Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Pegasus |
Right ascension | 23h 03m 46.45746s [1] |
Declination | +28° 04′ 58.0336″ [1] |
Apparent magnitude (V) | 2.42 [2] (2.31 – 2.74) [3] |
Characteristics | |
Spectral type | M2.5II–IIIe [4] |
U−B color index | +1.96 [2] |
B−V color index | +1.67 [2] |
Variable type | Semi-regular [5] |
Astrometry | |
Radial velocity (Rv) | +8.7 [6] 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] |
Distance | 196 ± 2
ly (60.1 ± 0.5 pc) [1] |
Absolute magnitude (MV) | −1.41 [7] |
Details | |
Mass | 1.7±0.3 [8] M☉ |
Radius | 104 [8] [a] R☉ |
Luminosity | 1,644 [8] [b] L☉ |
Surface gravity (log g) | 1.20 [9] cgs |
Temperature | 3,606 [8] K |
Metallicity [Fe/H] | −0.11 [9] dex |
Rotational velocity (v sin i) | 9.7 [10] km/s |
Other designations | |
Database references | |
SIMBAD | data |
Beta Pegasi (β Pegasi, abbreviated Beta Peg, β Peg), formally named Scheat /ˈʃiːæt/, [11] [12] 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, [13] a prominent rectangular asterism.
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. [13] In 2016, the International Astronomical Union organised a Working Group on Star Names (WGSN) [14] to catalog and standardise proper names for stars. The WGSN's first bulletin of July 2016 [15] 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 [12]).
In Chinese, 室宿 (Shì Xiù), meaning Encampment, refers to an asterism consisting β Pegasi and α Pegasi. [16] Consequently, the Chinese name for β Pegasi itself is 室宿二 (Shì Xiù èr), "the Second Star of Encampment". [17]
Based upon parallax measurements, Beta Pegasi is located about 196 light-years (60 parsecs) 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, [4] which indicates the spectrum has characteristics partway between a bright giant and a giant star. It has expanded until it is 104 times as large, and has a total luminosity of 1,640 times that of the Sun. [8] The effective temperature of the star's outer envelope is about 3,600 K, [8] giving the star the characteristic orange-red hue of an M-type star. [19] The photosphere is sufficiently cool for molecules of titanium oxide to form. [20]
Beta Pegasi is a semi-regular variable with a period of 43.3 days [5] 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). [21]
Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Pegasus |
Right ascension | 23h 03m 46.45746s [1] |
Declination | +28° 04′ 58.0336″ [1] |
Apparent magnitude (V) | 2.42 [2] (2.31 – 2.74) [3] |
Characteristics | |
Spectral type | M2.5II–IIIe [4] |
U−B color index | +1.96 [2] |
B−V color index | +1.67 [2] |
Variable type | Semi-regular [5] |
Astrometry | |
Radial velocity (Rv) | +8.7 [6] 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] |
Distance | 196 ± 2
ly (60.1 ± 0.5 pc) [1] |
Absolute magnitude (MV) | −1.41 [7] |
Details | |
Mass | 1.7±0.3 [8] M☉ |
Radius | 104 [8] [a] R☉ |
Luminosity | 1,644 [8] [b] L☉ |
Surface gravity (log g) | 1.20 [9] cgs |
Temperature | 3,606 [8] K |
Metallicity [Fe/H] | −0.11 [9] dex |
Rotational velocity (v sin i) | 9.7 [10] km/s |
Other designations | |
Database references | |
SIMBAD | data |
Beta Pegasi (β Pegasi, abbreviated Beta Peg, β Peg), formally named Scheat /ˈʃiːæt/, [11] [12] 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, [13] a prominent rectangular asterism.
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. [13] In 2016, the International Astronomical Union organised a Working Group on Star Names (WGSN) [14] to catalog and standardise proper names for stars. The WGSN's first bulletin of July 2016 [15] 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 [12]).
In Chinese, 室宿 (Shì Xiù), meaning Encampment, refers to an asterism consisting β Pegasi and α Pegasi. [16] Consequently, the Chinese name for β Pegasi itself is 室宿二 (Shì Xiù èr), "the Second Star of Encampment". [17]
Based upon parallax measurements, Beta Pegasi is located about 196 light-years (60 parsecs) 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, [4] which indicates the spectrum has characteristics partway between a bright giant and a giant star. It has expanded until it is 104 times as large, and has a total luminosity of 1,640 times that of the Sun. [8] The effective temperature of the star's outer envelope is about 3,600 K, [8] giving the star the characteristic orange-red hue of an M-type star. [19] The photosphere is sufficiently cool for molecules of titanium oxide to form. [20]
Beta Pegasi is a semi-regular variable with a period of 43.3 days [5] 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). [21]