RW Cephei

The first documented sighting of RW Cephei dates back to 1746 when it was included in a star catalog compiled by James Bradley. It has been described as a red star since at least the 1840s,{{efn|name=uncertain year|The exact year of the observation is unknown, but it is believed to have been taken some time between 1841 and 1844}} when Friedrich Wilhelm Argelander noted it as "very red" in his catalog. RW Cephei was independently discovered to be variable by Thomas William Backhouse and Henrietta Swan Leavitt in 1899 and 1907 respectively, but has been suspected to be variable by Angelo Secchi since at least 1868. The star was designated RW in 1908, being the fifteenth discovered variable in Cepheus. Analysis of spectra in 1942 revealed RW Cephei to be a highly luminous hypergiant star, appearing more luminous than Mu Cephei. More detailed spectral studies in 1956 and 1972 revealed unique spectral features, setting it apart from the other known hypergiants. Since then, the star has been studied infrequently over the decades. In late 2022, RW Cephei was announced to be undergoing a great dimming event, and it was subsequently observed by the CHARA interferometry array in December.

The distance to RW Cephei has been estimated on the basis of its spectroscopic luminosity and it is assumed to be a member of the Cepheus OB1 association, placing it within the Perseus Arm of the Milky Way. The Gaia Data Release 2 and Gaia Early Data Release 3 parallaxes lead to distance estimates of {{val|fmt=commas|3416|1366|829|ul=pc}} and {{val|fmt=commas|6666|1561|1006|u=pc}} respectively. Cepheus OB1 is generally considered to be at about {{val|fmt=commas|3400|u=pc}}. The open cluster Berkeley 94, of which RW Cephei may be a member, is thought to be at a distance of {{val|fmt=commas|3900|110|u=pc}}. The star and cluster are part of the larger star-forming region Sh 2-132.

File:RWCepLightCurve.png for RW Cephei, plotted from Hipparcos data]]

The magnitude range of RW Cephei was given as 8.2–8.8 using photographic plates in the initial report, while later studies found the photographic range to be from 8.6–10.7, noting that maxima and minima cannot be derived with any certainty. Other authors estimate an amplitude of only around 0.5 magnitudes. Modern estimates put the range of variability from 6.0 to 7.6 in the V-band.

RW Cephei has been classified as a semi-regular variable star of type SRd, meaning that it is a slowly varying yellow giant or supergiant. The General Catalogue of Variable Stars cites a 1952 study giving a period of approximately 346 days, while other studies suggest different periods and certainly no strong periodicity.

File:RW Cep dimming vs rebrightening comparison.png

In December of 2022, the star was reported by two astronomers to be going through a "great dimming", reaching a fainter than usual magnitude of 7.6. It was speculated to be caused by short periods of enhanced mass loss leading to the condensation of dust that partially obscures the stellar photosphere. This was later confirmed by observations with the CHARA array, revealing a dark patch on the western side of the star suggested to be a dust cloud released in a recent surface mass ejection. An unusually bright maximum attained in 2019 right before the dimming was suspected to be caused by an energetic convective upwelling of hot gas, later being expelled and cooling into a dust cloud obscuring the star. The event is compared to the great dimming of Betelgeuse that happened in late 2019 and the dimming events seen in the historical light curve of VY Canis Majoris.

Spectra taken by an amateur astronomer show the appearance of several new emission lines during the dimming, most notably H-α and the K I lines at 766.5 and 769.9 nm. The H-α line is blueshifted by ~40 km/s relative to the star, suggesting the source of the emission is expanding outwards.

Previous observations using photographic plates taken between 1948 and 1951 reveal a similar dimming from magnitude 9.16 down to 9.5, followed by a rapid re-brightening to magnitude 8.9.

RW Cephei displays many complex lines in its spectrum, many of which are stronger and more broad than usual. An initial study in 1956 focusing on the blue spectral region found many metal absorption lines with two components separated by a central maximum, attributed to emission superposed on an absorption line widened due to turbulence. The shortward absorption components were found to be significantly stronger than the longward components, caused by an outward moving shell of gas. A follow-up study in 1972 focusing on redder spectral regions found unusually strong Na D lines too intense to be caused by the interstellar medium. The Fe I line was found to be 30% stronger than in normal K-type supergiants, while the Ti I and V I lines were of the same strength or weaker. With these peculiar spectral features, the star finds no counterpart among the known hypergiants, with only Rho Cassiopeiae displaying remotely similar features.

The spectrum 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. RW Cephei was later listed as the standard star for spectral type G8 Ia, then as the standard for K0 0-Ia. Based on the same spectra it was adjusted to the standard star for type K2 0-Ia. Molecular bands characteristic of M-class stars are seen in infrared spectra, but not always in optical spectra.

The temperature of RW Cephei is uncertain, with contradictory excitation strengths in the spectrum. A simple color correlation temperature fit gives temperatures around 3,749 K, while a full spectrum fit gives a temperature of 5,018 K. Another fit using J-band spectral data and MARCS stellar models gives a temperature of {{val|3770|170|fmt=commas}} K. This fit also results in a metallicity of [Fe/H] = {{val|+0.17|0.20}}, indicating the star is slightly metal-rich relative to the Sun. A newer study finds a temperature of 4,400 K consistent with its spectral type. Based on the CO line strength at 2.29 μm it is indicated that RW Cephei dropped in temperature from 4,200 K to 3,900 K during the dimming.

Luminosities have been derived on the basis of a membership to Cepheus OB1, with studies finding exceptionally high luminosities of {{solar luminosity|545,000}}, or {{solar luminosity|468,000}}. A more recent study finds a somewhat lower luminosity of {{solar luminosity|300,000}} using the spectral energy distribution of a DUSTY model fit.

Imaging of RW Cephei by the CHARA array reveals the star to be box-like in shape. Images obtained using the SURFING algorithm result in a limb-darkened angular diameter of 2.45 mas, corresponding to a linear radius of {{val|900|–|1760|fmt=commas|u=solar radius}} depending on the adopted distance. In 2024, the star's size was shown to have increased by 8% since its 2022 dimming. The angular diameter, combined with an average distance of {{cvt|3935|pc|ly|abbr=off}} to Berkeley 94, gives a radius of {{solar radius|1,100}}.

File:RW Cephei extended mid-infrared emission.png

The star shows evidence for a significant amount of circumstellar material in its spectrum. The IRAS low resolution spectrum shows signatures of optically thick silicate emission at 10 and 18 μm, an indication for high amounts of mass loss. Emission in the first-overtone SiO bands was suspected in 1982, and later confirmed using higher resolution spectra showing clear signs of emission at 4.0, 4.04 and 4.08 μm. Direct imaging in mid-infrared bands reveals the source to be extended, having an azimuthally symmetric structure similar to IRC +10420. The radius of this emission has been estimated to be ~0.3–0.4 arcseconds at 11.9 μm, corresponding to a physical radius of ~1,000–1,400 au at a distance of 3.4 kpc.

The current mass loss rate of RW Cephei has been determined to be ~{{solar mass|{{val|7|e=-6}}}}/yr using a DUSTY model fit. A previous study estimated {{solar mass|{{val|1.8|e=-5}}}}/yr using silicate line strengths and adopting a distance of 2.8 kpc. Analysis of the surrounding mid-infrared emission indicates that RW Cephei ended a period of enhanced mass loss ~95–140 years ago,{{efn|name=wind velocity|Assuming a wind velocity of 50 km/s based on values for known red and yellow hypergiants}} suggesting that it has left the red supergiant phase and is currently evolving towards hotter temperatures. The current mass loss phase appears to be dominated by several mass ejections, including the observed "great dimming".

• Betelgeuse and VY Canis Majoris, similar cool massive stars that have undergone one or more dimming events
• HR 5171, a similar star
• WOH G64
• UY Scuti
• Westerlund 1 W26

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{{reflist|refs=

{{Cite journal |last1=Jones |first1=Terry Jay |last2=Shenoy |first2=Dinesh |last3=Humphreys |first3=Roberta |date=May 2023 |title=The Recent Mass Loss History of the Hypergiant RW Cep |journal=Research Notes of the American Astronomical Society |volume=7 |issue=5 |pages=92 |bibcode=2023RNAAS...7...92J |doi=10.3847/2515-5172/acd37f |s2cid=258701379 |issn=2515-5172|doi-access=free}}

{{Cite journal |last1=Anugu |first1=Narsireddy |last2=Gies |first2=Douglas R. |last3=Roettenbacher |first3=Rachael M. |last4=Monnier |first4=John D. |last5=Montargés |first5=Miguel |last6=Mérand |first6=Antoine |last7=Baron |first7=Fabien |last8=Schaefer |first8=Gail H. |last9=Shepard |first9=Katherine A. |last10=Kraus |first10=Stefan |last11=Anderson |first11=Matthew D. |last12=Codron |first12=Isabelle |last13=Gardner |first13=Tyler |last14=Gutierrez |first14=Mayra |last15=Köhler |first15=Rainer |date=September 2024 |title=Time Evolution Images of the Hypergiant RW Cephei during the Rebrightening Phase Following the Great Dimming |journal=The Astrophysical Journal Letters |arxiv=2408.11906 |language=en |volume=973 |issue=1 |pages=L5 |doi=10.3847/2041-8213/ad736c |doi-access=free |bibcode=2024ApJ...973L...5A |issn=2041-8205}}

{{cite web |title=Hipparcos Tools Interactive Data Access |url=https://www.cosmos.esa.int/web/hipparcos/interactive-data-access |website=Hipparcos |publisher=ESA |access-date=8 December 2021}}

{{cite journal|bibcode=1988BICDS..35...37K|title=1988 Revised MK Spectral Standards for Stars GO and Later|journal=Bulletin d'Information du Centre de Données Stellaires|volume=35|pages=37|last1=Keenan|first1=P. C.|last2=Yorka|first2=S. B.|year=1988}}

{{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|last1=Watson|first1=C. L.|year=2006}}

{{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 |last1= Ducati |first1= J. R. |year= 2002}}

{{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}}

{{cite Gaia DR3|2005992002061917312}}

{{cite journal|bibcode=1988AJ.....95..141S|title=Far-infrared circumstellar 'debris' shell of red supergiant stars|journal=Astronomical Journal|volume=95|pages=141|last1=Stencel|first1=Robert E.|last2=Pesce|first2=Joseph E.|last3=Hagen Bauer|first3=Wendy|year=1988|doi=10.1086/114622}}

{{cite journal|title=The brightest stars in the Magellanic Clouds and other late-type galaxies.|bibcode=1984IAUS..108..145H|doi=10.1017/S0074180900040134|last1=Humphreys|first1=R. M.|year=1984|journal=IAU Symposium|volume=108|pages=145–156|doi-access=free}}

{{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.|issue=1|doi-access=free |bibcode=2013MNRAS.435..429D|arxiv = 1307.4290 |s2cid=118642318}}

{{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=457–467|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 |s2cid=53127885}}

{{Cite book |last=Bradley |first=J. |title=Catalog von 4219 Sternen nach Beobachtungen am Durchgangsinstrument 1743 - 1750 und am Quadranten 1743 - 1753. |date=1855 |bibcode=1855csbd.book.....B}}

{{Cite journal |last=Oeltzen |first=Wilhelm |date=1852 |title=Argelander's Zonen-Beobachtungen vom 45. bis 80 Grade nördlicher Declination, in mittleren Positionen f̈r 1842.0 nach gerader Aufsteigung geordnet von Wilhelm Oeltzen, Assistent der Wiener Sternwarte. Zweite Abtheilung |journal=Annalen der Universitaets-Sternwarte Wien |series=Dritter Folge |volume=2 |pages=3–1 |bibcode=1852AnWiD...2....3O}}

{{Cite journal |last=Backhouse |first=T. W. |date=July 1899 |title=Confirmed or new variable stars |journal=The Observatory |volume=22 |pages=275–276 |bibcode=1899Obs....22..275B |issn=0029-7704}}

{{Cite journal |last=Pickering |first=Edward C. |date=August 1907 |title=71 new variable stars in Harvard Maps Nos. 9, 12, 21, 48 and 51 |journal=Astronomische Nachrichten |volume=175 |issue=20 |pages=333–338 |bibcode=1907AN....175..333P |doi=10.1002/asna.19071752006 |issn=0004-6337|url=https://zenodo.org/record/2030310}}

{{Cite book |last=Secchi |first=Angelo |title=Sugli spettri prismatici delle stelle fisse |date=1868 |bibcode=1868sspd.bookR....S}}

{{Cite journal |last1=Dunér |first1=Nils Christofer |last2=Hartwig |first2=Ernst |last3=Müller |first3=G. |date=October 1908 |title=Benennung von neu entdeckten veränderlichen Sternen |journal=Astronomische Nachrichten |volume=179 |issue=6 |pages=85 |bibcode=1908AN....179...85D |doi=10.1002/asna.19081790602 |issn=0004-6337}}

{{Cite journal |last1=Anugu |first1=Narsireddy |last2=Baron |first2=Fabien |last3=Gies |first3=Douglas R. |last4=Lanthermann |first4=Cyprien |last5=Schaefer |first5=Gail H. |last6=Shepard |first6=Katherine A. |last7=Brummelaar |first7=Theo ten |last8=Monnier |first8=John D. |last9=Kraus |first9=Stefan |last10=Le Bouquin |first10=Jean-Baptiste |last11=Davies |first11=Claire L. |last12=Ennis |first12=Jacob |last13=Gardner |first13=Tyler |last14=Labdon |first14=Aaron |last15=Roettenbacher |first15=Rachael M. |date=August 2023 |title=The Great Dimming of the Hypergiant Star RW Cephei: CHARA Array Images and Spectral Analysis |journal=The Astronomical Journal |volume=166 |issue=2 |pages=78 |arxiv=2307.04926 |bibcode=2023AJ....166...78A |doi=10.3847/1538-3881/ace59d |issn=0004-6256 |doi-access=free}}

{{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}}

{{Cite journal |last1=Rate |first1=Gemma |last2=Crowther |first2=Paul A. |last3=Parker |first3=Richard J. |date=June 2020 |title=Unlocking Galactic Wolf-Rayet stars with Gaia DR2 - II. Cluster and association membership |journal=Monthly Notices of the Royal Astronomical Society |volume=495 |issue=1 |pages=1209–1226 |arxiv=2005.02533 |bibcode=2020MNRAS.495.1209R |doi=10.1093/mnras/staa1290 |doi-access=free |issn=0035-8711}}

{{Cite journal |last=Payne-Gaposchkin |first=Cecilia |date=1952 |title=Variable stars in Milton field 9 |journal=Annals of Harvard College Observatory |volume=118 |pages=147 |bibcode=1952AnHar.118..147P}}

{{Cite journal |last=Rajchl |first=Rostislav |date=1933 |title=Observations d'etoiles variables |journal=Publications of the Astronomical Institute of the Charles University |volume=18 |pages=1–20 |bibcode=1933PAICU..18....1R}}

{{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|last1=Percy|first1=John R.|last2=Kolin|first2=David L.|year=2000|issue=1}}

{{Cite journal |last1=Vollmann |first1=Wolfgang |last2=Sigismondi |first2=Costantino |date=December 2022 |title=RW Cephei great dimming |journal=The Astronomer's Telegram |volume=15800 |pages=1|bibcode=2022ATel15800....1V}}

{{Cite web |last=Mack |first=Eric |title=One Of The Biggest Stars In The Milky Way Is Acting A Little Unstable |url=https://www.forbes.com/sites/ericmack/2022/12/10/one-of-the-biggest-stars-in-the-milky-way-is-acting-a-little-unstable/ |access-date=15 December 2022 |website=Forbes |language=en}}

{{Cite news |date=12 December 2022 |title=Catch the Geminid Meteor Shower; Plus, Watch RW Cephei Fade |url=https://skyandtelescope.org/astronomy-news/geminid-meteor-shower-rw-cephei-fades/ |access-date=15 December 2022 |website=Sky & Telescope |language=en-US}}

{{Cite journal |last=Leadbeater |first=Robin |date=March 2023 |title=The 2022 dimming of RW Cep – A first look |journal=British Astronomical Association Variable Star Section Circular |volume=195 |pages=7–12 |bibcode=2023BAAVC.195....7L}}

{{Cite journal |last=Semakin |first=N. K. |date=1954 |title=Photographic Observations of RW Cephei |journal=Peremennye Zvezdy |volume=10 |pages=191 |bibcode=1954PZ.....10..191S}}

{{Cite journal |last=Keenan |first=Philip C. |date=May 1942 |title=Luminosities of the M-Type Variables of Small Range. |journal=The Astrophysical Journal |volume=95 |pages=461 |bibcode=1942ApJ....95..461K |doi=10.1086/144418 |issn=0004-637X|doi-access=free}}

{{Cite journal |last1=Merrill |first1=Paul W. |last2=Wilson |first2=Olin C. |date=May 1956 |title=Complex Lines in the Spectrum of RW Cephei. |journal=The Astrophysical Journal |volume=123 |pages=392 |bibcode=1956ApJ...123..392M |doi=10.1086/146178 |issn=0004-637X|doi-access=free}}

{{Cite journal |last1=Gahm |first1=G. F. |last2=Hultqvist |first2=L. |date=1972 |title=Spectral properties of luminous late-type stars. |journal=Astronomy and Astrophysics |volume=16 |pages=329 |bibcode=1972A&A....16..329G |issn=0004-6361}}

{{cite journal|bibcode=1943assw.book.....M|title=An atlas of stellar spectra, with an outline of spectral classification|journal=Chicago|last1=Morgan|first1=William Wilson|last2=Keenan|first2=Philip Childs|last3=Kellman|first3=Edith|year=1943}}

{{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|last1=Morgan|first1=W. W.|last2=Roman|first2=Nancy G.|year=1950|doi=10.1086/145351}}

{{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|last1=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}}

{{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|last1=Keenan|first1=P. C.|last2=Pitts|first2=R. E.|year=1980|doi=10.1086/190662|doi-access=free}}

{{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|last1=McCuskey|first1=S. W.|year=1955|doi=10.1086/190017|doi-access=free}}

{{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 |s2cid=17789027}}

{{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|last1=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 |s2cid=119187195}}

{{Cite journal |last1=Davies |first1=Ben |last2=Kudritzki |first2=Rolf-Peter |last3=Figer |first3=Donald F. |date=September 2010 |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=1203–1211 |arxiv=1005.1008 |bibcode=2010MNRAS.407.1203D |doi=10.1111/j.1365-2966.2010.16965.x |doi-access=free |s2cid=118460729 |issn=0035-8711}}

{{Cite journal |last=de Jager |first=Cornelis |date=1998 |title=The yellow hypergiants |journal=Astronomy and Astrophysics Review |volume=8 |issue=3 |pages=145–180 |bibcode=1998A&ARv...8..145D |doi=10.1007/s001590050009 |s2cid=189936279 |issn=0935-4956}}

{{Cite journal |last=Simpson |first=Janet P. |date=February 1991 |title=IRAS Low-Resolution Spectral Observations of the 10 and 18 Micron Silicate Emission Features |journal=The Astrophysical Journal |volume=368 |pages=570 |bibcode=1991ApJ...368..570S |doi=10.1086/169721 |issn=0004-637X|doi-access=free}}

{{Cite journal |last1=Rayner |first1=John T. |last2=Cushing |first2=Michael C. |last3=Vacca |first3=William D. |date=December 2009 |title=The Infrared Telescope Facility (IRTF) Spectral Library: Cool Stars |journal=The Astrophysical Journal Supplement Series |volume=185 |issue=2 |pages=289–432 |arxiv=0909.0818 |bibcode=2009ApJS..185..289R |doi=10.1088/0067-0049/185/2/289 |s2cid=118500715 |issn=0067-0049}}

{{Cite journal |last1=Rinsland |first1=C. P. |last2=Wing |first2=R. F. |date=November 1982 |title=Observations of the first-overtone silicon monoxide bands in late-type stars. |journal=The Astrophysical Journal |volume=262 |pages=201–212 |bibcode=1982ApJ...262..201R |doi=10.1086/160411 |issn=0004-637X|doi-access=free}}

{{Cite journal |last1=Shenoy |first1=Dinesh |last2=Humphreys |first2=Roberta M. |last3=Jones |first3=Terry J. |last4=Marengo |first4=Massimo |last5=Gehrz |first5=Robert D. |last6=Helton |first6=L. Andrew |last7=Hoffmann |first7=William F. |last8=Skemer |first8=Andrew J. |last9=Hinz |first9=Philip M. |date=March 2016 |title=Searching for Cool Dust in the Mid-to-far Infrared: The Mass-loss Histories of the Hypergiants μ Cep, VY CMa, IRC+10420, and ρ Cas |journal=The Astronomical Journal |volume=151 |issue=3 |pages=51 |arxiv=1512.01529 |bibcode=2016AJ....151...51S |doi=10.3847/0004-6256/151/3/51 |s2cid=119281306 |issn=0004-6256 |doi-access=free}}

{{Cite journal |last1=Sylvester |first1=R. J. |last2=Skinner |first2=C. J. |last3=Barlow |first3=M. J. |date=December 1998 |title=Silicate and hydrocarbon emission from Galactic M supergiants |journal=Monthly Notices of the Royal Astronomical Society |volume=301 |issue=4 |pages=1083–1094 |bibcode=1998MNRAS.301.1083S |doi=10.1046/j.1365-8711.1998.02078.x |doi-access=free |issn=0035-8711|url=https://discovery.ucl.ac.uk/id/eprint/10096081/}}

{{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|last1=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 |s2cid=119323941}}

{{cite journal |bibcode=2018AJ....156...58B |title=Estimating Distance from Parallaxes. IV. Distances to 1.33 Billion Stars in Gaia Data Release 2 |last1=Bailer-Jones |first1=C. A. L. |last2=Rybizki |first2=J. |last3=Fouesneau |first3=M. |last4=Mantelet |first4=G. |last5=Andrae |first5=R. |journal=The Astronomical Journal |year=2018 |volume=156 |issue=2 |pages=58 |doi=10.3847/1538-3881/aacb21 |arxiv=1804.10121 |s2cid=119289017 |doi-access=free}}

{{cite journal |bibcode=2021AJ....161..147B |title=Estimating Distances from Parallaxes. V. Geometric and Photogeometric Distances to 1.47 Billion Stars in Gaia Early Data Release 3 |last1=Bailer-Jones |first1=C. A. L. |last2=Rybizki |first2=J. |last3=Fouesneau |first3=M. |last4=Demleitner |first4=M. |last5=Andrae |first5=R. |journal=The Astronomical Journal |year=2021 |volume=161 |issue=3 |page=147 |doi=10.3847/1538-3881/abd806 |arxiv=2012.05220 |s2cid=228063812 |doi-access=free}}

{{cite journal| bibcode=2010MNRAS.407..133S | title=Star clusters in the Sh2-132 complex: Clues about the connection between embedded and open clusters | last1=Saurin | first1=T. A. | last2=Bica | first2=E. | last3=Bonatto | first3=C. | journal=Monthly Notices of the Royal Astronomical Society | year=2010 | volume=407 | issue=1 | page=133 | doi=10.1111/j.1365-2966.2010.16929.x | doi-access=free | arxiv=1006.0246 | s2cid=53966692}}

}}

{{Stars of Cepheus}}

{{DEFAULTSORT:RW Cephei}}

Category:K-type hypergiants

Cephei, RW

Category:Cepheus (constellation)

212466

BD+55 2737

110504

Category:Semiregular variable stars

Category:G-type hypergiants

Category:M-type hypergiants