Beta Pegasi

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Beta Pegasi
Template:Location mark
Location of β Pegasi (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Pegasus
Right ascension Template:RA[1]
Declination Template:DEC[1]
Apparent magnitude (V) 2.42[2] (2.31Template:Snd2.74)[3]
Characteristics
Evolutionary stage AGB[4]
Spectral type M2.5II–IIIe[5]
U−B Template:Engvar +1.96[2]
B−V Template:Engvar +1.67[2]
Variable type Semi-regular[6]
Astrometry
Radial velocity (Rv)+8.7[7] km/s
Proper motion (μ) RA: +187.65[1] mas/yr
Dec.: +136.93[1] mas/yr
Parallax (π)16.64±0.15 mas[1]
DistanceTemplate:Rnd ± Template:Rnd ly
(Template:Rnd ± Template:Rnd pc)[1]
Absolute magnitude (MV)−1.41[8]
Details
MassScript error: No such module "val".[9] Template:Solar mass
RadiusScript error: No such module "val".[10] Template:Solar radius
Luminosity1,644[9]Template:Efn Template:Solar luminosity
Surface gravity (log g)1.20[11] cgs
Temperature3,606[9] K
Metallicity [Fe/H]−0.11[11] dex
Rotational velocity (v sin i)9.7[12] km/s
Metallicity [Fe/H]{{{metal_fe2}}} dex
Other designations
Scheat, 53 Pegasi, HR 8775, BD+27°4480, HD 217906, SAO 90981, FK5 870, HIP 113881[5]
Database references
SIMBADdata

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Beta Pegasi (β Pegasi, abbreviated Beta Peg, β Peg), formally named Scheat Template:IPAc-en,[13][14] is a red giant star and the second-brightest star (after Epsilon Pegasi) in the constellation of Pegasus. It forms the upper right corner of the Great Square of Pegasus,[15] a prominent rectangular asterism.

Nomenclature

β Pegasi (Latinised to Beta Pegasi) is the star's Bayer designation.

It bore the traditional name of Scheat, a name that had also been used for Delta Aquarii. The name was derived from the Arabic Al Sā'id "the upper arm", or from Sa'd.[15] In 2016, the International Astronomical Union organised a Working Group on Star Names (WGSN)[16] to catalog and standardise proper names for stars. The WGSN's first bulletin of July 2016[17] included a table of the first two batches of names approved by the WGSN; which included Scheat for this star (the name Skat was later approved for Delta Aquarii[14]).

In Chinese, Script error: No such module "Lang". (Script error: No such module "Lang".), meaning Encampment, refers to an asterism consisting β Pegasi and α Pegasi.[18] Consequently, the Chinese name for β Pegasi itself is Script error: No such module "Lang". (Script error: No such module "Lang".), "the Second Star of Encampment".[19]

Distance and properties

File:BetaPegLightCurve.png
A light curve for Beta Pegasi, plotted from Hipparcos data[20]

Based upon parallax measurements, Beta Pegasi is located about Script error: No such module "convert". from the Sun.[1] It is unusual among bright stars in having a relatively cool surface temperature compared to stars like the Sun. This star has a stellar classification of M2.3 II–III,[5] which indicates the spectrum has characteristics partway between a bright giant and a giant star. It has expanded until it is 109 times as large,[10] and has a total luminosity of 1,640 times that of the Sun.[9] The effective temperature of the star's outer envelope is about 3,600 K,[9] giving the star the characteristic orange-red hue of an M-type star.[21] The photosphere is sufficiently cool for molecules of titanium oxide to form.[22]

Johann Friedrich Julius Schmidt discovered that Beta Pegasi is a variable star, in 1847.[23] Beta Pegasi is a semi-regular variable with a period of 43.3 days[6] and a brightness that varies from magnitude +2.31 to +2.74 (averaging 2.42).[3] It is losing mass at a rate at or below 10−8 times the Sun's mass per year, which is creating an expanding shell of gas and dust with a radius of about 3,500 times the Sun's radius (16 astronomical units).[24]

Notes

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References

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  1. ↑ a b c d e f g Script error: No such module "citation/CS1".
  2. ↑ a b c Script error: No such module "Citation/CS1".
  3. ↑ a b Script error: No such module "citation/CS1".
  4. ↑ Script error: No such module "Citation/CS1".
  5. ↑ a b c Script error: No such module "citation/CS1".
  6. ↑ a b Script error: No such module "citation/CS1".
  7. ↑ Script error: No such module "citation/CS1".
  8. ↑ Script error: No such module "citation/CS1".
  9. ↑ a b c d e Script error: No such module "Citation/CS1".
  10. ↑ a b Script error: No such module "Citation/CS1".
  11. ↑ a b Script error: No such module "citation/CS1".
  12. ↑ Script error: No such module "citation/CS1".
  13. ↑ Script error: No such module "citation/CS1".
  14. ↑ a b Script error: No such module "citation/CS1".
  15. ↑ a b Script error: No such module "citation/CS1".
  16. ↑ Script error: No such module "citation/CS1".
  17. ↑ Script error: No such module "citation/CS1".
  18. ↑ Template:In lang 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, Template:ISBN.
  19. ↑ Template:In lang 香港太空館 - 研究資源 - 亮星中英對照表 Template:Webarchive, Hong Kong Space Museum. Accessed on line November 23, 2010.
  20. ↑ Script error: No such module "citation/CS1".
  21. ↑ Script error: No such module "citation/CS1".
  22. ↑ Script error: No such module "citation/CS1".
  23. ↑ Script error: No such module "Citation/CS1".
  24. ↑ Script error: No such module "citation/CS1".. Solar Radius = 0.0046491 AU.

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Template:Stars of Pegasus

Template:Sky

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