tau Persei

{{Short description|Star in the constellation Perseus}}

{{Starbox begin

|name=τ Persei

}}

{{Starbox image

| image=

{{Location mark

|image=Perseus constellation map.svg|alt=|float=center|width=260

|label=|position=right

|mark=Red circle.svg|mark_width=10|mark_link=τ Per

|x=672|y=329

}}

|caption=Location of τ Persei (circled)

}}

{{Starbox observe

|constell=Perseus

|epoch=J2000

|ra={{RA|02|45|15.46108}}{{cite journal|title=Validation of the new Hipparcos reduction|url=http://www.aanda.org/index.php?option=com_article&access=bibcode&Itemid=129&bibcode=2007A%2526A...474..653VFUL|author1=van Leeuwen, F.|display-authors=etal|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}}

|dec={{DEC|+52|45|44.9240}}

|appmag_v=3.94 - 4.07

}}

{{Starbox character

|b-v=+0.74

|u-b=+0.46

|variable=Algol{{cite journal|bibcode=2009yCat....102025S|title=VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)|journal=VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S|volume=1|display-authors=etal|last1=Samus|first1=N. N.|last2=Durlevich|first2=O. V.|year=2009}}

}}

{{Starbox character|no_heading=y

|component1=τ Per A

|class=G8 IIIa{{cite journal|title=Optical Spectra of Zeta-Aurigae Binary Systems - Part Three - the 1989 Eclipse of Tau-Persei|author1=Griffin, R. E. M.|author2=Schroder, K. P.|author3=Misch, A.|author4=Griffin, R. F.|journal=Astronomy and Astrophysics|volume=254|page=289|date=1992|bibcode=1992A&A...254..289G}}

|b-v=+0.91

|u-b=+0.68

|component2=τ Per B

|class2=A3-4 V

|b-v2=+0.15

|u-b2=+0.07

}}

{{Starbox astrometry

|radial_v=2.2 ± 0.7{{cite journal|title=Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system|author=Gontcharov, G. A.|date=2006|journal=Astronomy Letters|volume=32|issue=11|pages=759–771|bibcode=2006AstL...32..759G|doi=10.1134/S1063773706110065|arxiv=1606.08053|s2cid=119231169}}

|prop_mo_ra=−1.26

|prop_mo_dec=−4.37

|parallax=12.83

|p_error=0.36

|parallax_footnote=

|absmag_v=−0.65
−0.45 / 1.26

}}

{{Starbox orbit

|reference={{cite web|url=http://www.usno.navy.mil/USNO/astrometry/optical-IR-prod/wds/orb6|title=Sixth Catalog of Orbits of Visual Binary Stars|work=United States Naval Observatory|accessdate=4 April 2017|archive-date=1 August 2017|archive-url=https://web.archive.org/web/20170801102553/http://www.usno.navy.mil/USNO/astrometry/optical-IR-prod/wds/orb6|url-status=dead}}

|period=4.149

|axis_unitless=0.055

|inclination=94.5

|node=100.6

|eccentricity=0.728

|periarg=54.1

|periastron=B 2013.888

}}

{{Starbox detail

|component1=τ Per A

|mass=2.99 ± 0.10{{cite journal|title=The metallicity signature of evolved stars with planets|author1=Maldonado, J.|author2=Villaver, E.|author3=Eiroa, C.|journal=Astronomy & Astrophysics|volume=554|page=2013|bibcode=2013A&A...554A..84M|doi=10.1051/0004-6361/201321082|arxiv=1303.3418|year=2013|s2cid=119289111}}

|radius=16.08 ± 0.54

|temperature=5507 ± 83

|gravity=2.47 ± 0.03

|metal_fe=−0.20 ± 0.03

|luminosity=191

|age_gyr=0.39 ± 0.05

|component2=τ Per B

|mass2=1.8

|radius2=2.2

|temperature2=8970 ± 150

}}

{{Starbox catalog

|names=18 Per, BD+52°641, HD 17878, HD 17879, HIP 13531, HR 854, SAO 23685

}}

{{Starbox reference

|Simbad=tau+Per

}}

{{Starbox end}}

Tau Persei (τ Per), also known as 18 Persei, is a binary star in the constellation of Perseus. The system is fairly close, and is located about 254 light-years (78 parsecs) away, based on its parallax.

File:TauEriLightCurve.png

Tau Persei is an eclipsing binary, which means the two stellar components orbit each other in such an orientation that they periodically eclipse each other, while blocking the other's light. Unlike many eclipsing binaries that have short orbital periods, Tau Persei has an orbital period of 4.15 years. With a semi-major axis of 0.055 arcseconds, this is one of the few eclipsing binaries whose components can be resolved with interferometry.{{cite journal|doi=10.1086/113021|title=Speckle interferometry of Tau Persei|journal=The Astronomical Journal|volume=86|pages=1397|year=1981|last1=McAlister|first1=H. A.|bibcode = 1981AJ.....86.1397M }}

The primary component of Tau Persei is a red giant with a spectral type of G8III. It has a radius 16 times that of the Sun, and is about 390 million years old. Its companion is an A-type main-sequence star. In 1989, the primary star eclipsed the secondary, allowing for the stellar parameters to be derived via its light curve.