HD 161840

HD 161840
Observation data
Epoch J2000      Equinox J2000
Constellation Scorpius
Right ascension 17h 48m 10.47559s[1]
Declination −31° 42′ 11.5636″[1]
Apparent magnitude (V) 4.79[2]
Characteristics
Spectral type B8 Ib/II[3]
B−V color index −0.028±0.023[2]
Astrometry
Radial velocity (Rv)−13.3±2.8[2] km/s
Proper motion (μ) RA: +6.845[1] mas/yr
Dec.: −8.161[1] mas/yr
Parallax (π)6.5831 ± 0.3618 mas[1]
Distance500 ± 30 ly
(152 ± 8 pc)
Absolute magnitude (MV)−1.37[2]
Details
Mass3.93±0.08[4] M☉
Radius3.2[5] R☉
Luminosity565+59
−53[4] L☉
Surface gravity (log g)3.38[6] cgs
Temperature11066+77
−76[4] K
Rotational velocity (v sin i)24[4] km/s
Other designations
CD−31° 14609, HD 161840, HIP 87220, HR 6628, SAO 209303[7]
Database references
SIMBADdata

HD 161840 is a single,[8] blue-white hued star in the southern zodiac constellation of Scorpius. It is faintly visible to the naked eye with an apparent visual magnitude of 4.79.[2] With an annual parallax shift of 6.5 mas[1] it is located roughly 500 light years from the Sun. It is moving closer with a heliocentric radial velocity of −13 km/s.[2]

There has been some uncertainty as to the classification of this stage. Houk (1979) lists a stellar class of B8 Ib/II for HD 161840,[3] which corresponds to a B-type bright giant/lesser supergiant mix. Multiple studies still use an older classification of B8 V,[8][6][4] suggesting instead this is a B-type main-sequence star. Garrison and Gray (1994) assigned it a class of B8 III-IV,[9] which would put it on the subgiant/giant star track. It has an estimated 3.93[4] times the mass of the Sun and 3.2[5] times the Sun's radius. The star is radiating 565[4] times the Sun's luminosity from its photosphere at an effective temperature of 11,066 K.[4]

  1. ^ a b c d e f Cite error: The named reference GaiaDR2 was invoked but never defined (see the help page).
  2. ^ a b c d e f Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference houk1979 was invoked but never defined (see the help page).
  4. ^ a b c d e f g h Cite error: The named reference zorec2012 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference cadars2001 was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference Hempel2003 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  8. ^ a b Cite error: The named reference Eggleton2008 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference garrison1994 was invoked but never defined (see the help page).