IM Pegasi

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IM Pegasi
Pegasus constellation map.svg
Red circle.svg
Location of IM Pegasi (circled)
Observation data
Epoch J2000.0       Equinox J2000.0
Constellation Pegasus
Right ascension 22h 53m 02.26608s [1]
Declination +16° 50′ 28.2969″ [1]
Apparent magnitude  (V)5.55 [2] (5.60 – 5.85 [3] )
Characteristics
Spectral type K2 III + dG [4]
Variable type RS CVn [3]
Astrometry
Radial velocity (Rv)−14.43 [5]  km/s
Proper motion (μ)RA: −20.73 [1]   mas/yr
Dec.: −27.75 [1]   mas/yr
Parallax (π)11.17 ± 0.33  mas [1]
Distance 292 ± 9  ly
(90 ± 3  pc)
Orbit [2]
Period (P)24.64877±0.00003 d
Eccentricity (e)0.00
Inclination (i)65° ≤ i ≤ 80°°
Semi-amplitude (K1)
(primary)		34.29±0.04 km/s
Semi-amplitude (K2)
(secondary)		62.31±0.06 km/s
Details [4]
primary
Mass 1.8 ± 0.2  M☉
Radius 13.3 ± 0.6  R☉
Luminosity 54 ± 9  L☉
Temperature 4,550 ± 50  K
Rotation 24.4936 days
secondary
Mass 1.0 ± 0.07  M☉
Radius 1.00  R☉
Luminosity0.9 ± 0.3  L☉
Temperature 5,650 ± 200  K
Other designations
IM  Peg, HD  216489, HIP  112997, HR  8703, SAO  108231
Database references
SIMBAD data

IM Pegasi is a variable binary star system approximately 329 light-years away in the constellation of Pegasus. With an apparent magnitude of 5.7, it is visible to the naked eye. Increased public awareness of it is due to its use as the guide star for the Gravity Probe B general relativity experiment. It was chosen for this purpose because its microwave radio emissions are observable with a large radio telescope network on the ground in such a manner that its precise position can be related by interferometry to distant quasars. [6]

The two components of the binary system includes a K-type giant star and a G-type main sequence star. The primary star is estimated to be 1.8 times as massive and 13 times the diameter of the Sun. The secondary star is estimated to be similar to the Sun in size and mass. They orbit their common barycenter in a period precisely estimated to be 24.64877 days.

A visual band light curve for IM Pegasi, adapted from Eaton et al. (1983) IMPegLightCurve.png
A visual band light curve for IM Pegasi, adapted from Eaton et al. (1983)

The variability of IM Pegasi is due to the active chromosphere of the giant primary star, which causes brightness changes of a few tenths of a magnitude as it rotates.

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

II Pegasi is a binary star system in the constellation of Pegasus with an apparent magnitude of 7.4 and a distance of 130 light-years. It is a very active RS Canum Venaticorum variable, a close binary system with active starspots.

<span class="mw-page-title-main">HR 2554</span> Star in the constellation Carina

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<span class="mw-page-title-main">EZ Canis Majoris</span> Binary star system in the constellation Canis Major

EZ Canis Majoris is binary system in the constellation of Canis Major. The primary is a Wolf-Rayet star and it is one of the ten brightest Wolf-Rayet stars, brighter than apparent magnitude 7.

<span class="mw-page-title-main">AO Cassiopeiae</span> Star system in the constellation Cassiopeia

AO Cassiopeiae, also known as Pearce's Star, is a binary system composed of an O8 main sequence star and an O9.2 bright giant that respectively weigh anywhere between 20.30 and 57.75 times and 14.8 and 31.73 times the mass of the Sun.

<span class="mw-page-title-main">U Aquilae</span> Variable binary star system in the constellation Aquila

U Aquilae is a binary star system in the constellation Aquila, Located approximately 614 parsecs (2,000 ly) away from Earth.

<span class="mw-page-title-main">LY Aurigae</span> Binary star in the constellation Auriga

LY Aurigae is a multiple star system in the constellation Auriga. It is an eclipsing binary variable star, dropping in brightness by 0.7 magnitudes every 4 days. The system is around a thousand light years away in the Auriga OB1 stellar association.

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

LL Pegasi is a Mira variable star surrounded by a pinwheel-shaped nebula, IRAS 23166+1655, thought to be a preplanetary nebula. It is a binary system that includes an extreme carbon star. The pair is hidden by the dust cloud ejected from the carbon star and is only visible in infrared light.

<span class="mw-page-title-main">89 Herculis</span> Star in the constellation Hercules

89 Herculis is a binary star system located about 4,700 light years away from the Sun in the northern constellation of Hercules. It is visible to the naked eye as a faint, fifth magnitude star. The system is moving closer to the Earth with a heliocentric radial velocity of −28.5 km/s.

<span class="mw-page-title-main">Tau Persei</span> Star in the constellation Perseus

Tau Persei, also known as 18 Persei, is a binary star in the constellation of Perseus. The system is fairly close, and is located about 254 light-years away, based on its parallax.

<span class="mw-page-title-main">9 Pegasi</span> Star in the constellation Pegasus

9 Pegasi is a supergiant star in the constellation Pegasus. Its apparent magnitude is 4.35.

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

Psi Pegasi, which is Latinized from ψ Pegasi, is a binary star system within the great square in the northern constellation of Pegasus. It has a red hue and is faintly visible to the naked eye with an apparent visual magnitude of 4.66. This object is located at a distance of approximately 476 light-years away from the Sun based on parallax, but is drifting closer with a radial velocity of −6.6 km/s.

<span class="mw-page-title-main">72 Pegasi</span> Binary star system in the constellation Pegasus

72 Pegasi is a binary star system in the northern constellation of Pegasus. It is visible to the naked eye as a faint, orange-hued point of light with a combined apparent visual magnitude of 4.97. The system is located approximately 550 light years away from the Sun, based on parallax, but is drifting closer with a radial velocity of −25 km/s.

<span class="mw-page-title-main">KQ Puppis</span> Binary star in the constellation Puppis

KQ Puppis is a spectroscopic binary located about 2,700 light-years from Earth in the constellation Puppis. A red supergiant star and a B-type main-sequence star orbit each other every 27 years. Its apparent magnitude varies between 4.82 and 5.17, making it faintly visible to the naked eye.

<span class="mw-page-title-main">42 Persei</span> Binary star system in the constellation Perseus

42 Persei is a binary star system in the northern constellation of Perseus. It has the Bayer designation n Persei, while 42 Persei is the Flamsteed designation. The system is visible to the naked eye as a dim, white-hued point of light with an apparent visual magnitude of 5.11. It is located around 93 parsecs (302 ly) distant from the Sun, but is drifting closer with a radial velocity of −12.4 km/s.

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

AG Pegasi is a symbiotic binary star in the constellation Pegasus. It is a close binary composed of a red giant and white dwarf, estimated to be around 2.5 and 0.6 times the mass of the Sun respectively. It is classified as a symbiotic nova; it has undergone one extremely slow nova outburst and a smaller outburst.

<span class="mw-page-title-main">ZZ Boötis</span>

ZZ Boötis is a star system in the constellation Boötes. It varies from magnitude 6.79 to 7.44 over five days. Based on its parallax, measured by the Gaia spacecraft, it is about 350 light-years away.

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">WR 12</span> Star in the constellation Vela

WR 12 is a spectroscopic binary in the constellation Vela. It is an eclipsing binary consisting of a Wolf-Rayet star and a luminous companion of unknown spectral type. The primary is one of the most luminous stars known.

References

  1. 1 2 3 4 5 Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv: 0708.1752 . Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID   18759600.
  2. 1 2 Berdyugina, S. V.; Ilyin, I.; Tuominen, I. (1999). "The long-period RS Canum Venaticorum binary IM Pegasi. I. Orbital and stellar parameters". Astronomy and Astrophysics. 347: 932. Bibcode:1999A&A...347..932B.
  3. 1 2 Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S.
  4. 1 2 Zellem, Robert; Guinan, Edward F.; Messina, Sergio; Lanza, Antonino F.; Wasatonic, Richard; McCook, George P. (2010). "Multiband Photometry of the Chromospherically Active & Spotted Binary System IM Peg-the Guide Star for the Gravity Probe B Mission". The Publications of the Astronomical Society of the Pacific. 122 (892): 670. Bibcode:2010PASP..122..670Z. doi: 10.1086/653711 .
  5. ↑ Karataș, Yüksel; Bilir, Selçuk; Eker, Zeki; Demircan, Osman; Liebert, James; Hawley, Suzanne L.; Fraser, Oliver J.; Covey, Kevin R.; Lowrance, Patrick; Kirkpatrick, J. Davy; Burgasser, Adam J. (2004). "Kinematics of chromospherically active binaries and evidence of an orbital period decrease in binary evolution". Monthly Notices of the Royal Astronomical Society. 349 (3): 1069–1092. arXiv: astro-ph/0404219 . Bibcode:2004MNRAS.349.1069K. doi: 10.1111/j.1365-2966.2004.07588.x . S2CID   15290475.
  6. ↑ Shapiro, I. I.; Bartel, N.; Bietenholz, M. F.; Lebach, D. E.; Lestrade, J.-F.; Ransom, R. R.; Ratner, M. I. (2012). "VLBI for Gravity Probe B. I. Overview". The Astrophysical Journal Supplement. 201 (1): 1. arXiv: 1204.4630 . Bibcode:2012ApJS..201....1S. doi:10.1088/0067-0049/201/1/1. S2CID   51776288.
  7. ↑ Eaton, J. A.; Hall, D. S.; Henry, G. W.; Lovell, L. P.; Stephan, C. A.; Chambliss, C. R.; Detterline, P. K.; Landis, H. J.; Louth, H.; Renner, T. R.; Skillman, D. R. (January 1983). "Three Years of Photometry of IM-Pegasi = HR8703". Astrophysics and Space Science. 89 (1): 53–60. Bibcode:1983Ap&SS..89...53E. doi:10.1007/BF01008384. S2CID   122572493 . Retrieved 12 February 2022.
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