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词条 Beta Cassiopeiae
释义

  1. Nomenclature

  2. Visibility

  3. System

  4. References

  5. External links

{{Starbox begin |
| name=Caph, Beta Cassiopeiae }}{{Starbox image
| image={{Location mark
|image=Cassiopeia constellation map.svg|alt=|float=center|width=280
|label=|position=right
|mark=Red circle.svg|mark_width=12|mark_link=Beta Cassiopeiae|x=572|y=536
}}
|caption=Location of β Cassiopeiae (circled)

}}{{Starbox observe |

  epoch=J2000 |  ra={{RA|00|09|10.68518}} |  dec={{DEC|+59|08|59.2120}} |  appmag_v=+2.28 (2.25–2.31)[3] |  constell=Cassiopeia }}
{{Starbox character |
  class=F2 III[1] |  b-v=0.34[5] |  u-b=0.11[5] |  variable=δ Sct[7]

}}{{Starbox astrometry |
  radial_v=11.3[8] |  prop_mo_ra=523.50 |  prop_mo_dec=-179.77 |  parallax=59.58 |  p_error=0.38 |  parallax_footnote= |  absmag_v=+1.3[2]

}}{{Starbox detail|
  mass={{nowrap|1.91 ± 0.02}}[13] |  radius=3.43–3.69[13] |  luminosity=27.3[13] |  temperature=7,079[7] |  gravity=3.40[7] |  metal_fe=0.03[13] |  rotational_velocity = 71.0[19] |  age_gyr=1.09–1.18[13] }}
{{Starbox catalog |
}}{{Starbox reference
| Simbad = beta+Cas
}}{{Starbox end}}

Beta Cassiopeiae (β Cassiopeiae, abbreviated Beta Cas or β Cas), also named Caph,[3] is a Delta Scuti variable star in the constellation of Cassiopeia. It is a giant star belonging to the spectral class F2. The white star of second magnitude (+2.27 mag) has an absolute magnitude of +1.16 mag.

Nomenclature

Beta Cassiopeiae is the star's Bayer designation. It also bore the traditional names Caph (from the Arabic word {{lang|ar|كف}} {{transl|ar|kaf}}, "palm" - i.e. reaching from the Pleiades), Chaph and Kaff, as well as al-Sanam al-Nakah "the Camel's Hump".[21] In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[4] to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016[5] included a table of the first two batches of names approved by the WGSN; which included Caph for this star.

Originally, the pre-Islamic Arabic term al-Kaff al-Khadib "the stained hand" referred to the five stars comprising the 'W' of the constellation Cassiopeia, and depicted a hand stained with henna. The term was abbreviated and somehow came to signify β Cassiopeiae alone. The old "stained hand" was part of an asterism called Thuraya stretching from the Pleiades, which signified the "head" through Taurus and Perseus and into Cassiopeia, while the other "hand" was in Cetus.[27]

In Chinese, {{lang|zh|王良}} ({{lang|zh-Latn|Wáng Liáng}}), meaning Wang Liang[6], refers to an asterism consisting of β Cassiopeiae, κ Cassiopeiae, η Cassiopeiae, α Cassiopeiae and λ Cassiopeiae.[7] Consequently, β Cassiopeiae itself is known as {{lang|zh|王良一}} ({{lang|zh-Latn|Wáng Liáng yī}}, {{lang-en|the First Star of Wang Liang}}.)[8]

Together with Alpha Andromedae (Alpheratz) and Gamma Pegasi (Algenib), Beta Cassiopeiae was one of three bright stars known as the "Three Guides" marking the equinoctial colure.[21] This is an imaginary line running due south from Beta Cassiopeiae through Alpha Andromedae to the celestial equator, at a point where the Sun's path (the ecliptic) crosses it each autumn and spring equinox.[32]

Visibility

With a mean apparent magnitude (V-band) of +2.27, it is one of the five stars which make up the 'W' of Cassiopeia, adjacent to the just brighter Schedar (Alpha Cassiopeiae).[32] SN 1572, traditionally known as Tycho's Star, appeared about 5 degrees to the northwest of Caph in 1572.[21]

As a star in the deep northern hemisphere of the sky, Beta Cassiopeiae is prominent to viewers in the northern hemisphere but not often seen by those in the southern hemisphere. The constellation of Cassiopeia does not rise above the horizon to viewers in Tasmania, and only low if one were in Cairns.[9]

System

β Cassiopeiae is a yellow-white hued giant of stellar class F2 III with a surface temperature around {{val|7,000|ul=K}}. More than three times the size of and 28 times brighter than the Sun, Caph has an absolute magnitude of +1.16. It was once an A-type star with about double the Sun's mass.[13] It is now in the process of cooling and expanding to become a red giant. Its core is likely to have used up its hydrogen and is shrinking and heating, while its outer envelope of hydrogen is expanding and cooling. Stars do not spend much time in this state and are relatively uncommon. Caph's corona is unusually weak.[32]

β Cassiopeiae is a variable star of the Delta Scuti type, in fact the second brightest of such stars in the sky after Altair.[38] It is a monoperiodic pulsator,[39] with a brightness that ranges from magnitude +2.25 to +2.31 with a period of 2.5 hours.[32] This type of variable includes subgiant or main sequence stars of spectral classes F5–A0, having masses between 1.5–2.5 solar masses and nearing the end of their core hydrogen fusion lifetime.[39] Their pulsations are related to the same helium instability strip on the Hertzsprung–Russell diagram as that of classical Cepheids. Delta Scuti stars are located at the intersection of the strip with the main sequence.[42]

This star is rotating at about 92% of its critical speed, completing 1.12 rotations every day. This is giving the star an oblate spheroid shape with an equatorial bulge that is 24% larger than the polar radius. This shape is causing the polar region to have a higher temperature than the equator: the temperature difference is about 1,000 K. The axis of rotation is inclined about 20° to the line of sight from the Earth.[13]

β Cassiopeiae was once considered to be a spectroscopic binary with a faint companion in a 27-day orbit, but it is now thought to be a single star.[10]

References

1. ^{{cite journal|bibcode=2003AJ....126.2048G|title=Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 Parsecs: The Northern Sample. I|journal=The Astronomical Journal|volume=126|issue=4|pages=2048|author1=Gray|first1=R. O.|last2=Corbally|first2=C. J.|last3=Garrison|first3=R. F.|last4=McFadden|first4=M. T.|last5=Robinson|first5=P. E.|year=2003|doi=10.1086/378365|arxiv = astro-ph/0308182 }}
2. ^{{cite journal|bibcode=1998A&A...330..619J|title=The absolute magnitude of the early type MK standards from HIPPARCOS parallaxes|journal=Astronomy and Astrophysics|volume=330|pages=619|author1=Jaschek|first1=C.|last2=Gomez|first2=A. E.|year=1998}}
3. ^{{cite web | url=http://www.pas.rochester.edu/~emamajek/WGSN/IAU-CSN.txt | title=IAU Catalog of Star Names |accessdate=28 July 2016}}
4. ^{{cite web | url=https://www.iau.org/science/scientific_bodies/working_groups/280/ | title=IAU Working Group on Star Names (WGSN)|accessdate=22 May 2016}}
5. ^{{cite web | url=http://www.pas.rochester.edu/~emamajek/WGSN/WGSN_bulletin1.pdf | title=Bulletin of the IAU Working Group on Star Names, No. 1 |accessdate=28 July 2016}}
6. ^Wang Liang was a famous charioteer during the Spring and Autumn period
7. ^{{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}}.
8. ^{{zh icon}} 香港太空館 - 研究資源 - 亮星中英對照表 {{webarchive|url=https://web.archive.org/web/20090929163750/http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/c_research_chinengstars_c_d.htm |date=2009-09-29 }}, Hong Kong Space Museum. Accessed on line November 23, 2010.
9. ^{{cite book |title=The Australian Sky|author=Newell, W. J. |date=1965 |publisher=Jacaranda Press |location= |isbn=0-7016-0037-3|page=84}}
10. ^{{cite journal|bibcode=1989ApJ...343..916T|title=The chromosphere of Beta Cassiopeiae|journal=Astrophysical Journal|volume=343|pages=916|author1=Teays|first1=Terry J.|last2=Schmidt|first2=Edward G.|last3=Pasinetti Fracassini|first3=Laura E.|last4=Fracassini|first4=Massimo|year=1989|doi=10.1086/167761}}
11. ^1 {{cite book | last=Evans | first=D. S. | date=June 20–24, 1966 | editor=Batten, Alan Henry | editor2=Heard, John Frederick | contribution=The Revision of the General Catalogue of Radial Velocities | title=Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30 | location=University of Toronto | publisher=International Astronomical Union | bibcode=1967IAUS...30...57E }}
12. ^1 2 {{cite journal | display-authors=1 | last1=Johnson | 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 | date=1966 | bibcode=1966CoLPL...4...99J }}
13. ^1 {{cite book | display-authors=1 | last1=Kukarkin | first1=B. V. | last2=Kholopov | first2=P. N. | last3=Pskovsky | first3=Y. P. | last4=Efremov | first4=Y. N. | last5=Kukarkina | first5=N. P. | last6=Kurochkin | first6=N. E. | last7=Medvedeva | first7=G. I. | title=General Catalogue of Variable Stars containing information on 20437 variable stars discovered and designated till 1968 | edition=3rd | date=1971 | bibcode=1971GCVS3.C......0K }}
14. ^1 {{cite web | title=V* bet Cas—Variable Star of delta Sct type | work=SIMBAD | publisher=Centre de Données astronomiques de Strasbourg | url=http://simbad.u-strasbg.fr/simbad/sim-id?Ident=Beta+Cassiopeiae | accessdate=2011-12-16 }}
15. ^1 2 3 {{cite journal | last1=Daszyńska | first1=J. | last2=Cugier | first2=H. | date=2003 | title=Far-Ultraviolet light curves of the δ Scuti variable: β Cassiopeiae | journal=Advances in Space Research | volume=31 | issue=2 | pages=381–386 | doi=10.1016/S0273-1177(02)00630-0 | bibcode=2003AdSpR..31..381D }}
16. ^1 {{cite book | title=Dictionary of Modern Star Names | last1=Kunitzsch | first1=Paul | last2=Smart | first2=Tim | date=2006 | publisher=Sky Publishing | location=Cambridge, MA | isbn=1-931559-44-9 | page=26 }}
17. ^1 {{cite journal | last1=Schröder | first1=C. | last2=Reiners | first2=A. | last3=Schmitt | first3=J. H. M. M. | title=Ca II HK emission in rapidly rotating stars. Evidence for an onset of the solar-type dynamo | journal=Astronomy and Astrophysics | volume=493 | issue=3 | pages=1099–1107 |date=January 2009 | doi=10.1051/0004-6361:200810377 | bibcode=2009A&A...493.1099S | url=http://goedoc.uni-goettingen.de/goescholar/bitstream/handle/1/9690/aa10377-08.pdf?sequence=2 }}
18. ^1 {{cite journal | display-authors=1 | last1=Buzasi | first1=D. L. | last2=Bruntt | first2=H. | last3=Bedding | first3=T. R. | last4=Retter | first4=A. | last5=Kjeldsen | first5=H. | last6=Preston | first6=H. L. | last7=Mandeville | first7=W. J. | last8=Suarez | first8=J. C. | last9=Catanzarite | first9=J. | journal=The Astrophysical Journal | date=2005 | title=Altair: The Brightest δ Scuti Star | volume=619 | issue=2 | pages=1072–76 | doi=10.1086/426704 | bibcode=2005ApJ...619.1072B | arxiv=astro-ph/0405127 }}
19. ^1 2 3 4 5 6 7 {{cite journal | display-authors=1 | last1=Che | first1=X. | last2=Monnier | first2=J. D. | last3=Zhao | first3=M. | last4=Pedretti | first4=E. | last5=Thureau | first5=N. | last6=Mérand | first6=A. | last7=ten Brummelaar | first7=T. | last8=McAlister | first8=H. | last9=Ridgway | first9=S. T. | title=Colder and Hotter: Interferometric Imaging of β Cassiopeiae and α Leonis | journal=The Astrophysical Journal | volume=732 | issue=2 | pages=68 |date=May 2011 | doi=10.1088/0004-637X/732/2/68 | bibcode=2011ApJ...732...68C |arxiv = 1105.0740 }}
20. ^1 2 3 4 {{cite book | title=The Hundred Greatest Stars | last1=Kaler | first1=James B. | date=2002 | publisher=Copernicus Books | location=New York | isbn=0-387-95436-8 | page=27 }}
21. ^1 {{cite book | first1=John R. | last1=Percy | title=Understanding variable stars | date=2007 | publisher=Cambridge University Press | isbn=978-0-521-23253-1 | pages=139–144, 182–187 }}
22. ^1 2 3 4 {{cite book | title=Star-names and their meanings | last1=Allen | first1=Richard Hinckley | date=1963 | origyear=1899 | publisher=Dover Publications | location=New York, NY | isbn=1-931559-44-9 | page=146 }}
23. ^1 2 {{cite book | last1=Poretti | first1=E. | contribution=The Frequency Content of δ Scuti Stars as Determined by Photometry | title=Delta Scuti and Related Stars, Reference Handbook and Proceedings of the 6th Vienna Workshop in Astrophysics, held in Vienna, Austria, 4–7 August 1999 | series=ASP Conference Series | volume=210 | editor1-first=Michel | editor1-last=Breger | editor2-first=Michael | editor2-last=Montgomery | page=45 | date=2000 | bibcode=2000ASPC..210...45P |arxiv = astro-ph/0002304 }}
[11][12][13][14][15][16][17][18][19][20][21][22][23]
}}

External links

  • {{WikiSky}}
{{Stars of Cassiopeia}}

11 : Bayer objects|Flamsteed objects|Cassiopeia (constellation)|Delta Scuti variables|F-type giants|Stars with proper names|HR objects|Henry Draper Catalogue objects|Hipparcos objects|Durchmusterung objects|Gliese and GJ objects
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