Tau2 Eridani: Difference between revisions

τ² Eridani
Observation data; Epoch J2000.0 Equinox J2000.0 (ICRS)
Constellation	Eridanus
Right ascension	02h 51m 02.32186s
Declination	−21° 00′ 14.4654″
Apparent magnitude (V)	4.78
Characteristics
Spectral type	K0 III
U−B color index	+0.63
B−V color index	+0.92
Astrometry
Radial velocity (Rv)	−5.9 km/s
Proper motion (μ)	RA: −38.52 mas/yr ; Dec.: −16.05 mas/yr
Parallax (π)	17.45 ± 0.20 mas
Distance	187 ± 2 ly ; (57.3 ± 0.7 pc)
Absolute magnitude (MV)	1.008
Details
Mass	2.39±0.03 M☉
Radius	8.85±0.08 R☉
Luminosity	44.36±0.8 L☉
Surface gravity (log g)	2.95±0.03 cgs
Temperature	5,049±20 K
Metallicity [Fe/H]	0.08±0.06 dex
Rotational velocity (v sin i)	1.11 km/s
Age	720±50 Myr
Other designations
	Angetenar, τ2 Eridani, 2 Eri, BD−21° 509, HD 17824, HIP 13288, HR 850, SAO 168094.
Database references
SIMBAD	data

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Tau² Eridani (τ² Eridani, abbreviated Tau² Eri, τ² Eri), formally named Angetenar /æŋˈɡɛtənɑːr/,^[8]^[9] is a star in the constellation of Eridanus. It is visible to the naked eye with an apparent visual magnitude of 4.78.^[2] The distance to this star, as determined via the parallax method, is around 187 light-years.

Nomenclature

τ² Eridani (Latinised to Tau² Eridani) is the system's Bayer designation. It is one of a series of stars that share the Bayer designation Tau Eridani.

It bore the traditional name Angetenar, derived from the Arabic Al Ḥināyat an-Nahr, 'the Bend in the River', near which it lies.^[10] In 2016, the IAU organized a Working Group on Star Names (WGSN)^[11] to catalog and standardize proper names for stars. The WGSN approved the name Angetenar for this star on 30 June 2017 and it is now so included in the List of IAU-approved Star Names.^[9]

In Chinese, 天苑 (Tiān Yuàn), meaning Celestial Meadows, refers to an asterism consisting of Tau² Eridani, Gamma Eridani, Pi Eridani, Delta Eridani, Epsilon Eridani, Zeta Eridani, Eta Eridani, Pi Ceti, Tau¹ Eridani, Tau³ Eridani, Tau⁴ Eridani, Tau⁵ Eridani, Tau⁶ Eridani, Tau⁷ Eridani, Tau⁸ Eridani and Tau⁹ Eridani.^[12] Consequently, the Chinese name for Tau² Eridani itself is 天苑九 (Tiān Yuàn jiǔ, English: the Ninth Star of Celestial Meadows.)^[13]

Properties

Tau² Eridani is an evolved K-type giant star with a stellar classification of K0 III.^[3] It is a red clump giant on the horizontal branch of the Hertzsprung–Russell diagram, indicating that is it now generating energy through the thermonuclear fusion of helium at its core.^[5]

Around 720 million years old, Tau² Eridani has 2.4 times the mass of the Sun and has expanded to over 8 times the solar radius. It shines with nearly 44 times the Sun's luminosity^[6] from an outer atmosphere that has an effective temperature of 5,049 K.^[4]

It is a member of the Galactic thin disk population.^[4]

References

^ ^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.
^ ^a ^b ^c ^d Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV Data, SIMBAD, Bibcode:1986EgUBV........0M.
^ ^a ^b Houk, Nancy (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, vol. 4, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode:1988mcts.book.....H.
^ ^a ^b ^c ^d ^e ^f ^g Jofré, E.; et al. (2015), "Stellar parameters and chemical abundances of 223 evolved stars with and without planets", Astronomy & Astrophysics, 574: A50, arXiv:1410.6422, Bibcode:2015A&A...574A..50J, doi:10.1051/0004-6361/201424474, S2CID 53666931, A50.
^ ^a ^b Liu, Y. J.; et al. (2007), "The abundances of nearby red clump giants", Monthly Notices of the Royal Astronomical Society, 382 (2): 553–66, Bibcode:2007MNRAS.382..553L, doi:10.1111/j.1365-2966.2007.11852.x.
^ ^a ^b ^c ^d ^e Gallenne, A.; Pietrzyński, G.; Graczyk, D.; Nardetto, N.; Mérand, A.; Kervella, P.; Gieren, W.; Villanova, S.; Mennickent, R. E.; Pilecki, B. (2018-08-01), "Fundamental properties of red-clump stars from long-baseline H-band interferometry", Astronomy & Astrophysics, 616: A68, arXiv:1806.09572, doi:10.1051/0004-6361/201833341, ISSN 0004-6361
^ "* tau02 Eri". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2016-10-13.{{cite web}}: CS1 maint: postscript (link)
^ Rumrill, H. B. (June 1936). "Star Name Pronunciation". Publications of the Astronomical Society of the Pacific. 48 (283). San Francisco, California: 139. Bibcode:1936PASP...48..139R. doi:10.1086/124681. S2CID 120743052.
^ ^a ^b "Naming Stars". IAU.org. Retrieved 16 December 2017.
^ Allen, Richard Hinckley (1963) [1899]. Star Names: Their Lore and Meaning (Reprint ed.). New York, NY: Dover Publications Inc. p. 220. ISBN 0-486-21079-0.
^ "IAU Working Group on Star Names (WGSN)". Retrieved 22 May 2016.
^ (in Chinese) 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN 978-986-7332-25-7.
^ (in Chinese) 香港太空館 - 研究資源 - 亮星中英對照表 Archived 2010-08-11 at the Wayback Machine, Hong Kong Space Museum. Accessed on line November 23, 2010.

[vanLeeuwen2007-1] 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.

[Mermilliod1986-2] Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV Data, SIMBAD, Bibcode:1986EgUBV........0M.

[houk1978-3] Houk, Nancy (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, vol. 4, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode:1988mcts.book.....H.

[jofre2015-4] ^ ^a ^b ^c ^d ^e ^f ^g Jofré, E.; et al. (2015), "Stellar parameters and chemical abundances of 223 evolved stars with and without planets", Astronomy & Astrophysics, 574: A50, arXiv:1410.6422, Bibcode:2015A&A...574A..50J, doi:10.1051/0004-6361/201424474, S2CID 53666931, A50.

[Liu2007-5] Liu, Y. J.; et al. (2007), "The abundances of nearby red clump giants", Monthly Notices of the Royal Astronomical Society, 382 (2): 553–66, Bibcode:2007MNRAS.382..553L, doi:10.1111/j.1365-2966.2007.11852.x.

[Gallenne2018-6] Gallenne, A.; Pietrzyński, G.; Graczyk, D.; Nardetto, N.; Mérand, A.; Kervella, P.; Gieren, W.; Villanova, S.; Mennickent, R. E.; Pilecki, B. (2018-08-01), "Fundamental properties of red-clump stars from long-baseline H-band interferometry", Astronomy & Astrophysics, 616: A68, arXiv:1806.09572, doi:10.1051/0004-6361/201833341, ISSN 0004-6361

[SIMBAD-7] "* tau02 Eri". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2016-10-13.{{cite web}}: CS1 maint: postscript (link)

[Rumrill-8] Rumrill, H. B. (June 1936). "Star Name Pronunciation". Publications of the Astronomical Society of the Pacific. 48 (283). San Francisco, California: 139. Bibcode:1936PASP...48..139R. doi:10.1086/124681. S2CID 120743052.

[IAU-LSN-9] "Naming Stars". IAU.org. Retrieved 16 December 2017.

[allen1963-10] Allen, Richard Hinckley (1963) [1899]. Star Names: Their Lore and Meaning (Reprint ed.). New York, NY: Dover Publications Inc. p. 220. ISBN 0-486-21079-0.

[WGSN-11] "IAU Working Group on Star Names (WGSN)". Retrieved 22 May 2016.

[12] (in Chinese) 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN 978-986-7332-25-7.

[13] (in Chinese) 香港太空館 - 研究資源 - 亮星中英對照表 Archived 2010-08-11 at the Wayback Machine, Hong Kong Space Museum. Accessed on line November 23, 2010.

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@@ Line 1: / Line 1: @@
+{{short description|Star in the constellation Eridanus}}
-{{DISPLAYTITLE:Tau<sup>2</sup> Eridani}}
 {{For|other star systems with this [[Bayer designation]]|Tau Eridani}}
+{{DISPLAYTITLE:Tau<sup>2</sup> Eridani}}
 {{Starbox begin
- | name= τ<sup>2</sup> Eri
+ | name= τ<sup>2</sup> Eridani
 }}
 {{Starbox observe
@@ Line 27: / Line 28: @@
 }}
 {{Starbox detail
- | source = <ref name=jofre2015/>
+ | mass = {{val|2.39|0.03}}<ref name=Gallenne2018/>
+ | radius = {{val|8.85|0.08}}<ref name=Gallenne2018/>
- | mass = 2.40
+ | luminosity = {{val|44.36|0.8}}<ref name=Gallenne2018/>
- | radius = 8.12
+ | temperature = {{val|5049|20|fmt=commas}}<ref name=jofre2015/>
- | luminosity = 42.7
+ | metal_fe = {{val|0.08|0.06}}<ref name=jofre2015/>
- | temperature = 5,049
+ | gravity = {{val|2.95|0.03}}<ref name=jofre2015/>
- | metal_fe = 0.08
+ | rotational_velocity = 1.11<ref name=jofre2015/>
- | gravity = 2.95
+ | age_myr = {{val|720|50}}<ref name=Gallenne2018/>
- | rotational_velocity = 1.11
- | age_myr = 660
 }}
 {{Starbox catalog
- | names = Angetenar, τ<sup>2</sup> Eridani, τ<sup>2</sup> Eri, [[Flamsteed designation|2 Eridani]], [[Bonner Durchmusterung|BD]]-21° 509, [[Henry Draper catalogue|HD]] 17824, [[Hipparcos|HIP]] 13288, [[Bright Star Catalogue|HR]] 850, [[Smithsonian Astrophysical Observatory Star Catalog|SAO]] 168094.<ref name=SIMBAD/>
+ | names = Angetenar, τ<sup>2</sup> Eridani, [[Flamsteed designation|2 Eri]], {{nowrap|[[Bonner Durchmusterung|BD]]−21° 509}}, [[Henry Draper catalogue|HD]] 17824, [[Hipparcos|HIP]] 13288, [[Bright Star Catalogue|HR]] 850, [[Smithsonian Astrophysical Observatory Star Catalog|SAO]] 168094.<ref name=SIMBAD/>
+}}
+{{Starbox reference
+ | Simbad = tau02+Eri
 }}
 {{Starbox end}}
-{{DISPLAYTITLE:Tau<sup>2</sup> Eridani}}
-'''Tau<sup>2</sup> Eridani''' (τ<sup>2</sup> Eri, 2 Eridani) is a [[star]] in the [[constellation]] [[Eridanus (constellation)|Eridanus]]. It is one of a series of stars that share the [[Bayer designation]] [[Tau Eridani]]. The traditional name for this star is '''Angetenar''', meaning "bend of the river" in [[Arabic language|Arabic]]. It is visible to the naked eye with an [[apparent visual magnitude]] of 4.78.<ref name=Mermilliod1986/> The distance to τ<sup>2</sup> Eri, as determined via the [[stellar parallax|parallax method]], is around 187&nbsp;[[light year]]s.
+'''Tau<sup>2</sup> Eridani''' ('''τ<sup>2</sup> Eridani''', abbreviated '''Tau<sup>2</sup> Eri''', '''τ<sup>2</sup> Eri'''), formally named '''Angetenar''' {{IPAc-en|æ|ŋ|'|g|E|t|@n|ɑr}},<ref name=Rumrill>{{cite journal
-In [[Chinese language|Chinese]], {{lang|zh|天苑}} ({{lang|zh-Latn|Tiān Yuàn}}), meaning ''[[Hairy Head (Chinese constellation)|Celestial Meadows]]'', refers to an asterism consisting of τ<sup>2</sup> Eridani, [[Gamma Eridani|γ Eridani]], [[Pi Eridani|π Eridani]], [[Delta Eridani|δ Eridani]], [[Epsilon Eridani|ε Eridani]], [[Zeta Eridani|ζ Eridani]], [[Eta Eridani|η Eridani]], [[Pi Ceti|π Ceti]], [[Tau1 Eridani|τ<sup>1</sup> Eridani]], [[Tau3 Eridani|τ<sup>3</sup> Eridani]], [[Tau4 Eridani|τ<sup>4</sup> Eridani]], [[Tau5 Eridani|τ<sup>5</sup> Eridani]], [[Tau6 Eridani|τ<sup>6</sup> Eridani]], [[Tau7 Eridani|τ<sup>7</sup> Eridani]], [[Tau8 Eridani|τ<sup>8</sup> Eridani]] and [[Tau9 Eridani|τ<sup>9</sup> Eridani]].<ref>{{zh icon}} ''中國星座神話'', written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN 978-986-7332-25-7.</ref> Consequently, τ<sup>2</sup> Eridani itself is known as {{lang|zh|天苑九}} ({{lang|zh-Latn|Tiān Yuàn jiǔ}}, {{lang-en|the Ninth Star of Celestial Meadows}}.)<ref>{{zh icon}} [http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/c_research_chinengstars_ama_b.htm 香港太空館 - 研究資源 - 亮星中英對照表], Hong Kong Space Museum. Accessed on line November 23, 2010.</ref>
+|title=Star Name Pronunciation
+|last=Rumrill |first=H. B.
+|journal=Publications of the Astronomical Society of the Pacific
+|volume=48
+|number=283
+|date=June 1936
+|page=139 |location = San Francisco, California
+|doi=10.1086/124681
+|bibcode=1936PASP...48..139R |s2cid=120743052 |doi-access=free
+}}</ref><ref name="IAU-LSN">{{cite web | url=https://www.iau.org/public/themes/naming_stars/ | title=Naming Stars |publisher=IAU.org |access-date=16 December 2017}}</ref> is a [[star]] in the [[constellation]] of [[Eridanus (constellation)|Eridanus]]. It is visible to the naked eye with an [[apparent magnitude|apparent visual magnitude]] of 4.78.<ref name=Mermilliod1986/> The distance to this star, as determined via the [[stellar parallax|parallax method]], is around 187&nbsp;[[light-year]]s.
+== Nomenclature ==
-Tau<sup>2</sup> Eridani is an [[stellar evolution|evolved]] [[K-type star|K-type]] [[giant star]] with a [[stellar classification]] of K0&nbsp;III.<ref name=houk1978/>  It is a [[red clump]] giant on the [[horizontal branch]] of the [[Hertzsprung–Russell diagram]], indicating that is it now generating energy through the [[thermonuclear fusion]] of helium at its core.<ref name=Liu2007/> It is a member of the Galactic [[thin disk]] population.<ref name=jofre2015/>
+''τ<sup>2</sup> Eridani'' ([[Latinisation of names|Latinised]] to ''Tau<sup>2</sup> Eridani'') is the system's [[Bayer designation]]. It is one of a series of stars that share the Bayer designation [[Tau Eridani]].
-Around 660&nbsp;million years old, Tau<sup>2</sup> Eridani has 2.4 times the [[solar mass|mass of the Sun]] and has expanded to over 8 times the [[solar radius]]. It shines with nearly 43 times the [[solar luminosity|Sun's luminosity]] from an [[Stellar atmosphere|outer atmosphere]] that has an [[effective temperature]] of 5,049&nbsp;K.<ref name=jofre2015/>
+It bore the traditional name ''Angetenar'', derived from the [[Arabic]] ''Al Ḥināyat an-Nahr'', 'the Bend in the River', near which it lies.<ref name="allen1963">{{cite book | author=Allen, Richard Hinckley | author-link=Richard Hinckley Allen | date=1963 | orig-year=1899 | title=Star Names: Their Lore and Meaning | page=[https://archive.org/details/starnamestheirlo00alle/page/220 220] | edition=[[Reprint]] | publisher=[[Dover Publications]] Inc. | location=[[New York City|New York]], [[New York (state)|NY]] | url=https://archive.org/details/starnamestheirlo00alle/page/220 | isbn=0-486-21079-0 | url-access=registration }}</ref> In 2016, the IAU organized a [[IAU Working Group on Star Names|Working Group on Star Names]] (WGSN)<ref name="WGSN">{{cite web | url=https://www.iau.org/science/scientific_bodies/working_groups/280/ | title=IAU Working Group on Star Names (WGSN)|access-date=22 May 2016}}</ref> to catalog and standardize proper names for stars. The WGSN approved the name ''Angetenar'' for this star on 30 June 2017 and it is now so included in the List of IAU-approved Star Names.<ref name="IAU-LSN"/>
+In [[Chinese astronomy|Chinese]], {{lang|zh|天苑}} ({{lang|zh-Latn|Tiān Yuàn}}), meaning ''[[Hairy Head|Celestial Meadows]]'', refers to an [[Asterism (astronomy)|asterism]] consisting of Tau<sup>2</sup> Eridani, [[Gamma Eridani]], [[Pi Eridani]], [[Delta Eridani]], [[Epsilon Eridani]], [[Zeta Eridani]], [[Eta Eridani]], [[Pi Ceti]], [[Tau1 Eridani|Tau<sup>1</sup> Eridani]], [[Tau3 Eridani|Tau<sup>3</sup> Eridani]], [[Tau4 Eridani|Tau<sup>4</sup> Eridani]], [[Tau5 Eridani|Tau<sup>5</sup> Eridani]], [[Tau6 Eridani|Tau<sup>6</sup> Eridani]], [[Tau7 Eridani|Tau<sup>7</sup> Eridani]], [[Tau8 Eridani|Tau<sup>8</sup> Eridani]] and [[Tau9 Eridani|Tau<sup>9</sup> Eridani]].<ref>{{in lang|zh}} ''中國星座神話'', written by 陳久金. Published by 台灣書房出版有限公司, 2005, {{ISBN|978-986-7332-25-7}}.</ref> Consequently, the [[Chinese star names|Chinese name]] for Tau<sup>2</sup> Eridani itself is {{lang|zh|天苑九}} ({{lang|zh-Latn|Tiān Yuàn jiǔ}}, {{langx|en|the Ninth Star of Celestial Meadows}}.)<ref>{{in lang|zh}} [http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/c_research_chinengstars_ama_b.htm 香港太空館 - 研究資源 - 亮星中英對照表] {{webarchive|url=https://web.archive.org/web/20100811014924/http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/c_research_chinengstars_ama_b.htm |date=2010-08-11 }}, Hong Kong Space Museum. Accessed on line November 23, 2010.</ref>
+== Properties ==
+Tau<sup>2</sup> Eridani is an [[stellar evolution|evolved]] [[Stellar classification#Class K|K-type]] [[giant star]] with a [[stellar classification]] of K0&nbsp;III.<ref name=houk1978/>  It is a [[red clump]] giant on the [[horizontal branch]] of the [[Hertzsprung–Russell diagram]], indicating that is it now generating energy through the [[thermonuclear fusion]] of helium at its core.<ref name=Liu2007/>
+Around 720&nbsp;million years old, Tau<sup>2</sup> Eridani has 2.4 times the [[solar mass|mass of the Sun]] and has expanded to over 8 times the [[solar radius]]. It shines with nearly 44 times the [[solar luminosity|Sun's luminosity]]<ref name=Gallenne2018/> from an [[Stellar atmosphere|outer atmosphere]] that has an [[effective temperature]] of 5,049&nbsp;K.<ref name=jofre2015/>
+It is a member of the Galactic [[thin disk]] population.<ref name=jofre2015/>
 ==References==
@@ Line 59: / Line 82: @@
  | volume=474 | issue=2 | pages=653–664 | date=2007
  | arxiv=0708.1752 | bibcode=2007A&A...474..653V
- | doi=10.1051/0004-6361:20078357 | postscript=. }}</ref>
+ | doi=10.1051/0004-6361:20078357 | s2cid=18759600 | postscript=. }}</ref>
 <ref name=jofre2015>{{citation
@@ Line 70: / Line 93: @@
  | journal=Astronomy & Astrophysics
  | volume=574 | id=A50 | year=2015
- | bibcode= 2015A&A...574A..50J | doi=10.1051/0004-6361/201424474
+ | pages=A50 | bibcode= 2015A&A...574A..50J | doi=10.1051/0004-6361/201424474
- | postscript=. }}</ref>
+ | postscript=. |arxiv = 1410.6422 | s2cid=53666931 }}</ref>
 <ref name=houk1978>{{citation
  | last1=Houk | first1=Nancy
  | title=Michigan catalogue of two-dimensional spectral types for the HD stars
- | volume=4 | publication-place=Ann Arbor
+ | volume=4 | location=Ann Arbor
  | publisher=Dept. of Astronomy, University of Michigan
- | date=1978 | bibcode=1988MSS...C04....0H | postscript=. }}</ref>
+ | date=1978 | bibcode=1988mcts.book.....H | postscript=. }}</ref>
+<ref name=Gallenne2018>{{Citation |last=Gallenne |first=A. |last2=Pietrzyński |first2=G. |last3=Graczyk |first3=D. |last4=Nardetto |first4=N. |last5=Mérand |first5=A. |last6=Kervella |first6=P. |last7=Gieren |first7=W. |last8=Villanova |first8=S. |last9=Mennickent |first9=R. E. |last10=Pilecki |first10=B. |date=2018-08-01 |title=Fundamental properties of red-clump stars from long-baseline H-band interferometry |journal=[[Astronomy & Astrophysics]] |arxiv=1806.09572 |language=en |volume=616 |pages=A68 |doi=10.1051/0004-6361/201833341 |issn=0004-6361}}</ref>
 <ref name=Liu2007>{{citation
@@ Line 88: / Line 113: @@
  | volume=382 | issue=2 | pages=553–66 | date=2007
  | bibcode=2007MNRAS.382..553L  | doi=10.1111/j.1365-2966.2007.11852.x
- | postscript=. }}</ref>
+ | postscript=. | doi-access=free }}</ref>
 <ref name=Mermilliod1986>{{citation
  | last1=Mermilliod | first1=J.-C.
  | title=Compilation of Eggen's UBV data, transformed to UBV (unpublished)
+ | journal=Catalogue of Eggen's UBV Data
- | publisher=SIMBAD | date=1986 | bibcode=1986EgUBV........0M
+ | publisher=[[SIMBAD]] | date=1986 | bibcode=1986EgUBV........0M
  | postscript=. }}</ref>
-<ref name=SIMBAD>{{citation
+<ref name=SIMBAD>{{cite simbad
- | title=tau02 Eri -- Star
+ | title=* tau02 Eri
+ | access-date=2016-10-13 | postscript=. }}</ref>
- | work=SIMBAD Astronomical Database
- | publisher=Centre de Données astronomiques de Strasbourg
- | url=http://simbad.u-strasbg.fr/simbad/sim-id?Ident=tau02+Eri
- | accessdate=2016-10-13 | postscript=. }}</ref>
 }}
@@ Line 107: / Line 130: @@
 {{Stars of Eridanus|state=collapsed}}
+{{DEFAULTSORT:Tau2 Eridani}}
 [[Category:K-type giants]]
+[[Category:Horizontal-branch stars]]
 [[Category:Eridanus (constellation)]]
-[[Category:Stars with proper names]]
+[[Category:Stars with proper names|Angetenar]]
 [[Category:Bayer objects|Eridani, Tau2]]
+[[Category:Durchmusterung objects]]
 [[Category:Flamsteed objects|Eridani, 02]]
 [[Category:Henry Draper Catalogue objects|017824]]
 [[Category:Hipparcos objects|013288]]
-[[Category:HR objects|0850]]
+[[Category:Bright Star Catalogue objects|0850]]

Observation data Epoch J2000.0 Equinox J2000.0 (ICRS)
Constellation	Eridanus
Right ascension	02^h 51^m 02.32186^s^[1]
Declination	−21° 00′ 14.4654″^[1]
Apparent magnitude (V)	4.78^[2]
Characteristics
Spectral type	K0 III^[3]
U−B color index	+0.63^[2]
B−V color index	+0.92^[2]
Astrometry

Radial velocity (R_v)	−5.9^[4] km/s
Proper motion (μ)	RA: −38.52^[1] mas/yr Dec.: −16.05^[1] mas/yr
Parallax (π)	17.45 ± 0.20 mas^[1]
Distance	187 ± 2 ly (57.3 ± 0.7 pc)
Absolute magnitude (M_V)	1.008^[5]

Details

Mass	2.39±0.03^[6] `M`_☉
Radius	8.85±0.08^[6] `R`_☉
Luminosity	44.36±0.8^[6] `L`_☉
Surface gravity (log g)	2.95±0.03^[4] cgs
Temperature	5,049±20^[4] K
Metallicity [Fe/H]	0.08±0.06^[4] dex
Rotational velocity (v sin i)	1.11^[4] km/s
Age	720±50^[6] Myr

Other designations
Angetenar, τ² Eridani, 2 Eri, BD−21° 509, HD 17824, HIP 13288, HR 850, SAO 168094.^[7]
Database references
SIMBAD	data