", Astronomy and Astrophysics, 463 (2): 671–682, arXiv:astro-ph/0610785, Bibcode:2007A&A...463..671R, doi:10.1051/0004-6361:20065224.
  10. ↑ "chi01 Sgr". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-07-05.
  11. ↑ Abt, H. A. (March 1981), "Visual multiples. VII - MK classifications", Astrophysical Journal Supplement Series, 45: 437–456, Bibcode:1981ApJS...45..437A, doi:10.1086/190719.
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