Astronomy:HD 157661

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Short description
Star in the constellation Ara
HD 157661
Observation data
Equinox J2000.0]] (ICRS)
Constellation Ara
Right ascension  17h 26m 51.97802s[1]
Declination –45° 50′ 34.9096″[1]
Apparent magnitude (V) 5.29[2] (5.70/6.46/7.6)[3]
Spectral type B7V + B9.5V + A0V[3]
U−B color index –0.34[2]
B−V color index –0.07[2]
R−I color index –0.03
Radial velocity (Rv)+8[4] km/s
Proper motion (μ) RA: –6.46[1] mas/yr
Dec.: –27.91[1] mas/yr
Parallax (π)5.13 ± 0.72[1] mas
Distanceapprox. 640 ly
(approx. 190 pc)
Other designations
CD–45 11531, HD 157661, HIP 85389, HR 6477.[5]
Database references

HD 157661 is the Henry Draper Catalogue designation for a likely triple star[3] in the southern constellation of Ara. With a measured annual parallax of 5.13 mas,[1] is located at a distance of approximately 640 light-years (200 parsecs) from Earth. The combined apparent visual magnitude of the stars is 5.29,[2] which means it is faintly visible to the naked eye.

The inner components of this system consist of a pair of B-type main sequence stars. The brighter star has a magnitude of 5.70 and a stellar classification of B7 V. At an angular separation of 2.115 arcseconds is the magnitude 6.46 secondary component, which has a classification of B9.5 V. A third member of the system is a 7.6 magnitude A-type star at a separation of 103 arcseconds.[3]


  1. 1.0 1.1 1.2 1.3 1.4 1.5 van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, doi:10.1051/0004-6361:20078357, Bibcode2007A&A...474..653V. 
  2. 2.0 2.1 2.2 2.3 Nicolet, B. (1978), "Photoelectric photometric Catalogue of homogeneous measurements in the UBV System", Astronomy and Astrophysics Supplement Series 34: 1–49, Bibcode1978A&AS...34....1N. 
  3. 3.0 3.1 3.2 3.3 Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society 389 (2): 869–879, doi:10.1111/j.1365-2966.2008.13596.x, Bibcode2008MNRAS.389..869E. 
  4. Evans, D. S. (June 20–24, 1966), "The Revision of the General Catalogue of Radial Velocities", in Batten, Alan Henry; Heard, John Frederick, Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30, University of Toronto: International Astronomical Union, Bibcode1967IAUS...30...57E. 
  5. "CCDM J17268-4550AB". SIMBAD. Centre de données astronomiques de Strasbourg. 

External links

  • VizieR Detailed Page: HR 6477 Hoffleit, D., Warren, Jr., W. H., (1991). The Bright Star Catalogue, (5th Revised Ed), CDS.
  • VizieR Detailed Page: CCDM 17268-4550 Dommanget J., (2002) Catalog of Components of Double & Multiple stars, CDS.
  • Aladin previewer: Image of SV* ZI 1312