U Vulpeculae

U Vulpeculae is a variable and binary star in the constellation Vulpecula.

U Vulpeculae
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Vulpecula
Right ascension  19h 36m 37.7281s[1]
Declination 20° 19′ 58.5692″[1]
Apparent magnitude (V) 6.73 - 7.54[2]
Characteristics
Spectral type F6Iab-G2[3]
Variable type δ Cep[2]
Astrometry
Proper motion (μ) RA: 0.906±0.050[1] mas/yr
Dec.: −0.960±0.062[1] mas/yr
Parallax (π)1.0530 ± 0.0390[1] mas
Distance3,100 ± 100 ly
(950 ± 40 pc)
Absolute magnitude (MV)-3.69[4]
Orbit[5]
Period (P)2,510 days
Eccentricity (e)0.675
Periastron epoch (T)2444800
Argument of periastron (ω)
(secondary)		353°
Semi-amplitude (K1)
(primary)		3.64 km/s
Details
Mass6.5[6] M☉
Radius60[6] R☉
Surface gravity (log g)1.75 - 1.85[7] cgs
Temperature5,655 - 5,965[7] K
Metallicity [Fe/H]0.09[8] dex
Age82[8] Myr
Other designations
BD+20° 4200, HD 185059, HIP 96458, HR 7458, SAO 87447[9]
Database references
SIMBADdata

It is a classical Cepheid variable and its apparent magnitude ranges from 6.73 to 7.54 over a precise cycle of 7.99 days.[3] Its variable nature was discovered in 1898 at Potsdam Observatory by Gustav Müller and Paul Kempf.[10]

In 1991 a study of radial velocities showed that it U Vulpeculae is a spectroscopic binary and a full orbit with a period of 2510 days (6.9 years) was first calculated in 1996.[11][6] The secondary star is invisible and is only known from its effect on the motion of the primary.[5]

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. Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/gcvs. Originally Published in: 2009yCat....102025S. 1: B/gcvs. Bibcode:2009yCat....102025S.
  3. Watson, Christopher (4 January 2010). "U Vulpeculae". AAVSO Website. American Association of Variable Star Observers. Retrieved 2 August 2015.
  4. Kovtyukh, V. V.; Chekhonadskikh, F. A.; Luck, R. E.; Soubiran, C.; Yasinskaya, M. P.; Belik, S. I. (2010). "Accurate luminosities for F-G supergiants from FeII/FeI line depth ratios". Monthly Notices of the Royal Astronomical Society. 408 (3): 1568. Bibcode:2010MNRAS.408.1568K. doi:10.1111/j.1365-2966.2010.17217.x.
  5. Groenewegen, M. A. T. (2008). "Baade-Wesselink distances and the effect of metallicity in classical cepheids". Astronomy and Astrophysics. 488 (1): 25–35. arXiv:0807.1269. Bibcode:2008A&A...488...25G. doi:10.1051/0004-6361:200809859.
  6. Imbert, M. (1996). "Cepheids and binarity. II. Radial velocities and spectroscopic orbits of four galactic Cepheids: RX Camelopardalis, MW Cygni, Z Lacertae and U Vulpeculae". Astronomy and Astrophysics Supplement (in French). 116: 497–514. Bibcode:1996A&AS..116..497I. doi:10.1051/aas:1996312.
  7. Andrievsky, S. M.; Lépine, J. R. D.; Korotin, S. A.; Luck, R. E.; Kovtyukh, V. V.; MacIel, W. J. (2013). "Barium abundances in Cepheids". Monthly Notices of the Royal Astronomical Society. 428 (4): 3252. Bibcode:2013MNRAS.428.3252A. doi:10.1093/mnras/sts270.
  8. Marsakov, V. A.; Koval', V. V.; Kovtyukh, V. V.; Mishenina, T. V. (2013). "Properties of the population of classical Cepheids in the Galaxy". Astronomy Letters. 39 (12): 851. Bibcode:2013AstL...39..851M. doi:10.1134/s1063773713120050.
  9. "U Vulpeculae". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2 August 2015.
  10. Müller, G.; Kempf, P. (1898). "Zwei neue Veränderliche von kurzer Periode". Astronomische Nachrichten (in German). 146 (3): 37–42. Bibcode:1898AN....146...37M. doi:10.1002/asna.18981460303.
  11. Szabados, L. (1991). "Northern Cepheids: Period Update and Duplicity Effects". Communications of the Konkoly Observatory. 11 part 3 (96): 123–244. Bibcode:1991CoKon..96..123S.
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