BW Vulpeculae

BW Vulpeculae

A light curve for BW Vulpeculae, plotted from TESS data[1]
Observation data
Epoch J2000      Equinox J2000
Constellation Vulpecula
Right ascension 20h 54m 22.39491s[2]
Declination +28° 31′ 19.1827″[2]
Apparent magnitude (V) 6.54[3] (6.44 – 6.68)[4]
Characteristics
Spectral type B2 IIIv[5]
U−B color index −0.147±0.011[6]
Variable type β Cep[7]
Astrometry
Radial velocity (Rv)−6.1±3.0[8] km/s
Proper motion (μ) RA: +0.437[2] mas/yr
Dec.: −4.981[2] mas/yr
Parallax (π)1.1494 ± 0.0652 mas[2]
Distance2,800 ± 200 ly
(870 ± 50 pc)
Absolute magnitude (MV)−2.47[9]
Details
Mass6.8±0.1[10] or 11−14[11] M☉
Luminosity515.14[6] L☉
Surface gravity (log g)3.71[12] cgs
Temperature23,014+919
−883[12] K
Metallicity [Fe/H]0.07±0.12[12] dex
Rotational velocity (v sin i)24±6[3] km/s
Age3.4±2.5[10] Myr
Other designations
AAVSO 2050+28, BW Vul, BD+27° 3909, HD 199140, HIP 103191, HR 8007, SAO 89265[13]
Database references
SIMBADdata

BW Vulpeculae or BW Vul, is a variable star in the northern constellation of Vulpecula. It is near the lower limit of visibility to the naked eye with a typical apparent visual magnitude of 6.54.[3] Based on an annual parallax shift of 1.15 mas,[2] the distance to BW Vul is about 2,800 light years. It is moving closer to the Earth with a baseline heliocentric radial velocity of around −6 km/s.[8]

This is a B-type giant star with a stellar classification of B2 IIIv,[5] where the 'v' suffix indicates variability in spectral features. Various authors have printed mass estimates ranging from 11 to 14 times the mass of the Sun,[11] although Tetzlaff et al. (2011) gives a mass of just 6.8 M☉.[10] It is about 3.4[10] million years old and is spinning with a projected rotational velocity of 24 km/s.[3] The star is typically radiating 515[6] times the Sun's luminosity from its photosphere at an effective temperature of 23,014 K.[12]

The variability of this star was announced in 1937, at the 58th Meeting of the American Astronomical Society by Canadian astronomer, Robert Methven Petrie.[14] It is a Beta Cephei variable that ranges between magnitudes 6.44 and 6.68 over a period of 4.8 hours.[4] For unknown reasons, the periodicity of the star has undergone sudden changes, followed by long periods of stability.[15] BW Vul is one of the most extreme β Cephei stars in terms of variability of light and radial velocity.[3][16] This is hypothesized as being due to the star's relatively high metallicity, meaning the abundance of elements other than hydrogen and helium.[11] A distinctive feature of its radial velocity cycle is a unique "standstill" feature, which is caused by a shockwave generated by infall of material from a previous cycle.[16]

  1. ^ Cite error: The named reference MAST was invoked but never defined (see the help page).
  2. ^ a b c d e f Cite error: The named reference GaiaDR2 was invoked but never defined (see the help page).
  3. ^ a b c d e Cite error: The named reference Stankov2003 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference AAVSOBW was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference Lynds1959 was invoked but never defined (see the help page).
  6. ^ a b c Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference gcvs was invoked but never defined (see the help page).
  8. ^ a b Cite error: The named reference Gontcharov2006 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference Gontcharov2012 was invoked but never defined (see the help page).
  10. ^ a b c d Cite error: The named reference Tetzlaff2011 was invoked but never defined (see the help page).
  11. ^ a b c Cite error: The named reference Fokin2004 was invoked but never defined (see the help page).
  12. ^ a b c d Cite error: The named reference Niemczura2005 was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  14. ^ Cite error: The named reference Petrie1939 was invoked but never defined (see the help page).
  15. ^ Cite error: The named reference Odell2012 was invoked but never defined (see the help page).
  16. ^ a b Cite error: The named reference Smith2005 was invoked but never defined (see the help page).