View source for AZ Cygni

{{Short description|Red supergiant star in the constellation Cygnus}}

{{starbox begin}}
{{Starbox image
| image=[[File:AZCygLightCurve.png|250px]] 
| caption=A [[light curve]] for AZ Cygni, plotted from [[All Sky Automated Survey for SuperNovae|ASAS-SN]] data.<ref name="ASAS-SN"/>
}}
{{starbox observe
| epoch = [[J2000.0]]
| ra = {{RA|20|57|59.4444}}<ref name="dr3"/>
| dec = {{DEC|+46|28|00.583}}<ref name="dr3"/>
| appmag_v = 7.8{{snd}}9.6<ref name=vsx/>
| constell= [[Cygnus (constellation)|Cygnus]]
}}
{{Starbox character
| type = [[Red supergiant]]
| class = M3 Iab<ref name="ducati"/><ref name="norrisr2"/><ref name="nir"/><br/>(M2–4 Iab)<ref name="keenan"/><ref name="supernova"/>
| appmag_1_passband=U
| appmag_1=13.91<ref name="ducati"/>
| appmag_2_passband=B
| appmag_2={{val|10.897|0.065}}<ref name="tess"/>
| appmag_3_passband=G
| appmag_3={{val|6.190986|0.010832}}<ref name="dr3"/>
| appmag_4_passband=T
| appmag_4={{val|4.618|0.018}}<ref name="tess"/>
| appmag_5_passband=J
| appmag_5={{val|2.765|0.234}}<ref name="tess"/>
| appmag_6_passband=H
| appmag_6={{val|1.744|0.164}}<ref name="tess"/>
| appmag_7_passband=K
| appmag_7=1.22<ref name="dr2-l"/>–{{val|1.288|0.172}}<ref name="tess"/>
| b-v=+2.56<ref name="ducati"/>
| j-k=+1.48<ref name="vsx"/>
| variable=[[Semiregular variable star|SRc]]<ref name=vsx/>
}}
{{Starbox astrometry
| radial_v={{val|-5.52|0.99}}<ref name="dr3"/>
| prop_mo_ra={{val|-1.905|0.031}}<ref name="dr3" />
| prop_mo_dec={{val|-2.871|0.029}}<ref name="dr3" />
| parallax=0.4027
| p_error=0.027
| parallax_footnote = <ref name="dr3"/>
| dist_pc = {{val|2,090|130|115|fmt=commas}}<ref name="ryanp"/>
| dist_ly = {{val|6,820|420|380|fmt=commas}}<ref name="ryanp"/>
| absmag_v = –5.32<ref name=melnik/>
}}
{{starbox detail
| mass = 15<ref name="ryanp"/>{{snd}}{{val|20|9}}<ref name="norrisr"/>
| radius = {{val|911|57|50}}<ref name="ryanp"/>
| luminosity = 109,800<ref name="ryanp"/>{{nowrap|(94,800{{snd}}249,400)<ref name="ryanp"/>}}
| temperature = {{val|3989|117|fmt=commas}}<ref name="norrisr"/> {{nowrap|(3,972{{snd}}4,000)<ref name="ryanp"/>}}
| gravity = −0.5{{snd}}0.0,<ref name="ryanp"/>
| metal_fe = 0.0<ref name="ryanp"/><ref name="norrisr"/><ref name="dr2"/>
}}
{{starbox catalog
| names = AZ&nbsp;Cyg, BD+45&nbsp;3349, TYC&nbsp;3575-553-1, 2MASS&nbsp;J20575942+4628004, SAO&nbsp;50296<ref name="simbad"/>
}}
{{Starbox reference
| Simbad=V*+AZ+Cyg
}}
{{Starbox end}}

'''AZ Cygni''' ('''BD+45 3349''') is a large [[red supergiant]] (M3 Iab)<ref name="ducati"/> in the constellation of [[Cygnus (constellation)|Cygnus.]] Located 2,090 parsecs (6,800 ly) from Earth, it has been studied by the [[CHARA array]] in order to understand the surface variations of red supergiants.<ref name="ryanp"/>

==Observation history==
AZ Cygni first observed in the observations used to produce the [[Bonner Durchmusterung]] catalogue, published by [[Friedrich Argelander]] in the mid 19th century.<ref name="bd1903"/> Thomas William Backhouse showed that BD +45°3349 (the 19th century name for AZ Cygni) is a variable star, based on observations from 1894 to 1904. It was given the [[variable star designation]] AZ Cygni, in 1912.<ref name="Duner1912"/>  It has since then been included in many star surveys and catalogues, including the [[Two-Micron Sky Survey]],<ref name="tmss"/> [[2MASS]],<ref name="2mass"/> [[Tycho-2 Catalogue]]<ref name="tycho"/> and [[Gaia catalogues|Gaia]] (DR2<ref name="dr2"/> and DR3<ref name="dr3"/>).

From 2011 to 2016, it was observed using the Michigan Infra-Red Combiner (MIRC) at the six-telescope [[CHARA Array|Center for High Angular Resolution Astronomy Array]] (CHARA array)<ref name="ryanp"/><ref name="norrisr"/><ref name="norrisr2"/> to investigate the evolution of surface features on red supergiants. These observations were used to derive the fundamental stellar parameters of the star, reconstruct images of the star and test models of 3D radiative hydrodynamics in red supergiants.

{| class="wikitable sortable"
|+ Parameters of AZ Cygni derived from CHARA array data<ref name="norrisr"/><ref name="norrisr2"/><ref name="ryanp"/>
|-
! style="background:#efefef" width=300px | Year of observation
! style="background:#efefef" width=300px | Angular diameter ([[Milliarcsecond|mas]])
! style="background:#efefef" width=300px | [[Radius|Linear radius]]<br/>([[Solar radius|{{solar radius}}]])<br/>
! style="background:#efefef width=300px | Estimation used

|-
! colspan="4" | Norris (2019)<ref name="norrisr"/>
|-

|-
|2011
|{{val|3.93|0.01}}
|{{val|856|20|14}}
|LDD

|-
|2012
|{{val|4.26|0.02}}
|{{val|927|21|15}}
|LDD

|-
|2014
|{{val|4.09|0.01}}
|{{val|890|21|15}}
|LDD

|-
|2015
|{{val|4.11|0.01}}
|{{val|895|21|15}}
|LDD

|-
|2016
|{{val|4.09|0.01}}
|{{val|890|21|15}}
|LDD

|-
! colspan="4" | Norris (2021)<ref name="norrisr2"/>
|-

|-
| – 
|3.74
|{{val|814|175|124}}
|?

|-
! colspan="4" | Norris et al. (2021)<ref name="ryanp"/>
|-

|-
|2011
|{{val|3.82|0.01}}
|{{val|{{Solar radius calculator|type=AD|3.82|2.09}}|56|49}}{{efn|name=AD}}
|UD

|-
|2011
|{{val|3.93|0.01}}
|{{val|{{Solar radius calculator|type=AD|3.93|2.09}}|57|51}}{{efn|name=AD}}
|LDD

|-
|2014
|{{val|3.81|0.01}}
|{{val|{{Solar radius calculator|type=AD|3.81|2.09}}|56|49}}{{efn|name=AD}}
|UD

|-
|2014
|{{val|4.09|0.01}}
|{{val|{{Solar radius calculator|type=AD|4.09|2.09}}|60|53}}{{efn|name=AD}}
|LDD

|-
|2015
|{{val|3.9|0.01}}
|{{val|{{Solar radius calculator|type=AD|3.9|2.09}}|57|50}}{{efn|name=AD}}
|UD

|-
|2015
|{{val|4.11|0.01}}
|{{val|{{Solar radius calculator|type=AD|4.11|2.09}}|59|53}}{{efn|name=AD}}
|LDD

|-
|2016
|{{val|3.99|0.01}}
|{{val|{{Solar radius calculator|type=AD|3.99|2.09}}|57|52}}{{efn|name=AD}}
|UD

|-
|2016
|{{val|4.09|0.01}}
|{{val|{{Solar radius calculator|type=AD|4.09|2.09}}|60|53}}{{efn|name=AD}}
|LDD

|-style="background:#dfdfdf"
|''Average'' (UD)
|''{{val|3.85|0.01}}''
|''{{val|{{Solar radius calculator|type=AD|3.85|2.09}}|56|50}}{{efn|name=AD}}''
|''UD''

|-style="background:#dfdfdf"
|''Average'' (LDD)
|''{{val|4.05|0.01}}''
|''{{val|{{Solar radius calculator|type=AD|4.05|2.09}}|59|52}}{{efn|name=AD}}''
|''LDD''

|}

{| class="wikitable sortable"
|+ Parameters of AZ Cygni derived from best fitting atmosphere models and model spectra<ref name="ryanp"/><ref name="norrisr"/>
|-
! style="background:#efefef" width=200px | Model
! style="background:#efefef" width=200px | [[Effective temperature|''T''<sub>eff</sub>]] ([[Kelvin|''K'']])
! style="background:#efefef" width=300px | Surface gravity <br/>([[Surface gravity|''log g'']])<br/>
! style="background:#efefef" width=200px | Radius <br/>([[Solar radius|{{solar radius}}]])<br/>
! style="background:#efefef" width=250px | Luminosity <br/>([[Solar luminosity|{{solar luminosity}}]])<br/>
! style="background:#efefef" width=200px | Mass <br/>([[Solar mass|{{solar mass}}]])<br/>
! style="background:#efefef" width=250px | Metallicity <br/>[Fe/H] ([[Common logarithm|''dex'']])
! style="background:#efefef" width=200px | ''E(B – V)''

|-
! colspan="8" | Norris (2019)<ref name="norrisr"/>
|-

|-
|MARCS
|4,000
|0.5
|481
|53,206
|15
|0.0
|0.76

|-
|PHOENIX
|4,100
|0.0
|642
|94,614
|15
|0.0
|0.59

|-
|SATLAS
|3,867
|0.36
|600
|110,495
|30
|0.0
|0.89

|-style="background:#dfdfdf"
|''Average''
|''{{val|3,989|117|fmt=commas}}''
|''{{val|0.29|0.26}}''
|''{{val|574|84}}''
|''{{val|82,772|35,173|fmt=commas}}''
|''{{val|20|9}}''
|''{{val|0.0|0.0}}''
|''{{val|0.75|0.15}}''

|-
! colspan="8" | Norris et al. (2021)<ref name="ryanp"/>
|-

|-
|MARCS
|4,000
| -0.5
|1,040
|249,443
|15
|0.0
|0.56

|-
|PHOENIX
|4,000
|0.0
|641
|94,759
|15
|0.0
|0.55

|-
|SATLAS
|3,972
| -0.07
|700
|109,828
|15
|0.0
|0.54

|}

==Physical parameters==

===Luminosity===
The [[Gaia DR2]] catalogue estimated AZ Cygni's [[absolute bolometric magnitude]] at  {{val|-6.4839|0.6427}}, corresponding to a luminosity of approximately {{solar luminosity|{{val|30870|13790|24930|fmt=commas}}|link=y}}.<ref name="dr2_lpv" /> Although the distance is potentially unreliable due to a very high amount of astrometric noise, rated at a significance of 47.4, anything above a rating of 2 is 'probably significant'.<ref name="dr2"/><ref>{{Cite journal |last1=Lindegren |first1=L. |last2=Klioner |first2=S. A. |last3=Hernández |first3=J. |last4=Bombrun |first4=A. |last5=Ramos-Lerate |first5=M. |last6=Steidelmüller |first6=H. |last7=Bastian |first7=U. |last8=Biermann |first8=M. |last9=de Torres |first9=A. |last10=Gerlach |first10=E. |last11=Geyer |first11=R. |last12=Hilger |first12=T. |last13=Hobbs |first13=D. |last14=Lammers |first14=U. |last15=McMillan |first15=P. J. |date=May 2021 |title=Gaia Early Data Release 3: The astrometric solution |journal=Astronomy & Astrophysics |volume=649 |pages=A2 |doi=10.1051/0004-6361/202039709 |arxiv=2012.03380 |bibcode=2021A&A...649A...2L |issn=0004-6361}}</ref>

A paper in 2019 calculated the luminosity of AZ Cygni using the Gaia distance and a bolometric magnitude of -7.58, which would result in a luminosity of around {{solar luminosity|84,700}}.<ref name="brown" /> Another paper in 2019 estimated three luminosity values of {{solar luminosity|53,206}}, {{solar luminosity|94,416}} and {{solar luminosity|110,495}} with an average of {{solar luminosity|{{val|82772|35173|fmt=commas}}}}.<ref name="norrisr" /> According to a 2021 paper, the best fitting atmosphere models would correspond to luminosities of  {{solar luminosity|249,443}}, {{solar luminosity|94,759}} and {{solar luminosity|109,828}}.<ref name="ryanp" />

===Radius===

[[File:CHARA_1497.jpg|thumb|200px|left|One of six telesopes in the CHARA array, used to derive AZ Cygni's angular diameter.]]The radius of AZ Cygni was first determined to be around {{solar radius|748}} in a 2019 paper based on the Gaia-derived distance,<ref name="brown" /> although it is potentially unreliable due to a high amount of astrometric noise.<ref name="dr2" /> 

By using the angular diameter and Gaia parallax-derived distance in the 2019 Mid-infrared stellar Diameters and Fluxes compilation Catalogue (MDFC), a radius between {{solar radius|913}} and {{solar radius|920}} can be derived.<ref name="diameter" /> Another paper in 2019 estimated five different radii from observations between 2011 and 2016 based on the MDFC angular diameter and Gaia parallax: {{solar radius|{{val|856|20|14}}}} (2011), {{solar radius|{{val|927|21|15}}}} (2012), {{solar radius|{{val|890|21|15}}}} (2014), {{solar radius|{{val|895|21|15}}}} (2015) and {{solar radius|{{val|890|21|15}}}} (2016). The same paper also approximated AZ Cygni's radius based on model spectra, in which three values of {{solar radius|481}}, {{solar radius|642}} and {{solar radius|600}} were estimated with an average of {{solar radius|{{val|574|84}}}}.<ref name="norrisr" />

The radius of AZ Cygni was again estimated at {{solar radius|{{val|814|175|124}}}} based on its angular diameter and Gaia parallax in a 2021 study.<ref name="norrisr2" /> A separate paper in 2021 calculated a radius of {{solar radius|{{val|911|57|50}}}}, an average value after using the star's angular diameter and Gaia parallaxes. Based on the best fitting atmosphere models, three different radii were calculated: {{solar radius|1,040|fmt=commas}}, {{solar radius|641}} and {{solar radius|700}}.<ref name="ryanp" />

===Temperature and spectral type===

In a 1989 paper it was estimated that AZ Cygni would have [[Spectral type|spectral types]] of between M2Iab and M4Iab.<ref name="keenan"/>  A study in 2000 estimated that the spectral type of AZ Cygni is M3.1Iab.<ref name="dust"/>  The spectral type of AZ Cygni was estimated at M3 Iab in a 2002 paper.<ref name="ducati"/>

A paper in 2004 estimated that the [[effective temperature]] of AZ Cygni is 3,200 K with a spectral type of M3 Iab.<ref name="nir"/>  AZ Cygni had 3 different effective temperature estimates in a paper in 2019 derived from model spectra: 4,000 K, 4,100 K and 3,867 K with an average of {{val|3989|117|fmt=commas}} K.<ref name="norrisr"/>  In another study in 2021 AZ Cygni would have three effective temperature estimates based on the best fitting atmosphere models: 4,000 K, 4,000 K and 3,972 K and also mentions that it is an M2–4.5 Iab star.<ref name="ryanp"/> The RSG and Close Stars Catalog (2024) features an adopted mean spectral type of M3 for AZ Cygni based on previous spectral types.<ref>{{Cite journal |last1=Healy |first1=Sarah |last2=Horiuchi |first2=Shunsaku |last3=Molla |first3=Marta Colomer |last4=Milisavljevic |first4=Dan |last5=Tseng |first5=Jeff |last6=Bergin |first6=Faith |last7=Weil |first7=Kathryn |last8=Tanaka |first8=Masaomi |date=2024-03-23 |title=Red Supergiant Candidates for Multimessenger Monitoring of the Next Galactic Supernova |journal=Monthly Notices of the Royal Astronomical Society |volume=529 |issue=4 |pages=3630–3650 |doi=10.1093/mnras/stae738 |doi-access=free |issn=0035-8711|arxiv=2307.08785 |bibcode=2024MNRAS.529.3630H }}</ref><ref>{{Cite web |title=candidate_list/data/RSG_and_close_stars_catalog_4_11_24.csv at main · SNEWS2/candidate_list |url=https://github.com/SNEWS2/candidate_list/blob/main/data/RSG_and_close_stars_catalog_4_11_24.csv |access-date=2024-08-05 |website=GitHub |language=en}}</ref>

===Mass===

The mass of AZ Cygni was first determined based on the best fitting model spectra, which would correspond to three mass estimates: {{solar mass|15}}, {{solar mass|15}} and {{solar mass|30}} with an average of {{solar mass|{{val|20|9}}}}.<ref name="norrisr"/>  A paper in 2021 estimated three mass estimates equal to {{solar mass|15}} based on the best fitting atmosphere models.<ref name="ryanp"/>

==Surface features==

AZ Cygni has a complex surface, with large and small features that vary over different timescales. Patterns of large convection cells, varying over periods of more than a year, are combined with smaller hot granules of rising gas that vary over shorter timescales. The size of the larger surface features is in line with models of 3D radiative hydrodynamics in red supergiants.<ref name="ryanp"/>

==Notes==
{{notelist|refs=

{{efn|name=AD|Calculated assuming the given distance of {{val|2,090|130|115|fmt=commas}} mentioned in Norris et al. (2021) and the estimated angular diameter. <br/><math>\delta = 206,265 ~ (d / D) ~ \mathrm{arcseconds} \Longrightarrow d = \frac{\delta * D}{206,265} \Longrightarrow R = \frac{d}{2}</math><br/>
The average linear radius of {{solar radius|{{val|911|57|50}}}} is the only one mentioned in the paper.<ref name="ryanp"/>}}

}}

==See also==

{{cmn|colwidth=35em|
* [[6 Geminorum]]
* [[BI Cygni]]
* [[NR Vulpeculae]]
* [[RS Persei]]
* [[RW Cygni]]
* [[S Persei]]
* [[TV Geminorum]]
* [[V424 Lacertae]]
* [[List of largest known stars]]
}}

==References==
{{reflist|refs=

<ref name=vsx>{{cite web |url=https://www.aavso.org/vsx/index.php?view=detail.top&oid=10999 |title=AZ Cygni |website=International Variable Star Index |publisher=[[AAVSO]] |access-date=2023-01-23 }}</ref>

<ref name=dr3>{{Cite Gaia DR3|2163751614044043136}}</ref>

<ref name="Duner1912">{{cite journal |last1=Dunér |last2=Hartwig |last3=Müller |title=Benennung von neu entdeckten veränderlichen Sternen |journal=Astronomische Nachrichten |date=June 1912 |volume=191 |issue=19 |pages=341-358 |doi=10.1002/asna.19121911902 |bibcode=1912AN....191..341. |url=https://articles.adsabs.harvard.edu/pdf/1912AN....191..341. |access-date=9 December 2024}}</ref>

<ref name=ducati>{{Cite journal|last=Ducati|first=J. R.|date=2002|title=VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system.|journal=Collection of Electronic Catalogues|volume=2237 |url=https://ui.adsabs.harvard.edu/abs/2002yCat.2237....0D/abstract|bibcode=2002yCat.2237....0D}}</ref>

<ref name=keenan>{{Cite journal|last1=Keenan|first1=Philip C.|last2=McNeil|first2=Raymond C.|date=October 1989|title=The Perkins Catalog of Revised MK Types for the Cooler Stars|journal=The Astrophysical Journal|volume=71 |page=245 |url=https://ui.adsabs.harvard.edu/abs/1989ApJS...71..245K/abstract|bibcode=1989ApJS...71..245K|doi=10.1086/191373|s2cid=123149047 }}</ref>

<ref name=ryanp>{{Cite journal|last1=Norris|first1=Ryan P.|last2=Baron|first2=Fabien R.|last3=Monnier|first3=John D.|last4=Paladini|first4=Claudia|last5=Anderson|first5=Matthew D.|last6=Martinez|first6=Arturo O.|last7=Schaefer|first7=Gail H.|last8=Che|first8=Xiao|last9=Chiavassa|first9=Andrea|last10=Connelley|first10=Michael S.|last11=Farrington|first11=Christopher D.|last12=Gies|first12=Douglas R.|last13=Kiss|first13=László L.|last14=Lester|first14=John B.|last15=Montargès|first15=Miguel|last16=Neilson|first16=Hilding R.|last17=Majoinen|first17=Olli|last18=Pedretti|first18=Ettore|last19=Ridgway|first19=Stephen T.|last20=Roettenbacher|first20=Rachael M.|last21=Scott|first21=Nicholas J.|last22=Sturmann|first22=Judit|last23=Sturmann|first23=Laszlo|last24=Thureau|first24=Nathalie|last25=Vargas|first25=Norman|last26=Ten Brummelaar|first26=Theo A.|date=29 June 2021|title=Long Term Evolution of Surface Features on the Red Supergiant AZ Cyg|journal=The Astrophysical Journal|volume=919|issue=2|page=124|doi=10.3847/1538-4357/ac0c7e|arxiv=2106.15636|bibcode=2021ApJ...919..124N|s2cid=235683123 |doi-access=free }}</ref>

<ref name=simbad>{{Cite web|title=V* AZ Cyg|publisher=Université de Strasbourg|url=http://simbad.u-strasbg.fr/simbad/sim-id?Ident=V*+AZ+Cyg&submit=submit+id}}</ref>

<ref name=bd1903>{{Cite journal|last=Argelander|first=Friedrich Wilhelm August|url=https://ui.adsabs.harvard.edu/abs/1903BD....C......0A/abstract|date=1903|title=Bonner Durchmusterung des nordlichen Himmels.|journal=Eds Marcus and Weber's Verlag |bibcode=1903BD....C......0A}}</ref>

<ref name="ASAS-SN">{{cite web |url=https://asas-sn.osu.edu/variables/lookup |website=ASAS-SN Variable Stars Database|title=ASAS-SN Variable Stars Database|publisher=ASAS-SN |access-date=6 January 2022}}</ref>

<ref name=diameter>{{Cite journal|last1=Cruzalèbes|first1=P.|last2=Petrov|first2=R. G.|last3=Robbe-Dubois|first3=S.|last4=Varga|first4=J.|last5=Burtscher|first5=L.|last6=Allouche|first6=F.|last7=Berio|first7=P.|last8=Hoffman|first8=K. -H|last9=Hron|first9=J.|last10=Jaffe|first10=W.|last11=Lagarde|first11=S.|last12=Lopez|first12=B.|last13=Matter|first13=A.|last14=Meilland|first14=A.|last15=Meisenheimer|first15=K.|last16=Millour|first16=F.|last17=Schertl|first17=D.|date=1 October 2019|title=A catalogue of stellar diameters and fluxes for mid-infrared interferometry|journal=The Royal Astronomical Society|volume=490|issue=3|pages=3158–3176|bibcode=2019MNRAS.490.3158C|doi=10.1093/mnras/stz2803|doi-access=free |arxiv=1910.00542|issn=0035-8711|s2cid=203610229}}</ref>

<ref name=tmss>{{Cite book|last1=Neugebauer|first1=G.|last2=Leighton|first2=R. B.|date=1969|title=Two-micron sky survey. A preliminary catalogue|url=https://ui.adsabs.harvard.edu/abs/1969tmss.book.....N/abstract|bibcode=1969tmss.book.....N}}</ref>

<ref name=2mass>{{Cite journal|last1=Cutri|first1=R. M.|last2=Skrutskie|first2=M. F.|last3=van Dyk|first3=S.|last4=Beichman|first4=C. A.|last5=Carpenter|first5=J. M.|last6=Chester|first6=T.|last7=Cambresy|first7=L.|last8=Evans|first8=T.|last9=Fowler|first9=J.|last10=Gizis|first10=J.|last11=Howard|first11=E.|last12=Huchra|first12=J.|last13=Jarrett|first13=T.|last14=Kopan|first14=E. L.|last15=Kirkpatrick|first15=J. D.|last16=Light|first16=R. M.|last17=Marsh|first17=K. A.|last18=McCallon|first18=H.|last19=Schneider|first19=S.|last20=Stiening|first20=R.|last21=Sykes|first21=M.|last22=Weinberg|first22=M.|last23=Wheaton|first23=W.A.|last24=Whealock|first24=S.|last25=Zacarias|first25=N.|date=June 2003|title=VizieR Online Data Catalog: 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)|journal=Vizier Online Data Catalog |url=https://ui.adsabs.harvard.edu/abs/2003yCat.2246....0C/abstract|bibcode=2003yCat.2246....0C}}</ref>

<ref name=brown>{{Cite journal|last1=Messineo|first1=M.|last2=Brown|first2=A. G. A|date=13 May 2019|title=A Catalog of Known Galactic K-M Stars of Class I Candidate Red Supergiants in Gaia DR2|journal=The Astronomical Journal|volume=158|issue=1|pages=20|arxiv=1905.03744|bibcode=2019AJ....158...20M|doi=10.3847/1538-3881/ab1cbd|s2cid=148571616 |doi-access=free }}</ref>

<ref name=tycho>{{Cite journal|last1=Høg|first1=E.|last2=Fabricius|first2=C.|last3=Makarov|first3=V. V.|last4=Urban|first4=S.|last5=Corbin|first5=T.|last6=Wycoff|first6=G.|last7=Bastian|first7=U.|last8=Schwekendiek|first8=P.|last9=Wicenec|first9=A.|date=3 January 2000|title=The Tycho-2 catalogue of the 2.5 million brightest stars|journal=Astronomy and Astrophysics|volume=355|issue=500|pages=L27–L30|url=https://ui.adsabs.harvard.edu/abs/2000A%26A...355L..27H/abstract|bibcode=2000A&A...355L..27H}}</ref>

<ref name=dr2>{{Cite Gaia DR2|2163751614044043136}}</ref>

<ref name=dr2_lpv>{{Cite web|title=Long Period Variable stars (Gaia DR2)|publisher=VizieR|url=https://vizier.cds.unistra.fr/viz-bin/VizieR-3?-source=I/345/lpv}}</ref>

<ref name=norrisr>{{Cite thesis|last=Norris|first=Ryan Patrick|date=13 December 2019|title=Seeing stars like never before: A long-term interferometric imaging survey of red supergiants|journal=Physics and Astronomy Dissertations |publisher=Georgia State University |doi=10.57709/15009706 |url=https://scholarworks.gsu.edu/phy_astr_diss/118/|bibcode=2019PhDT........63N}}</ref>

<ref name=norrisr2>{{Cite conference|last=Norris|first=Ryan|date=27 February 2021|title=An Interferometric Imaging Survey of Red Supergiant Stars|conference=The 20.5th Cambridge Workshop on Cool Stars |page=263 |bibcode=2021csss.confE.263N|doi=10.5281/zenodo.4567641 |doi-access=free }}</ref>

<ref name=dr2-l>{{Cite journal|last1=Chatys|first1=Filip W.|last2=Bedding|first2=Timothy R.|last3=Murphy|first3=Simon J.|last4=Kiss|first4=László L.|last5=Dobie|first5=Dougal|last6=Grindlay|first6=Jonathan E.|date=10 June 2019|title=The period-luminosity relation of red supergiants with Gaia DR2|journal=The Royal Astronomical Society|volume=487|issue=4|pages=4832–4846|bibcode=2019MNRAS.487.4832C|doi=10.1093/mnras/stz1584|doi-access=free |arxiv=1906.03879}}</ref>

<ref name=dust>{{Cite journal|last1=Speck|first1=A. K.|last2=Barlow|first2=M. J.|last3=Sylvester|first3=R. J.|last4=Hofmeister|first4=A. M.|date=15 November 2000|title=Dust features in the 10-mu m infrared spectra of oxygen-rich evolved stars|journal=Astronomy and Astrophysics|volume=146|issue=3 |pages=437–464|bibcode=2000A&AS..146..437S|doi=10.1051/aas:2000274|doi-access=free}}</ref>

<ref name=nir>{{Cite journal|last1=Ivanov|first1=Valentin D.|last2=Rieke|first2=Marcia J.|last3=Engelbracht|first3=Charles W.|last4=Alonso-Herrero|first4=Almudena|author4-link=Almudena Alonso-Herrero|last5=Rieke|first5=George H.|last6=Luhman|first6=Kefin L.|year=2004|title=A Medium-Resolution Near-Infrared Spectral Library of Late-Type Stars. I.|journal=The Astrophysical Journal|volume=151|issue=2|pages=387–397|bibcode=2004ApJS..151..387I|doi=10.1086/381752|arxiv=astro-ph/0311596|s2cid=55537399 |doi-access=free }}</ref>

<ref name=supernova>{{Cite journal|last1=Nakamura|first1=Ko|last2=Horiuchi|first2=Shunsaku|last3=Tanaka|first3=Masaomi|last4=Hayama|first4=Kazuhiro|last5=Takiwaki|first5=Tomoya|last6=Kotake|first6=Kei|date=9 February 2016|title=Multimessenger signals of long-term core-collapse supernova simulations: synergetic observation strategies|journal=The Royal Astronomical Society|volume=461|issue=3|pages=3296–3313|bibcode=2016MNRAS.461.3296N|doi=10.1093/mnras/stw1453|arxiv=1602.03028|doi-access=free}}</ref>

<ref name=tess>{{Cite journal|bibcode=2019AJ....158..138S|title=The revised TESS Input Catalog and Candidate Target List|author=Stassun K.G.|display-authors=etal|date=October 2019|journal=[[The Astronomical Journal]]|volume=158|issue=4|page=138|arxiv=1905.10694|doi=10.3847/1538-3881/ab3467|s2cid=166227927 |doi-access=free }}</ref>

<ref name=melnik>{{cite journal |bibcode=2020Ap&SS.365..112M |title=Distance scale for high-luminosity stars in OB associations and in field with Gaia DR2. Spurious systematic motions |last1=Melnik |first1=A. M. |last2=Dambis |first2=A. K. |journal=Astrophysics and Space Science |date=2020 |volume=365 |issue=7 |page=112 |doi=10.1007/s10509-020-03827-0 |arxiv=2006.14649 }}</ref>

}}

{{Commons category}}
{{Stars of Cygnus}}

[[Category:M-type supergiants]]
[[Category:Cygnus (constellation)]]
[[Category:Objects with variable star designations|Cygni, AZ]]
[[Category:TIC objects]]
[[Category:2MASS objects|J20575942+4628004]]
[[Category:Semiregular variable stars]]
[[Category:Durchmusterung objects]]