48 Librae

{{Starbox begin

| name = 48 Librae

}}

{{Starbox image

| image = 250px

| caption = A broad-band optical light curve for FX Librae, adapted from Ozuyar et al. (2018)

}}

{{Starbox observe

| epoch = J2000

| constell = Libra

| ra = {{RA|15|58|11.36869}}

| dec = {{DEC|−14|16|45.6894}}

| appmag_v = 4.95

}}

{{Starbox character

| class = B3 Vsh

| b-v = {{Val|−0.08|0.11}}

| u-b =

| variable = γ Cas

}}

{{Starbox astrometry

| radial_v = {{Val|−7.5|1.8}}

| prop_mo_ra = −12.44

| prop_mo_dec = −16.73

| parallax = 6.97

| p_error = 0.24

| parallax_footnote =

| absmag_v = −0.83

}}

{{Starbox detail

| source =

| mass = 6.07

| radius = 4.12

| luminosity = 1,100

| gravity =

| temperature = 7,612

| metal_fe =

| rotational_velocity = 400

| age_myr =

}}

{{Starbox catalog

| names = {{odlist | V=FX Lib | F=48 Lib | BD=−13° 4302 | FK5=1417 | HD=142983 | HIP=78207 | HR=5941 | SAO=159607 | AAVSO=1552-14 }}

}}

{{Starbox reference

| Simbad = 48+Lib

}}

48 Librae is a single 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. Based upon an annual parallax shift of {{Val|6.97|0.24|ul=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.

This is a main sequence Be star with a stellar classification of B3 Vsh, 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. This is giving the star a pronounced oblate shape with an equatorial bulge that is estimated to be 43% larger than the polar radius. It has six times the mass of the Sun and four times the Sun's radius. The star is radiating 1,100 times the Sun's luminosity from its photosphere at an effective temperature of 7,612 K.

The surrounding gaseous disk stretches out to at least 15 times the star's radius and is nearly aligned with the line of sight from the Earth, having an estimated inclination of {{Val|85|3|u=°}}. Some time between 1931 and 1935, the disk became active and has remained so since that time, becoming the subject of multiple studies. 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.

References

{{reflist|refs=

{{cite journal |last1=Ozuyar |first1=D. |last2=Caliskan |first2=S. |last3=Stevens |first3=I. R. |last4=Elmasli |first4=A. |title=Photometric and spectroscopic variability of the Be star 48 Lib: The relation between photometric variations and rotation |journal=Publications of the Astronomical Society of Australia |date=November 2018 |volume=35 |doi=10.1017/pasa.2018.38 |bibcode=2018PASA...35...34O |s2cid=126232532 |url=https://ui.adsabs.harvard.edu/abs/2018PASA...35...34O |access-date=20 January 2022}}

{{citation

| title=Validation of the new Hipparcos reduction

| last1=van Leeuwen | first1=F. | postscript=.

| journal=Astronomy and Astrophysics

| volume=474 | issue=2 | pages=653–664 | year=2007

| arxiv=0708.1752 | bibcode=2007A&A...474..653V

| doi=10.1051/0004-6361:20078357 | s2cid=18759600 }}

{{citation

| display-authors=1 | last1=McDonald | first1=I.

| last2=Zijlstra | first2=A. A. | last3=Boyer | first3=M. L.

| title=Fundamental parameters and infrared excesses of Hipparcos stars

| journal=Monthly Notices of the Royal Astronomical Society

| doi=10.1111/j.1365-2966.2012.21873.x | doi-access=free | bibcode=2012MNRAS.427..343M

| arxiv=1208.2037 | s2cid=118665352 }}

{{citation

| title=XHIP: An extended hipparcos compilation

| last1=Anderson | first1=E. | last2=Francis | first2=Ch.

| journal=Astronomy Letters

| volume=38 | issue=5 | pages=331 | year=2012

| bibcode=2012AstL...38..331A | doi=10.1134/S1063773712050015

| arxiv=1108.4971 | s2cid=119257644 | postscript=. }}

{{citation

| display-authors=1 | last1=Samus | first1=N. N.

| last2=Kazarovets | first2=E. V. | last3=Durlevich | first3=O. V.

| last4=Kireeva | first4=N. N. | last5=Pastukhova | first5=E. N.

| title=General Catalogue of Variable Stars | version=GCVS 5.1

| journal=Astronomy Reports | postscript=.

| year=2017 | volume=61 | issue=1 | pages=80–88

| bibcode=2017ARep...61...80S | doi=10.1134/S1063772917010085 | s2cid=125853869 }}

{{citation

| last1=van Belle | first1=Gerard T.

| title=Interferometric observations of rapidly rotating stars

| journal=The Astronomy and Astrophysics Review

| volume=20 | issue=1 | page=51 | date=March 2012

| doi=10.1007/s00159-012-0051-2 | bibcode=2012A&ARv..20...51V

| arxiv=1204.2572 | s2cid=119273474

| postscript=. }}

{{citation

| last1=de Bruijne | first1=J. H. J. | last2=Eilers | first2=A.-C.

| title=Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project

| journal=Astronomy & Astrophysics

| volume=546 | id=A61 | pages=14 | date=October 2012

| doi=10.1051/0004-6361/201219219 | bibcode=2012A&A...546A..61D

| arxiv=1208.3048 | s2cid=59451347 | postscript=. }}

{{citation

| title=Spitzer IRS Spectra of Debris Disks in the Scorpius–Centaurus OB Association

| last1=Jang-Condell | first1=Hannah | last2=Chen | first2=Christine H.

| last3=Mittal | first3=Tushar | last4=Manoj | first4=P.

| last5=Watson | first5=Dan | last6=Lisse | first6=Carey M.

| last7=Nesvold | first7=Erika | last8=Kuchner | first8=Marc

| journal=The Astrophysical Journal | display-authors=1

| doi=10.1088/0004-637X/808/2/167 | bibcode=2015ApJ...808..167J

| arxiv=1506.05428 | s2cid=118549483 | postscript=. }}

{{citation

| title=Investigating the Circumstellar Disk of the Be Shell Star 48 Librae

| display-authors=1 | last1=Silaj | first1=J.

| last2=Jones | first2=C. E. | last3=Carciofi | first3=A. C.

| last4=Escolano | first4=C. | last5=Okazaki | first5=A. T.

| last6=Tycner | first6=C. | last7=Rivinius | first7=T.

| last8=Klement | first8=R. | last9=Bednarski | first9=D.

| journal=The Astrophysical Journal

| doi=10.3847/0004-637X/826/1/81 | bibcode=2016ApJ...826...81S

| arxiv=1608.00943 | s2cid=119112873 | postscript=. | doi-access=free }}

{{citation | arxiv=1202.4523

| title=New activity in the large circumstellar disk of the Be-shell star 48 Librae

| last1=Štefl | first1=S. | last2=Le Bouquin | first2=J. -B.

| last3=Carciofi | first3=A. C. | last4=Rivinius | first4=T.

| last5=Baade | first5=D. | last6=Rantakyrö | first6=F.

| journal=Astronomy & Astrophysics | display-authors=1

| volume=540 | id=A76 | pages=12 | date=April 2012

| doi=10.1051/0004-6361/201118054 | bibcode=2012A&A...540A..76S | s2cid=54663995

}}

{{citation

| title=A study of 48 Librae in the period 1950 - 1962

| last1=Faraggiana | first1=R.

| journal=Astronomy and Astrophysics

| volume=2 | page=162 | date=June 1969

| bibcode=1969A&A.....2..162F | postscript=. }}

{{citation

| title=Classical Be stars. Rapidly rotating B stars with viscous Keplerian decretion disks

| journal=The Astronomy and Astrophysics Review

| display-authors=1 | last1=Rivinius | first1=Thomas

| last2=Carciofi | first2=Alex C. | last3=Martayan | first3=Christophe

| volume=21 | pages=69 | year=2013

| doi=10.1007/s00159-013-0069-0 | bibcode=2013A&ARv..21...69R

| arxiv=1310.3962 | s2cid=118652497

| postscript=. }}

}}

Category:B-type main-sequence stars

Category:Shell stars

Category:Libra (constellation)

Category:Durchmusterung objects