The HW Virginis system in Celestia. | |
Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Virgo |
Right ascension | 12h 44m 20.2387s [1] |
Declination | −08° 40′ 16.8486″ [1] |
Apparent magnitude (V) | 10.69 [2] |
Characteristics | |
Spectral type | sdB / dM [3] |
Variable type | eclipsing binary |
Astrometry | |
Proper motion (μ) | RA: 8.969±0.175 [1] mas/yr Dec.: −15.677±0.107 [1] mas/yr |
Parallax (π) | 5.7972 ± 0.0849 mas [1] |
Distance | 563 ± 8 ly (172 ± 3 pc) |
Absolute magnitude (MV) | 4.22 (sdB) + 15.59 (dM) [4] |
Absolute bolometric magnitude (Mbol) | 1.46 (sdB) + 11.20 (dM) [4] |
Orbit [4] | |
Period (P) | 0.11671967 d |
Semi-major axis (a) | 0.860 ± 0.010 R☉ |
Eccentricity (e) | <0.0003 |
Inclination (i) | 80.98 ± 0.10° |
Details [4] | |
sdB | |
Mass | 0.485 ± 0.013 M☉ |
Radius | 0.183 ± 0.026 R☉ |
Luminosity | 19.7 ± 5.6 L☉ |
Temperature | 28488 ± 208 K |
dM | |
Mass | 0.142 ± 0.004 M☉ |
Radius | 0.175 ± 0.026 R☉ |
Luminosity | 0.003 ± 0.001 L☉ |
Temperature | 3084 ± 889 K |
Other designations | |
Database references | |
SIMBAD | data |
HW Virginis, abbreviated HW Vir, is an eclipsing binary system (of the Algol type), approximately 563 light-years away based on the parallax measured by the Gaia spacecraft, [1] in the constellation of Virgo. The system comprises an eclipsing B-type subdwarf star and red dwarf star. The two stars orbit each other every 0.116795 days. [6]
Based on variations in the timing of the system's eclipses, in 2008 it was claimed that two giant planets were in orbit around the binary, with masses of 8.47 and 19.2 times the mass of Jupiter orbiting with periods of 9.1 and 15.8 years respectively. [8] The proposed system was later shown to be extremely unstable, with mean lifetimes less than 1000 years in the parameter space allowed by the uncertainties in the data. [9] An alternate, dynamically-stable orbital solution was proposed with a 14.3 Jupiter mass object on a 12-year orbit and an outer companion of 65 Jupiter masses on a 55-year orbit, [10] however it has been noted that the outer companion's orbital parameters are highly unconstrained, again casting doubt on the reality of this model. [9] The problems with modelling this system and the proposed planets orbiting several other post-common envelope binaries has led to the suggestion that the eclipse timing variations used to infer the existence of planets has a non-planetary origin. [11] The eclipse timing variations of HW Virginis were shown to be incompatible with all previous planetary system models as of 2018, [12] and again in 2021. [4] However, eclipse timing variations cannot be explained by known stellar mechanisms either. [4] There is tentative evidence for the presence of a planet from astrometric measurements, [13] with future data releases of the Gaia spacecraft [1] being predicted to be able to fully confirm this.
70 Virginis is a binary star located 59 light years from the Sun in the equatorial constellation of Virgo, near the northern constellation border with Coma Berenices. 70 Virginis is its Flamsteed designation. The star is visible to the naked eye as a faint, yellow-hued point of light with an apparent visual magnitude of +4.97. It is drifting further away with a heliocentric radial velocity of +4.4 km/s and has a high proper motion, traversing the celestial sphere at the rate of 0.621 arc seconds per annum.
Chi Virginis is a double star in the constellation Virgo. Based upon parallax measurements, it is approximately 315 light-years from Earth. It has an apparent visual magnitude of 4.65, which is bright enough to be seen with the unaided eye under suitable viewing conditions.
Omega Virginis is a solitary star in the zodiac constellation Virgo. It has an apparent visual magnitude of +5.2, which is bright enough to be faintly visible to the naked eye. Based upon an annual stellar parallax shift of 6.56 milliarcseconds, it is located about 500 light years from the Sun.
DT Virginis, also known as Ross 458, is a binary star system in the constellation of Virgo. It has an apparent visual magnitude of 9.79 and is located at a distance of 37.6 light-years from the Sun. Both of the stars are low-mass red dwarfs with at least one of them being a flare star. This binary system has a circumbinary sub-stellar companion.
CM Draconis is an eclipsing binary star system 48.5 light-years away in the constellation of Draco. The system consists of two nearly identical red dwarf stars that orbit each other with a period of 1.268 days and a separation of 2.6 million kilometres. Along with two stars in the triple system KOI-126, the stars in CM Draconis are among the lightest stars with precisely measured masses and radii. Consequently, the system plays an important role in testing stellar structure models for very low mass stars. These comparisons find that models underpredict the stellar radii by approximately 5%. This is attributed to consequences of the stars' strong magnetic activity.
A circumbinary planet is a planet that orbits two stars instead of one. The two stars orbit each other in a binary system, while the planet typically orbits farther from the center of the system than either of the two stars. In contrast, circumstellar planets in a binary system have stable orbits around one of the two stars, closer in than the orbital distance of the other star. Studies in 2013 showed that there is a strong hint that a circumbinary planet and its stars originate from a single disk.
NN Serpentis is an eclipsing post-common envelope binary system approximately 1670 light-years away. The system comprises an eclipsing white dwarf and red dwarf. The two stars orbit each other every 0.13 days.
QS Virginis is an eclipsing binary system approximately 163 light-years away from the Sun, forming a cataclysmic variable. The system comprises an eclipsing white dwarf and red dwarf that orbit each other every 3.37 hours.
HU Aquarii is an eclipsing binary system approximately 620 light-years away from the Sun, forming a cataclysmic variable of AM Herculis-type. The two stars orbit each other every 2.08 hours and the ultra-short binary system includes an eclipsing white dwarf and red dwarf.
Kepler-34 is an eclipsing binary star system in the constellation of Cygnus. Both stars have roughly the same mass as the Sun and, like the Sun, both are spectral class G. They are separated by 0.22 AU, and complete an eccentric (e=0.5) orbit around a common center of mass every 27 days.
Kepler-35 is a binary star system in the constellation of Cygnus. These stars, called Kepler-35A and Kepler-35B have masses of 89% and 81% solar masses respectively, and both are assumed to be of spectral class G. They are separated by 0.176 AU, and complete an eccentric orbit around a common center of mass every 20.73 days.
RR Caeli is an eclipsing binary star system, located 69 light-years from Earth in the constellation Caelum. It is made up of a red dwarf star and a white dwarf, which complete an orbit around each other every seven hours. There is evidence of two circumbinary planets orbiting even further away.
Kepler-451 is an eclipsing post-common envelope binary star system that comprises two stars, a pulsating subdwarf B star and a small red dwarf star. It is located about 1,340 light-years away in the constellation Cygnus. It has been hypothesized to host one or more exoplanets.
NSVS 14256825, also known as V1828 Aquilae, is an eclipsing binary system in the constellation of Aquila. The system comprises a subdwarf OB star and red dwarf star. The two stars orbit each other every 2.648976 hours. Based on the stellar parallax of the system, observed by Gaia, the system is located approximately 2,700 light-years away.
TOI-1338 is a binary star system located in the constellation Pictor, about 1,320 light-years from Earth. It is orbited by two known circumbinary planets, TOI-1338 b, discovered by the Transiting Exoplanet Survey Satellite (TESS) and BEBOP-1c, discovered by the Binaries Escorted By Orbiting Planets project.
NY Virginis is a binary star about 1,940 light-years away. The primary belongs to the rare class of subdwarf B stars, being former red giants with their hydrogen envelope completely stripped by a stellar companion. The companion is a red dwarf star. The binary nature of NY Virginis was first identified in 1998, and the extremely short orbital period of 0.101016 d, together with brightness variability on the timescale of 200 seconds was noticed, resulting in the identification of the primary star as a B-type subdwarf in 2003. Under a proposed classification scheme for hot subdwarfs it would be class sdB1VII:He1. This non-standard system indicates that it is a "normal" luminosity for a hot subdwarf and that the spectrum is dominated by hydrogen rather than helium.
AG Virginis is an eclipsing binary star system in the equatorial constellation of Virgo. With a maximum apparent visual magnitude of 8.51 it is too faint to be visible to the naked eye. The system is located at a distance of approximately 820 light years from the Sun based on parallax measurements.
BH Virginis is a binary star system in the equatorial constellation of Virgo. With a typical apparent visual magnitude of 9.6, it is too faint to be visible to the naked eye. Based on parallax measurements, it is located at a distance of approximately 488 light years from the Sun. The system is drifting closer with a net radial velocity of −23 km/s.
GG Carinae is a binary star system in the southern constellation of Carina, abbreviated GG Car. It is a variable star with a brightness that fluctuates around an apparent visual magnitude of 8.67, making it too faint to be visible to the naked eye. The distance to this system is approximately 8,000 light years based on parallax measurements.
AH Virginis is a contact binary star system in the equatorial constellation of Virgo, abbreviated AH Vir. It is a variable star with a brightness that peaks at an apparent visual magnitude of 9.18, making it too faint to be viewed with the naked eye. The distance to this system is approximately 338 light years based on parallax measurements, and it is drifting further away with a mean radial velocity of 7 km/s. O. J. Eggen in 1969 included this system as a probable member of the Wolf 630 group of co-moving stars.