Lambda2 Tucanae
{{short description|Binary star in the constellation Tucana}}
{{DISPLAYTITLE:Lambda2 Tucanae}}
{{about|Lambda2 Tucanae|other stars with this Bayer designation|Lambda Tucanae{{!}}Lambda Tucanae}}
{{Starbox begin
| name = Lambda2 Tucanae
}}
{{Starbox observe
| epoch = J2000.0
| constell = Tucana
| dec = {{DEC|−69|31|37.5025}}
}}
{{Starbox character
| u-b =
| r-i =
| variable =
}}
{{Starbox astrometry
| parallax = 14.6214
| p_error = 0.0817
}}
{{Starbox detail
| mass = 1.75
| radius = {{Val|9.84|0.22|0.42}}
| luminosity = {{Val|39.2|0.3}}
| temperature = {{Val|4605|101|52|fmt=commas}}
| gravity = 2.74
| metal_fe = {{Val|−0.07|0.14}}
| rotational_velocity = 3.14
| age_gyr =
}}
{{Starbox catalog
| names = {{odlist | B=λ2 Tuc | CD=–70°40 | FK5=34 | HD=5457 | HIP=4293 | HR=270 | SAO=248281 }}
}}
{{Starbox reference
| Simbad = lam02+Tuc
}}
{{Starbox end}}
Lambda2 Tucanae is a solitary star in the southern constellation of Tucana. It is faintly visible to the naked eye with an apparent visual magnitude of +5.45. Based upon an annual parallax shift of {{Val|14.6|ul=mas}} as seen from Earth, it is located around 223 light years from the Sun. At that distance, the visual magnitude of the star is diminished by an extinction factor of 0.09 due to interstellar dust.
This is an orange-hued K-type giant star on the red giant branch, with a stellar classification of K2 III. It has an estimated 1.75 times the mass of the Sun but after evolving away from the main sequence it has expanded to 9.8 times the Sun's radius. The star is radiating 39 times the solar luminosity from its photosphere at an effective temperature of 4,605 K.
References
{{reflist|refs=
{{Cite Gaia DR2|4691986930313219072}}
| 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=. }}
| 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
| doi=10.1111/j.1365-2966.2008.13596.x | doi-access=free | bibcode=2008MNRAS.389..869E
| postscript=. |arxiv = 0806.2878 | s2cid=14878976 }}
| title=Michigan catalogue of two-dimensional spectral types for the HD stars
| volume=1 | last1=Houk | first1=Nancy | postscript=.
| publication-place=Ann Arbor, Michigan
| publisher=Dept. of Astronomy, University of Michigan
| year=1979 | bibcode=1978mcts.book.....H }}
| title=Study of the impact of the post-MS evolution of the host star on the orbits of close-in planets. I. Sample definition and physical properties
| last1=Jones | first1=M. I. | last2=Jenkins | first2=J. S.
| last3=Rojo | first3=P. | last4=Melo | first4=C. H. F.
| journal=Astronomy & Astrophysics | display-authors=1
| volume=536 | id=A71 | pages=7 | date=December 2011
| doi=10.1051/0004-6361/201117887 | bibcode=2011A&A...536A..71J
| arxiv=1110.6459 | s2cid=55769003 | postscript=. }}
| 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=. }}
| title=lam Tuc
| accessdate=2017-04-21 | postscript=. }}
}}
{{Stars of Tucana|state=collapsed}}
{{DEFAULTSORT:Lambda2 Tucanae}}