Epoch J2000 Equinox J2000
|Right ascension||17h 26m 51.97802s|
|Declination||–45° 50′ 34.9096″|
|Apparent magnitude (V)||5.29 (5.70/6.46/7.6)|
|Spectral type||B7V + B9.5V + A0|
|U−B color index||–0.34|
|B−V color index||–0.07|
|R−I color index||–0.03|
|Radial velocity (Rv)||+8 km/s|
|Proper motion (μ)||RA: –6.46 mas/yr
Dec.: –27.91 mas/yr
|Parallax (π)||5.13 ± 0.72 mas|
|Distance||approx. 640 ly
(approx. 190 pc)
HD 157661 is the Henry Draper Catalogue designation for a likely triple star in the southern constellation of Ara. With a measured annual parallax of 5.13 mas, 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, 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.
- 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.
- 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.
- 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, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x.
- 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, Bibcode:1967IAUS...30...57E.
- "CCDM J17268-4550AB -- Double or multiple star", SIMBAD Astronomical Database (Centre de Données astronomiques de Strasbourg), retrieved 2012-08-03.
- 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