25 Vulpeculae

25 Vulpeculae is a single[2] star in the northern constellation of Vulpecula, located roughly 1,170 light years away from the Sun. It is visible to the naked eye as a faint, blue-white hued star with an apparent visual magnitude of 5.50[2] This object is moving closer to the Earth with a heliocentric radial velocity of −11 km/s.[5]

25 Vulpeculae
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Vulpecula
Right ascension 20h 22m 03.43076s[1]
Declination +24° 26′ 45.9526″[1]
Apparent magnitude (V) 5.50[2]
Characteristics
Spectral type B6 IVe[3][4]
B−V color index −0.09±0.02[4]
Astrometry
Radial velocity (Rv)−11.0±3.6[5] km/s
Proper motion (μ) RA: +0.605[1] mas/yr
Dec.: −5.732[1] mas/yr
Parallax (π)2.7932 ± 0.1493[1] mas
Distance1,170 ± 60 ly
(360 ± 20 pc)
Absolute magnitude (MV)−1.88[4]
Details
Mass7±1[6] M☉
Radius11±1[6] R☉
Luminosity (bolometric)1,345+215
−184[7] L☉
Surface gravity (log g)3.52±0.21[7] cgs
Temperature13,170±330[7] K
Rotational velocity (v sin i)160±14[7] km/s
Other designations
25 Vul, BD+23°3986, HD 193911, HIP 100435, HR 7789, SAO 88580[8]
Database references
SIMBADdata

This is a Be star with a stellar classification of B6 IVe,[3] matching the spectrum of an aging subgiant with a circumstellar disk of ionized gas. Cowley (1972) had it rated as a more evolved giant star with a class of B8 IIIn,[9] where the 'n' notation indicates "nebulous" lines due to rapid rotation. It has a high rate of spin, showing a projected rotational velocity of 160 km/s.[7] The star has 7 times the mass of the Sun and 11 times the Sun's radius.[6] It is radiating 1,345 times the luminosity of the Sun from its photosphere at an effective temperature of 13,170 K.[7]

References
  1. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  2. Eggleton, P. P.; Tokovinin, A. A. (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.
  3. Slettebak, A. (1982), "Spectral types and rotational velocities of the brighter Be stars and A-F type shell stars", Astrophysical Journal Supplement Series, 50: 55–83, Bibcode:1982ApJS...50...55S, doi:10.1086/190820.
  4. Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015.
  5. Gontcharov, G. A. (November 2006), "Pulkovo Compilation of Radial Velocities for 35495 Hipparcos stars in a common system", Astronomy Letters, 32 (11): 759–771, arXiv:1606.08053, Bibcode:2006AstL...32..759G, doi:10.1134/S1063773706110065.
  6. Vieira, R. G.; et al. (January 2017), "The life cycles of Be viscous decretion discs: time-dependent modelling of infrared continuum observations", Monthly Notices of the Royal Astronomical Society, 464 (3): 3071–3089, arXiv:1707.02861, Bibcode:2017MNRAS.464.3071V, doi:10.1093/mnras/stw2542.
  7. Zorec, J.; et al. (November 2016), "Critical study of the distribution of rotational velocities of Be stars. I. Deconvolution methods, effects due to gravity darkening, macroturbulence, and binarity", Astronomy & Astrophysics, 595: 26, Bibcode:2016A&A...595A.132Z, doi:10.1051/0004-6361/201628760.
  8. "25 Vulpeculae". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-03-16.
  9. Cowley, A. (November 1972), "Spectral classification of the bright B8 stars", Astronomical Journal, 77: 750–755, Bibcode:1972AJ.....77..750C, doi:10.1086/111348.

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