Epsilon Cassiopeiae

{{Starbox image

| image =

{{Location mark

| image=Cassiopeia constellation map.png

| float=center | width=240 | position=right

| mark=Red circle.svg | mark_width=10 | mark_link=ι Exa

| x%=24.4 | y%=37.4

}}

| caption = Location of ε Cas (circled)

}}

{{Starbox observe

| epoch = J2000

| ra = {{RA|01|54|23.73409}}

| dec = {{DEC|+63|40|12.3602}}

| appmag_v = 3.37

| constell = Cassiopeia

}}

{{Starbox character

| class = B3 V

| b-v = −0.15

| u-b = −0.62

| variable = Periodic

}}

{{Starbox astrometry

| radial_v = −8.1

| prop_mo_ra = +29.587

| prop_mo_dec = −18.387

| parallax = 7.0037

| p_error = 0.1599

| parallax_footnote =

| absmag_v = −2.19

}}

{{Starbox detail

| mass = {{val|9.2|0.2}}

| radius = {{val|6.10|0.06}}

| luminosity = 3,059

| temperature = 15,174

| gravity = 3.5

| metal_fe = −0.28

| rotational_velocity = 30

| age_myr = {{val|15.4|3.0}}

}}

{{Starbox catalog

| names = {{odlist | name=Segin | B=Epsilon Cas, ε Cas | F=45 Cassiopeiae | BD=+62 320 | FK5=63 | HD=11415 | HIP=8886 | HR=542 | SAO=12031 }}

}}

{{Starbox reference

| Simbad=HR542

}}

Epsilon Cassiopeiae or ε Cassiopeiae, officially named Segin ({{IPAc-en|'|s|E|g|I|n}}), is a single star in the northern constellation of Cassiopeia. With an apparent visual magnitude of 3.4, this is one of the brightest stars in the constellation. The distance to this star has been determined directly using parallax measurements, yielding a value of around {{Convert|460|-|430|ly|pc|abbr=off|lk=on}} from the Sun. It is drifting closer with a radial velocity of −8 km/s.

Nomenclature

ε Cassiopeiae, Latinised to Epsilon Cassiopeiae, is the star's Bayer catalog designation.

The star bore the traditional name Segin, which probably originates from an erroneous transcription of Seginus, the traditional name for Gamma Boötis, which itself is of uncertain origin. Different sources report varying pronunciations, with SEG-in the most common but the variants SAY-gin and seg-EEN also appearing. In 2016, the IAU organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN approved the name Segin for this star on 5 September 2017 and it is now so included in the List of IAU-approved Star Names.

While some published reports incorrectly claim that this star was designated by NASA as Navi ('Ivan', backwards), in honor of astronaut Virgil Ivan "Gus" Grissom, one of the three astronauts who died in the Apollo 1 accident, the actual star so designated is Gamma Cassiopeiae in the center of the constellation.

In Chinese, {{lang|zh|閣道}} ({{lang|zh-Latn|Gé Dào}}), meaning Flying Corridor, refers to an asterism consisting of Epsilon Cassiopeiae, Iota Cassiopeiae, Delta Cassiopeiae, Theta Cassiopeiae, Nu Cassiopeiae and Omicron Cassiopeiae. Consequently, the Chinese name for Epsilon Cassiopeiae itself is {{lang|zh|閣道二}} ({{lang|zh-Latn|Gé Dào èr}}, {{langx|en|the Second Star of Flying Corridor}}.)

Properties

File:EpsilonCasLightCurve.png for Epsilon Cassiopeiae, plotted from Hipparcos data]]

Epsilon Cassiopeiae has a stellar classification of B3 V, indicating that it is a main sequence star fusing hydrogen in its core. Cote et al. (2003) indicate that it displays the spectral properties of a Be star, even though it is not categorized as such. The presence of emission lines in the spectrum indicates the presence of a circumstellar shell of gas that has been thrown off by the star. Epsilon Cassiopeiae has nine times the mass and six times the radius of the Sun. It is radiating 3,000 times the luminosity of the Sun from its photosphere at an effective temperature of {{convert|15174|K|abbr=on|lk=on}}, giving it the blue-white hue of a B-type star.

Observation during the Hipparcos mission suggest that the star may undergo weak periodic variability. The amplitude of this variation is 0.0025 in magnitude with a frequency of 11.17797 times per day, or one cycle every 2.15 hours. The signal-to-noise ratio for this measured variation is 4.978. Hipparcos measurements of the space velocity components for this star suggest that it is a member of the Cas-Tau group of co-moving stars, with a 93% likelihood. This group may be kinematically associated with the alpha Persei Cluster, indicating that the Cas-Tau group, including Epsilon Cassiopeiae, may have been separated from the cluster through tidal interactions.

References

{{reflist|colwidth=25em|refs=

{{cite journal | last1 = Anderson | first1 = E. | last2 = Francis | first2 = Ch. | title = XHIP: An extended hipparcos compilation | journal = Astronomy Letters | date = May 2012 | volume = 38 | issue = 5 | pages = 331–346 | issn = 1063-7737 | eissn = 1562-6873 | doi = 10.1134/S1063773712050015 | bibcode = 2012AstL...38..331A | arxiv = 1108.4971| s2cid = 119257644 }}

{{in lang|zh}} [http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/c_research_chinengstars_s.htm 香港太空館 - 研究資源 - 亮星中英對照表] {{webarchive |url=https://web.archive.org/web/20100818141141/http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/c_research_chinengstars_s.htm |date=August 18, 2010 }}, Hong Kong Space Museum. Accessed on line November 23, 2010.

{{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}}.

{{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}}

{{cite web|title=Audio Pronunciation Guide|url=http://www.starrynighteducation.com/resources_pronunciation.html|website=Starry Night Education|access-date=7 August 2014}}

{{cite book|last1=Simpson|first1=Phil|title=Guidebook to the constellations|date=2012|publisher=Springer|location=New York|isbn=9781441969408|chapter=3}}

starrynighteducation.com, Audio Pronunciation Guide

{{cite web | url=https://www.iau.org/public/themes/naming_stars/ | title=Naming Stars |publisher=IAU.org |access-date=16 December 2017}}

{{cite journal |title=Light Curve |url=https://www.cosmos.esa.int/web/hipparcos/java-tools/light-curve |website=Hipparcos ESA |publisher=ESA |access-date=10 October 2022}}

{{cite news |first=Joe |last=Rao |url=http://www.space.com/spacewatch/star_names_030829.html |title=NightSky Friday: Rotanev, Derf, Navi, and other Backward Star Names |publisher=Space.com |date=August 29, 2003}}

{{cite web |work=Apollo 15 Lunar Surface Journal |url=https://history.nasa.gov/alsj/a15/a15.postland.html |title=Post-landing Activities |publisher=NASA}} commentary at 105:11:33

{{cite web |publisher=Heritage Auction Galleries |title=Apollo 10 Flown CSM Star Chart Directly from the Personal Collection of Mission Command Module Pilot John Young |url=http://historical.ha.com/common/view_item.php?Sale_No=6037&Lot_No=0&LotIdNo=12016&ts=off#Photo |access-date=March 11, 2010}}

{{cite journal | display-authors=1 | title=Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions | journal=Veröff. Astron. Rechen-Inst. Heidelb | volume=35 | last1=Wielen | first1=R. | last2=Schwan | first2=H. | last3=Dettbarn | first3=C. | last4=Lenhardt | first4=H. | last5=Jahreiß | first5=H. | last6=Jährling | first6=R. | publisher=Astronomisches Rechen-Institut Heidelberg | issue=35 | year=1999 | page=1 | bibcode=1999VeARI..35....1W }}

{{cite journal | last1=Abt | first1=Helmut A. | last2=Levato | first2=Hugo | last3=Grosso | first3=Monica | title=Rotational Velocities of B Stars | journal=The Astrophysical Journal | volume=573 | issue=1 | pages=359–365 |date=July 2002 | doi=10.1086/340590 | bibcode=2002ApJ...573..359A | doi-access=free }}

{{cite journal | last1=Johnson | display-authors=1 | first1=H. L. | last2=Iriarte | first2=B. | last3=Mitchell | first3=R. I. | last4=Wisniewskj | first4=W. Z. | title=UBVRIJKL photometry of the bright stars | journal=Communications of the Lunar and Planetary Laboratory | volume=4 | issue=99 | pages=99 | year=1966 | bibcode=1966CoLPL...4...99J }}

{{cite journal | display-authors=1 | last1=Takeda | first1=Yoichi | last2=Kambe | first2=Eiji | last3=Sadakane | first3=Kozo | last4=Masada | first4=Seiji | title=Oxygen and Neon Abundances of B-Type Stars in Comparison with the Sun | journal=Publications of the Astronomical Society of Japan | volume=62 | issue=5 | pages=1239–1248 |date=October 2010 | bibcode=2010PASJ...62.1239T |arxiv = 1008.1220 | doi=10.1093/pasj/62.5.1239| s2cid=118536224 }}

{{cite journal | last1=Koen | first1=Chris | last2=Eyer | first2=Laurent | title=New periodic variables from the Hipparcos epoch photometry | journal=Monthly Notices of the Royal Astronomical Society | volume=331 | issue=1 | pages=45–59 |date=March 2002 | doi=10.1046/j.1365-8711.2002.05150.x | doi-access=free | bibcode=2002MNRAS.331...45K |arxiv = astro-ph/0112194 | s2cid=10505995 }}

{{cite journal | display-authors=1 | last1=de Zeeuw | first1=P. T. | last2=Hoogerwerf | first2=R. | last3=de Bruijne | first3=J. H. J. | last4=Brown | first4=A. G. A. | last5=Blaauw | first5=A. | title=A HIPPARCOS Census of the Nearby OB Associations | journal=The Astronomical Journal | volume=117 | issue=1 | pages=354–399 |date=January 1999 | doi=10.1086/300682 | bibcode=1999AJ....117..354D |arxiv = astro-ph/9809227 | s2cid=16098861 }}

{{cite web |title=The Colour of Stars |date=December 21, 2004 |work=Australia Telescope, Outreach and Education |publisher=Commonwealth Scientific and Industrial Research Organisation |url=http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html |access-date=2012-01-16 |url-status=dead |archive-url=https://web.archive.org/web/20120318151427/http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html |archive-date=2012-03-18 }}

{{cite journal | last1=Cote | first1=J. | last2=van Kerkwijk | first2=M. H. | title=New Bright Be-Stars and the Be-Star Frequency | journal=Astronomy and Astrophysics | volume=274 | issue=3 | page=870 |date=July 1993 | bibcode=1993A&A...274..870C }}

{{cite journal | last1=Andrillat | first1=A. | last2=Jaschek | first2=M. | last3=Jaschek | first3=C. | title=A survey of Be stars in the infrared. II - Determination of envelope dimensions | journal=Astronomy and Astrophysics Supplement Series | volume=84 | issue=1 | pages=11–28 |date=July 1990 | bibcode=1990A&AS...84...11A }}

{{cite journal | last1=Tetzlaff | first1=N. | last2=Neuhäuser | first2=R. | last3=Hohle | first3=M. M. | title=A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun | journal=Monthly Notices of the Royal Astronomical Society | volume=410 | issue=1 | pages=190–200 |date=January 2011 | doi=10.1111/j.1365-2966.2010.17434.x | doi-access=free | bibcode=2011MNRAS.410..190T |arxiv = 1007.4883 | s2cid=118629873 }}

{{cite journal|bibcode=1982ApJS...50...55S|title=Spectral types and rotational velocities of the brighter Be stars and A-F type shell stars|journal=Astrophysical Journal Supplement Series|volume=50|pages=55|last1=Slettebak|first1=A.|year=1982|doi=10.1086/190820|doi-access=free}}

{{cite journal

| display-authors=1 | last1=Huang | first1=W.

| last2=Wallerstein | first2=G. | last3=Stone | first3=M.

| title=A catalogue of Paschen-line profiles in standard stars

| journal=Astronomy & Astrophysics

| volume=547 | pages=A62 | year=2012

| bibcode=2012A&A...547A..62H | arxiv=1210.7893

| doi=10.1051/0004-6361/201219804 | s2cid=119286159 }}

{{cite journal

| title=Surveying the Bright Stars by Optical Interferometry. III. A Magnitude-limited Multiplicity Survey of Classical Be Stars | year=2021

| last1=Hutter | first1=D. J. | last2=Tycner | first2=C.

| last3=Zavala | first3=R. T. | last4=Benson | first4=J. A.

| last5=Hummel | first5=C. A. | last6=Zirm | first6=H.

| journal=The Astrophysical Journal Supplement Series

| volume=257 | issue=2 | page=69

| doi=10.3847/1538-4365/ac23cb | arxiv=2109.06839

| bibcode=2021ApJS..257...69H | s2cid=237503492 | doi-access=free

}}

External links

{{cite web | title=SEGIN (Epsilon Cassiopeiae) | publisher=University of Illinois | first1=James B. | last1=Kaler | url=http://stars.astro.illinois.edu/sow/Segin.html | access-date=2010-02-21}}

Category:B-type main-sequence stars

Category:Be stars

Category:Suspected variables

Category:Cassiopeia (constellation)

Cassiopeiae, Epsilon

Category:Durchmusterung objects