Theta Librae

{{Starbox begin

| name = θ Librae

}}

{{Starbox image

| image=

{{Location mark

|image=Libra constellation map.svg|alt=|float=center|width=240

|label=|position=right

|mark=Red circle.svg|mark_width=10|mark_link=θ Librae

|x=184|y=439

}}

|caption=Location of θ Librae (circled)

}}

{{Starbox observe

| epoch = J2000

| ra = {{RA|15|53|49.53806}}

| dec = {{DEC|−16|43|45.4582}}

| appmag_v = 4.136

| constell = Libra

}}

{{Starbox character

| type = red clump

| class = G9IIIb

| b-v = +1.01

| u-b = +0.82

| variable =

}}

{{Starbox astrometry

| radial_v = {{Val|4.56|0.25}}

| prop_mo_ra = +100.33

| prop_mo_dec = +135.02

| parallax = 19.36

| p_error = 0.15

| parallax_footnote =

| absmag_v = 0.665

}}

{{Starbox detail

| mass = 1.47

| radius = 12.27

| luminosity = 68.1

| temperature = 4,739

| metal_fe = −0.35

| rotational_velocity = 0.0

| gravity = 2.44

| age_gyr = 3.4

}}

{{Starbox catalog

| names = {{odlist | B=θ Lib | F=46 Librae | BD=−16°4174 | HD=142198 | HIP=77853 | HR=5908 | SAO=159563 }}

}}

{{Starbox reference

| Simbad = tet+Lib

}}

θ Librae, Latinised as Theta Librae, is a single star in the southern zodiac constellation of Libra, near the constellation border with Scorpius. It is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of 4.14. The distance to this star is approximately 168 light years, as determined by parallax, and it is drifting further away with a radial velocity of 5 km/s. The position of this star near the ecliptic means it is subject to lunar occultations.

This object is an aging giant star with a stellar classification of G9IIIb. Having exhausted the supply of hydrogen at its core, it has cooled and expanded; at present it has 12.3 times the girth of the Sun. The star has an estimated mass about 47% greater than the Sun. It is radiating about 68 times the luminosity of the Sun from its photosphere at an effective temperature of about {{val|4,739|fmt=commas|ul=K}}. It is probably on the red giant branch, which indicates it is generating energy through hydrogen fusion in a shell outside an inert helium core. However, there is a 41% chance that it is a red clump giant on the horizontal branch, which would mean it was somewhat older and less massive. It has sometimes been classified spectroscopically as a subgiant, but detailed study shows that it is too cool and luminous to be on the subgiant branch.

References

{{reflist|refs=

{{cite journal

| title=Photoelectric observations of lunar occultations. XI.

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| display-authors=1 | journal=Astronomical Journal

| volume=85 | pages=478–489 | date=April 1980

| doi=10.1086/112700 | bibcode=1980AJ.....85..478E }}

{{cite journal

| last1=Keenan | first1=Philip C. | last2=McNeil | first2=Raymond C.

| title=The Perkins catalog of revised MK types for the cooler stars

| journal=The Astrophysical Journal Supplement Series

| volume=71 | pages=245 | year=1989

| doi=10.1086/191373 | bibcode=1989ApJS...71..245K }}

{{citation

| last1=Massarotti | first1=Alessandro | last2=Latham | first2=David W.

| last3=Stefanik | first3=Robert P. | last4=Fogel | first4=Jeffrey

| title=Rotational and Radial Velocities for a Sample of 761 HIPPARCOS Giants and the Role of Binarity

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

| volume=135 | issue=1 | pages=209–231 | date=January 2008

| doi=10.1088/0004-6256/135/1/209 | bibcode=2008AJ....135..209M | s2cid=121883397 | doi-access=free }}

{{cite journal

| title=Validation of the new Hipparcos reduction

| last1=van Leeuwen | first1=F.

| journal=Astronomy and Astrophysics

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

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

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

{{cite journal

| last1=Eggleton | first1=P. P. | last2=Tokovinin | first2=A. A.

| title=A catalogue of multiplicity among bright stellar systems

| journal=Monthly Notices of the Royal Astronomical Society

| volume=389 | issue=2 | pages=869–879 | date=September 2008

| bibcode=2008MNRAS.389..869E | arxiv=0806.2878

| doi=10.1111/j.1365-2966.2008.13596.x | doi-access=free | s2cid=14878976 }}

{{cite journal

| display-authors=1 | last1=Liu | first1=Y. J.

| last2=Zhao | first2=G. | last3=Shi | first3=J. R.

| last4=Pietrzyński | first4=G. | last5=Gieren | first5=W.

| title=The abundances of nearby red clump giants

| journal=Monthly Notices of the Royal Astronomical Society

| volume=382 | issue=2 | pages=553–66 | date=2007

| bibcode=2007MNRAS.382..553L | doi=10.1111/j.1365-2966.2007.11852.x | doi-access=free }}

{{Cite journal

| last1=Johnson | first1=H. L. | last2=Iriarte | first2=B.

| last3=Mitchell | first3=R. I. | last4=Wisniewskj | first4=W. Z.

| display-authors=1 | title=UBVRIJKL photometry of the bright stars

| journal=Communications of the Lunar and Planetary Laboratory

| volume=4 | issue=99 | date=1966

| page=99 | bibcode=1966CoLPL...4...99J }}

{{cite journal |bibcode=2015A&A...574A.116R |title=Precise radial velocities of giant stars. VII. Occurrence rate of giant extrasolar planets as a function of mass and metallicity |journal=Astronomy and Astrophysics |volume=574 |pages=A116 |last1=Reffert |first1=Sabine |last2=Bergmann |first2=Christoph |last3=Quirrenbach |first3=Andreas |last4=Trifonov |first4=Trifon |last5=Künstler |first5=Andreas |year=2015 |arxiv=1412.4634 |doi=10.1051/0004-6361/201322360 |s2cid=59334290 }}

{{cite journal |bibcode=2004A&A...425..187T |title=Subgiants as probes of galactic chemical evolution |journal=Astronomy and Astrophysics |volume=425 |pages=187–206 |last1=Thorén |first1=P. |last2=Edvardsson |first2=B. |last3=Gustafsson |first3=B. |year=2004 |arxiv=astro-ph/0407260 |doi=10.1051/0004-6361:20040421 |s2cid=2116895 }}

}}

Category:G-type giants

Category:Horizontal-branch stars

Category:Libra (constellation)

Librae, Theta

Category:Durchmusterung objects