48 Librae

From Wikipedia, the free encyclopedia
Jump to navigation Jump to search
48 Librae
File:FXLibLightCurve.png
A broad-band optical light curve for FX Librae, adapted from Ozuyar et al. (2018)[1]
Observation data
Epoch J2000      Equinox J2000
Constellation Libra[2]
Right ascension 15h 58m 11.36869s[3]
Declination −14° 16′ 45.6894″[3]
Apparent magnitude (V) 4.95[2]
Characteristics
Evolutionary stage main sequence[4]
Spectral type B3 Vsh[5][6]
B−V color index −0.08±0.11[2]
Variable type γ Cas[7]
Astrometry
Radial velocity (Rv)−7.5±1.8[8] km/s
Proper motion (μ) RA: −12.44[3] mas/yr
Dec.: −16.73[3] mas/yr
Parallax (π)6.97±0.24 mas[3]
Distance470 ± 20 ly
(143 ± 5 pc)
Absolute magnitude (MV)−0.83[2]
Details
Mass6.07[6] M☉
Radius4.12[6] R☉
Luminosity1,100[6] L☉
Surface gravity (log g)3.71±0.04[9] cgs
Temperature18,000±180[9] K
Rotation9.6 hours[1]
Rotational velocity (v sin i)400[6] km/s
Age10[10] Myr
Other designations
48 Lib, FX Lib, AAVSO 1552-14, BD−13°4302, FK5 1417, HD 142983, HIP 78207, HR 5941, SAO 159607[11]
Database references
SIMBADdata

48 Librae is a single[6] shell star in the constellation Libra. It is a variable star with the designation FX Lib, ranging in magnitude from 4.74 to 4.96.[7] Based upon an annual parallax shift of 6.97±0.24 mas as seen from Earth's orbit, it is located approximately 470 light years from the Sun. It is a candidate member of the Upper Scorpius group of the Scorpius–Centaurus association, with the former having an age of about 11 million years.[12]

This is a main sequence Be star with a stellar classification of B3 Vsh,[5] although it has been variously classed as B3V, B5IIIp shell He-n, B6p shell, B4III, B3IV:e-shell, and B3 shell by different sources. As is the norm for a shell star, it is spinning very rapidly with a projected rotational velocity of 400 km/s − matching or exceeding 80% of the critical velocity.[6] This is giving the star a pronounced oblate shape with an equatorial bulge that is estimated to be 43% larger than the polar radius.[13] It has six times the mass of the Sun and four times the Sun's radius. The star is radiating 1,100[6] times the Sun's luminosity from its photosphere at an effective temperature of 18,000 K.[9]

The surrounding gaseous disk stretches out to at least 15[14] times the star's radius and is nearly aligned with the line of sight from the Earth, having an estimated inclination of 85°±3°.[6] Some time between 1931 and 1935, the disk became active and has remained so since that time, becoming the subject of multiple studies.[15] The unusual asymmetry in its emission lines have led to it being misclassified as a supergiant of type B8 Ia/Ib by SIMBAD and others. This asymmetry displays quasi-periodic behavior of the type found in about a third of all Be stars, with a period of about 10 to 17 years. This variation may arise from the precession of a one-armed density wave in the disk.[6]

The Bayer designation Phi Scorpii has been associated with this star. No star is found at the position marked φ Scorpii in Johann Bayer's Uranometria.[16] The closest stars to that position are 48 and 49 Librae; 48 Librae is clearly shown but not given a designation while no star is shown at the position of 49 Librae. In his Uranographia Bode assigned the designation φ Scorpii to the star now known as 49 Librae.[17] The designation is no longer in use.[18]

References

[edit | edit source]
  1. ^ a b Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  2. ^ a b c d Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value). XHIP record for this object at VizieR.
  3. ^ a b c d e Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  4. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value). Gaia DR3 record for this source at VizieR.
  5. ^ a b Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  6. ^ a b c d e f g h i j Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  7. ^ a b Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  8. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  9. ^ a b c Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  10. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  11. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  12. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  13. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  14. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  15. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  16. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  17. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  18. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
Retrieved from "http://70.231.62.181/index.php?title=48_Librae&oldid=10945588"