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词条 Sigma Draconis
释义

  1. Name

  2. Properties

  3. Planet search

  4. See also

  5. Notes

  6. References

  7. External links

{{Starbox begin
| name=Sigma Draconis }}{{Starbox observe
| epoch=J2000
| constell=Draco
| ra={{RA|19|32|21.59026}}[1]
| dec={{DEC|+69|39|40.2354}}[1]
| appmag_v=4.674[3] }}{{Starbox character
| class=G9 V[4][5]
| b-v=+0.791[3]
| u-b=+0.386[3]
| variable=None[8] }}{{Starbox astrometry
| radial_v=26.7[9]
| prop_mo_ra=598.07[1]
| prop_mo_dec=−1738.40[1]
| parallax=173.77
| p_error=0.18
| parallax_footnote=[1]
| absmag_v=5.89[13] }}{{Starbox detail
| age_gyr={{Val|3.00|0.60}}[14]
| gravity={{Val|4.59|0.02}}[14]
| metal_fe={{Val|−0.20|0.04}}[14]
| mass={{Val|0.85|0.01|0.03}}[14]
| radius={{Val|0.776|0.008}}[18]
| rotational_velocity=1.4[19]
| luminosity={{Val|0.410|0.006}}[18]
| temperature={{Val|5255|31|fmt=commas}}[18] }}{{Starbox catalog
| names=Alsafi, σ Draconis, 61 Draconis, BD+69°1053, GCTP 4607.00, GJ 764, HD 185144, HIP 96100, HR 7462, LHS 477.[9] }}{{Starbox reference
| Simbad = HD+185144
| ARICNS = 01582
}}{{Starbox end}}

Sigma Draconis (σ Draconis, abbreviated Sig Dra, σ Dra), also named Alsafi,[1] is a 4.7-magnitude star located at a distance of 18.8 light-years from the Sun in the constellation of Draco.

Name

σ Draconis (Latinised to Sigma Draconis) is the star's Bayer designation, established in 1603 as part of the Uranometria, a star catalogue produced by German celestial cartographer Johann Bayer.

It bore the traditional name Alsafi, derived from the Arabic Athāfi, itself erroneously transcribed from the Arabic plural Athāfiyy, by which the nomads designated the tripods of their open-air kitchens. It was the name of an association of this star, Tau Draconis and Upsilon Draconis.[24] According to a 1971 NASA memorandum, Athāfi or Alsafi were the title for three stars: Sigma Draconis as Alsafi, Tau Draconis as Athāfi I and Upsilon Draconis as Athāfi II.[25] In 2016, the IAU organized a Working Group on Star Names (WGSN)[2] to catalog and standardize proper names for stars. The WGSN approved the name Alsafi for Sigma Draconis on 30 June 2017 and it is now so included in the List of IAU-approved Star Names.[1]

In Chinese, {{lang|zh|天廚}} ({{lang|zh-Latn|Tiān Chú}}), meaning Celestial Kitchen, refers to an asterism consisting of Sigma Draconis, Delta Draconis, Epsilon Draconis, Rho Draconis, 64 Draconis (see 64 Draconis (Portuguese)) and Pi Draconis.[3] Consequently, Sigma Draconis itself is known as {{lang|zh|天廚二}} ({{lang|zh-Latn|Tiān Chú èr}}, {{lang-en|the Second Star of Celestial Kitchen}}.)[4]

Properties

Sigma Draconis is a main sequence dwarf which has long served as a K0 V spectral standard star.[30][31][32] Its classification as K0 V defines one of the rare anchor points of the Morgan–Keenan system that have remained unchanged since the original 1943 MKK Atlas.[33] However, modern spectroscopy gives it as designation of G9 V.[4][5]

The radius of Sigma Draconis has been directly measured using interferometry with the CHARA array, which yields a result of 77.6% of the Sun's radius.[18] It has 85% of the Sun's mass, but the luminosity of this star is only 41% that of the Sun.[14][18] The projected rotation rate (v sin i) is relatively low at 1.4 km/s.[19] It is considered a slightly metal-poor star, meaning that it has a lower proportion of elements with masses greater than helium when compared to the Sun.[40]

The temperature, luminosity and surface activity appear to vary slightly in a manner very similar to the sunspot cycle, although the full length of the cycle has not yet been determined (as of 1992).[41] The total variability is among the lowest of all stars that have been measured by the Hipparcos spacecraft.[40]

Sigma Draconis has a high proper motion, advancing across the celestial sphere at a rate of 1.835 arc seconds per year.[43] The star made its perihelion passage about 46,725 years ago, when it came within {{Convert|5.075|pc|ly|abbr=on|lk=off|order=flip}}.[44] The components of Sigma Draconis's space velocity are U=+36, V=+40 and W=-10 km/s. This gives the star an unusually large orbital eccentricity about the Milky Way galaxy of 0.30 (compared to 0.06 for the Sun.) The mean galactocentric distance for the orbit is 10.3 kiloparsecs (about 34,000 light-years).[40]

As of 2013, no Jupiter-size or larger companion had been detected about the star and there was no indication of excess infrared radiation that would be evidence of circumstellar matter (such as a debris disk).[19][47]

Planet search

Between 2004 and 2013, extensive radial velocity measurements were gathered on Sigma Draconis using the High Resolution Echelle Spectrometer on the Keck Observatory. The Keck/HIRES data indicated a possible period of about 300 days and a likely alias period of 2800 days. Adding data taken with the Automated Planet Finder at the Lick Observatory strengthened and narrowed the 300-day period while reducing the significance of the 2800-day period. The combined analysis suggests there may be a Uranus-mass planet on a 308-day orbit, though the authors do not yet consider the discovery to be publishable as they have not yet attempted to rule out other non-planetary explanations for the velocity variations.[48]

{{OrbitboxPlanet begin
| name=unconfirmed Sigma Draconis
| table_ref=[48]
| period_unit=day
}}{{OrbitboxPlanet hypothetical
| exoplanet =
| mass_earth = ≳12
| period = 308
| semimajor =≈0.814{{#tag:ref|Kepler's Third Law, assuming a circular orbit gives . The mass of the star (ignoring the comparatively insignificant mass of the planet as the star Sigma Draconis has approximately 25,000 times more mass than the unconfirmed planet) and period of planet's orbit are known from the paper,[48] so the semimajor axis can be calculated using .[51]|group="note"|name=Kelper Circular}}
| eccentricity = ~0 (assumed)
}}{{Orbitbox end}}

See also

  • Sigma Draconis in fiction

Notes

1. ^1 {{cite web | url=https://www.iau.org/public/themes/naming_stars/ | title=Naming Stars |publisher=IAU.org |accessdate=16 December 2017}}
2. ^{{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}}
3. ^{{cite book|language=zh |title=中國星座神話 |trans-title=Chinese Constellation Mythology |author=陳久金 [Chen Jiujin] |publisher=台灣書房出版有限公司 [Taiwan Shufang Publishing Co., Ltd.] |year=2005 |isbn=978-986-7332-25-7}}
4. ^{{cite web |language=zh |url=http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/c_research_chinengstars_ala_alz.htm |title=香港太空館 - 研究資源 - 亮星中英對照表 |trans-title=Hong Kong Space Museum - Research Resources - Bright Star Chinese-English Table |archive-url=https://web.archive.org/web/20081025110153/http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/c_research_chinengstars_ala_alz.htm |archive-date=2008-10-25 |publisher=Hong Kong Space Museum |access-date=November 23, 2010}}
5. ^1 2 3 4 5 {{citation | last1=van Leeuwen | first1=F. | title=Validation of the new Hipparcos reduction | journal=Astronomy and Astrophysics | volume=474 | issue=2 |date=November 2007 | pages=653–664 | doi=10.1051/0004-6361:20078357 | bibcode=2007A&A...474..653V | arxiv=0708.1752 }}
6. ^1 2 3 4 5 {{citation | display-authors=1 | last1=Ramírez | first1=I. | last2=Fish | first2=J. R. | last3=Lambert | first3=D. L. | last4=Allende Prieto | first4=C. | title=Lithium Abundances in nearby FGK Dwarf and Subgiant Stars: Internal Destruction, Galactic Chemical Evolution, and Exoplanets | journal=The Astrophysical Journal | volume=756 | issue=1 | page=46 | date=September 2012 | doi=10.1088/0004-637X/756/1/46 | bibcode=2012ApJ...756...46R | arxiv=1207.0499 | postscript=. }}
7. ^1 2 3 4 5 {{citation | display-authors=1 | last1=Boyajian | first1=Tabetha S. | last2=McAlister | first2=Harold A. | last3=van Belle | first3=Gerard | last4=Gies | first4=Douglas R. | last5=ten Brummelaar | first5=Theo A. | last6=von Braun | first6=Kaspar | last7=Farrington | first7=Chris | last8=Goldfinger | first8=P. J. | last9=O'Brien | first9=David | last10=Parks | first10=J. Robert | last11=Richardson | first11=Noel D. | last12=Ridgway | first12=Stephen | last13=Schaefer | first13=Gail | last14=Sturmann | first14=Laszlo | last15=Sturmann | first15=Judit | last16=Touhami | first16=Yamina | last17=Turner | first17=Nils H. | last18=White | first18=Russel | title=Stellar Diameters and Temperatures. I. Main-sequence A, F, and G Stars | journal=The Astrophysical Journal | volume=746 | issue=1 | page=101 |date=February 2012 | doi=10.1088/0004-637X/746/1/101 | bibcode=2012ApJ...746..101B |arxiv = 1112.3316 }}. See Table 10.
8. ^1 {{citation | title=Patterns of Variation among Sun-like Stars | display-authors=1 | last1=Radick | first1=Richard R. | last2=Lockwood | first2=G. W. | last3=Skiff | first3=B. A. | last4=Baliunas | first4=S. L. | journal=The Astrophysical Journal Supplement Series | volume=118 | issue=1 | pages=239–258 | date=September 1998 | doi=10.1086/313135 | bibcode=1998ApJS..118..239R | postscript=. }}
9. ^1 {{citation | title=Spectroscopic Survey of G and K Dwarfs in the Hipparcos Catalog. I. Comparison between the Hipparcos and Photometric Parallaxes | display-authors=1 | last1=Kim | first1=Bokyoung | last2=An | first2=Deokkeun | last3=Stauffer | first3=John R. | last4=Lee | first4=Young Sun | last5=Terndrup | first5=Donald M. | last6=Johnson | first6=Jennifer A. | journal=The Astrophysical Journal Supplement Series | volume=222 | issue=2 | id=19 | pages=29 | date=February 2016 | doi=10.3847/0067-0049/222/2/19 | bibcode=2016ApJS..222...19K | postscript=. |arxiv = 1601.01459 }}
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12. ^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/Draco*.html | accessdate=2010-12-12 | edition=Reprint | publisher=Dover Publications Inc | location=New York, NY | isbn=0-486-21079-0 | page=210}}
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14. ^1 2 3 {{citation | last1=Porto de Mello | first1=Gustavo | last2=del Peloso | first2=Eduardo F. | last3=Ghezzi | first3=Luan | title=Astrobiologically Interesting Stars Within 10 Parsecs of the Sun | journal=Astrobiology | date=2006 | volume=6 | issue=2 | pages=308–331 | bibcode=2006AsBio...6..308P | doi=10.1089/ast.2006.6.308 | pmid=16689649 | arxiv=astro-ph/0511180 }}
15. ^1 {{citation | display-authors=1 | first1=E. K. | last1=Holmes | first2=H. M. | last2=Butner | first3=S. B. | last3=Fajardo-Acosta | first4=L. M. | last4=Rebull | title=A Survey of Nearby Main-Sequence Stars for Submillimeter Emission | journal=The Astronomical Journal | date=2003 | volume=125 | issue=6 | pages=3334–3343 | bibcode=2003AJ....125.3334H | doi=10.1086/375202 | doi-access=free}}
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17. ^1 {{citation | url=https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19720005197_1972005197.pdf | first=Jack W. | last=Rhoads | title=Technical Memorandum 33-507-A Reduced Star Catalog Containing 537 Named Stars | publisher=Jet Propulsion Laboratory, California Institute of Technology | date=November 15, 1971 }}
18. ^1 2 3 {{citation | last1=Oja | first1=T. | title=UBV photometry of stars whose positions are accurately known. III | journal=Astronomy and Astrophysics Supplement Series | volume=65 | issue=2 | pages=405–409 |date=August 1986 | bibcode=1986A&AS...65..405O }}
19. ^1 2 3 {{citation | display-authors=1 | last1=Vogt | first1=Steven S. | last2=Radovan | first2=Matthew | last3=Kibrick | first3=Robert | last4=Butler | first4=R. Paul | last5=Alcott | first5=Barry | last6=Allen | first6=Steve | last7=Arriagada | first7=Pamela | last8=Bolte | first8=Mike | last9=Burt | first9=Jennifer | last10=Cabak | first10=Jerry | last11=Chloros | first11=Kostas | last12=Cowley | first12=David | last13=Deich | first13=William | last14=Dupraw | first14=Brian | last15=Earthman | first15=Wayne | last16=Epps | first16=Harland | last17=Faber | first17=Sandra | last18=Fischer | first18=Debra | last19=Gates | first19=Elinor | last20=Hilyard | first20=David | last21=Holden | first21=Brad | last22=Johnston | first22=Ken | last23=Keiser | first23=Sandy | last24=Kanto | first24=Dick | last25=Katsuki | first25=Myra | last26=Laiterman | first26=Lee | last27=Lanclos | first27=Kyle | last28=Laughlin | first28=Greg | last29=Lewis | first29=Jeff | last30=Lockwood | first30=Chris | last31=Lynam | first31=Paul | last32=Marcy | first32=Geoffrey | last33=McLean | first33=Maureen | last34=Miller | first34=Joe | last35=Misch | first35=Tony | last36=Peck | first36=Michael | last37=Pfister | first37=Terry | last38=Phillips | first38=Andrew | last39=Rivera | first39=Eugenio | last40=Sandford | first40=Dale | last41=Saylor | first41=Mike | last42=Stover | first42=Richard | last43=Thompson | first43=Matthew | last44=Walp | first44=Bernie | last45=Ward | first45=James | last46=Wareham | first46=John | last47=Wei | first47=Mingzhi | last48=Wright | first48=Chris | title=APF - The Lick Observatory Automated Planet Finder | journal=Publications of the Astronomical Society of the Pacific | volume=126 | issue=938 | pages=359–379 |date=February 2014 | bibcode=2014PASP..126..359V | doi=10.1086/676120 | arxiv=1402.6684 }}
20. ^1 {{cite arXiv |last1=Agnew|first1=Matthew T. |last2=Maddison |first2=Sarah T.|last3=Horner |first3=Jonathan |last4=Kane |first4=Stephen R. |display-authors=1 |date=2019 |title=Predicting multiple planet stability and habitable zone companions in the TESS era |eprint=1901.11297}} — A random example of Kepler's 3rd law equation rearranged to change the subject to the orbital radius, and it being used in that rearranged state thereafter. See in the paper section 3.1, under the title "Numerical approach".
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22. ^1 {{citation | last1=Bailer-Jones | first1=C. A. L. | title=Close encounters of the stellar kind | journal=Astronomy & Astrophysics | volume=575 | id=A35 | pages=13 | date=March 2015 | doi=10.1051/0004-6361/201425221 | bibcode=2015A&A...575A..35B | postscript=.|arxiv = 1412.3648 }}
23. ^1 {{citation | last1=Lépine | first1=Sébastien | last2=Shara | first2=Michael M. | title=A Catalog of Northern Stars with Annual Proper Motions Larger than 0.15" (LSPM-NORTH Catalog) | journal=The Astronomical Journal | volume=129 | issue=3 | pages=1483–1522 | date=March 2005 | doi=10.1086/427854 | bibcode=2005AJ....129.1483L | postscript=. |arxiv = astro-ph/0412070 }}
24. ^1 {{cite journal|bibcode=1953ApJ...117..313J|title=Fundamental stellar photometry for standards of spectral type on the revised system of the Yerkes spectral atlas|journal=Astrophysical Journal|volume=117|pages=313|author1=Johnson|first1=H. L.|last2=Morgan|first2=W. W.|year=1953|doi=10.1086/145697}}
25. ^1 {{cite journal|bibcode=1973ARA&A..11...29M|title=Spectral Classification|journal=Annual Review of Astronomy and Astrophysics|volume=11|pages=29|author1=Morgan|first1=W. W.|last2=Keenan|first2=P. C.|year=1973|doi=10.1146/annurev.aa.11.090173.000333}}
26. ^1 {{cite journal|bibcode=1989ApJS...71..245K|title=The Perkins catalog of revised MK types for the cooler stars|journal=Astrophysical Journal Supplement Series|volume=71|pages=245|author1=Keenan|first1=Philip C.|last2=McNeil|first2=Raymond C.|year=1989|doi=10.1086/191373}}
27. ^1 {{cite web|url=http://www.astro.utoronto.ca/~garrison/mkstds.html|title=MK ANCHOR POINTS|author=Robert F. Garrison|accessdate=2017-04-30}}

References

{{reflist|30em|refs=[5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27]
}}

External links

  • {{cite web

| url=http://www.solstation.com/stars/sigdraco.htm
| title=Sigma Draconis | publisher =SolStation
| accessdate = 2007-06-15 }}{{Nearest systems|4}}{{Stars of Draco}}

10 : Bayer objects|Draco (constellation)|G-type main-sequence stars|Stars with proper names|Hipparcos objects|Flamsteed objects|Gliese and GJ objects|HR objects|Henry Draper Catalogue objects|Durchmusterung objects
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