S Vulpeculae

{{Short description|Star in the constellation Vulpecula}}

{{Starbox begin

| name = S Vulpeculae

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{{Starbox image

| image = 250px

| caption = A visual band light curve for S Vulpeculae, adapted from Heiser (1996)

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{{Starbox observe

| epoch = J2000

| constell = Vulpecula

| ra = {{RA|19|48|23.8064}}

| dec = {{DEC|27|17|11.4265}}

| appmag_v = 8.974 {{nowrap|(8.69 - 9.42)}}

}}

{{Starbox character

| class=G0-K2(M1){{cite journal|bibcode=1952ApJ...115...25J|title=The Semiregular Variable Stars of the RV Tauri and Related Classes|journal=Astrophysical Journal|volume=115|pages=25|last1=Joy|first1=Alfred H.|year=1952|doi=10.1086/145506}}

| b-v=+1.7 - +2.1{{cite journal|bibcode=1986IBVS.2856....1B|title=On the Type of Variability of S Vul|journal=Information Bulletin on Variable Stars|volume=2856|pages=1|last1=Berdnikov|first1=L. N.|last2=Ivanov|first2=G. R.|year=1986}}

| u-b=+1.3 - +2.0

| variable=δ Cep{{cite journal|bibcode=2009yCat....102025S|title=VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)|journal=VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S|volume=1|display-authors=etal|last1=Samus|first1=N. N.|last2=Durlevich|first2=O. V.|year=2009}}

}}

{{Starbox astrometry

| radial_v = 0.0 ± 2{{cite journal|bibcode= 1953GCRV..C......0W|title= General catalogue of stellar radial velocities|journal= Washington|last1= Wilson|first1= Ralph Elmer|year= 1953}}

| prop_mo_ra = {{val|−3.401|0.058}}

| prop_mo_dec = {{val|−5.923|0.059}}

| parallax = 0.3050

| p_error = 0.0406

| parallax_footnote =

| absmag_v = −6.08{{cite journal|bibcode=2013OAP....26..115T|title=Towards a Determination of Definitive Parameters for the Long Period Cepheid S Vulpeculae|journal=Odessa Astronomical Publications|volume=26|pages=115|arxiv=1403.1968|last1=Turner|first1=David G.|year=2014}}

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{{Starbox detail

| source=

| mass=14.2

| radius={{val|286|7}}

| luminosity={{val|67800|3900|fmt=commas}}

| temperature={{val|5512|45|fmt=commas}}

| metal_fe=−0.01{{cite journal|bibcode=2013AstL...39..851M|title=Properties of the population of classical Cepheids in the Galaxy|journal=Astronomy Letters|volume=39|issue=12|pages=851|last1=Marsakov|first1=V. A.|last2=Koval'|first2=V. V.|last3=Kovtyukh|first3=V. V.|last4=Mishenina|first4=T. V.|year=2013|doi=10.1134/S1063773713120050|s2cid=119788977}}

| rotation=

| age_myr=12.6

}}

{{Starbox catalog

| names= S Vulpeculae, SAO 87743, HD 338867, BD+26°3674, AAVSO 1944+27

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{{Starbox reference

|Simbad=S+Vulpeculae

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{{Starbox end}}

S Vulpeculae is a variable star located in the constellation Vulpecula.

John Russell Hind announced that the star's brightness varies, in 1861. In 1862, Joseph Baxendell showed that the star is a periodic variable. It appears with its variable star designation in Annie Jump Cannon's 1907 work Second Catalogue of Variable Stars. A pulsating variable that grows and shrinks as it changes in brightness, S Vulpeculae has been variously classified as an RV Tauri variable, a semiregular variable star, or a Cepheid variable.{{cite journal|bibcode=1943AJ.....50...97N|title=S Vulpeculae|journal=Astronomical Journal|volume=50|pages=97|last1=Nassau|first1=J. J.|last2=Ashbrook|first2=J.|year=1943|doi=10.1086/105732}}

S Vulpeculae is now confirmed as a classical Cepheid variable with one of the longest known periods at 68 days, although the period has changed several times.{{cite journal|bibcode=1996PASP..108..603H|title=BV Observations of the Long-Period Cepheid S Vulpeculae|journal=Publications of the Astronomical Society of the Pacific|volume=108|pages=603|last1=Heiser|first1=Arnold M.|year=1996|doi=10.1086/133771|doi-access=free}} As such, it is also one of the cooler and more luminous of the Cepheids, and it lies close to the zone where semiregular variable stars are found. The shape and amplitude of the light curve varies significantly from cycle to cycle and secularly. The apparent magnitude ranges from 8.69 to 9.42. The spectrum varies from early G to late K as it pulsates, with TiO bands typical of an M1 star when the star is coolest.