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Created page with "{{Night Sky | image = | designation =Rho Cas<br/>7 Cassiopeiae | rightascension =23<sup>h</sup> 54<sup>m</sup> 23.0339<sup>s</sup><ref name=simbad>{{cite web|ur..."
{{Night Sky
| image =
| designation =Rho Cas<br/>7 Cassiopeiae
| rightascension =23<sup>h</sup> 54<sup>m</sup> 23.0339<sup>s</sup><ref name=simbad>{{cite web|url=http://simbad.u-strasbg.fr/simbad/sim-id?Ident=Rho+Cassiopiae&NbIdent=1&Radius=2&Radius.unit=arcmin&submit=submit+id|title=Rho Cassiopiae|accessdate=June 29, 2020|work=Simbad Astronomical Database|publisher=simbad.u-strasbg.fr}}</ref><ref name=Gaia>{{cite journal
|last1=Gaia Collaboration |first1=
|title=VizieR Online Data Catalog: Gaia DR2
|journal=VizieR Online Data Catalog
|volume=I/345
|issue=|page=I/345|date=2018
|doi=
|bibcode=2018yCat.1345....0G
|ref=harv
}} {{arXiv|0708.1752}}</ref>
| declination =+57° 29′ 57.7669″<ref name=simbad/><ref name=Gaia/>
| distance =11648.69 ly<ref name=universeguide>{{cite web|url=https://www.universeguide.com/star/rhocassiopeiae|title=Rho Cassiopeiae (7 Cassiopeiae) Star Facts|accessdate=June 29, 2020|publisher=universeguide.com}}</ref>
| constellation =Cassiopeia
| type =Hypergiant
| dimensions =
| magnitude =Apparent Mag: +4.51<ref name=universeguide/><br/>Absolute Mag: -8.25<ref name=universeguide/>
| redshift =
| radvelocity =-54.30 ± 0.4 km/s<ref name=simbad/><ref>
{{cite journal
|last1=Gontcharov|first1=G. A.
|display-authors=3
|title=Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system
|journal=Astronomy Letters
|volume=32
|issue=11|page=759-771|date=2006
|doi=10.1134/S1063773706110065
|bibcode=2006AstL...32..759G
|ref=harv
}} {{arXiv|1606.08053}}
</ref>
| propmotion =RA: -5.449 mas/yr<ref name=simbad/><ref name=Gaia/><br/>Dec: -2.613 mas/yr<ref name=simbad/><ref name=Gaia/>
| parallax =0.9470 ± 0.2021 mas<ref name=simbad/><ref name=Gaia/>
}}
'''Rho Cassiopeiae''' (Rho Cas, 7 Cassiopeiae) is a [[Hypergiant|hypergiant star]] in the [[constellation]] of [[Cassiopeia]].<ref name=universeguide/> The star is one of the brightest stars in the [[Milky Way]] and is thought to be a type of [[variable star]].<ref name=daviddarling>{{cite web|url=https://www.daviddarling.info/encyclopedia/R/Rho_Cassiopeiae.html|title=Rho Cassiopeiae|accessdate=June 29, 2020|publisher=daviddarling.info}}</ref> It is also a particularly rare type of star as it is a yellow hypergiant, and only six other such stars have been observed in our [[Milky Way|galaxy]].<ref name=constellation-guide>{{cite web|url=https://www.constellation-guide.com/constellation-list/cassiopeia-constellation/|title=Cassiopeia Constellation|accessdate=June 29, 2020|publisher=constellation-guide.com}}</ref>
Its name "Rho Cassiopiae" is the [[Bayer Designation]] for the star, where the [[Greek]] letter Rho indicates the star's relative brightness to the other stars in the constellation it is in. Higher letters indicate dimmer stars, so Rho Cassiopeiae's designation as rho indicates it is a dim star in Cassiopeiae. Though one of the dimmer stars in Cassiopia, it can still be observed with the unaided eye relatively easily.
==Properties and structure==
Rho Cassiopeia is an enormous star, emitting roughly 550,000 times more energy than the [[Sun]] and an [[absolute magnitude]] of -7.5.<ref name=constellation-guide/> It is thought the star's mass is roughly 40 [[solar mass]]es and a radius of 4.3 [[AU]], making it 450 times larger than the sun.<ref name=Gorlova>
{{cite journal
|last1=Gorlova |first1=Nadya
|last2=Lobel |first2=Alex
|last3=Burgasser |first3=Adam
|last4=Rieke |first4=George
|last5=Ilyin |first5=Ilya
|last6=Stauffer |first6=John
|display-authors=3
|title=On the CO Near-IR Band and the Line Splitting Phenomenon in the Yellow Hypergiant Rho Cassiopeiae
|journal=The Astrophysical Journal
|volume=651
|issue=2|page=1130-1150|date=2006
|doi=10.1086/507590
|bibcode=2006ApJ...651.1130G
|ref=harv
}} {{arXiv|astro-ph/0607158}}
</ref> Its surface has a temperature of 7,300 kelvin, a little hotter than sol.<ref name=illinois>{{cite web|url=http://stars.astro.illinois.edu/sow/rhocas.html|title=Rho Cassiopeiae|accessdate=June 29, 2020|publisher=stars.astro.illinois.edu|author=Jim Kaler|work=Stars|date=March 7, 2000}}</ref> The star belongs to the [[spectral class]] G2Ia0e and the sun, most of the radiation it emits is in the [[visible light|visible]] region of the [[electromagnetic spectrum]]. Due to a large cloud of dust in between earth and the star, the star appears fainter by two orders of [[magnitude]], but is still sufficiently bright to be seen with the unaided eye.
The star is a semi-regular [[variable star]], meaning its intrinsic brightness varies slowly over time. Several periods have been observed including multiple periods of 820, 350, 510, and 645 days.<ref name=illinois/> These periods appear to themselves vary, meaning the star is quite unpredictable.
The star is thought to be loosing mass at a rate of 10<sup>-4</sup> solar masses per year or equivalently, 33 earth masses.<ref name=Gorlova/> This is lost in a [[solar wind]] being projected from the star at a speed of 10 km/s. However every 50 years, the star undergoes an "outburst" event in which up to 10,000 earth masses of material may be lost.<ref name=constellation-guide/> Such outbursts occured in the summer of 1946 and more recently in june-September 2000.<ref name=illinois/><ref>
{{cite journal
|last1=Lobel |first1=Alex
|last2=Dupree |first2=Andrea
|last3=Torres |first3=Belanna
|last4=Israelian |first4=Garik
|last5=Morrison |first5=Nancy
|last6=de Jager |first6=Cornelis
|last7=Nieuwenhuijzen |first7=Hans
|last8=Ilyin |first8=Ilya
|display-authors=3
|title=The Millennium Outburst of the Cool Hypergiant rho Cassiopeiae: Spectroscopy and Modeling
|journal=Modelling of Stellar Atmospheres, Poster Contributions. Proceedings of the 210th Symposium of the International Astronomical Union
|volume=
|issue=|page=|date=2003
|doi=
|bibcode=2003IAUS..210P.F10L
|ref=harv
}} {{arXiv|astro-ph/0211508}}
</ref> In 1946, the stars brightness decreased by two magnitudes to the sixth magnitude. Its surface also reduced its temperature from around 7,000 kelvin to only 3,000 kelvin.<ref>{{cite web|url=https://skyandtelescope.org/astronomy-news/a-star-prepares-to-blow-its-top/|title=A Star Prepares To Blow Its Top|accessdate=June 29, 2020|publisher=skyandtelescope.org|author=David Tytell|date=July 23, 2003}}</ref> Curiously the spectral class also changed to M, though a year later it had returned to its usual G.
==References==
{{reflist}}
{{Stars}}
[[Category:Astronomy]]
[[Category:Stars]]
| image =
| designation =Rho Cas<br/>7 Cassiopeiae
| rightascension =23<sup>h</sup> 54<sup>m</sup> 23.0339<sup>s</sup><ref name=simbad>{{cite web|url=http://simbad.u-strasbg.fr/simbad/sim-id?Ident=Rho+Cassiopiae&NbIdent=1&Radius=2&Radius.unit=arcmin&submit=submit+id|title=Rho Cassiopiae|accessdate=June 29, 2020|work=Simbad Astronomical Database|publisher=simbad.u-strasbg.fr}}</ref><ref name=Gaia>{{cite journal
|last1=Gaia Collaboration |first1=
|title=VizieR Online Data Catalog: Gaia DR2
|journal=VizieR Online Data Catalog
|volume=I/345
|issue=|page=I/345|date=2018
|doi=
|bibcode=2018yCat.1345....0G
|ref=harv
}} {{arXiv|0708.1752}}</ref>
| declination =+57° 29′ 57.7669″<ref name=simbad/><ref name=Gaia/>
| distance =11648.69 ly<ref name=universeguide>{{cite web|url=https://www.universeguide.com/star/rhocassiopeiae|title=Rho Cassiopeiae (7 Cassiopeiae) Star Facts|accessdate=June 29, 2020|publisher=universeguide.com}}</ref>
| constellation =Cassiopeia
| type =Hypergiant
| dimensions =
| magnitude =Apparent Mag: +4.51<ref name=universeguide/><br/>Absolute Mag: -8.25<ref name=universeguide/>
| redshift =
| radvelocity =-54.30 ± 0.4 km/s<ref name=simbad/><ref>
{{cite journal
|last1=Gontcharov|first1=G. A.
|display-authors=3
|title=Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system
|journal=Astronomy Letters
|volume=32
|issue=11|page=759-771|date=2006
|doi=10.1134/S1063773706110065
|bibcode=2006AstL...32..759G
|ref=harv
}} {{arXiv|1606.08053}}
</ref>
| propmotion =RA: -5.449 mas/yr<ref name=simbad/><ref name=Gaia/><br/>Dec: -2.613 mas/yr<ref name=simbad/><ref name=Gaia/>
| parallax =0.9470 ± 0.2021 mas<ref name=simbad/><ref name=Gaia/>
}}
'''Rho Cassiopeiae''' (Rho Cas, 7 Cassiopeiae) is a [[Hypergiant|hypergiant star]] in the [[constellation]] of [[Cassiopeia]].<ref name=universeguide/> The star is one of the brightest stars in the [[Milky Way]] and is thought to be a type of [[variable star]].<ref name=daviddarling>{{cite web|url=https://www.daviddarling.info/encyclopedia/R/Rho_Cassiopeiae.html|title=Rho Cassiopeiae|accessdate=June 29, 2020|publisher=daviddarling.info}}</ref> It is also a particularly rare type of star as it is a yellow hypergiant, and only six other such stars have been observed in our [[Milky Way|galaxy]].<ref name=constellation-guide>{{cite web|url=https://www.constellation-guide.com/constellation-list/cassiopeia-constellation/|title=Cassiopeia Constellation|accessdate=June 29, 2020|publisher=constellation-guide.com}}</ref>
Its name "Rho Cassiopiae" is the [[Bayer Designation]] for the star, where the [[Greek]] letter Rho indicates the star's relative brightness to the other stars in the constellation it is in. Higher letters indicate dimmer stars, so Rho Cassiopeiae's designation as rho indicates it is a dim star in Cassiopeiae. Though one of the dimmer stars in Cassiopia, it can still be observed with the unaided eye relatively easily.
==Properties and structure==
Rho Cassiopeia is an enormous star, emitting roughly 550,000 times more energy than the [[Sun]] and an [[absolute magnitude]] of -7.5.<ref name=constellation-guide/> It is thought the star's mass is roughly 40 [[solar mass]]es and a radius of 4.3 [[AU]], making it 450 times larger than the sun.<ref name=Gorlova>
{{cite journal
|last1=Gorlova |first1=Nadya
|last2=Lobel |first2=Alex
|last3=Burgasser |first3=Adam
|last4=Rieke |first4=George
|last5=Ilyin |first5=Ilya
|last6=Stauffer |first6=John
|display-authors=3
|title=On the CO Near-IR Band and the Line Splitting Phenomenon in the Yellow Hypergiant Rho Cassiopeiae
|journal=The Astrophysical Journal
|volume=651
|issue=2|page=1130-1150|date=2006
|doi=10.1086/507590
|bibcode=2006ApJ...651.1130G
|ref=harv
}} {{arXiv|astro-ph/0607158}}
</ref> Its surface has a temperature of 7,300 kelvin, a little hotter than sol.<ref name=illinois>{{cite web|url=http://stars.astro.illinois.edu/sow/rhocas.html|title=Rho Cassiopeiae|accessdate=June 29, 2020|publisher=stars.astro.illinois.edu|author=Jim Kaler|work=Stars|date=March 7, 2000}}</ref> The star belongs to the [[spectral class]] G2Ia0e and the sun, most of the radiation it emits is in the [[visible light|visible]] region of the [[electromagnetic spectrum]]. Due to a large cloud of dust in between earth and the star, the star appears fainter by two orders of [[magnitude]], but is still sufficiently bright to be seen with the unaided eye.
The star is a semi-regular [[variable star]], meaning its intrinsic brightness varies slowly over time. Several periods have been observed including multiple periods of 820, 350, 510, and 645 days.<ref name=illinois/> These periods appear to themselves vary, meaning the star is quite unpredictable.
The star is thought to be loosing mass at a rate of 10<sup>-4</sup> solar masses per year or equivalently, 33 earth masses.<ref name=Gorlova/> This is lost in a [[solar wind]] being projected from the star at a speed of 10 km/s. However every 50 years, the star undergoes an "outburst" event in which up to 10,000 earth masses of material may be lost.<ref name=constellation-guide/> Such outbursts occured in the summer of 1946 and more recently in june-September 2000.<ref name=illinois/><ref>
{{cite journal
|last1=Lobel |first1=Alex
|last2=Dupree |first2=Andrea
|last3=Torres |first3=Belanna
|last4=Israelian |first4=Garik
|last5=Morrison |first5=Nancy
|last6=de Jager |first6=Cornelis
|last7=Nieuwenhuijzen |first7=Hans
|last8=Ilyin |first8=Ilya
|display-authors=3
|title=The Millennium Outburst of the Cool Hypergiant rho Cassiopeiae: Spectroscopy and Modeling
|journal=Modelling of Stellar Atmospheres, Poster Contributions. Proceedings of the 210th Symposium of the International Astronomical Union
|volume=
|issue=|page=|date=2003
|doi=
|bibcode=2003IAUS..210P.F10L
|ref=harv
}} {{arXiv|astro-ph/0211508}}
</ref> In 1946, the stars brightness decreased by two magnitudes to the sixth magnitude. Its surface also reduced its temperature from around 7,000 kelvin to only 3,000 kelvin.<ref>{{cite web|url=https://skyandtelescope.org/astronomy-news/a-star-prepares-to-blow-its-top/|title=A Star Prepares To Blow Its Top|accessdate=June 29, 2020|publisher=skyandtelescope.org|author=David Tytell|date=July 23, 2003}}</ref> Curiously the spectral class also changed to M, though a year later it had returned to its usual G.
==References==
{{reflist}}
{{Stars}}
[[Category:Astronomy]]
[[Category:Stars]]