“Eta Cephei”的意思、由来-开放百科全书

Eta Cephei, along with α Cep (Alderamin) and β Cep (Alfirk), were identified as Al Kawākib al Firḳ (الكوكب الفرق), meaning "the Stars of The Flock" by Ulug Beg.^[23]^[24]

In Chinese, {{lang|zh|天鈎}} ({{lang|zh-Latn|Tiān Gōu}}), meaning Celestial Hook, refers to an asterism consisting of η Cephei, 4 Cephei, HD 194298, θ Cephei, α Cephei, ξ Cephei, 26 Cephei, ι Cephei and ο Cephei.^[1] Consequently, η Cephei itself is known as {{lang|zh|天鈎四}} ({{lang|zh-Latn|Tiān Gōu sì}}, {{lang-en|the Fourth Star of Celestial Hook}}.).^[2]

Properties

Eta Cephei is a subgiant star with a stellar classification of K0 IV,^[4] which indicates it is exhausting the supply of hydrogen at its core and is in the process of evolving into a giant star. With 1.6^[12] times the Sun's mass, at an age of 2.5^[12] billion years it has reached a radius four times larger than the Sun^[13] and a luminosity ten times greater.^[13] It is radiating this energy from its outer atmosphere at an effective temperature of 4,950 K,^[13] giving it the orange-hued glow of a K-type star. Eta Cephei has a high proper motion across the celestial sphere^[20] and a large peculiar velocity of {{nowrap|112 km s⁻¹}}.^[12]

Hunt for substellar objects

According to Nelson & Angel (1998),^[35] Eta Cephei would show two significant periodicities of 164 days and 10 years respectively, hinting at the possible presence of one or more jovian planets in orbit around the subgiant. The authors have set an upper limit of 0.64 Jupiter masses for the putative inner planet and 1.2 Jupiter masses for the putative outer one. Also Campbell et al. (1988)^[36] inferred the existence of planetary objects or even brown dwarfs less massive than 16.3 Jupiter masses.

However, more recent studies have not yet confirmed the existence of any substellar companion around Eta Cephei. McDonald Observatory team has set limits to the presence of one or more planets^[37] with masses between 0.13 and 2.4 Jupiter masses and average separations spanning between 0.05 and 5.2 AU.

References

1. ^{{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}}.
2. ^{{zh icon}} AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 6 日
3. ^¹²³⁴⁵⁶⁷⁸{{citation | display-authors=1 | last1=Piau | first1=L. | last2=Kervella | first2=P. | last3=Dib | first3=S. | last4=Hauschildt | first4=P. | title=Surface convection and red-giant radius measurements | journal=Astronomy and Astrophysics | volume=526 | page=A100 |date=February 2011 | doi=10.1051/0004-6361/201014442 | bibcode=2011A&A...526A.100P | arxiv=1010.3649 }}
4. ^¹²³{{citation | display-authors=1 | last1=Soubiran | first1=C. | last2=Bienaymé | first2=O. | last3=Mishenina | first3=T. V. | last4=Kovtyukh | first4=V. V. | title=Vertical distribution of Galactic disk stars. IV. AMR and AVR from clump giants | journal=Astronomy and Astrophysics | date=2008 | volume=480 | issue=1 | pages=91–101 | bibcode=2008A&A...480...91S | doi=10.1051/0004-6361:20078788 |arxiv = 0712.1370 }}
5. ^¹{{citation | display-authors=1 | last1=Famaey | first1=B. | last2=Jorissen | first2=A. | last3=Luri | first3=X. | last4=Mayor | first4=M. | last5=Udry | first5=S. | last6=Dejonghe | first6=H. | last7=Turon | first7=C. | title=Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters | journal=Astronomy and Astrophysics | volume=430 | issue=1 | pages=165–186 |date=January 2005 | doi=10.1051/0004-6361:20041272 | bibcode=2005A&A...430..165F |arxiv = astro-ph/0409579 }}
6. ^¹{{citation | last=Allen | first=R. H. | date=1963 | authorlink=Richard Hinckley Allen | title=Star Names: Their Lore and Meaning | url=http://penelope.uchicago.edu/Thayer/E/Gazetteer/Topics/astronomy/_Texts/secondary/ALLSTA/Cepheus*.html | accessdate=2010-12-12 | edition=Reprint | publisher=Dover Publications Inc | location=New York | isbn=0-486-21079-0 | page=157 }}
7. ^¹{{citation | last1=Davis Jr. | first1=G. A. | bibcode=1944PA.....52....8D | title=The Pronunciations, Derivations, and Meanings of a Selected List of Star Names | journal=Popular Astronomy | volume=LII | issue=3 |date=October 1944 | page=16 }}
8. ^¹{{citation | display-authors=1 | last1=Martínez–Arnáiz | first1=R. | last2=Maldonado | first2=J. | last3=Montes | first3=D. | last4=Eiroa | first4=C. | last5=Montesinos | first5=B. | title=Chromospheric activity and rotation of FGK stars in the solar vicinity. An estimation of the radial velocity jitter | journal=Astronomy and Astrophysics | volume=520 | page=A79 |date=September 2010 | doi=10.1051/0004-6361/200913725 | bibcode=2010A&A...520A..79M |arxiv = 1002.4391 }}
9. ^¹²³⁴{{citation | last1=Jennens | first1=P. A. | last2=Helfer | first2=H. L. | title=A new photometric metal abundance and luminosity calibration for field G and K giants. | journal=Monthly Notices of the Royal Astronomical Society | volume=172 | pages=667–679 |date=September 1975 | bibcode=1975MNRAS.172..667J | doi=10.1093/mnras/172.3.667}}
10. ^¹²{{citation | title=LHS 3578 -- High proper-motion Star | work=SIMBAD Astronomical Object Database | publisher=Centre de Données astronomiques de Strasbourg | url=http://simbad.u-strasbg.fr/simbad/sim-id?Ident=Eta+Cephei | accessdate=2012-03-27 }}
11. ^¹{{citation | last1=Murdoch | first1=Kaylene A. | last2=Hearnshaw | first2=J. B. | last3=Clark | first3=M. | title=A search for substellar companions to southern solar-type stars | journal=Astrophysical Journal, Part 1 | volume=413 | issue=1 | pages=349–363 |date=August 1993 | doi=10.1086/173003 | bibcode=1993ApJ...413..349M }}
12. ^¹{{citation | display-authors=1 | last1=Wittenmyer | first1=Robert A. | last2=Endl | first2=Michael | last3=Cochran | first3=William D. | last4=Hatzes | first4=Artie P. | last5=Walker | first5=G. A. H. | last6=Yang | first6=S. L. S. | last7=Paulson | first7=Diane B. | title=Detection Limits from the McDonald Observatory Planet Search Program | journal=The Astronomical Journal | volume=132 | issue=1 | pages=177–188 |date=July 2006 | doi=10.1086/504942 | bibcode=2006AJ....132..177W |arxiv = astro-ph/0604171 }}
13. ^¹²{{citation | last1=Nelson | first1=A. F. | last2=Angel | first2=J. R. P. | title=The Range of Masses and Periods Explored by Radial Velocity Searches for Planetary Companions | journal=Astrophysical Journal | volume=500 | issue=2 | pages=940–957 |date=June 1998 | doi=10.1086/305741 | bibcode=1998ApJ...500..940N |arxiv = astro-ph/9802194 }}
14. ^¹²³⁴⁵{{citation | display-authors=1 | last1=Affer | first1=L. | last2=Micela | first2=G. | last3=Morel | first3=T. | last4=Sanz-Forcada | first4=J. | last5=Favata | first5=F. | title=Spectroscopic determination of photospheric parameters and chemical abundances of 6 K-type stars | journal=Astronomy and Astrophysics | volume=433 | issue=2 |date=April 2005 | pages=647–658 | doi=10.1051/0004-6361:20041308 | bibcode=2005A&A...433..647A | url=http://orbi.ulg.ac.be/bitstream/2268/4891/1/AA_433_647.pdf }}

词条	Eta Cephei
释义	Etymology Properties Hunt for substellar objects References External links {{Starbox begin \| name = η Cephei }}{{Starbox image \| image={{Location mark \|image=Cepheus constellation map.svg\|alt=\|float=center\|width=240 \|label=\|position=right \|mark=Red circle.svg\|mark_width=10\|mark_link=η Cephei \|x=920\|y=854 }} \|caption=Location of η Cephei (circled) }}{{Starbox observe \| epoch = J2000.0 \| constell = Cepheus \| ra = {{RA\|20\|45\|17.37555}} \| dec = {{DEC\|+61\|50\|19.6167}} \| appmag_v = 3.426^[3] }}{{Starbox character \| class = K0 IV^[4] \| b-v = +0.918^[3] \| u-b = +0.613^[3] \| variable = }}{{Starbox astrometry \| radial_v = –87.55 ± 0.11^[7] \| prop_mo_ra = +86.50 \| prop_mo_dec = +818.02 \| parallax = 70.10 \| p_error = 0.11 \| parallax_footnote = \| absmag_v = 2.631^[4] }}{{Starbox detail \| mass = 1.6^[12] \| radius = {{nowrap\|4.12 ± 0.07}}^[13] \| luminosity = {{nowrap\|9.7 ± 0.5}}^[13] \| temperature = 4,950^[13] \| gravity = 3.41^[13] \| metal_fe = –0.32^[13] \| rotational_velocity = 6.79^[18] \| age_gyr = 2.5 ± 0.3^[12] }}{{Starbox catalog \| names = 3 Cephei, BD+61 2050, FK5 783, HD 198149, HIP 102422, HR 7957, SAO 19019.^[20] }}{{Starbox reference \|Simbad=eta+Cep }}{{Starbox end}}Eta Cephei (η Cep, η Cephei) is a star in the northern circumpolar constellation of Cepheus. It shares the name Al Kidr with θ Cep, although the meaning of this name is unknown. With an apparent visual magnitude of 3.4,^[3] this is a third magnitude star that, according to the Bortle Dark-Sky Scale, is readily visible to the naked eye. Parallax measurements put it at a distance of {{Convert\|46.53\|ly\|pc\|abbr=off\|lk=on}} from Earth. Etymology Eta Cephei, along with α Cep (Alderamin) and β Cep (Alfirk), were identified as Al Kawākib al Firḳ (الكوكب الفرق), meaning "the Stars of The Flock" by Ulug Beg.^[23]^[24] In Chinese, {{lang\|zh\|天鈎}} ({{lang\|zh-Latn\|Tiān Gōu}}), meaning Celestial Hook, refers to an asterism consisting of η Cephei, 4 Cephei, HD 194298, θ Cephei, α Cephei, ξ Cephei, 26 Cephei, ι Cephei and ο Cephei.^[1] Consequently, η Cephei itself is known as {{lang\|zh\|天鈎四}} ({{lang\|zh-Latn\|Tiān Gōu sì}}, {{lang-en\|the Fourth Star of Celestial Hook}}.).^[2] Properties Eta Cephei is a subgiant star with a stellar classification of K0 IV,^[4] which indicates it is exhausting the supply of hydrogen at its core and is in the process of evolving into a giant star. With 1.6^[12] times the Sun's mass, at an age of 2.5^[12] billion years it has reached a radius four times larger than the Sun^[13] and a luminosity ten times greater.^[13] It is radiating this energy from its outer atmosphere at an effective temperature of 4,950 K,^[13] giving it the orange-hued glow of a K-type star. Eta Cephei has a high proper motion across the celestial sphere^[20] and a large peculiar velocity of {{nowrap\|112 km s⁻¹}}.^[12] Hunt for substellar objects {{anchor\|Eta Cephei}} According to Nelson & Angel (1998),^[35] Eta Cephei would show two significant periodicities of 164 days and 10 years respectively, hinting at the possible presence of one or more jovian planets in orbit around the subgiant. The authors have set an upper limit of 0.64 Jupiter masses for the putative inner planet and 1.2 Jupiter masses for the putative outer one. Also Campbell et al. (1988)^[36] inferred the existence of planetary objects or even brown dwarfs less massive than 16.3 Jupiter masses. However, more recent studies have not yet confirmed the existence of any substellar companion around Eta Cephei. McDonald Observatory team has set limits to the presence of one or more planets^[37] with masses between 0.13 and 2.4 Jupiter masses and average separations spanning between 0.05 and 5.2 AU. {{OrbitboxPlanet begin \| table_ref=^[35] \| period_unit=day }}{{OrbitboxPlanet hypothetical \| exoplanet = b \| mass = ≥0.64 \| period = 163.57 \| semimajor = 0.638 \| eccentricity = ?0.17 }}{{Orbitbox end}} References 1. ^{{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}}. 2. ^{{zh icon}} AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 6 日 3. ^¹²³⁴⁵⁶⁷⁸{{citation \| display-authors=1 \| last1=Piau \| first1=L. \| last2=Kervella \| first2=P. \| last3=Dib \| first3=S. \| last4=Hauschildt \| first4=P. \| title=Surface convection and red-giant radius measurements \| journal=Astronomy and Astrophysics \| volume=526 \| page=A100 \|date=February 2011 \| doi=10.1051/0004-6361/201014442 \| bibcode=2011A&A...526A.100P \| arxiv=1010.3649 }} 4. ^¹²³{{citation \| display-authors=1 \| last1=Soubiran \| first1=C. \| last2=Bienaymé \| first2=O. \| last3=Mishenina \| first3=T. V. \| last4=Kovtyukh \| first4=V. V. \| title=Vertical distribution of Galactic disk stars. IV. AMR and AVR from clump giants \| journal=Astronomy and Astrophysics \| date=2008 \| volume=480 \| issue=1 \| pages=91–101 \| bibcode=2008A&A...480...91S \| doi=10.1051/0004-6361:20078788 \|arxiv = 0712.1370 }} 5. ^¹{{citation \| display-authors=1 \| last1=Famaey \| first1=B. \| last2=Jorissen \| first2=A. \| last3=Luri \| first3=X. \| last4=Mayor \| first4=M. \| last5=Udry \| first5=S. \| last6=Dejonghe \| first6=H. \| last7=Turon \| first7=C. \| title=Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters \| journal=Astronomy and Astrophysics \| volume=430 \| issue=1 \| pages=165–186 \|date=January 2005 \| doi=10.1051/0004-6361:20041272 \| bibcode=2005A&A...430..165F \|arxiv = astro-ph/0409579 }} 6. ^¹{{citation \| last=Allen \| first=R. H. \| date=1963 \| authorlink=Richard Hinckley Allen \| title=Star Names: Their Lore and Meaning \| url=http://penelope.uchicago.edu/Thayer/E/Gazetteer/Topics/astronomy/_Texts/secondary/ALLSTA/Cepheus.html \| accessdate=2010-12-12 \| edition=Reprint \| publisher=Dover Publications Inc \| location=New York \| isbn=0-486-21079-0 \| page=157 }} 7. ^¹{{citation \| last1=Davis Jr. \| first1=G. A. \| bibcode=1944PA.....52....8D \| title=The Pronunciations, Derivations, and Meanings of a Selected List of Star Names \| journal=Popular Astronomy \| volume=LII \| issue=3 \|date=October 1944 \| page=16 }} 8. ^¹{{citation \| display-authors=1 \| last1=Martínez–Arnáiz \| first1=R. \| last2=Maldonado \| first2=J. \| last3=Montes \| first3=D. \| last4=Eiroa \| first4=C. \| last5=Montesinos \| first5=B. \| title=Chromospheric activity and rotation of FGK stars in the solar vicinity. An estimation of the radial velocity jitter \| journal=Astronomy and Astrophysics \| volume=520 \| page=A79 \|date=September 2010 \| doi=10.1051/0004-6361/200913725 \| bibcode=2010A&A...520A..79M \|arxiv = 1002.4391 }} 9. ^¹²³⁴{{citation \| last1=Jennens \| first1=P. A. \| last2=Helfer \| first2=H. L. \| title=A new photometric metal abundance and luminosity calibration for field G and K giants. \| journal=Monthly Notices of the Royal Astronomical Society \| volume=172 \| pages=667–679 \|date=September 1975 \| bibcode=1975MNRAS.172..667J \| doi=10.1093/mnras/172.3.667}} 10. ^¹²{{citation \| title=LHS 3578 -- High proper-motion Star \| work=SIMBAD Astronomical Object Database \| publisher=Centre de Données astronomiques de Strasbourg \| url=http://simbad.u-strasbg.fr/simbad/sim-id?Ident=Eta+Cephei \| accessdate=2012-03-27 }} 11. ^¹{{citation \| last1=Murdoch \| first1=Kaylene A. \| last2=Hearnshaw \| first2=J. B. \| last3=Clark \| first3=M. \| title=A search for substellar companions to southern solar-type stars \| journal=Astrophysical Journal, Part 1 \| volume=413 \| issue=1 \| pages=349–363 \|date=August 1993 \| doi=10.1086/173003 \| bibcode=1993ApJ...413..349M }} 12. ^¹{{citation \| display-authors=1 \| last1=Wittenmyer \| first1=Robert A. \| last2=Endl \| first2=Michael \| last3=Cochran \| first3=William D. \| last4=Hatzes \| first4=Artie P. \| last5=Walker \| first5=G. A. H. \| last6=Yang \| first6=S. L. S. \| last7=Paulson \| first7=Diane B. \| title=Detection Limits from the McDonald Observatory Planet Search Program \| journal=The Astronomical Journal \| volume=132 \| issue=1 \| pages=177–188 \|date=July 2006 \| doi=10.1086/504942 \| bibcode=2006AJ....132..177W \|arxiv = astro-ph/0604171 }} 13. ^¹²{{citation \| last1=Nelson \| first1=A. F. \| last2=Angel \| first2=J. R. P. \| title=The Range of Masses and Periods Explored by Radial Velocity Searches for Planetary Companions \| journal=Astrophysical Journal \| volume=500 \| issue=2 \| pages=940–957 \|date=June 1998 \| doi=10.1086/305741 \| bibcode=1998ApJ...500..940N \|arxiv = astro-ph/9802194 }} 14. ^¹²³⁴⁵{{citation \| display-authors=1 \| last1=Affer \| first1=L. \| last2=Micela \| first2=G. \| last3=Morel \| first3=T. \| last4=Sanz-Forcada \| first4=J. \| last5=Favata \| first5=F. \| title=Spectroscopic determination of photospheric parameters and chemical abundances of 6 K-type stars \| journal=Astronomy and Astrophysics \| volume=433 \| issue=2 \|date=April 2005 \| pages=647–658 \| doi=10.1051/0004-6361:20041308 \| bibcode=2005A&A...433..647A \| url=http://orbi.ulg.ac.be/bitstream/2268/4891/1/AA_433_647.pdf }} Note:* see VizieR catalogue I/311.^[3]^[4]^[5]^[6]^[7]^[8]^[9]^[10]^[11]^[12]^[13]^[14] }} External links {{Stars of Cepheus}} 10 : Bayer objects\|Cepheus (constellation)\|Hypothetical planetary systems\|K-type subgiants\|Solar-type stars\|Flamsteed objects\|Hipparcos objects\|Henry Draper Catalogue objects\|Durchmusterung objects\|HR objects
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Etymology

Properties

Hunt for substellar objects

References

External links