- References
- Notes
| name = RW Cephei
}}{{Starbox image
| image={{Location mark
|image=Cepheus constellation map.svg|alt=|float=center|width=240
|label=|position=right
|mark=Red circle.svg|mark_width=10|mark_link=RW Cep
|x=650|y=1130
}}
|caption=Position of RW Cephei
}}{{Starbox observe
| epoch = J2000.0
| constell = Cepheus
| ra = {{RA|22|23|07.01657}}[1]
| dec = {{DEC|+55|57|47.6262}}[1]
| appmag_v = +6.65[3] {{nowrap|(6.0 - 7.3[4])}}
}}{{Starbox character
| class = K2 0-Ia[2] {{nowrap|(G8 - M2Ia-0[3])}}
| appmag_1_passband = K
| appmag_1 = 1.88[3]
| b-v = 2.22[4]
| u-b = 2.38[4]
| variable = SRd[5]
}}{{Starbox astrometry
| prop_mo_ra = -2.74[1]
| prop_mo_dec = -2.66[1]
| radial_v = -56.00[6]
| parallax = 0.2357
| p_error = 0.0944
| parallax_footnote = [7]
| dist_pc =
| absmag_v = −8.0[8] - −9.4[16]
}}{{Starbox detail
| age_myr = 18.7[9]
| mass = 13.9[9]
| radius = 981 - 1,758{{efn|name=radius}}
| luminosity = 550,000[10]
| temperature = 4,015[11] {{nowrap|(3,749 - 5,018)}}[21]
| gravity = 0.2[21]
}}{{Starbox catalog
| names=HD 212466, HIP 110504, SAO 34387, BD+55°2737, AAVSO 2219+55A
}}{{Starbox reference
| Simbad=RW+Cephei
}}{{Starbox end}}
RW Cephei is an orange hypergiant star in the constellation Cepheus, at the edge of the Sharpless 132 HII region and close to the small open cluster Berkeley 94. One of the largest stars known, RW Cephei is between {{convert|981 and 1,758|solar radius|km au|lk=on}},[10][21] which is larger than the outer limits of the asteroid belt, or possibly the orbit of Jupiter.
RW Cephei is also a semi-regular variable star of type SRd, meaning that it is a slowly varying yellow giant or supergiant. The visual magnitude range is from 6.0 to 7.3,[3] while the photographic range is from 8.6 - 10.7.[12] The General Catalogue of Variable Stars gives a period of approximately 346 days, but other studies suggest different periods and certainly no strong periodicity.[13]
The spectral has been classified as early as G8 and as late as M2, but it isn't clear that there has been actual variation. In the first MK spectral atlas, it was listed M0:Ia.[14] RW Cep was later listed as the standard star for spectral type G8 Ia,[15] then as the standard for K0 0-Ia.[16] Based on the same spectra it was adjusted to the standard star for type K2 0-Ia.[17] Molecular bands characteristic of M-class stars are seen in infrared spectra, but not always in optical spectra.[18][19] The temperature is equally uncertain, with contradictory excitation strengths in the spectrum. A simple colour correlation temperature fit gives temperatures around 3,750 K, while a full spectrum fit gives a temperature of 5,000 K.[20]
The distance to RW Cephei has been estimated on the basis of its spectroscopic luminosity and is assumed to be a member of the Cepheus OB1 association at 3,500 parsecs, consistent with the parallax from Gaia Data Release 2.[10][7]
The temperature intermediate between the red supergiants and yellow hypergiants, and itself varying considerably, has led to it being variously considered as a red hypergiant[21] or yellow hypergiant.[22]
The mass of the star is about 13.9 solar masses, which is about 6.92 times the mass of PSR J0348+0432, the most massive neutron star ever observed.
References
1. ^1 2 3 {{cite journal|bibcode=2007A&A...474..653V|title=Validation of the new Hipparcos reduction|journal=Astronomy and Astrophysics|volume=474|issue=2|pages=653|author1=Van Leeuwen|first1=F.|year=2007|doi=10.1051/0004-6361:20078357|arxiv = 0708.1752 }}
2. ^{{cite journal|bibcode=1988BICDS..35...37K|title=1988 Revised MK Spectral Standards for Stars GO and Later|journal=Bulletin d'Information du Centre de Donnees Stellaires|volume=35|pages=37|author1=Keenan|first1=P. C.|last2=Yorka|first2=S. B.|year=1988}}
3. ^1 2 {{cite journal|bibcode=2006SASS...25...47W|title=The International Variable Star Index (VSX)|journal=The Society for Astronomical Sciences 25th Annual Symposium on Telescope Science. Held May 23–25|volume=25|pages=47|author1=Watson|first1=C. L.|year=2006}}
4. ^1 2 3 {{cite journal|bibcode= 2002yCat.2237....0D |title= VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system |journal= CDS/ADC Collection of Electronic Catalogues |volume= 2237 |pages= 0 |author1= Ducati |first1= J. R. |year= 2002 }}
5. ^{{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|author1=Samus|first1=N. N.|last2=Durlevich|first2=O. V.|year=2009}}
6. ^{{cite journal|bibcode=2007AN....328..889K|title=Astrophysical supplements to the ASCC-2.5: Ia. Radial velocities of ˜55000 stars and mean radial velocities of 516 Galactic open clusters and associations|journal=Astronomische Nachrichten|volume=328|issue=9|pages=889|author1=Kharchenko|first1=N. V.|last2=Scholz|first2=R.-D.|last3=Piskunov|first3=A. E.|last4=Röser|first4=S.|last5=Schilbach|first5=E.|year=2007|doi=10.1002/asna.200710776|arxiv = 0705.0878 }}
7. ^1 {{cite DR2|2005992002061917312}}
8. ^{{cite journal|bibcode=1988AJ.....95..141S|title=Far-infrared circumstellar 'debris' shell of red supergiant stars|journal=Astronomical Journal|volume=95|pages=141|author1=Stencel|first1=Robert E.|last2=Pesce|first2=Joseph E.|last3=Hagen Bauer|first3=Wendy|year=1988|doi=10.1086/114622}}
9. ^1 {{cite journal|bibcode=2011MNRAS.410..190T|arxiv=1007.4883|title=A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun|journal=Monthly Notices of the Royal Astronomical Society|volume=410|pages=190|author1=Tetzlaff|first1=N.|last2=Neuhäuser|first2=R.|last3=Hohle|first3=M. M.|year=2011|doi=10.1111/j.1365-2966.2010.17434.x}}
10. ^1 2 3 {{cite journal|doi=10.1086/190559|title=Studies of luminous stars in nearby galaxies. I. Supergiants and O stars in the Milky Way|journal=The Astrophysical Journal Supplement Series|volume=38|pages=309|year=1978|last1=Humphreys|first1=R. M.|bibcode=1978ApJS...38..309H}}
11. ^{{cite journal|doi=10.1111/j.1365-2966.2010.16965.x|title=The potential of red supergiants as extragalactic abundance probes at low spectral resolution|journal=Monthly Notices of the Royal Astronomical Society|volume=407|issue=2|pages=1203|year=2010|last1=Davies|first1=Ben|last2=Kudritzki|first2=Rolf-Peter|last3=Figer|first3=Donald F.|bibcode=2010MNRAS.407.1203D|arxiv = 1005.1008 }}
12. ^{{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|author1=Samus|first1=N. N.|last2=Durlevich|first2=O. V.|year=2009}}
13. ^{{cite journal|bibcode=2000JAVSO..28....1P|title=Studies of Yellow Semiregular(SRd) Variables|journal=The Journal of the American Association of Variable Star Observers|volume=28|pages=1|author1=Percy|first1=John R.|last2=Kolin|first2=David L.|year=2000}}
14. ^{{cite journal|bibcode=1943assw.book.....M|title=An atlas of stellar spectra, with an outline of spectral classification|journal=Chicago|author1=Morgan|first1=William Wilson|last2=Keenan|first2=Philip Childs|last3=Kellman|first3=Edith|year=1943}}
15. ^{{cite journal|bibcode=1950ApJ...112..362M|title=Revised Standards for Supergiants on the System of the Yerkes Spectral Atlas|journal=Astrophysical Journal|volume=112|pages=362|author1=Morgan|first1=W. W.|last2=Roman|first2=Nancy G.|year=1950|doi=10.1086/145351}}
16. ^{{cite journal|bibcode=1981ApJ...243..894M|title=Some aspects of the spectroscopic behavior of the stars of highest luminosity in the region of the Hertzsprung gap|journal=Astrophysical Journal|volume=243|pages=894|author1=Morgan|first1=W. W.|last2=Keenan|first2=P. C.|last3=Abt|first3=H. A.|last4=Tapscott|first4=J. W.|year=1981|doi=10.1086/158654}}
17. ^{{cite journal|bibcode=1980ApJS...42..541K|title=Revised MK spectral types for G, K, and M stars|journal=Astrophysical Journal Supplement Series|volume=42|pages=541|author1=Keenan|first1=P. C.|last2=Pitts|first2=R. E.|year=1980|doi=10.1086/190662}}
18. ^{{cite journal|bibcode=1955ApJS....2...75M|title=Stellar Spectra in Milky way REGIONS.III.A Region in Cepheus-Lacerta|journal=Astrophysical Journal Supplement|volume=2|pages=75|author1=McCuskey|first1=S. W.|year=1955|doi=10.1086/190017}}
19. ^{{cite journal|doi=10.1051/0004-6361:20066353|title=Atmospheric dynamics and the mass loss process in red supergiant stars|journal=Astronomy and Astrophysics|volume=469|issue=2|pages=671|year=2007|last1=Josselin|first1=E.|last2=Plez|first2=B.|bibcode=2007A&A...469..671J|arxiv = 0705.0266 }}
20. ^1 2 3 {{cite journal|bibcode=2015A&A...582A..96M|title=Single stellar populations in the near-infrared. I. Preparation of the IRTF spectral stellar library|journal=Astronomy & Astrophysics|volume=582|pages=A96|author1=Meneses-Goytia|first1=S.|last2=Peletier|first2=R. F.|last3=Trager|first3=S. C.|last4=Falcón-Barroso|first4=J.|last5=Koleva|first5=M.|last6=Vazdekis|first6=A.|year=2015|doi=10.1051/0004-6361/201423837|arxiv = 1506.07184 }}
21. ^{{cite journal|doi=10.1093/mnras/stt1311|title=Berkeley 94 and Berkeley 96: Two young clusters with different dynamical evolution|journal=Monthly Notices of the Royal Astronomical Society|volume=435|pages=429|year=2013|last1=Delgado|first1=A. J.|last2=Djupvik|first2=A. A.|last3=Costado|first3=M. T.|last4=Alfaro|first4=E. J.|bibcode=2013MNRAS.435..429D|arxiv = 1307.4290 }}
22. ^{{cite journal|doi=10.1051/0004-6361:20066169|title=Arcsecond-resolution 12CO mapping of the yellow hypergiants IRC +10420 and AFGL 2343|journal=Astronomy and Astrophysics|volume=465|issue=2|pages=457|year=2007|last1=Castro-Carrizo|first1=A.|last2=Quintana-Lacaci|first2=G.|last3=Bujarrabal|first3=V.|last4=Neri|first4=R.|last5=Alcolea|first5=J.|bibcode=2007A&A...465..457C|arxiv = astro-ph/0702400 }}
2. ^{{cite journal|bibcode=1988BICDS..35...37K|title=1988 Revised MK Spectral Standards for Stars GO and Later|journal=Bulletin d'Information du Centre de Donnees Stellaires|volume=35|pages=37|author1=Keenan|first1=P. C.|last2=Yorka|first2=S. B.|year=1988}}
3. ^1 2 {{cite journal|bibcode=2006SASS...25...47W|title=The International Variable Star Index (VSX)|journal=The Society for Astronomical Sciences 25th Annual Symposium on Telescope Science. Held May 23–25|volume=25|pages=47|author1=Watson|first1=C. L.|year=2006}}
4. ^1 2 3 {{cite journal|bibcode= 2002yCat.2237....0D |title= VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system |journal= CDS/ADC Collection of Electronic Catalogues |volume= 2237 |pages= 0 |author1= Ducati |first1= J. R. |year= 2002 }}
5. ^{{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|author1=Samus|first1=N. N.|last2=Durlevich|first2=O. V.|year=2009}}
6. ^{{cite journal|bibcode=2007AN....328..889K|title=Astrophysical supplements to the ASCC-2.5: Ia. Radial velocities of ˜55000 stars and mean radial velocities of 516 Galactic open clusters and associations|journal=Astronomische Nachrichten|volume=328|issue=9|pages=889|author1=Kharchenko|first1=N. V.|last2=Scholz|first2=R.-D.|last3=Piskunov|first3=A. E.|last4=Röser|first4=S.|last5=Schilbach|first5=E.|year=2007|doi=10.1002/asna.200710776|arxiv = 0705.0878 }}
7. ^1 {{cite DR2|2005992002061917312}}
8. ^{{cite journal|bibcode=1988AJ.....95..141S|title=Far-infrared circumstellar 'debris' shell of red supergiant stars|journal=Astronomical Journal|volume=95|pages=141|author1=Stencel|first1=Robert E.|last2=Pesce|first2=Joseph E.|last3=Hagen Bauer|first3=Wendy|year=1988|doi=10.1086/114622}}
9. ^1 {{cite journal|bibcode=2011MNRAS.410..190T|arxiv=1007.4883|title=A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun|journal=Monthly Notices of the Royal Astronomical Society|volume=410|pages=190|author1=Tetzlaff|first1=N.|last2=Neuhäuser|first2=R.|last3=Hohle|first3=M. M.|year=2011|doi=10.1111/j.1365-2966.2010.17434.x}}
10. ^1 2 3 {{cite journal|doi=10.1086/190559|title=Studies of luminous stars in nearby galaxies. I. Supergiants and O stars in the Milky Way|journal=The Astrophysical Journal Supplement Series|volume=38|pages=309|year=1978|last1=Humphreys|first1=R. M.|bibcode=1978ApJS...38..309H}}
11. ^{{cite journal|doi=10.1111/j.1365-2966.2010.16965.x|title=The potential of red supergiants as extragalactic abundance probes at low spectral resolution|journal=Monthly Notices of the Royal Astronomical Society|volume=407|issue=2|pages=1203|year=2010|last1=Davies|first1=Ben|last2=Kudritzki|first2=Rolf-Peter|last3=Figer|first3=Donald F.|bibcode=2010MNRAS.407.1203D|arxiv = 1005.1008 }}
12. ^{{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|author1=Samus|first1=N. N.|last2=Durlevich|first2=O. V.|year=2009}}
13. ^{{cite journal|bibcode=2000JAVSO..28....1P|title=Studies of Yellow Semiregular(SRd) Variables|journal=The Journal of the American Association of Variable Star Observers|volume=28|pages=1|author1=Percy|first1=John R.|last2=Kolin|first2=David L.|year=2000}}
14. ^{{cite journal|bibcode=1943assw.book.....M|title=An atlas of stellar spectra, with an outline of spectral classification|journal=Chicago|author1=Morgan|first1=William Wilson|last2=Keenan|first2=Philip Childs|last3=Kellman|first3=Edith|year=1943}}
15. ^{{cite journal|bibcode=1950ApJ...112..362M|title=Revised Standards for Supergiants on the System of the Yerkes Spectral Atlas|journal=Astrophysical Journal|volume=112|pages=362|author1=Morgan|first1=W. W.|last2=Roman|first2=Nancy G.|year=1950|doi=10.1086/145351}}
16. ^{{cite journal|bibcode=1981ApJ...243..894M|title=Some aspects of the spectroscopic behavior of the stars of highest luminosity in the region of the Hertzsprung gap|journal=Astrophysical Journal|volume=243|pages=894|author1=Morgan|first1=W. W.|last2=Keenan|first2=P. C.|last3=Abt|first3=H. A.|last4=Tapscott|first4=J. W.|year=1981|doi=10.1086/158654}}
17. ^{{cite journal|bibcode=1980ApJS...42..541K|title=Revised MK spectral types for G, K, and M stars|journal=Astrophysical Journal Supplement Series|volume=42|pages=541|author1=Keenan|first1=P. C.|last2=Pitts|first2=R. E.|year=1980|doi=10.1086/190662}}
18. ^{{cite journal|bibcode=1955ApJS....2...75M|title=Stellar Spectra in Milky way REGIONS.III.A Region in Cepheus-Lacerta|journal=Astrophysical Journal Supplement|volume=2|pages=75|author1=McCuskey|first1=S. W.|year=1955|doi=10.1086/190017}}
19. ^{{cite journal|doi=10.1051/0004-6361:20066353|title=Atmospheric dynamics and the mass loss process in red supergiant stars|journal=Astronomy and Astrophysics|volume=469|issue=2|pages=671|year=2007|last1=Josselin|first1=E.|last2=Plez|first2=B.|bibcode=2007A&A...469..671J|arxiv = 0705.0266 }}
20. ^1 2 3 {{cite journal|bibcode=2015A&A...582A..96M|title=Single stellar populations in the near-infrared. I. Preparation of the IRTF spectral stellar library|journal=Astronomy & Astrophysics|volume=582|pages=A96|author1=Meneses-Goytia|first1=S.|last2=Peletier|first2=R. F.|last3=Trager|first3=S. C.|last4=Falcón-Barroso|first4=J.|last5=Koleva|first5=M.|last6=Vazdekis|first6=A.|year=2015|doi=10.1051/0004-6361/201423837|arxiv = 1506.07184 }}
21. ^{{cite journal|doi=10.1093/mnras/stt1311|title=Berkeley 94 and Berkeley 96: Two young clusters with different dynamical evolution|journal=Monthly Notices of the Royal Astronomical Society|volume=435|pages=429|year=2013|last1=Delgado|first1=A. J.|last2=Djupvik|first2=A. A.|last3=Costado|first3=M. T.|last4=Alfaro|first4=E. J.|bibcode=2013MNRAS.435..429D|arxiv = 1307.4290 }}
22. ^{{cite journal|doi=10.1051/0004-6361:20066169|title=Arcsecond-resolution 12CO mapping of the yellow hypergiants IRC +10420 and AFGL 2343|journal=Astronomy and Astrophysics|volume=465|issue=2|pages=457|year=2007|last1=Castro-Carrizo|first1=A.|last2=Quintana-Lacaci|first2=G.|last3=Bujarrabal|first3=V.|last4=Neri|first4=R.|last5=Alcolea|first5=J.|bibcode=2007A&A...465..457C|arxiv = astro-ph/0702400 }}
Notes
{{notelist|refs={{efn | name=radius | Applying the Stefan-Boltzmann Law with a nominal solar effective temperature of 5,772 K:
and 
}}}}{{Stars of Cepheus}}
7 : K-type hypergiants|Objects with variable star designations|Cepheus (constellation)|Henry Draper Catalogue objects|Durchmusterung objects|Hipparcos objects|Semiregular variable stars
- Battle of the strippers
- Battle of the Strippers
- Battle of the Stuhna River
- Battle of the Styles
- Battle of the Sun
- Battle of the surfaces
- Battle of the Surfaces
- Battle of the Taku Forts (1900)
- Battle of the Talas River
- Battle of the Tanais River
- Battle of the Tannenberg Line
- Battle of the Tarigo Convoy
- Battle of the Tasman Sea
- Battle of the Tenaru
- Battle of the Ten Kings
- Battle of the ten Kings
- Battle of the Terek River
- Battle of the Terek river
- Battle of the Teutoberg forest
- Battle of the Teutoberg Forest
- Battle of the Teutoburg forest
- Battle of the Theben Pass
- Battle of the thousand islands
- Battle of the Thousand Islands
- Battle of the Titans