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 [1] mas |
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☉ |
Luminosity | 0.9 ± 0.3 L☉ |
Temperature | 5,650 ± 200 K |
Other designations | |
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.
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.
Xi Ursae Majoris, also named Alula Australis, is a star system in the constellation of Ursa Major. On 2 May 1780, Sir William Herschel discovered that this was a binary star system, making it the first such system ever discovered. It was the first visual double star for which an orbit was calculated, when it was computed by Félix Savary in 1828. It is also a variable star with a small amplitude. Xi Ursae Majoris is found in the left hind paw of the Great Bear.
RT Aurigae is a yellow supergiant variable star in the constellation Auriga, about 1,500 light years from Earth.
Y Carinae is a Classical Cepheid variable, a type of variable star, in the constellation Carina. Its apparent magnitude varies from 7.53 to 8.48.
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.
HR 2554, also known as V415 Carinae and A Carinae, is an eclipsing spectroscopic binary of the Algol type in the constellation of Carina whose apparent visual magnitude varies by 0.06 magnitude and is approximately 4.39 at maximum brightness. Its primary is a G-type bright giant star and its secondary is an A-type main-sequence star. It is approximately 553 light-years from Earth.
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.
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.
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.
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.
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.
KQ Puppis is a spectroscopic binary variable star in the constellation Puppis. A red supergiant star and a hot main sequence star orbit each other every 9,742 days. Its apparent magnitude varies between 4.82 and 5.17.
S Muscae is a classical (δ) Cepheid variable star in the constellation Musca about 2,600 light years away.
W Cygni is a semi-regular variable star in the constellation Cygnus, located 570 light-years from Earth. It lies less than half a degree southeast of ρ Cygni. W Cygni is, at times, a naked-eye star but it was not given a Bayer or Flamsteed designation. It has been proposed as a binary star system with a hotter main sequence companion, but this has not been confirmed.
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.
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.
CD Crucis, also known as HD 311884, is an eclipsing binary star system in the constellation Crux. It is around 14,000 light years away near the faint open cluster Hogg 15. The binary contains a Wolf–Rayet star and is also known as WR 47.
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 made by the Hipparcos spacecraft put the star at a distance of around 58 light years.
WR 140 is a visually moderately bright Wolf-Rayet star placed within the spectroscopic binary star, SBC9 1232, whose primary star is an evolved spectral class O4-5 star. It is located in the constellation of Cygnus, lying in the sky at the centre of the triangle formed by Deneb, γ Cygni and δ Cygni.
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.