المعرفة

گليزه 229

گليزه 229 (Gliese 229) قزم أحمر ونجم بارد يبعد 19 سنة ضوئية عن كوكبة الأرنب، ومن المعروف أنه نجم متوهج. صور له جرم مرافق في 1994 وأوكد في 1995 أنه قزم بني (گليزه 229 ب) يدور حول النجم. بالرغم من أن المرافق أصغر من أن يسمح باندماج نووي مستمر إلا أنه أكبر من أن يكون كوكبًا. وكان گليزه 229 ب أول جرم كبير أقل من نجم يحدد بدون شك.

Gliese 229
Brown Dwarf Gliese 229B.jpg
Gliese 229 A and B.
بيانات الرصـد
الحقبة J2000      اعتدال J2000
الكوكبة Lepus
الصعود المستقيم 06h 10m 34.6154s[1]
الميل −21° 51′ 52.715″[1]
القدر الظاهري (V)8.14
الخـصـائص
النوع الطيفيM1Ve / T7[2]
U-B دليل الألوان+1.222[2]
B-V دليل الألوان+1.478[2]
النوع المتغيرFlare star
علم القياسات الفلكية
السرعة القطرية (Rv)+3.9[3] كم/ث
الحركة الحقيقية (μ) RA: –137.01[1] mas/yr
Dec.: –714.05[1] mas/س
اختلاف المنظر (π)173.81 ± 0.99[4] mas
المسافةس ض
( ف ن)
القدر المطلق (MV)9.33[5]
التـفـاصـيل
الكتلة0.58/0.02[6] M☉
نصف القطر0.69/0.047[7] R☉
الضياء (bolometric)0.052[nb 1]/~0.000011 L☉
الضياء (visual, LV)0.0158[nb 2] L☉
درجة الحرارة3,700[8]/950[9] ك
سرعة الدوران (v sin i)1[10] كم/ث
تسميات أخرى
BD-21°1377, HD 42581, HIP 29295, LHS 1827, NSV 2863, SAO 171334, TYC 5945- 765-1
مراجع قواعد البيانات


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النظام الكوكبي

A substellar companion was discovered in 1994 by Caltech astronomers Kulkarni, Tadashi Nakajima, Keith Matthews, and Rebecca Oppenheimer, and Johns Hopkins scientists Sam Durrance and David Golimowski. It was confirmed in 1995 as Gliese 229B,[11][12] one of the first two instances of clear evidence for a brown dwarf, along with Teide 1. Although too small to sustain hydrogen-burning nuclear fusion as in a main sequence star, with a mass of 21 to 52.4 times that of Jupiter (0.02 to 0.05 solar masses), it is still too massive to be a planet. As a brown dwarf, its core temperature is high enough to initiate the fusion of deuterium with a proton to form helium-3, but it is thought that it used up all its deuterium fuel long ago.[13] This object now has a surface temperature of 950 K.[9]

In March 2014, a super-Neptune mass planet candidate was announced in a much closer-in orbit around GJ 229.[14] Given the proximity to the Sun, the orbit of GJ 229Ab might be fully characterized by the Gaia space-astrometry mission or via direct imaging. In 2020, a super-Earth mass planet was discovered around GJ 229. GJ 229Ac orbits the star closer in than GJ 229Ab, it is located towards the outer edge but still well inside the star's habitable zone and in that sense quite similar to Mars in our own solar system.[15]


نظام Gliese 229 [15]
المرافق
(بالترتيب من النجم) 		الكتلة نصف المحور الرئيسي
(و.ف.) 		الدور المداري
(day) 		الانحراف الميل نصف القطر
Ac ≥7.93 M⊕ 0.339 122.005 0.29 —
Ab ≥10.02 M⊕ 0.896 523.242 0.17 —
B ≥1.62[أ] MJ 19.433 ~50000 0.03 ~1.1 [17] RJ
  1. ^ Minimum mass of GJ 229B as measured by radial velocity measurements is 1.62 Mj.[15] However, observations of GJ 229B suggest, that the system is viewed with a relative face-on orientation with an inclination of 13+10
    −12    .[16] If that is true and the planetary system is coplanar, then the real masses of all planets would be about 4.5 times more massive than the minimal mass derived from radial velocity measurements (2.6 up to 57 times of minimal mass, depending on the exact angle of inclination). Additionally, some measurements of Gliese 229B in particular indicate a much higher mass, up to around 70 Mj.[16]


المراجع

  1. ^ أ ب ت ث Perryman, M. A. C.; et al. (1997). "The Hipparcos Catalogue". Astronomy and Astrophysics. 323: L49–L52. Bibcode:1997A&A...323L..49P.
  2. ^ أ ب ت خطأ استشهاد: وسم <ref> غير صحيح؛ لا نص تم توفيره للمراجع المسماة mnras214
  3. ^ Evans, D. S. (June 20–24, 1966). "The Revision of the General Catalogue of Radial Velocities"., University of Toronto: International Astronomical Union. 
  4. ^ Perryman; et al. (1997). "HIP 29295". The Hipparcos and Tycho Catalogues. Retrieved 2014-11-29.
  5. ^ "The One Hundred Nearest Star Systems". RECONS. Georgia State University. January 1, 2012. Retrieved 2013-04-16.
  6. ^ Zechmeister, M.; Kürster, Martin; Endl, M. (October 2009). "The M dwarf planet search programme at the ESO VLT + UVES. A search for terrestrial planets in the habitable zone of M dwarfs". Astronomy and Astrophysics. 505 (2): 859–871. arXiv:0908.0944. Bibcode:2009A&A...505..859Z. doi:10.1051/0004-6361/200912479. S2CID 16845441.
  7. ^ White, Stephen M.; Jackson, Peter D.; Kundu, Mukul R. (December 1989). "A VLA survey of nearby flare stars". Astrophysical Journal Supplement Series. 71: 895–904. Bibcode:1989ApJS...71..895W. doi:10.1086/191401.
  8. ^ Morales, J. C.; Ribas, I.; Jordi, C. (February 2008). "The effect of activity on stellar temperatures and radii". Astronomy and Astrophysics. 478 (2): 507–512. arXiv:0711.3523. Bibcode:2008A&A...478..507M. doi:10.1051/0004-6361:20078324. S2CID 16238033. Data from CDS table J/A+A/478/507.
  9. ^ أ ب Geißler, K.; Chauvin, G.; Sterzik, M. F. (March 2008). "Mid-infrared imaging of brown dwarfs in binary systems". Astronomy and Astrophysics. 480 (1): 193–198. arXiv:0712.1887. Bibcode:2008A&A...480..193G. doi:10.1051/0004-6361:20078229. S2CID 9331798.
  10. ^ Reiners, Ansgar (May 2007). "The narrowest M-dwarf line profiles and the rotation-activity connection at very slow rotation". Astronomy and Astrophysics. 467 (1): 259–268. arXiv:astro-ph/0702634. Bibcode:2007A&A...467..259R. doi:10.1051/0004-6361:20066991. S2CID 8672566.
  11. ^ "Astronomers Announce First Clear Evidence of a Brown Dwarf". Space Telescope Science Institute news release STScI-1995-48. November 29, 1995. Retrieved 24 September 2013.
  12. ^ Oppenheimer, Ben R. (2014), "Companions of Stars: From Other Stars to Brown Dwarfs to Planets and the Discovery of the First Methane Brown Dwarf", in Joergens, Viki, 50 Years of Brown Dwarfs - From Prediction to Discovery to Forefront of Research, Astrophysics and Space Science Library, 401, Springer, pp. 81–111, doi:10.1007/978-3-319-01162-2_6, ISBN 978-3-319-01162-2 
  13. ^ J. Kelly Beatty; Carolyn Collins Petersen; Andrew Chaikin (1999). The New Solar System. Cambridge University Press.
  14. ^ Tuomi, Mikko; et al. (2014). "Bayesian search for low-mass planets around nearby M dwarfs – Estimates for occurrence rate based on global detectability statistics". Monthly Notices of the Royal Astronomical Society. 441 (2): 1545. arXiv:1403.0430. Bibcode:2014MNRAS.441.1545T. doi:10.1093/mnras/stu358. S2CID 32965505.
  15. ^ أ ب ت https://arxiv.org/abs/2001.02577 Search for Nearby Earth Analogs. II. detection of five new planets, eight planet candidates, and confirmation of three planets around nine nearby M dwarfs
  16. ^ أ ب Brandt, Timothy D.; Dupuy, Trent J.; Bowler, Brendan P.; Gagliuffi, Daniella C. Bardalez; Faherty, Jacqueline; Brandt, G. Mirek; Michalik, Daniel (2020). "A Dynamical Mass of 70±5 Jupiter Masses for Gliese 229B, the First Imaged T Dwarf". Astronomical Journal. 160: 4. arXiv:1910.01652. doi:10.3847/1538-3881/abb45e. S2CID 222277091.{{cite journal}}: CS1 maint: unflagged free DOI (link)
  17. ^ Nakajima, T.; Tsuji, T.; Takeda, Y. (July 2015). "PHYSICAL PROPERTIES OF GLIESE 229B BASED ON NEWLY DETERMINED CARBON AND OXYGEN ABUNDANCES OF GLIESE 229A". The Astronomical Journal (in الإنجليزية). 150 (2): 53. arXiv:1506.03178. doi:10.1088/0004-6256/150/2/53. ISSN 1538-3881.

ملاحظات

  1. ^ Using the absolute bolometric magnitude of Gliese 229 A   and the absolute bolometric magnitude of the Sun  , the bolometric luminosity can be calculated by  
  2. ^ Using the absolute visual magnitude of Gliese 229 A   and the absolute visual magnitude of the Sun  , the visual luminosity can be calculated by  

وصلات خارجية

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