LO Pegasi

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LO Pegasi
LOPegLightCurve.png
A visual band light curve for LO Pegasi. The main plot (adapted from Karmakar et al. [1] ) shows the long-term variability. Inset plot "A" (adapted from Kiraga [2] ) shows the periodic variability, and inset "B" (also adapted from Karmakar et al. [1] ) shows a flare.
Observation data
Epoch J2000.0       Equinox J2000.0
Constellation Pegasus
Right ascension 21h 31m 01.714s [3]
Declination 23° 20′ 07.37″ [3]
Apparent magnitude  (V)9.23 [4] (9.04 to 9.27) [5]
Characteristics
Spectral type K3Vke [6]
B−V color index 1.050±0.015 [4]
Variable type BY Dra [5]
Astrometry
Radial velocity (Rv)−23.36±1.75 [7]  km/s
Proper motion (μ)RA: 134.654  mas/yr [3]
Dec.: −144.889  mas/yr [3]
Parallax (π)41.2912 ± 0.0169  mas [3]
Distance 78.99 ± 0.03  ly
(24.218 ± 0.010  pc)
Absolute magnitude  (MV)7.26 [4]
Details [8]
Mass 0.66±0.02  M☉
Radius 0.72±0.10  R☉
Luminosity 0.25±0.02  L☉
Surface gravity (log g)4.5±0.5  cgs
Temperature 4,750±250  K
Rotation 0.4236 d [9]
Rotational velocity (v sin i)48.2±2.5 [10]  km/s
Age 10–300 [11]   Myr
Other designations
LO Peg, AG+23 2203, BD+22 4409, GJ  4199, HIP  106231, WDS J21310+2320A [12]
Database references
SIMBAD data

LO Pegasi is a single star [13] in the northern constellation of Pegasus that has been the subject of numerous scientific studies. [14] LO Pegasi, abbreviated LO Peg, is the variable star designation. It is too faint to be viewed with the naked eye, having an apparent visual magnitude that ranges from 9.04 down to 9.27. [5] Based on parallax measurements, LO Peg is located at a distance of 79  light years from the Sun. It is a member of the young AB Doradus moving group, [13] [11] and is drifting closer with a radial velocity of −23 km/s. [7]

Contents

This is a K-type main-sequence star with a stellar classification of K3Vke, [6] where the 'k' suffix indicates interstellar absorption lines and 'e' means there are emission lines in the spectrum. It became of interest to astronomers when significant X-ray emission was detected from this star in 1994. R. D. Jeffries and associates reported flare activity based on a rotationally-broadened hydrogen α emission line and found the star varied in brightness. [15]

LO Peg is an ultrafast rotator, completing a full rotation every 10.15 hours. [16] It is classified as a BY Draconis variable that is magnetically active and has star spots. The combination of non-uniform surface brightness and rotation makes it appear to vary in luminosity. [5] Up to 25.7% of the surface is covered in spots. Long term changes in periodicity suggest activity cycles, similar to the solar cycle, [1] with periods of approximately 3 and 7.4 years. [11] The element lithium has been detected in its atmosphere, whose abundance, in combination with the star's rapid rotation, indicates this is a young star with an age of no more than a few hundred million years. [15]

See also

Related Research Articles

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<span class="mw-page-title-main">Alpha Pegasi</span> Star in the constellation Pegasus

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<span class="mw-page-title-main">Gamma Pegasi</span> Variable B-type star in the constellation Pegasus

Gamma Pegasi is a star in the constellation of Pegasus, located at the southeast corner of the asterism known as the Great Square. It has the formal name Algenib ; the Bayer designation Gamma Pegasi is Latinized from γ Pegasi and abbreviated Gamma Peg or γ Peg. The average apparent visual magnitude of +2.84 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.

<span class="mw-page-title-main">Mu Pegasi</span> Star in the constellation Pegasus

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<span class="mw-page-title-main">Eta Pegasi</span> Binary star in the constellation Pegasus

Eta Pegasi or η Pegasi, formally named Matar, is a binary star in the constellation of Pegasus. The apparent visual magnitude of this star is +2.95, making it the fifth-brightest member of Pegasus. Based upon parallax measurements, the distance to this star is about 214 light-years from the Sun.

<span class="mw-page-title-main">1 Camelopardalis</span> Double star system in the constellation Camelopardalis

1 Camelopardalis is a double star system in the constellation Camelopardalis. Its combined apparent magnitude is 5.56 and it is approximately 800 parsecs (2,600 ly) away.

Pi<sup>2</sup> Pegasi Single star in the constellation Pegasus

π2 Pegasi, Latinized as Pi2 Pegasi, is a single star in the northern constellation Pegasus. It is yellow-white in hue and visible to the naked eye as a faint point of light with an apparent visual magnitude of +4.28. The distance to this object is approximately 263 light years based on parallax, and it is drifting further away with a radial velocity of +5 km/s. This star is an outlying member of the Ursa Major Moving Group.

<span class="mw-page-title-main">Upsilon Pegasi</span> Aging giant star in the constellation Pegasus

Upsilon Pegasi, Latinised from υ Pegasi, is a star within the great square in the northern constellation of Pegasus. It has the proper name Alkarab. This object has a yellow-white hue and is faintly visible to the naked eye with an apparent magnitude of 4.40. It is located at a distance of approximately 170 light-years from the Sun based on parallax, but is drifting closer with a radial velocity of −8.6 km/s. The star is moving through the galaxy at a speed of 50.6 km/s relative to the Sun. Its projected galactic orbit carries it between 18,600 and 26,300 light-years from the center of the galaxy.

<span class="mw-page-title-main">55 Pegasi</span> Star in the constellation of Pegasus

55 Pegasi is a single star in the northern constellation of Pegasus. It is visible to the naked eye as a faint, reddish-hued point of light with a baseline apparent visual magnitude of 4.51. The star is located approximately 302 light years away from the Sun based on parallax, but it is moving closer with a radial velocity of −5 km/s.

<span class="mw-page-title-main">56 Pegasi</span> Star in the constellation Pegasus

56 Pegasi is a binary star system in the northern constellation of Pegasus. It is visible to the naked eye with a combined apparent visual magnitude of 4.74. The system is approximately 590 light years away from the Sun based on parallax, but is drifting closer with a radial velocity of −28 km/s. It is listed as a member of the Wolf 630 moving group.

<span class="mw-page-title-main">35 Pegasi</span> Star in the constellation of Pegasus

35 Pegasi is a single star in the northern constellation of Pegasus. It is visible to the naked eye as a faint, orange-hued point of light with an apparent visual magnitude of 4.80. The star is located approximately 155 light years away from the Sun based on parallax, and is drifting further away with a radial velocity of +54 km/s. The star has a relatively high proper motion, traversing the celestial sphere at the rate of 0.318 arc seconds per annum.

<span class="mw-page-title-main">Chi Pegasi</span> Red giant star in the constellation Pegasus

Chi Pegasi, Latinised from χ Pegasi, is a single star in the northern constellation of Pegasus, along the eastern constellation border with Pisces. It has a reddish hue and is faintly visible to the naked eye with an apparent visual magnitude of 4.80. The distance to this star is approximately 368 light-years based on parallax, but it is drifting closer with a radial velocity of −46 km/s.

<span class="mw-page-title-main">Nu Pegasi</span> Star in the constellation Pegasus

ν Pegasi, Latinized as Nu Pegasi is a single star in the northern constellation of Pegasus. It is an orange-hued star that is faintly visible to the naked eye with an apparent visual magnitude of 4.84. The star is located approximately 261 light years away based on parallax, but is drifting closer with a radial velocity of −19 km/s.

<span class="mw-page-title-main">Rho Pegasi</span> Star in the constellation Pegasus

Rho Pegasi, Latinized from ρ Pegasi, is a star in the northern constellation of Pegasus, near the southern constellation boundary with Pisces. This is a probable astrometric binary system, as determined by changes to the proper motion of the visible component. It has a white hue and is faintly visible to the naked eye with an apparent visual magnitude of 4.90. The system is located at a distance of approximately 274 light years from the Sun based on parallax, but it is drifting closer with a radial velocity of −10.6 km/s.

33 Pegasi is the Flamsteed designation for a visual binary star in the northern constellation of Pegasus. It has an apparent visual magnitude of 6.2, placing it near the limit of naked eye visibility. Measurements show an annual parallax shift of 0.0298125″, which is equivalent to a distance of 109 ly (33 pc) from the Sun. It is drifting further away with a radial velocity of 24 km/s.

<span class="mw-page-title-main">Phi Pegasi</span> Variable star in the constellation Pegasus

φ Pegasi, Latinised as Phi Pegasi, is a solitary, reddish hued star in the northern constellation of Pegasus. With an apparent visual magnitude of around 5.1, it is a faint star that can be seen with the naked eye. Based upon an annual parallax shift of 7.05 mas as seen from Earth, the system is located around 460 light years distant from the Sun. At that distance, the visual magnitude of the star is diminished by an extinction factor of 0.15 due to interstellar dust.

EQ Pegasi is a nearby binary system of two red dwarfs. Both components are flare stars, with spectral types of M4Ve and M6Ve respectively, and a current separation between the components of 5.8 arcseconds. The system is at a distance of 20.4 light-years, and is 950 million years old. The primary star is orbited by one known exoplanet.

<span class="mw-page-title-main">HN Pegasi</span> Star in the constellation Pegasus

HN Pegasi is the variable star designation for a young, Sun-like star in the northern constellation of Pegasus. It has an apparent visual magnitude of 5.9, which, according to the Bortle scale, indicates that it is visible to the naked eye from suburban skies. Parallax measurements put the star at a distance of around 59 light years from the Sun, but it is drifting closer with a radial velocity of −16.7 km/s.

<span class="mw-page-title-main">MT Pegasi</span> Star in the constellation Pegasus

MT Pegasi is a single, yellow-hued star in the northern constellation of Pegasus. It has the designation HD 217813 in the Henry Draper Catalogue; MT Pegasi is the variable star designation. With an apparent visual magnitude of 6.616, it is a dim star that is at or below the nominal limit for visibility with the naked eye. Based upon an annual parallax shift of 41.16 mas as measured from Earth's orbit, it is located 79.24 light years away. This star is a member of the Ursa Major Moving Group, a collection of stars that originated in the same open cluster and now share a common motion through space.

<span class="mw-page-title-main">57 Pegasi</span> Binary star in the constellation Pegasus

57 Pegasi is a variable binary star system in the northern constellation of Pegasus (constellation). It has the variable star designation GZ Pegasi, while 57 Pegasi is the Flamsteed designation. The system is faintly visible to the naked eye as a point of light with an apparent visual magnitude that fluctuates around 5.105. It is located at a distance of approximately 780 light years from the Sun based on parallax, and is drifting further away with a radial velocity of +14 km/s.

References

  1. 1 2 3 Karmakar, Subhajeet; et al. (July 2016), "LO Peg: surface differential rotation, flares, and spot-topographic evolution", Monthly Notices of the Royal Astronomical Society, 459 (3): 3112–3129, arXiv: 1608.06522 , Bibcode:2016MNRAS.459.3112K, doi: 10.1093/mnras/stw855 .
  2. ↑ Kiraga, M. (2012), "ASAS photometry of ROSAT sources I. Periodic variable stars coincident with bright sources from ROSAT all sky survey", Acta Astronomica, 62 (1): 67, arXiv: 1204.3825 , Bibcode:2012AcA....62...67K
  3. 1 2 3 4 5 Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics . 649: A1. arXiv: 2012.01533 . Bibcode:2021A&A...649A...1G. doi: 10.1051/0004-6361/202039657 . S2CID   227254300. (Erratum:  doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
  4. 1 2 3 Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv: 1108.4971 , Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID   119257644.
  5. 1 2 3 4 Samus', N. N; et al. (2017), "General catalogue of variable stars", Astronomy Reports, GCVS 5.1, 61 (1): 80, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID   125853869.
  6. 1 2 Gray, R. O.; et al. (2003), "Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 Parsecs: The Northern Sample. I", The Astronomical Journal, 126 (4): 2048, arXiv: astro-ph/0308182 , Bibcode:2003AJ....126.2048G, doi:10.1086/378365, S2CID   119417105.
  7. 1 2 Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics . 616. A1. arXiv: 1804.09365 . Bibcode: 2018A&A...616A...1G . doi: 10.1051/0004-6361/201833051 . Gaia DR2 record for this source at VizieR.
  8. ↑ Pandey, J. C.; et al. (September 2005), "Optical and X-Ray Studies of Chromospherically Active Stars: FR Cancri, HD 95559, and LO Pegasi", The Astronomical Journal, 130 (3): 1231–1246, arXiv: astro-ph/0506010 , Bibcode:2005AJ....130.1231P, doi:10.1086/432539, S2CID   119357548.
  9. ↑ Strassmeier, Klaus G. (September 2009), "Starspots", The Astronomy and Astrophysics Review, 17 (3): 251–308, Bibcode:2009A&ARv..17..251S, doi: 10.1007/s00159-009-0020-6 .
  10. ↑ Frasca, A.; et al. (May 1, 2018), "A spectroscopic survey of the youngest field stars in the solar neighborhood . II. The optically faint sample", Astronomy and Astrophysics, 612: A96, arXiv: 1801.00671 , Bibcode:2018A&A...612A..96F, doi:10.1051/0004-6361/201732028, S2CID   119537437.
  11. 1 2 3 Savanov, I. S.; et al. (September 2016), "Photometric Observations of LO Peg in 2014-2015", Acta Astronomica, 66 (3): 381–390, Bibcode:2016AcA....66..381S.
  12. ↑ "LO Peg", SIMBAD , Centre de données astronomiques de Strasbourg , retrieved 2022-03-28.
  13. 1 2 Azulay, R.; et al. (June 2017), "Young, active radio stars in the AB Doradus moving group", Astronomy & Astrophysics, 602: 15, arXiv: 1703.08877 , Bibcode:2017A&A...602A..57A, doi:10.1051/0004-6361/201629899, S2CID   73553147, A57.
  14. ↑ Savanov, I.; et al. (May 2019), "Activity of rapidly rotating dwarf LO Peg an [sic] giant FK Com", Contributions of the Astronomical Observatory Skalnaté Pleso, 49 (2): 415–419, Bibcode:2019CoSka..49..415S.
  15. 1 2 Jeffries, R. D.; et al. (September 1994), "BD +22 4409 : a rapidly rotating, low-mass member of the Local Association", Monthly Notices of the Royal Astronomical Society, 270: 153–172, Bibcode:1994MNRAS.270..153J, doi: 10.1093/mnras/270.1.153 .
  16. ↑ Lalitha, S.; et al. (February 10, 2017), "Structure and variability in the corona of the ultrafast rotator LO Pegasi", Astronomy & Astrophysics, 602: 11, arXiv: 1702.03158 , Bibcode:2017A&A...602A..26L, doi:10.1051/0004-6361/201629482, S2CID   55929044, A26.

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