GT Muscae

GT Muscae

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]
Distance390 ± 20 ly
(119 ± 7 pc)
Orbit[6]
PrimaryA (HD 101379)
CompanionB (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]
PrimaryAa
CompanionAb
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]
PrimaryBa
CompanionBb
Period (P)2.75459 d
Details[7]
A
Mass1.1±0.3 M☉
Radius16.6±1 R☉
Luminosity126 L☉
Surface gravity (log g)1.89±0.05 cgs
Temperature4,744±125 K
Other designations
12 Muscae, HD 101379, HD 101380, HIP 56862, HR 4492, SAO 251522, WDS J11395-6524AB,[8] B 1705 AB[9]
Database references
SIMBADdata

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]

  1. ^ a b c Cite error: The named reference Murdoch1995 was invoked but never defined (see the help page).
  2. ^ Cite error: The named reference MAST was invoked but never defined (see the help page).
  3. ^ a b c d e f g Cite error: The named reference dr3 was invoked but never defined (see the help page).
  4. ^ a b c d Cite error: The named reference IVSI was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference gcvs was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference WDS was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference kallinger was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  9. ^ a b Cite error: The named reference Bos1929 was invoked but never defined (see the help page).
  10. ^ a b Cite error: The named reference Sasaki2021 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference Strohmeier1964 was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference Weiler1979 was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference ACCPhD was invoked but never defined (see the help page).
  14. ^ Cite error: The named reference Kholopov1989 was invoked but never defined (see the help page).
  15. ^ Cite error: The named reference Collier1982 was invoked but never defined (see the help page).
  16. ^ Cite error: The named reference Giacconi1972 was invoked but never defined (see the help page).
  17. ^ Cite error: The named reference Forman1978 was invoked but never defined (see the help page).
  18. ^ Cite error: The named reference Garcia1980 was invoked but never defined (see the help page).