  | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Libra[1] |
| Right ascension | 15h 58m 11.36869s[2] |
| Declination | −14° 16′ 45.6894″[2] |
| Apparent magnitude (V) | 4.95[1] |
| Characteristics | |
| Evolutionary stage | main sequence[3] |
| Spectral type | B3 Vsh[4][5] |
| B−V color index | −0.08±0.11[1] |
| Variable type | γ Cas[6] |
| Astrometry | |
| Radial velocity (Rv) | −7.5±1.8[7] km/s |
| Proper motion (μ) | RA: −12.44[2] mas/yr Dec.: −16.73[2] mas/yr |
| Parallax (π) | 6.97±0.24 mas[2] |
| Distance | 470 ± 20 ly (143 ± 5 pc) |
| Absolute magnitude (MV) | −0.83[1] |
| Details | |
| Mass | 6.07[5] M☉ |
| Radius | 4.12[5] R☉ |
| Luminosity | 1,100[5] L☉ |
| Surface gravity (log g) | 3.71±0.04[8] cgs |
| Temperature | 18,000±180[8] K |
| Rotation | 9.6 hours[9] |
| Rotational velocity (v sin i) | 400[5] km/s |
| Age | 10[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 | |
| SIMBAD | data |
48 Librae is a single[5] 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.[6] 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,[4] 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.[5] 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[5] times the Sun's luminosity from its photosphere at an effective temperature of 18,000 K.[8]
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°.[5] 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.[5]
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
- ^ a b c d Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. XHIP record for this object at VizieR.
- ^ a b c d e van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600.
- ^ Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
- ^ a b Rivinius, Thomas; et al. (2013), "Classical Be stars. Rapidly rotating B stars with viscous Keplerian decretion disks", The Astronomy and Astrophysics Review, 21: 69, arXiv:1310.3962, Bibcode:2013A&ARv..21...69R, doi:10.1007/s00159-013-0069-0, S2CID 118652497.
- ^ a b c d e f g h i j Silaj, J.; et al. (July 2016), "Investigating the Circumstellar Disk of the Be Shell Star 48 Librae", The Astrophysical Journal, 826 (1): 11, arXiv:1608.00943, Bibcode:2016ApJ...826...81S, doi:10.3847/0004-637X/826/1/81, S2CID 119112873, 81.
- ^ a b Samus, N. N.; et al. (2017), "General Catalogue of Variable Stars", Astronomy Reports, GCVS 5.1, 61 (1): 80–88, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID 125853869.
- ^ de Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: 14, arXiv:1208.3048, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, S2CID 59451347, A61.
- ^ a b c Arcos, C.; Kanaan, S.; Chávez, J.; Vanzi, L.; Araya, I.; Curé, M. (2018), "Stellar parameters and H α line profile variability of be stars in the BeSOS survey", Monthly Notices of the Royal Astronomical Society, 474 (4): 5287, arXiv:1711.08675, Bibcode:2018MNRAS.474.5287A, doi:10.1093/mnras/stx3075.
- ^ a b Ozuyar, D.; Caliskan, S.; Stevens, I. R.; Elmasli, A. (November 2018). "Photometric and spectroscopic variability of the Be star 48 Lib: The relation between photometric variations and rotation". Publications of the Astronomical Society of Australia. 35 e034. Bibcode:2018PASA...35...34O. doi:10.1017/pasa.2018.38. S2CID 126232532.
- ^ Squicciarini, V.; Mazoyer, J.; Lagrange, A. -M.; Chomez, A.; Delorme, P.; Flasseur, O.; Kiefer, F.; Bergeon, S.; Albert, D.; Meunier, N. (2025). "The COBREX archival survey: Improved constraints on the occurrence rate of wide-orbit substellar companions: I. A uniform re-analysis of 400 stars from the GPIES survey". Astronomy and Astrophysics. 693. arXiv:2411.06157. Bibcode:2025A&A...693A..54S. doi:10.1051/0004-6361/202452310.
- ^ "48 Lib". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-03-04.
- ^ Jang-Condell, Hannah; et al. (August 2015), "Spitzer IRS Spectra of Debris Disks in the Scorpius–Centaurus OB Association", The Astrophysical Journal, 808 (2): 19, arXiv:1506.05428, Bibcode:2015ApJ...808..167J, doi:10.1088/0004-637X/808/2/167, S2CID 118549483, 167.
- ^ van Belle, Gerard T. (March 2012), "Interferometric observations of rapidly rotating stars", The Astronomy and Astrophysics Review, 20 (1) 51, arXiv:1204.2572, Bibcode:2012A&ARv..20...51V, doi:10.1007/s00159-012-0051-2, S2CID 119273474.
- ^ Štefl, S.; et al. (April 2012), "New activity in the large circumstellar disk of the Be-shell star 48 Librae", Astronomy & Astrophysics, 540: 12, arXiv:1202.4523, Bibcode:2012A&A...540A..76S, doi:10.1051/0004-6361/201118054, S2CID 54663995, A76
- ^ Faraggiana, R. (June 1969), "A study of 48 Librae in the period 1950 - 1962", Astronomy and Astrophysics, 2: 162, Bibcode:1969A&A.....2..162F.
- ^ Bayer, Johann; Mair, Alexander (1603). Uranometria (in Latin). Excvdit Christophorvs Mangvs. Retrieved 2025-11-10.
- ^ Ian Ridpath. "Scorpius". Star Tales. Retrieved 2025-09-10.
- ^ "Chi and Psi Scorpii", stars.astro.illinois.edu, retrieved 2025-07-13.
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