Psi Persei
{{Short description|Star in the constellation Perseus}}
{{Starbox begin
| name = ψ 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=ψ Per
|x=492|y=464
}}
|caption=Location of ψ Persei (circled)
}}
{{Starbox observe
| epoch = J2000
| dec = {{DEC|+48|11|33.4789}}
| constell = Perseus
}}
{{Starbox character
| variable = γ Cas
}}
{{Starbox astrometry
| parallax = 5.59
| p_error = 0.22
}}
{{Starbox detail
| metal_fe =
}}
{{Starbox catalog
| names=ψ Persei, ψ Per, Psi Per, 37 Persei, BD+47°857, GC 4287, HD 22192, HIP 16826, HR 1087, PPM 46127, SAO 46366
}}
{{Starbox reference
|Simbad=psi+Per
}}
{{Starbox end}}
Psi Persei (Psi Per, ψ Persei, ψ Per) is a single Be star in the northern constellation of Perseus. It has an apparent visual magnitude of about 4.2, so it is visible to the naked eye at night under suitably dark skies. Based on parallax measurements, it is located at a distance of roughly {{Convert|580|ly|pc|abbr=off|lk=on}} from the Earth.
Properties
File:PsiPerLightCurve.png for Psi Persei, plotted from TESS data, with the period derived by Percy et al. shown in red.]]
This star has a stellar classification of B5Ve, which indicates it is a B-type main sequence star that is generating energy at its core through the nuclear fusion of hydrogen. It is a shell star with a circumstellar disc of gas surrounding the equator and extending out to about 11 times the radius of the star. As a result of this disc, the spectrum of this star shows emission lines (as indicated by the 'e' in the stellar class) and its magnitude varies over a period 1.021 days. The General Catalog of Variable Stars classifies Psi Persei as a gamma Cassiopeiae variable star, whose visual band brightness varies from magnitude 4.17 to 4.28.
Psi Persei is rotating rapidly with a projected rotational velocity (v sin i) along the equator of 390 km/s or more. The axis of rotation is inclined about {{nowrap|75° ± 8°}} to the line of sight from the Earth, so this velocity is close to the actual azimuthal velocity along the star's equator. It is expelling mass at the rate of about {{nowrap|5.0 × 10−8}} times the mass of the Sun per year, or the equivalent of the Sun's mass every 20 million years. The rapid rotation causes Psi Persei to be an oblate shape, with the equatorial radius being {{solar radius|7.3|link=y}} and the polar radius to be {{solar radius|5.5}}.
This star may be a member of the Alpha Persei Cluster, although its proper motion is high compared to other members. Membership probabilities of 26% and 50% have been published from GALAH plus APOGEE data and from Gaia Data Release 2 data respectively.
Name and etymology
This star, together with δ Per, σ Per, α Per, γ Per and η Per, has been called the Segment of Perseus.
In Chinese, {{lang|zh|天船}} ({{lang|zh-Latn|Tiān Chuán}}), meaning Celestial Boat, refers to an asterism consisting of ψ Persei, η Persei, α Persei, γ Persei, δ Persei, 48 Persei, μ Persei and HD 27084. Consequently, the Chinese name for ψ Persei itself is {{lang|zh|天船四}} ({{lang|zh-Latn|Tiān Chuán sì}}, {{langx|en|the Fourth Star of Celestial Boat}}.)
References
{{reflist|refs
| last1=Samus | first1=N. N. | last2=Kazarovets | first2=E. V.
| last3=Durlevich | first3=O. V. | last4=Kireeva | first4=N. N.
| last5=Pastukhova | first5=E. N. | display-authors=1
| title=General Catalogue of Variable Stars
| version=GCVS 5.1 | journal=Astronomy Reports
| year=2017 | volume=61 | issue=1 | pages=80–88
| doi=10.1134/S1063772917010085 | bibcode=2017ARep...61...80S | s2cid=125853869 }}
| title=The binary fraction and mass segregation in Alpha Persei open cluster
| last1=Sheikhi | first1=Najmeh | last2=Hasheminia | first2=Maryam
| last3=Khalaj | first3=Pouria | last4=Haghi | first4=Hosein
| last5=Zonoozi | first5=Akram Hasani | last6=Baumgardt | first6=Holger
| display-authors=1 | journal=Monthly Notices of the Royal Astronomical Society
| volume=457 | issue=1 | pages=1028–1036 | date=March 2016
| doi=10.1093/mnras/stw059 | doi-access=free | arxiv=1601.02186
| bibcode=2016MNRAS.457.1028S }}
| last=Allen
| first=R. H.
| date=1963
| author-link=Richard Hinckley Allen
| title=Star Names: Their Lore and Meaning
| url=https://archive.org/details/starnamestheirlo00alle/page/331
| access-date=2012-09-04
| edition=Reprint
| publisher=Dover Publications Inc
| location=New York
| isbn=0-486-21079-0
| page=[https://archive.org/details/starnamestheirlo00alle/page/331 331]
| url-access=registration
}}
| title=Critical study of the distribution of rotational velocities of Be stars. I. Deconvolution methods, effects due to gravity darkening, macroturbulence, and binarity
| journal=Astronomy & Astrophysics | display-authors=1
| last1=Zorec | first1=J. | last2=Frémat | first2=Y.
| last3=Domiciano de Souza | first3=A. | last4=Royer | first4=F.
| last5=Cidal | first5=L. | last6=Hubert | first6=A. -M.
| last7=Seemann | first7=T. | last8=Martayan | first8=C.
| last9=Cochetti | first9=Y. R. | last10=Arias | first10=M. L.
| last11=Aidelman | first11=Y. | last12=Stee | first12=P.
| volume=595 | date=November 2016 | pages=26
| bibcode=2016A&A...595A.132Z | doi=10.1051/0004-6361/201628760 | doi-access=free | hdl=11336/37946 | hdl-access=free }}
{{cite conference | last=Evans | first=D. S. | publication-date=1967 | editor=Batten, Alan Henry | editor2=Heard, John Frederick | title=The Revision of the General Catalogue of Radial Velocities | book-title=Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30 | location=University of Toronto | date=June 20–24, 1966 | pages=57–63 | publisher=International Astronomical Union | bibcode=1967IAUS...30...57E }}
{{cite journal | display-authors=1 | last1=Underhill | first1=A. B. | last2=Divan | first2=L. | last3=Prevot-Burnichon | first3=M.-L. | last4=Doazan | first4=V. | title=Effective temperatures, angular diameters, distances and linear radii for 160 O and B stars | journal=Monthly Notices of the Royal Astronomical Society | volume=189 | pages=601–605 |date=November 1979 | issue=3 | bibcode=1979MNRAS.189..601U | doi=10.1093/mnras/189.3.601| doi-access=free }}
}}
{{Stars of Perseus}}
{{DEFAULTSORT:Psi Persei}}
Category:Perseus (constellation)