- La Superba
Starbox begin
name = La SuperbaStarbox observe
epoch=J2000.0
constell=Canes Venatici
ra=12h 45m 07.83s
dec=+45° 26' 24.92"
appmag_v=+4.8 to +6.3Starbox astrometry
prop_mo_ra=-2.20
prop_mo_dec=13.05
parallax= 4.590
dist_ly=711 ± 113
dist_pc=218 ± 35Starbox character
class = C54J, C-N5, C-J4.5
variable = Semi-regularStarbox detail
age =
metal =
mass = 3
radius = 215
rotation =
luminosity = 4,400
(bolometric)
temperature = 2,800 Starbox catalog
names=Y Canum Venaticorum, HR 4846, HD 110914, BD+46°1817, FK5 1327, HIP 62223, SAO 44317, GC 17342La Superba (Y CVn / Y Canum Venaticorum) is a star in the
constellation Canes Venatici , well-known for its strikingly red appearance.Physical Characteristics
La Superba is a semi-regular
variable star , peaking at about +4.8 mag and diminishing to around +6.3 over a 160 day cycle. Known in short form as Y CVn, it is one of the reddest stars in the sky, and it is among the brightest of the giant red "carbon stars". It is the brightest J-star in the sky, a very rare category of carbon stars that have contain large amounts ofcarbon-13 (carbon atoms with 7neutrons instead of the usual 6). 19th centuryastronomer Angelo Secchi , impressed with its beauty, gave the star its common name. [ [http://www.astro.uiuc.edu/~kaler/sow/lasuperba.html Jim Kaler: La Superba] ]La Superba's
temperature is believed to be about 2800 K, making it one of the coldest true stars known. Y CVn is almost never visible to the naked eye since most of its output is outside the visible spectrum. Yet, wheninfrared radiation is considered, Y CVn has aluminosity 4400 times that of the Sun, and itsradius is approximately 2 AU. If it were placed at the position of our sun, the star's surface would extend beyond the orbit ofMars .Appearance
To explain its remarkable coloration, it is necessary to understand that mid-sized stars, once they have finished fusing
hydrogen tohelium in their core, begin to fuse helium to carbon. During this so calledred giant stage, the outer layers expand and cool, causing the star's radiation output to move towards the red end of theelectromagnetic spectrum . Near the end of the star's life cycle, fusion products are moved outwards from the core byconvection , thus creating acarbon abundance in the outer atmosphere wherecarbon monoxide and other compounds are formed. These molecules tend to absorb radiation at shorter wavelengths, resulting in a remarkablespectrum with even less blue and violet compared to ordinary red giants, giving the star its distinguished red color.Outlook
La Superba is most likely in the final stages of fusing its remaining secondary fuel (helium) into carbon and shedding its mass at the rate of about a million times that of the Sun's
solar wind . It is also surrounded by a 2.5light year -wide shell of previously ejected material, implying that at one point it must have been losing mass even 50 times faster than it is now. La Superba thus appears almost ready to eject its outer layers to form aplanetary nebula , leaving behind its core in the form of a vanishingwhite dwarf .References
External links
* http://www.nckas.org/carbonstars/
* http://www.backyard-astro.com/deepsky/top100/11.html
* http://jumk.de/astronomie/big-stars/la-superba.shtml
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