HD 171978

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HD 171978
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Serpens
Right ascension 18h 37m 35.9613s[1]
Declination −00° 18′ 34.100″[1]
Apparent magnitude (V) 5.74 to 5.86[2]
Spectral type A1V / A1V
(spectroscopic binary)[3]
U−B color index +0.06[3]
B−V color index +0.07[3]
R−I color index +0.04[3]
Radial velocity (Rv) 11.4[3][4] km/s
Proper motion (μ) RA: 11.74[1] mas/yr
Dec.: −19.83[1] mas/yr
Parallax (π) 5.06 ± 0.93[1] mas
Distance approx. 600 ly
(approx. 200 pc)
Absolute magnitude (MV) −0.7[5]
Other designations
e Ser, BD−00 3521, FK5 3480, GC 25456, HIP 91322, HR 6993, PPM 180381, SAO 142444.[1]
Database references

The star HD 171978 is a spectroscopic binary in the constellation of Serpens. It consists of two A-type main sequence stars orbiting each other with a period of approximately 14.7 days.[3] The overall apparent visual magnitude of the system varies between 5.74 and 5.86.[2]


  1. ^ a b c d e f NSV 11122 -- Spectroscopic binary, database entry, SIMBAD. Accessed on line October 3, 2008.
  2. ^ a b NSV 11122, database entry, New Catalogue of Suspected Variable Stars, the improved version, Sternberg Astronomical Institute, Moscow, Russia. Accessed on line October 3, 2008.
  3. ^ a b c d e f HR 6993, database entry, The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version), D. Hoffleit and W. H. Warren, Jr., CDS ID V/50. Accessed on line October 3, 2008.
  4. ^ Figure is for the barycenter of the spectroscopic binary system.
  5. ^ From apparent magnitude and parallax.