HD 77258

HD 77258
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Vela
Right ascension 09h 00m 05.4104s[1]
Declination −41° 15′ 12.9734″[1]
Apparent magnitude (V) 4.45[2]
Characteristics
Spectral type G8-K1III[3] + A7[4]
B−V color index 0.75±0.02[2]
Variable type Constant[3]
Astrometry
Radial velocity (Rv)−7.4±4.1[2] km/s
Proper motion (μ) RA: −42.227[1] mas/yr
Dec.: 50.599[1] mas/yr
Parallax (π)14.9687 ± 0.2155 mas[1]
Distance218 ± 3 ly
(66.8 ± 1.0 pc)
Absolute magnitude (MV)0.40[2]
Orbit[3]
Period (P)74.13715±0.00073 d
Semi-major axis (a)≥ (2.0057±0.0004)×107 km
Eccentricity (e)0.00085±0.00019
Periastron epoch (T)2453625.5112±0.0017 HJD
Argument of periastron (ω)
(secondary)		106±13°
Semi-amplitude (K1)
(primary)		19.6744±0.0041 km/s
Details
A
Radius7.97+0.66
−1.42[1] R☉
Luminosity68.769±1.152[1] L☉
Temperature5889+607
−232[1] K
Metallicity [Fe/H]0.72±0.15[5] dex
Other designations
w Vel, CD−40° 4810, FK5 1234, HD 77258, HIP 44191, HR 3591, SAO 220730[6]
Database references
SIMBADdata

HD 77258 is a binary star system in the southern constellation of Vela. It has the Bayer designation w Velorum, while HD 77258 is the identifier from the Henry Draper Catalogue. The system is visible to the naked eye as a faint point of light with a combined apparent visual magnitude of 4.45.[2] It is located at a distance of approximately 218 light years from the Sun based on parallax.[1] The radial velocity of the system barycenter is poorly constrained, but it appears to be drifting away at a rate of ~7 km/s.[2]

The radial velocity variation of this system was first reported by H. K. Palmer in 1904. It is a single-lined spectroscopic binary with an orbital period of 74.14 days and an eccentricity (ovalness) of 0.00085, indicating the orbit is essentially circular.[3] The visible component has a stellar classification of G8-K1III,[3] matching a late G-type giant star. This is an evolved star that has exhausted the supply of hydrogen at its core, then cooled and expanded away from the main sequence. In 1975, S. Maladora flagged the spectrum as peculiar.[7]

The level of ultraviolet flux coming from this system suggests the companion is a hot A-type star of class A6.5 or A7.[4] The system is a source of X-ray emission.[8]

  1. ^ a b c d e f g h i Cite error: The named reference Gaia DR2 was invoked but never defined (see the help page).
  2. ^ a b c d e f Cite error: The named reference Anderson_Francis_2012 was invoked but never defined (see the help page).
  3. ^ a b c d e Cite error: The named reference Hearnshaw_et_al_2012 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference Parsons_Ake_1998 was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference Gáspár_et_al_2016 was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference Simbad was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference Malaroda1975 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference Pizzolato_et_al_1998 was invoked but never defined (see the help page).