Light curves for GT Muscae. The upper panel (adapted from Murdoch et al. [1] ) shows the long-term variability after a model of the eclipsing binary variability has been removed. The orbital period of HD 101379 is shown in red. The lower panel shows TESS data, [2] in which the eclipses (both primary and secondary) are clearly visible. The orbital period of HD 101380 is shown in red. | |
Observation data Epoch J2000.0 Equinox J2000.0 | |
---|---|
Constellation | Musca |
Right ascension | 11h 39m 29.56610s [3] |
Declination | −65° 23′ 52.0995″ [3] |
Apparent magnitude (V) | 4.96 - 5.23 [4] |
Characteristics | |
Spectral type | A: G5/8III+F, B: A0V+A2V [4] |
Variable type | Algol + RS CVn [5] |
Astrometry | |
Proper motion (μ) | RA: −29.762±0.561 [3] mas/yr Dec.: 5.783±0.504 [3] mas/yr |
Parallax (π) | 8.3972 ± 0.5075 mas [3] |
Distance | 390 ± 20 ly (119 ± 7 pc) |
Orbit [6] | |
Primary | A (HD 101379) |
Companion | B (HD 101380) |
Period (P) | 96.8±2.4 yr |
Semi-major axis (a) | 0.276″ ±0.004″ |
Eccentricity (e) | 0.634±0.015 |
Inclination (i) | 60.9±2° |
Longitude of the node (Ω) | 259.8±1.5° |
Periastron epoch (T) | 2452778±110 |
Argument of periastron (ω) (secondary) | 92.4±1.5° |
Orbit [1] | |
Primary | Aa |
Companion | Ab |
Period (P) | 61.448±0.007 d |
Periastron epoch (T) | 2444929±6 |
Argument of periastron (ω) (secondary) | 238±24° |
Semi-amplitude (K1) (primary) | 12.7±0.2 km/s |
Orbit [4] | |
Primary | Ba |
Companion | Bb |
Period (P) | 2.75459 d |
Details [7] | |
A | |
Mass | 1.1±0.3 M☉ |
Radius | 16.6±1 R☉ |
Luminosity | 126 L☉ |
Surface gravity (log g) | 1.89±0.05 cgs |
Temperature | 4,744±125 K |
Other designations | |
Database references | |
SIMBAD | data |
GT Muscae, also known as 12 Muscae, is a variable star about 400 light years from the Earth, in the constellation Musca. [3] It is a 5th magnitude star, so it should be faintly visible to the naked eye of an observer far from city lights. [3] It is a quadruple star system, consisting of a spectroscopic binary containing an RS Canum Venaticorum variable (RS CVn) star (HD 101379), orbiting an eclipsing binary (HD 101380). [1] It varies in brightness from magnitude 4.96 to 5.23. [4] GT Muscae is a very active X-ray source. [10]
In 1929, Willem van den Bos discovered that GT Muscae is a visual double star, whose A (HD 101379) and B (HD 101380) components were separated by 0.2 arc seconds at the time he observed it. [9] Examining photographic plates in 1964, Wolfgang Strohmeier et al. discovered that GT Muscae is a variable star. [11] In 1979, based on spectroscopic features, Edward Weiler and Robert Stencel listed GT Muscae as a likely RS CVn variable. [12] Eclipses of the HD 101380 pair were first reported by Andrew Collier Cameron in his 1982 PhD thesis, in which he also determined that pair's orbital period. [13] The entire star system was given the variable star designation GT Muscae in 1988. [14]
Strong, variable, 5 GHz radio emission from GT Muscae, indicative of flares, was detected in 1982 and was interpreted as indicating high levels of chromospheric and coronal activity. [15]
GT Muscae was detected in the early observations of the Uhuru X-ray satellite, originally denoted as 2U 1134–161, later renamed 4U 1137–65. [16] [17] Michael Garcia et al. identified HD 101379 as the source seen by Uhuru, in 1980. [18] During the 2010-2019 decade, GT Muscae showed the most X-ray flare activity of any star in the sky, producing flares with energies as high as ~1038 ergs. [10]
Ross 154 is a star in the southern zodiac constellation of Sagittarius. It has an apparent visual magnitude of 10.44, making it much too faint to be seen with the naked eye. At a minimum, viewing Ross 154 requires a telescope with an aperture of 6.5 cm (3 in) under ideal conditions. The distance to this star can be estimated from parallax measurements, which places it at 9.71 light-years away from Earth. It is the nearest star in the southern constellation Sagittarius, and one of the nearest stars to the Sun.
Musca is a small constellation in the deep southern sky. It was one of 12 constellations created by Petrus Plancius from the observations of Pieter Dirkszoon Keyser and Frederick de Houtman, and it first appeared on a celestial globe 35 cm (14 in) in diameter published in 1597 in Amsterdam by Plancius and Jodocus Hondius. The first depiction of this constellation in a celestial atlas was in Johann Bayer's Uranometria of 1603. It was also known as Apis for 200 years. Musca remains below the horizon for most Northern Hemisphere observers.
Centaurus X-3 is an X-ray pulsar with a period of 4.84 seconds. It was the first X-ray pulsar to be discovered, and the third X-ray source to be discovered in the constellation Centaurus. The system consists of a neutron star orbiting a massive, O-type supergiant star dubbed Krzemiński's star after its discoverer, Wojciech Krzemiński. Matter is being accreted from the star onto the neutron star, resulting in X-ray emission.
A flare star is a variable star that can undergo unpredictable dramatic increases in brightness for a few minutes. It is believed that the flares on flare stars are analogous to solar flares in that they are due to the magnetic energy stored in the stars' atmospheres. The brightness increase is across the spectrum, from X-rays to radio waves. Flare activity among late-type stars was first reported by A. van Maanen in 1945, for WX Ursae Majoris and YZ Canis Minoris. However, the best-known flare star is UV Ceti, first observed to flare in 1948. Today similar flare stars are classified as UV Ceti type variable stars in variable star catalogs such as the General Catalogue of Variable Stars.
15 Cancri is an α2 CVn-type variable star in the zodiac constellation of Cancer, located around 980 light years away. It has the variable star designation BM Cancri ; 15 Cancri is the Flamsteed designation. This system is visible to the naked eye as a faint, white-hued star with an apparent visual magnitude of about 5.6. It is moving away from the Earth with a heliocentric radial velocity of 25 km/s.
Alpha Muscae, Latinized from α Muscae, is a star in the southern circumpolar constellation of Musca. With an apparent visual magnitude of +2.7, it is the brightest star in the constellation. The distance to this star has been determined using parallax measurements, giving an estimate of about 315 light-years from Earth.
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.
4U 1700-37 is one of the stronger binary X-ray sources in the sky, and is classified as a high-mass X-ray binary. It was discovered by the Uhuru satellite. The "4U" designation refers to the fourth Uhuru catalog.
Hercules X-1, also known as 4U1656+35, is a moderately strong X-ray binary source first studied by the Uhuru satellite. It is composed of a neutron star accreting matter from a normal star probably due to Roche lobe overflow.
X Persei is a high-mass X-ray binary system located in the constellation Perseus, approximately 950 parsecs away. It is catalogued as 4U 0352+309 in the final Uhuru catalog of X-ray objects.
Sigma Geminorum is a binary star system in the constellation Gemini, just to the northwest of Pollux. It is visible to the naked eye with an apparent visual magnitude of 4.20. Its annual parallax shift of 26.08 mas indicates that it is located 125 light years from the Sun.
R Muscae is a yellow-white hued variable star in the southern constellation of Musca. It has a nominal apparent visual magnitude of 6.31, which is near the lower limit of visibility to the naked eye. The distance to this star, as determined from its annual parallax shift of 1.00 mas, is around 3,260 light years.
S Muscae is a classical (δ) Cepheid variable star in the constellation Musca about 2,600 light years away.
TU Muscae, also known as HD100213, is an eclipsing binary star in the constellation Musca. Its apparent magnitude ranges from 8.17 to 8.75 over around 1.4 days.
RS Canum Venaticorum is a binary star system in the northern constellation of Canes Venatici. It serves as the prototype to the class of RS Canum Venaticorum variables. The peak apparent visual magnitude of this system is below the level needed to observe it with the naked eye. It is located at a distance of approximately 443 light years from the Sun based on parallax, but is drifting closer with a net radial velocity of −14 km/s. Olin J. Eggen (1991) included this system as a member of the IC 2391 supercluster, but it was later excluded.
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DM Ursae Majoris is a binary star system in the northern circumpolar constellation of Ursa Major, abbreviated DM UMa. It is sometimes identified by the Bonner Durchmusterung catalogue designation BD +61 1211; DM UMa is the variable star designation. The system has a combined apparent visual magnitude of 9.29, which is too faint to be visible to the naked eye. Based on parallax measurements, the system is located at a distance of approximately 606 light years from the Sun, but it is drifting closer with a heliocentric radial velocity of −7 km/s.
HR 1099 is a triple star system in the equatorial constellation of Taurus, positioned 11′ to the north of the star 10 Tauri. This system has the variable star designation V711 Tauri, while HR 1099 is the star's identifier from the Bright Star Catalogue. It ranges in brightness from a combined apparent visual magnitude of 5.71 down to 5.94, which is bright enough to be dimly visible to the naked eye. The distance to this system is 96.6 light years based on parallax measurements, but it is drifting closer with a radial velocity of about −15 km/s.
AR Piscium is a binary star system in the northern constellation of Canes Venatici, abbreviated AR Psc. It has the Henry Draper Catalogue identifier HD 8357; AR Piscium is its variable star designation. The pair have a combined apparent visual magnitude that fluctuates around 7.24, which is too faint to be readily visible to the naked eye. Parallax measurements place it at a distance of 148 light years from the Sun. The motion of this star through the Milky Way suggests it is a member of the intermediate disc population.
AR Lacertae is a frequently-studied triple star system in the northern constellation of Lacerta, abbreviated AR Lac. This variable star system is the prototype for "detached systems of the AR Lacertae type". It is dimly visible to the naked eye with a combined peak apparent visual magnitude of 6.08. Based on parallax measurements, AR Lac is located at a distance of 138.6 light years from the Sun. It is drifting closer with a heliocentric radial velocity of −34 km/s.