KY Cygni

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Template:Short description

KY Cygni
Template:Location mark
Location of KY Cygni in the Sadr region (circled, east is up)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Cygnus
Right ascension Template:RA[1]
Declination Template:DEC[1]
Apparent magnitude (V) 10.60 - 11.74[2]
Characteristics
Evolutionary stage red supergiant[3]
Spectral type M3 Ia[4] (M3.5 Ia[5])
U−B Template:Engvar +2.91[6]
B−V Template:Engvar +3.39[6]
Variable type Lc[5]
Astrometry
Proper motion (μ) RA: −3.556[1] mas/yr
Dec.: −6.061[1] mas/yr
Parallax (π)0.6687±0.0517 mas[1]
DistanceScript error: No such module "val". ly
(Script error: No such module "val". pc)[7]
Absolute magnitude (MV)−8.18[3]
Details[8]
Mass19 Template:Solar mass
RadiusTemplate:Solar radius calculatorTemplate:Efn Template:Solar radius
Luminosity150,000 Template:Solar luminosity
Surface gravity (log g)−0.5[3] cgs
Temperature3,535 K
Age>9Template:Efn Myr
Metallicity [Fe/H]{{{metal_fe2}}} dex
Other designations
KY Cyg, GSC 03152-01140, IRAS 20241+3811, IRC+40415, TYC 3152-1140-1, RAFGL 2575, UCAC2 45230193, 2MASS J20255805+3821076
Database references
SIMBADdata

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KY Cygni is a variable red supergiant of spectral class M3Ia located in the constellation Cygnus. It is approximately 4,700 light-years away.

Observations

KY Cyg lies near the bright open cluster NGC 6913, but is not thought to be a member. The location is close to the bright star γ Cygni.[9] It was identified as a variable star in 1930,[10] and later named as KY Cygni.[11] The spectrum was given the MK classification of M3 Ia, with only minor adjustments since.[4]

KY Cygni is heavily reddened due to interstellar extinction, losing an estimated 7.75 magnitudes at visual wavelengths. It would be a naked eye star if no light was lost.[3]

Properties

File:Mukyv354.png
Size comparison of Betelgeuse, Mu Cephei, KY Cygni, and V354 Cephei, according to estimates derived in 2005[3]

KY Cygni is classified as a luminous red supergiant with a strong stellar wind. It is losing mass at around Script error: No such module "val". and has been described as a cool hypergiant.[6][12]

Its properties are uncertain, but the temperature is around 3,500 K. A model fit based on K-band infrared brightness gives a luminosity of Template:Solar luminosity, corresponding to a radius of Template:Solar radius. Another model based on visual brightness gives an unexpectedly large luminosity of Template:Solar luminosity, with the difference due mainly to the assumptions about the level of extinction. The radius corresponding to the higher luminosity would be Template:Solar radius. These parameters are larger and more luminous than expected for any red supergiant, making them doubtful.[3] More recently, integration of the spectral energy distributions across a full range of wavelengths from U band to the 60 micron microwave flux gives an even lower luminosity of Template:Solar luminosity,[6] and a 2020 paper published a luminosity of Template:Solar luminosity, which give a smaller radius of Template:Solar radius calculator using an effective temperature of 3,535Script error: No such module "String".K.[8]

File:KYCygLightCurve.png
A visual band light curve for KY Cygni, plotted from data published by Kochanek et al. (2017)[13]

KY Cygni is a variable star with a large amplitude but no clear periodicity. At times, it varies rapidly, at others it is fairly constant for long periods.[9] The photographic magnitude range is given as 13.5 - 15.5,[5] while a visual range is 10.60 - 11.74.[2]

See also

Notes

Template:Notelist

References

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  1. ↑ a b c d e Template:Cite Gaia DR3
  2. ↑ a b Script error: No such module "Citation/CS1".
  3. ↑ a b c d e f Script error: No such module "Citation/CS1".
  4. ↑ a b Script error: No such module "Citation/CS1".
  5. ↑ a b c KY Cyg, database entry, The combined table of GCVS Vols I-III and NL 67-78 with improved coordinates, General Catalogue of Variable Stars Template:Webarchive, Sternberg Astronomical Institute, Moscow, Russia. Accessed on line November 12, 2010.
  6. ↑ a b c d Script error: No such module "Citation/CS1".
  7. ↑ Script error: No such module "Citation/CS1". Data about this star can be seen here.
  8. ↑ a b Script error: No such module "Citation/CS1".
  9. ↑ a b Script error: No such module "Citation/CS1".
  10. ↑ Script error: No such module "Citation/CS1".
  11. ↑ Script error: No such module "Citation/CS1".
  12. ↑ Script error: No such module "Citation/CS1".
  13. ↑ Script error: No such module "Citation/CS1".

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External links

Template:Stars of Cygnus

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