Gamma Pegasi

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"Algenib" redirects here. For the another star named Algenib, see Alpha Persei.
Gamma Pegasi
Location of γ Pegasi (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Pegasus
Right ascension 00h 13m 14.15123s[1]
Declination +15° 11′ 00.9368″[1]
Apparent magnitude (V) +2.78 to 2.89[2]
Characteristics
Spectral type B2 IV[3]
U−B color index −0.85[4]
B−V color index −0.23[4]
Variable type β Cep[5]
Distance
470 ± 30 ly
(144 ± 9 pc)
Absolute magnitude (MV)−2.64[8]
Details
Myr
HR 39, SAO 91781[13]
Database references
SIMBADdata

Gamma Pegasi is a

apparent visual magnitude of +2.84[4] makes this the fourth-brightest star in the constellation. The distance to this star has been measured using the parallax technique, yielding a value of roughly 470 light-years (144 parsecs
).

Nomenclature

Gamma Pegasi is the star's Bayer designation. Although it also had the traditional name Algenib, this name was also used for Alpha Persei. In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[16] to catalog and standardize 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 Algenib for this star (Alpha Persei was given the name Mirfak).

The asterism of γ Pegasi and

Chinese name for γ Pegasi itself is 壁宿一 (Bìxiù yī, English: the First Star of Wall.)[19]

Properties

A light curve for Gamma Pegasi, plotted from TESS data[20]

In 1911, American astronomer

hybrid pulsator.[22] Its magnitude varies between +2.78 and +2.89 over the course of each pulsation cycle.[2]

This is a large star with almost nine

subgiant star that is exhausting the hydrogen at its core and is in the process of evolving away from the main sequence. It is either rotating very slowly with no measurable rotational velocity or else it is being viewed from nearly pole-on.[12] Gamma Pegasi has a total luminosity of 5,840 times that of the Sun,[10] which is being radiated from its outer atmosphere at an effective temperature of more than 21,000 K.[9] At this temperature, the star glows with a blue-white hue.[23]

The star has a weak magnetic field (from -10 G to 30 G,[24] an upper bound on a dipolar magnetic field strength of about 40 G[25]).

References

  1. ^
    S2CID 18759600
  2. ^
    S2CID 125853869
    .
  3. ^
    S2CID 118629873
  4. ^
    doi:10.1086/111220
  5. ^
    S2CID 119218384
  6. Bibcode:1953GCRV..C......0W
  7. doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR
    .
  8. S2CID 119286159
    .
  9. ^
    S2CID 119512018
  10. ^
    S2CID 111387483
  11. doi:10.1086/171116
  12. ^
    doi:10.1086/340590
    . The zero value is for v sin i, so v and/or i must be small.
  13. ^ "gam Peg". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2012-02-23.
  14. ISBN 978-1-931559-44-7
    .
  15. ^ "IAU Catalog of Star Names". Retrieved 28 July 2016.
  16. ^ "IAU Working Group on Star Names (WGSN)". Retrieved 22 May 2016.
  17. ^ "Bulletin of the IAU Working Group on Star Names, No. 1" (PDF). Retrieved 28 July 2016.
  18. ISBN 978-986-7332-25-7
    .
  19. ^ (in Chinese) 香港太空館 – 研究資源 – 亮星中英對照表 Archived October 25, 2008, at the Wayback Machine, Hong Kong Space Museum. Accessed on line November 23, 2010.
  20. ^ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 8 December 2021.
  21. doi:10.1086/126561
  22. doi:10.1088/0004-637X/698/1/L56
  23. Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived from the original
    on 2012-03-18, retrieved 2012-01-16
  24. doi:10.1051/0004-6361:20065563
    . We have detected the presence of a weak magnetic field on the star. The longitudinal component of the field varies from -10 G to 30 G with the stellar rotation. The most probable rotational period is P_rot = 6.6538 ± 0.0016 days. Both the orbital and the rotational periods are integral multiples of the difference between them: P_orb/|P_orb - P_rot| = 42.002, and P_rot/|P_orb - P_rot| = 41.002. Variation in the longitudinal magnetic field during the pulsation period with an amplitude about 7 G was detected.
  25. S2CID 54652836
    , A59, We find that no magnetic signatures are visible in the very high quality spectropolarimetric data. The average longitudinal field measured in the Narval data is Bl = −0.1 ± 0.4 G. We derive a very strict upper limit of the dipolar field strength of Bpol ~ 40 G.

External links
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