“Eta Ceti”的意思、由来-开放百科全书

This is a giant star with a stellar classification of K1 III,^[4] having exhausted the hydrogen at its core and evolved away from the main sequence of stars like the Sun. (The classification is sometimes listed as K1.5 IIICN1Fe0.5, indicating a higher than normal abundance of cyanogen and iron relative to other stars of its class.)^[24] It is a red clump star that is generating energy through the nuclear fusion of helium at its core.^[25]

Eta Ceti may have slightly more mass than the Sun and its outer envelope has expanded to 15 times the Sun's radius.^[13] It is radiating 74^[13] times as much luminosity as the Sun from its outer atmosphere at an effective temperature of 4,356 K.^[13] This heat gives the star the orange-hued glow of a K-type star.^[29]

In culture

The name Deneb Algenubi was from Arabic ذنب القيطس الجنوبي - al-dhanab al-qayṭas al-janūbī, meaning the southern tail of the sea monster. In the catalogue of stars in the Calendarium of Al Achsasi al Mouakket, this star was designated Aoul al Naamat (أول ألنعمة - awwil al naʽāmāt), which was translated into Latin as Prima Struthionum, meaning the first ostrich.^[30] This star, along with θ Cet (Thanih al Naamat), τ Cet (Thalath Al Naamat), ζ Cet (Baten Kaitos) and υ Cet, were Al Naʽāmāt (ألنعمة), the Hen Ostriches.^[31]

In Chinese, {{lang|zh|天倉}} ({{lang|zh-Latn|Tiān Cāng}}), meaning Square Celestial Granary, refers to an asterism consisting of η Ceti, ι Ceti, θ Ceti, ζ Ceti, τ Ceti and 57 Ceti.^[1] Consequently, η Ceti itself is known as {{lang|zh|天倉二}} ({{lang|zh-Latn|Tiān Cāng èr}}, {{lang-en|the Second Star of Square Celestial Granary}}.)^[2]

Planetary system

In 2014, two exoplanets around the star were discovered using the radial velocity method. Planets discovered by radial velocity have poorly known masses because if the orbit of the planets were inclined away from the line of sight, a much larger mass would have to compensate for the angle.^[3]

Eta Ceti b has a minimum mass of {{jupiter mass|2.55}} and an orbital period of 403.5 days (about 1.1 years), while Eta Ceti c has a minimum mass of {{jupiter mass|3.32}} and an orbital period of 751.9 days (2.06 years). Assuming the orbits of the two are coplanar, then the two planets must be locked in a 2:1 orbital resonance, otherwise the system would become dynamically unstable. Although the inclinations from the line of sight are unknown, the value is constrained to be 70° or less: if any higher, the higher masses would render the system dynamically unstable, with no stable solutions.^[4]

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}} 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=September 29, 2009 }}, Hong Kong Space Museum. Accessed on line November 23, 2010.
3. ^{{cite web|url=http://www.planetary.org/explore/space-topics/exoplanets/radial-velocity.html|title=Radial Velocity|work=The Planetary Society|accessdate=3 March 2017}}
4. ^¹{{cite journal|title=Precise radial velocities of giant stars. VI. A possible 2:1 resonant planet pair around the K giant star η Ceti|author1=Trifonov, Trifon|author2=Reffert, Sabine|author3=Tan, Xianyu|author4=Lee, Man Hoi|author5=Quirrenbach, Andreas|journal=Astronomy & Astrophysics|volume=568|bibcode=2014A&A...568A..64T|doi=10.1051/0004-6361/201322885|arxiv=1407.0712|year=2014|page=A64}}
5. ^¹{{citation | title=Mg II chromospheric radiative loss rates in cool active and quiet stars | last1=Cardini | first1=D. | postscript=. | journal=Astronomy and Astrophysics | volume=430 | pages=303–311 | date=January 2005 | doi=10.1051/0004-6361:20041440 | bibcode=2005A&A...430..303C |arxiv = astro-ph/0409683 }}
6. ^¹²³⁴{{citation | display-authors=1 | last1=Massarotti | first1=Alessandro | last2=Latham | first2=David W. | last3=Stefanik | first3=Robert P. | last4=Fogel | first4=Jeffrey | title=Rotational and Radial Velocities for a Sample of 761 HIPPARCOS Giants and the Role of Binarity | journal=The Astronomical Journal | volume=135 | issue=1 | pages=209–231 |date=January 2008 | doi=10.1088/0004-6256/135/1/209 | bibcode=2008AJ....135..209M }}
7. ^¹²{{citation | display-authors=1 | last1=Gray | first1=R. O. | last2=Corbally | first2=C. J. | last3=Garrison | first3=R. F. | last4=McFadden | first4=M. T. | last5=Bubar | first5=E. J. | last6=McGahee | first6=C. E. | last7=O'Donoghue | first7=A. A. | last8=Knox | first8=E. R. | title=Contributions to the Nearby Stars (NStars) Project: spectroscopy of stars earlier than M0 within 40 pc-The Southern Sample | journal=The Astronomical Journal | volume=132 | issue=1 | pages=161–170 |date=July 2006 | doi=10.1086/504637 | bibcode=2006AJ....132..161G | arxiv=astro-ph/0603770 }}
8. ^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}}
9. ^¹²³⁴⁵{{citation | display-authors=1 | last1=Berio | first1=P. | last2=Merle | first2=T. | last3=Thévenin | first3=F. | last4=Bonneau | first4=D. | last5=Mourard | first5=D. | last6=Chesneau | first6=O. | last7=Delaa | first7=O. | last8=Ligi | first8=R. | last9=Nardetto | first9=N. | title=Chromosphere of K giant stars. Geometrical extent and spatial structure detection | journal=Astronomy & Astrophysics | volume=535 | page=A59 |date=November 2011 | doi=10.1051/0004-6361/201117479 | bibcode=2011A&A...535A..59B |arxiv = 1109.5476 }}
10. ^¹{{citation | display-authors=1 | last1=Puzeras | first1=E. | last2=Tautvaišienė | first2=G. | last3=Cohen | first3=J. G. | last4=Gray | first4=D. F. | last5=Adelman | first5=S. J. | last6=Ilyin | first6=I. | last7=Chorniy | first7=Y. | title=High-resolution spectroscopic study of red clump stars in the Galaxy: iron-group elements | journal=Monthly Notices of the Royal Astronomical Society | volume=408 | issue=2 | pages=1225–1232 |date=October 2010 | doi=10.1111/j.1365-2966.2010.17195.x | bibcode=2010MNRAS.408.1225P |arxiv = 1006.3857 }}
11. ^¹{{citation | last=Knobel | first=E. B. | title=Al Achsasi Al Mouakket, on a catalogue of stars in the Calendarium of Mohammad Al Achsasi Al Mouakket | journal=Monthly Notices of the Royal Astronomical Society | volume=55 | pages=429–438 |date=June 1895 | bibcode=1895MNRAS..55..429K | doi=10.1093/mnras/55.8.429}}
12. ^¹{{citation |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 |accessdate=2012-01-16 |deadurl=yes |archiveurl=https://www.webcitation.org/6630AbtJZ?url=http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html |archivedate=2012-03-10 |df= }}
13. ^¹{{citation | last1=Eggleton | first1=P. P. | last2=Tokovinin | first2=A. A. | title=A catalogue of multiplicity among bright stellar systems | journal=Monthly Notices of the Royal Astronomical Society | volume=389 | issue=2 | pages=869–879 |date=September 2008 | doi=10.1111/j.1365-2966.2008.13596.x | bibcode=2008MNRAS.389..869E |arxiv = 0806.2878 }}
14. ^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/Cetus*.html | accessdate=2010-12-12 | edition=Reprint | publisher=Dover Publications Inc. | location=New York | isbn=0-486-21079-0 | page=162 }}
15. ^¹η Cet as Aoul al Naamat or Prima Struthionum (the first ostrich), θ Cet as Thanih al Naamat or Secunda Struthionum (the second ostrich), τ Cet as Thalath al Naamat or Tertia Struthionum (the third ostrich), and ζ Cet as Rabah al Naamat or Quarta Struthionum (the fourth ostrich). υ Cet should be Khamis al Naamat or Quinta Struthionum (the fifth ostrich) consistently, but Al Achsasi Al Mouakket designated the title the fifth ostrich to γ Gam with uncleared consideration.
16. ^¹{{cite simbad | title=eta Cet | accessdate=2017-03-17 | postscript=. }}
17. ^¹²³{{citation | title=Abundances in the Local Region. I. G and K Giants | journal=The Astronomical Journal | last1=Luck | first1=R. Earle | postscript=. | volume=150 | issue=3 | pages=88 | year=2015 | bibcode=2015AJ....150...88L | doi=10.1088/0004-6256/150/3/88 |arxiv = 1507.01466 }}

词条	Eta Ceti
释义	In culture Planetary system References {{Starbox begin \| name=η Ceti }}{{Starbox image \| image={{Location mark \|image=Cetus constellation map.svg\|alt=\|float=center\|width=280 \|label=\|position=right \|mark=Red circle.svg\|mark_width=10\|mark_link=η Ceti \|x=654\|y=460 }} \|caption=Location of η Ceti (circled) }}{{Starbox observe \| epoch = J2000.0 \| ra = {{RA\|01\|08\|35.39148}} \| dec = {{DEC\|–10\|10\|56.1570}} \| appmag_v = +3.446^[3] \| constell = Cetus }}{{Starbox character \| class = K1 III^[4] \| b-v = +1.161^[3] \| u-b = +1.194^[3] \| variable = }}{{Starbox astrometry \| radial_v = +11.74 ± 0.30^[7] \| prop_mo_ra = +215.61 \| prop_mo_dec = –139.02 \| parallax = 26.32 \| p_error = 0.14 \| parallax_footnote = \| absmag_v = +0.68^[11] }}{{Starbox detail \| mass = 1.84^[12] \| radius = {{nowrap\|15.10 ± 0.10}}^[13] \| metal_fe = –0.03^[7] \| gravity = 2.5^[7] \| age_gyr = 1.80^[12] \| luminosity = {{nowrap\|74.0 ± 3.7}}^[13] \| temperature = {{Val\|4543\|24\|fmt=commas}}^[12] \| rotational_velocity = 4.8^[7] }}{{Starbox catalog \| names = Deneb Algenubi, Algenudi, 31 Ceti, BD–10 240, FK5 40, HD 6805, HIP 5364, HR 334, SAO 147632.^[20] }}{{Starbox reference \| Simbad = eta+Cet }}{{Starbox end}}Eta Ceti (η Cet, η Ceti) is a star in the equatorial constellation of Cetus. It has the traditional name Deneb Algenubi or Algenudi. The apparent visual magnitude of this star is +3.4,^[3] making it the fourth-brightest star in this otherwise relatively faint constellation. The distance to this star can be measured directly using the parallax technique, yielding a value of {{Convert\|123.9\|ly\|pc\|abbr=off\|lk=on}}. This is a giant star with a stellar classification of K1 III,^[4] having exhausted the hydrogen at its core and evolved away from the main sequence of stars like the Sun. (The classification is sometimes listed as K1.5 IIICN1Fe0.5, indicating a higher than normal abundance of cyanogen and iron relative to other stars of its class.)^[24] It is a red clump star that is generating energy through the nuclear fusion of helium at its core.^[25] Eta Ceti may have slightly more mass than the Sun and its outer envelope has expanded to 15 times the Sun's radius.^[13] It is radiating 74^[13] times as much luminosity as the Sun from its outer atmosphere at an effective temperature of 4,356 K.^[13] This heat gives the star the orange-hued glow of a K-type star.^[29] In culture The name Deneb Algenubi was from Arabic ذنب القيطس الجنوبي - al-dhanab al-qayṭas al-janūbī, meaning the southern tail of the sea monster. In the catalogue of stars in the Calendarium of Al Achsasi al Mouakket, this star was designated Aoul al Naamat (أول ألنعمة - awwil al naʽāmāt), which was translated into Latin as Prima Struthionum, meaning the first ostrich.^[30] This star, along with θ Cet (Thanih al Naamat), τ Cet (Thalath Al Naamat), ζ Cet (Baten Kaitos) and υ Cet, were Al Naʽāmāt (ألنعمة), the Hen Ostriches.^[31] In Chinese, {{lang\|zh\|天倉}} ({{lang\|zh-Latn\|Tiān Cāng}}), meaning Square Celestial Granary, refers to an asterism consisting of η Ceti, ι Ceti, θ Ceti, ζ Ceti, τ Ceti and 57 Ceti.^[1] Consequently, η Ceti itself is known as {{lang\|zh\|天倉二}} ({{lang\|zh-Latn\|Tiān Cāng èr}}, {{lang-en\|the Second Star of Square Celestial Granary}}.)^[2] Planetary system In 2014, two exoplanets around the star were discovered using the radial velocity method. Planets discovered by radial velocity have poorly known masses because if the orbit of the planets were inclined away from the line of sight, a much larger mass would have to compensate for the angle.^[3] Eta Ceti b has a minimum mass of {{jupiter mass\|2.55}} and an orbital period of 403.5 days (about 1.1 years), while Eta Ceti c has a minimum mass of {{jupiter mass\|3.32}} and an orbital period of 751.9 days (2.06 years). Assuming the orbits of the two are coplanar, then the two planets must be locked in a 2:1 orbital resonance, otherwise the system would become dynamically unstable. Although the inclinations from the line of sight are unknown, the value is constrained to be 70° or less: if any higher, the higher masses would render the system dynamically unstable, with no stable solutions.^[4] {{OrbitboxPlanet begin \| table_ref = ^[4] }}{{OrbitboxPlanet \| exoplanet = b \| mass = ≥2.55 ± 0.13 \| semimajor = 1.27 \| period = 403.5 ± 1.5 \| eccentricity = 0.13 ± 0.05 }}{{OrbitboxPlanet \| exoplanet = c \| mass = ≥3.32 ± 0.18 \| semimajor = 1.93 \| period = 751.9 ± 3.8 \| eccentricity = 0.1 ± 0.06 }}{{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}} 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=September 29, 2009 }}, Hong Kong Space Museum. Accessed on line November 23, 2010. 3. ^{{cite web\|url=http://www.planetary.org/explore/space-topics/exoplanets/radial-velocity.html\|title=Radial Velocity\|work=The Planetary Society\|accessdate=3 March 2017}} 4. ^¹{{cite journal\|title=Precise radial velocities of giant stars. VI. A possible 2:1 resonant planet pair around the K giant star η Ceti\|author1=Trifonov, Trifon\|author2=Reffert, Sabine\|author3=Tan, Xianyu\|author4=Lee, Man Hoi\|author5=Quirrenbach, Andreas\|journal=Astronomy & Astrophysics\|volume=568\|bibcode=2014A&A...568A..64T\|doi=10.1051/0004-6361/201322885\|arxiv=1407.0712\|year=2014\|page=A64}} 5. ^¹{{citation \| title=Mg II chromospheric radiative loss rates in cool active and quiet stars \| last1=Cardini \| first1=D. \| postscript=. \| journal=Astronomy and Astrophysics \| volume=430 \| pages=303–311 \| date=January 2005 \| doi=10.1051/0004-6361:20041440 \| bibcode=2005A&A...430..303C \|arxiv = astro-ph/0409683 }} 6. ^¹²³⁴{{citation \| display-authors=1 \| last1=Massarotti \| first1=Alessandro \| last2=Latham \| first2=David W. \| last3=Stefanik \| first3=Robert P. \| last4=Fogel \| first4=Jeffrey \| title=Rotational and Radial Velocities for a Sample of 761 HIPPARCOS Giants and the Role of Binarity \| journal=The Astronomical Journal \| volume=135 \| issue=1 \| pages=209–231 \|date=January 2008 \| doi=10.1088/0004-6256/135/1/209 \| bibcode=2008AJ....135..209M }} 7. ^¹²{{citation \| display-authors=1 \| last1=Gray \| first1=R. O. \| last2=Corbally \| first2=C. J. \| last3=Garrison \| first3=R. F. \| last4=McFadden \| first4=M. T. \| last5=Bubar \| first5=E. J. \| last6=McGahee \| first6=C. E. \| last7=O'Donoghue \| first7=A. A. \| last8=Knox \| first8=E. R. \| title=Contributions to the Nearby Stars (NStars) Project: spectroscopy of stars earlier than M0 within 40 pc-The Southern Sample \| journal=The Astronomical Journal \| volume=132 \| issue=1 \| pages=161–170 \|date=July 2006 \| doi=10.1086/504637 \| bibcode=2006AJ....132..161G \| arxiv=astro-ph/0603770 }} 8. ^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}} 9. ^¹²³⁴⁵{{citation \| display-authors=1 \| last1=Berio \| first1=P. \| last2=Merle \| first2=T. \| last3=Thévenin \| first3=F. \| last4=Bonneau \| first4=D. \| last5=Mourard \| first5=D. \| last6=Chesneau \| first6=O. \| last7=Delaa \| first7=O. \| last8=Ligi \| first8=R. \| last9=Nardetto \| first9=N. \| title=Chromosphere of K giant stars. Geometrical extent and spatial structure detection \| journal=Astronomy & Astrophysics \| volume=535 \| page=A59 \|date=November 2011 \| doi=10.1051/0004-6361/201117479 \| bibcode=2011A&A...535A..59B \|arxiv = 1109.5476 }} 10. ^¹{{citation \| display-authors=1 \| last1=Puzeras \| first1=E. \| last2=Tautvaišienė \| first2=G. \| last3=Cohen \| first3=J. G. \| last4=Gray \| first4=D. F. \| last5=Adelman \| first5=S. J. \| last6=Ilyin \| first6=I. \| last7=Chorniy \| first7=Y. \| title=High-resolution spectroscopic study of red clump stars in the Galaxy: iron-group elements \| journal=Monthly Notices of the Royal Astronomical Society \| volume=408 \| issue=2 \| pages=1225–1232 \|date=October 2010 \| doi=10.1111/j.1365-2966.2010.17195.x \| bibcode=2010MNRAS.408.1225P \|arxiv = 1006.3857 }} 11. ^¹{{citation \| last=Knobel \| first=E. B. \| title=Al Achsasi Al Mouakket, on a catalogue of stars in the Calendarium of Mohammad Al Achsasi Al Mouakket \| journal=Monthly Notices of the Royal Astronomical Society \| volume=55 \| pages=429–438 \|date=June 1895 \| bibcode=1895MNRAS..55..429K \| doi=10.1093/mnras/55.8.429}} 12. ^¹{{citation \|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 \|accessdate=2012-01-16 \|deadurl=yes \|archiveurl=https://www.webcitation.org/6630AbtJZ?url=http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html \|archivedate=2012-03-10 \|df= }} 13. ^¹{{citation \| last1=Eggleton \| first1=P. P. \| last2=Tokovinin \| first2=A. A. \| title=A catalogue of multiplicity among bright stellar systems \| journal=Monthly Notices of the Royal Astronomical Society \| volume=389 \| issue=2 \| pages=869–879 \|date=September 2008 \| doi=10.1111/j.1365-2966.2008.13596.x \| bibcode=2008MNRAS.389..869E \|arxiv = 0806.2878 }} 14. ^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/Cetus.html \| accessdate=2010-12-12 \| edition=Reprint \| publisher=Dover Publications Inc. \| location=New York \| isbn=0-486-21079-0 \| page=162 }} 15. ^¹η Cet as Aoul al Naamat* or Prima Struthionum (the first ostrich), θ Cet as Thanih al Naamat or Secunda Struthionum (the second ostrich), τ Cet as Thalath al Naamat or Tertia Struthionum (the third ostrich), and ζ Cet as Rabah al Naamat or Quarta Struthionum (the fourth ostrich). υ Cet should be Khamis al Naamat or Quinta Struthionum (the fifth ostrich) consistently, but Al Achsasi Al Mouakket designated the title the fifth ostrich to γ Gam with uncleared consideration. 16. ^¹{{cite simbad \| title=eta Cet \| accessdate=2017-03-17 \| postscript=. }} 17. ^¹²³{{citation \| title=Abundances in the Local Region. I. G and K Giants \| journal=The Astronomical Journal \| last1=Luck \| first1=R. Earle \| postscript=. \| volume=150 \| issue=3 \| pages=88 \| year=2015 \| bibcode=2015AJ....150...88L \| doi=10.1088/0004-6256/150/3/88 \|arxiv = 1507.01466 }} ^[5]^[6]^[7]^[8]^[9]^[10]^[11]^[12]^[13]^[14] ^[16]^[17] }}{{Stars of Cetus}} 9 : Cetus (constellation)\|Bayer objects\|Stars with proper names\|K-type giants\|Flamsteed objects\|Hipparcos objects\|HR objects\|Henry Draper Catalogue objects\|Durchmusterung objects
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