القفزة الأولى الجنوبية

(تم التحويل من Xi Ursae Majoris)
القفزة الأولى الجنوبية
القفزة الأولى الجنوبية is located in 100x100
القفزة الأولى الجنوبية

The red circle shows the location of Xi Ursae Majoris in Ursa Major.
بيانات الرصـد
Epoch J2000      Equinox J2000
Constellation Ursa Major
ξ UMa A
Right ascension 11h 18m 10.902s[1]
Declination +31° 31′ 44.98″[1]
Apparent magnitude (V) 4.264[1]
ξ UMa B
Right ascension 11h 18m 10.950s[1]
Declination +31° 31′ 45.74″[1]
Apparent magnitude (V) 4.729[1]
الخـصـائص
النوع الطيفيF8.5:V / G2V[2]
U-B دليل الألوان0.04[3]
B-V دليل الألوان0.59[3]
النوع المتغيرRS CVn[4]
علم القياسات الفلكية
السرعة القطرية (Rv)−18.2±2.7[5] كم/ث
الحركة الحقيقية (μ) RA: −339.398 mas/yr
Dec.: −607.892 mas/س
اختلاف المنظر (π)114.4867 ± 0.4316[6] mas
المسافةس ض
( ف ن)
علم القياسات الفلكية
القدر المطلق (MV)4.66[note 1]
المدار[7]
الرئيسيξ UMa A
الرفيقξ UMa B
الدورة (P)59.878 س
Semimajor axis (a)2.536"
اختلاف المركز (e)0.398
ميل (i)127.94°
خط طول العقدة (Ω)101.85 (ascending)°
نقطة التقارب الحقبة (T)1935.195
المدار[7]
الرئيسيξ UMa Aa
الرفيقξ UMa Ab
الدورة (P)1.832 س
Semimajor axis (a)0.057"
اختلاف المركز (e)0.53
ميل (i)94.9°
التـفـاصـيل[8]
ξ UMa Aa
الكتلة0.97 M☉
نصف القطر1.02±0.04 R☉
الضياء1.21 L☉
جاذبية السطح (ج)4.39±0.10 س.ج.ث.
درجة الحرارة6,005±80 ك
تسارع الدوران (v sin i)1.0±1.0 كم/ث
ξ UMa Ab
الكتلة0.38±0.02 M☉
نصف القطر0.32 R☉
درجة الحرارة~3,700[note 2] ك
ξ UMa Ba
الكتلة0.86 M☉
نصف القطر0.92±0.04 R☉
الضياء0.79 L☉
جاذبية السطح (ج)4.46±0.10 س.ج.ث.
درجة الحرارة5,692±90 ك
المعدنية [Fe/H]−0.35±0.08 العشرية
تسارع الدوران (v sin i)3.0±1.0 كم/ث
ξ UMa Bb
الكتلة0.14+0.05
−0.09 M☉
تسميات أخرى
Alula Australis، ξ Ursae Majoris, ξ UMa, Xi UMa، 53 Ursae Majoris، BD+32°2132، GC 15537، GJ 423، HIP 55203، SAO 62484، CCDM J11182+3132، WDS J11182+3132
مراجع قواعد البيانات
SIMBADdata

القفزة الأولى الجنوبية أو كساي الدب الأكبر Xi Ursae Majoris اسمه التقليدي Alula Australis مشتق من الاسم العربي.[9] وهو نظام نجمي في كوكبة الدب الأكبر. وكان أول نجم اكتشف بأنه نجم مزدوج بواسطة ويليام هيرشيل في سنة 1780. كما كان أول نجم مرئي ام حساب مداره بواسطة فليكس سافاري سنة 1828.

Xi Ursae Majoris is a quintuple star system 28.5 light-years (8.7 parsecs) away in the constellation of Ursa Major. It has the traditional name Alula Australis;[10][11] Xi Ursae Majoris is the Bayer designation, which is Latinised from ξ Ursae Majoris and abbreviated Xi UMa or ξ UMa. It was the first visual double star for which an orbit was calculated, when it was computed by Félix Savary in 1828.[بحاجة لمصدر] It is also a variable star with a small amplitude. Xi Ursae Majoris is found in the left hind paw of the Great Bear.[12]

النظام النجمي

Orbit of Xi Ursae Majoris

وينتمي كلا النوعين إلى الفئة الطيفية G وهما قزمان أبيضان من النسق الأساسي. ويملك النجم الأسطع القفزة الأولى الجنوبي A قدر ظاهري +4.41، بينما يملك القفزة الأولى الجنوبي B قدراً ظاهرياً +4.87، وتبلغ الفترة المدارية للنجمين 59.84 سنة.

كل نجم من هذين النجمين هما عبارة عن نظام نجمي مزدوج بذات نفسه، ويرمز لكل من الرفيق النجمي للثنائية برمز b ليصبح الرفيقان النجميان: القفزة الأولى الجنوبي Ab والقفزة الأولى الجنوبي Bb. وقد تم تحديد كتلة كل من الرفيقين b عن طريق حساب كتلة النظام الكلي ويطرح منها كتلة النجمين A,B قدر رجحت أنهم في الغالب قزمين أحمرين ومن الممكن أن يكون Bb أبرد وهو قزم بني.[13]

The two main components are yellow main-sequence stars. The brighter component (designated Xi Ursae Majoris A), has a mean apparent magnitude of +4.41. The companion star (Xi Ursae Majoris B) has an apparent magnitude of +4.87. The orbital period of the two stars is 59.84 years. They are currently (2022) separated by 2.3 arcseconds, and will widen to a maximum 3.0 arcseconds in 2035.

Double star Xi Ursae Majoris.(θ):156.6° (ρ):2.1 arc"

Each component of this double star is itself a single-lined spectroscopic binary. The orbit of the A pair has been determined from spectroscopy and speckle interferometry, giving a period of 669 days and an eccentricity of 0.53.[7] B's binary companion (Xi Ursae Majoris Bb) has not been detected visually, but the radial velocity variations of the spectral lines show a circular orbit with a period of 3.98 days.[14] The masses of both A and B's companions (Ab and Bb) (deduced by the sum total mass of the system minus the likely masses of Aa and Ba determined by their class) indicate that they are probably red dwarfs, Bb being on the cool end of the M spectrum, not much hotter than a brown dwarf.[15] However, component Ba has been found to be enriched in barium relative to component Aa, suggesting that its companion Bb may be a white dwarf.[16]

In 2012 Wright et al. discovered the fifth component and the first brown dwarf of the system using Wide-field Infrared Survey Explorer (WISE) data—a T8.5 brown dwarf WISE J111838.70+312537.9 with angular separation 8.5 arcmin, and the projected physical separation about 4,000 AU.[17]


نجم متغير

A light curve for Xi Ursae Majoris, plotted from TESS data[18]

ξ Ursae Majoris is classified as an RS Canum Venaticorum variable and its brightness varies by 0.01 magnitude.[19] Component B is believed to be the variable star, showing characteristic emission lines in its spectrum that are not present for component A.[20]

التسمية

ξ Ursae Majoris (Latinised to Xi Ursae Majoris) is the star's Bayer designation.

It also bore the traditional names Alula Australis[21] (and erroneously Alula Australe[22]). Alula (shared with Nu Ursae Majoris) comes from the Arabic phrase Al Ḳafzah al Ūla 'the First Spring'[23] and Australis is Latin for 'southern'. In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[24] to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016[25] included a table of the first two batches of names approved by the WGSN; which included Alula Australis for this star.

In Chinese, 三台 (Sān Tái), meaning Three Steps, refers to an asterism consisting of Xi Ursae Majoris, Iota Ursae Majoris, Kappa Ursae Majoris, Lambda Ursae Majoris, Mu Ursae Majoris and Nu Ursae Majoris. Consequently, the Chinese name for Xi Ursae Majoris itself is 下台二 (Xià Tái èr, إنگليزية: Star of Second Lower Step).[26]

انظر أيضا


المراجع

  1. ^ أ ب ت ث ج ح Høg, E.; et al. (2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27–L30. Bibcode:2000A&A...355L..27H.
  2. ^ Keenan, Philip C; McNeil, Raymond C (1989). "The Perkins catalog of revised MK types for the cooler stars". Astrophysical Journal Supplement Series. 71: 245. Bibcode:1989ApJS...71..245K. doi:10.1086/191373.
  3. ^ أ ب Nicolet, B (1978). "Catalogue of homogeneous data in the UBV photoelectric photometric system". Astronomy and Astrophysics. 34: 1. Bibcode:1978A&AS...34....1N.
  4. ^ Dempsey, Robert C; Linsky, Jeffrey L; Fleming, Thomas A; Schmitt, J. H. M. M (1993). "The ROSAT All-Sky Survey of active binary coronae. I - Quiescent fluxes for the RS Canum Venaticorum systems". Astrophysical Journal Supplement Series. 86: 599. Bibcode:1993ApJS...86..599D. doi:10.1086/191791.
  5. ^ Nordström, B.; et al. (2004). "The Geneva-Copenhagen survey of the Solar neighbourhood. Ages, metallicities, and kinematic properties of ~14000 F and G dwarfs". Astronomy and Astrophysics. 418 (3): 989–1019. arXiv:astro-ph/0405198. Bibcode:2004A&A...418..989N. doi:10.1051/0004-6361:20035959. S2CID 11027621.
  6. ^ قالب:Cite Gaia DR2
  7. ^ أ ب ت Mason, Brian D.; McAlister, Harold A.; Hartkopf, William I.; Shara, M. M.; Shara, M. M. (January 1995). "Binary star orbits from speckle interferometry. 7: The multiple system XI Ursae Majoris". The Astronomical Journal. 109 (1669): 332–340. Bibcode:1995AJ....109..332M. doi:10.1086/117277.
  8. ^ Fuhrmann, Klaus (2008). "Nearby stars of the Galactic disc and halo - IV". Monthly Notices of the Royal Astronomical Society. 384 (1): 173–224. Bibcode:2008MNRAS.384..173F. doi:10.1111/j.1365-2966.2007.12671.x.
  9. ^ Burritt, E. H., Atlas, Designed to Illustrate the Geography of the Heavens, New York, 1835.
  10. ^ خطأ استشهاد: وسم <ref> غير صحيح؛ لا نص تم توفيره للمراجع المسماة Kunitzsch
  11. ^ "IAU Catalog of Star Names". Retrieved 28 July 2016.
  12. ^ Griffin, R. F. (1998). "Spectroscopic binary orbits from photoelectric radial velocities. Paper 142: Xi Ursae Majoris". The Observatory. 118: 273. Bibcode:1998Obs...118..273G.
  13. ^ http://www.astro.illinois.edu/~jkaler/sow/alulaaus.html
  14. ^ Berman, Louis (1931). "The spectroscopic orbit of the fainter component in the system [xi] Ursae Majoris". Lick Observatory Bulletin. 15: 109–116. Bibcode:1931LicOB..15..109B. doi:10.5479/ADS/bib/1931LicOB.15.109B.
  15. ^ Jim Kaler. "Alula Australis". Retrieved 2019-05-20.
  16. ^ Fuhrmann, K.; Chini, R.; et al. (June 2016). "Evidence for very nearby hidden white dwarfs". Monthly Notices of the Royal Astronomical Society. 459 (2): 1682–1686. Bibcode:2016MNRAS.459.1682F. doi:10.1093/mnras/stw760.
  17. ^ Wright, Edward L.; Skrutskie, M. F.; Kirkpatrick, J. Davy; Gelino, Christopher R.; Griffith, Roger L.; Marsh, Kenneth A.; Jarrett, Tom; Nelson, M. J.; Borish, H. J.; Mace, Gregory; Mainzer, Amanda K.; Eisenhardt, Peter R.; McLean, Ian S.; Tobin, John J.; Cushing, Michael C. (2012). "A T8.5 Brown Dwarf Member of the Xi Ursae Majoris System". The Astronomical Journal. 145 (3): 84. arXiv:1203.5764v1. Bibcode:2013AJ....145...84W. doi:10.1088/0004-6256/145/3/84. S2CID 8588271.
  18. ^ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 30 October 2022.
  19. ^ Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S.
  20. ^ Strassmeier, Klaus G; Hall, Douglas S; Boyd, Louis J; Genet, Russell M (1989). "Photometric variability in chromospherically active stars. III - the binary stars". Astrophysical Journal Supplement Series. 69: 141. Bibcode:1989ApJS...69..141S. doi:10.1086/191310.
  21. ^ Piazzi, G. (1814). The Palermo Catalogue. Palermo.
  22. ^ Antonín Bečvář (1951). Atlas of the heavens: Atlas coeli. Skalnaté pleso II. Katalog 1950.0. Prírodovedecké vydavatelstvi.
  23. ^ Richard Hinckley Allen. "Star Names — Their Lore and Meaning – Ursa Major, the Greater Bear". Retrieved 2019-05-20.
  24. ^ "IAU Working Group on Star Names (WGSN)". Retrieved 22 May 2016.
  25. ^ "Bulletin of the IAU Working Group on Star Names, No. 1" (PDF). Retrieved 28 July 2016.
  26. ^ (in صينية) (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 6 月 21 日 Archived 2016-03-03 at the Wayback Machine

Note

  1. ^ Calculated from the bolometric magnitude 4.54 ± 0.06 and the bolometric correction −0.12 ± 0.05 using the formula: BC = Mbol − MV
  2. ^ This estimate assumes that ξ UMa Ab is a red dwarf.

External links

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