Alpha Sextantis
{{short description|Star in the constellation Sextans}}
{{Starbox begin
| name = α Sextantis
}}
{{Starbox image
| image =
{{Location mark
| image = Sextans constellation map.svg
| float = center | width = 260 | position = right
| mark = Red circle.svg | mark_width = 10 | mark_link = Alpha Sextantis
| x = 537 | y = 531
}}
| caption = Location of α Sextantis on the map (circled)
}}
{{Starbox observe
| epoch = J2000.0
| constell = Sextans
}}
{{Starbox character
| r-i =
| variable =
}}
{{Starbox astrometry
| parallax = 11.51
| p_error = 0.98
| absmag_v = {{Val|−0.29|0.21}}
}}
{{Starbox detail
| metal_fe = {{Val|−0.03|0.18}}
| rotation =
}}
{{Starbox catalog
| names = α Sex, 15 Sextantis, BD+00°2615, FK5 2814, HD 87887, HIP 49641, HR 3981, SAO 137366.
}}
{{Starbox reference
|Simbad=alf+Sex
}}
{{starbox end}}
Alpha Sextantis (α Sex, α Sextantis) is the brightest star in the equatorial constellation of Sextans. It is visible to the naked eye on a dark night with an apparent visual magnitude of 4.49. The distance to this star, as determined from parallax measurements, is around 280 light years. This is considered an informal "equator star", as it lies less than a quarter of a degree south of the celestial equator. In 1900, it was 7 minutes of arc north of the equator. As a result of Earth's axial precession, it crossed over to the southern hemisphere in December 1923.
The variability of Alpha Sextantis was discovered by Aven Magded Hamadamen and included in the International Variable Star Index.{{Cite web |title=VSX : Detail for alf Sex |url=https://www.aavso.org/vsx/index.php?view=detail.top&oid=2227107 |access-date=2023-12-02 |website=www.aavso.org}} The star undergoes pulsations with a period of 9.1 hours.
This is an evolved A-type giant star with a stellar classification of A0 III. It has around 2.5 times the mass of the Sun and three times the Sun's radius. The abundance of elements is similar to that in the Sun. It radiates 90 times the solar luminosity from its outer atmosphere at an effective temperature of 9,984 K. Alpha Sextantis is nearing the end of its life as a main-sequence star; it is around 385 million years old with a projected rotational velocity of 21 km/s.
References
{{reflist|refs=
| 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 | postscript=. }}
| title=Pulkovo Compilation of Radial Velocities for 35,495 Hipparcos stars in a common system
| last1=Gontcharov | first1=G. A.
| journal=Astronomy Letters | volume=32| issue=11| pages=759–771| date=November 2006
| doi=10.1134/S1063773706110065| bibcode=2006AstL...32..759G |arxiv = 1606.08053 | s2cid=119231169 }}
| title=Search for reference A0 dwarf stars: Masses and luminosities revisited with HIPPARCOS parallaxes
| last1=Gerbaldi, M. | last2=Faraggiana, R.
| last3=Burnage, R. | last4=Delmas, F.
| last5=Gómez, A. E. | last6=Grenier, S.
| journal=Astronomy and Astrophysics Supplement | display-authors=1
| volume=137 | pages=273–292 | date=June 1999
| issue=2 | doi=10.1051/aas:1999248 | bibcode=1999A&AS..137..273G
| postscript=. | doi-access=free }}
| title=Elemental abundance analyses with the EBASIM spectrograph of the 2.1-m CASLEO Observatory Telescope. I. The late B and early A stars vec xi Octantis, alpha Sextantis, and 68 Tauri
| last1=Pintado | first1=O. I. | last2=Adelman | first2=S. J.
| journal=Astronomy and Astrophysics
| volume=406 | pages=987–994 | date=August 2003
| issue=3 | doi=10.1051/0004-6361:20030813
| bibcode=2003A&A...406..987P
| postscript=. | doi-access=free}}
| last1=Cowley | first1=A. | last2=Cowley | first2=C.
| last3=Jaschek | first3=M. | last4=Jaschek | first4=C.
| title=A study of the bright A stars. I. A catalogue of spectral classifications
| journal=Astronomical Journal | display-authors=1
| volume=74 | pages=375–406 | date=April 1969
| doi=10.1086/110819 | bibcode=1969AJ.....74..375C
| postscript=. }}
| 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
| volume=427 | issue=1 | pages=343–57 | date=2012
| bibcode=2012MNRAS.427..343M | arxiv=1208.2037
| doi=10.1111/j.1365-2966.2012.21873.x | doi-access=free | s2cid=118665352 | postscript=. }}
| title=Rotational velocities of A-type stars in the northern hemisphere. II. Measurement of v sin i
| display-authors=1 | last1=Royer | first1=F.
| last2=Grenier | first2=S. | last3=Baylac | first3=M.-O.
| last4=Gómez | first4=A. E. | last5=Zorec | first5=J.
| journal=Astronomy and Astrophysics
| volume=393 | pages=897–911 | date=October 2002
| issue=3 | doi=10.1051/0004-6361:20020943 | bibcode=2002A&A...393..897R
| arxiv=astro-ph/0205255 | s2cid=14070763 | postscript=. }}
| title=Sextans (abbr. Sex, gen. Sextantis)
| url=http://www.daviddarling.info/encyclopedia/S/Sex.html
| encyclopedia=The Internet Encyclopedia of Science
| accessdate=2016-12-12 | postscript=. }}
| first1=James B. | last1=Kaler
| title=Alpha Sextantis | work=Stars | publisher=University of Illinois
| url=http://stars.astro.illinois.edu/sow/alphasext.html
| accessdate=2016-12-12 | postscript=. }}
| 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 | postscript=.
| date=1986 | bibcode=1986EgUBV........0M }}
| title=alf Sex
| accessdate=2016-12-12 | postscript=. }}
}}
External links
- [https://web.archive.org/web/20060705214728/http://www.site.uottawa.ca:4321/astronomy/index.html#AlphaSextantis Astronomy Knowledge Database]
{{Stars of Sextans|state=collapsed}}
{{DEFAULTSORT:Alpha Sextantis}}