比鄰星b：修订间差异
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2016年8月25日 (四) 02:51的版本
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| 太陽系外行星 | 太陽系外行星列表 | |
|---|---|---|
 | ||
| 母恆星 | ||
| 母恆星 | 比鄰星 | |
| 星座 | 半人馬座 | |
| 距離 | 4.224 ly (1.295[1] pc) | |
| 光譜類型 | M6Ve[2] | |
| 物理性质 | ||
| 最小质量 | (m sin i) | 1.27+0.19 −0.17[1] M🜨 |
| 辐射功率 | (F⊙) | 0.65[1] 🜨 |
| 温度 | (T) | 234 K（−39 °C） K |
| 軌道參數 | ||
| 半長軸 | (a) | 0.05 AU |
| 軌道離心率 | (e) | <0.35[1] |
| 公轉週期 | (P) | 11.186 d |
| 發現 | ||
| 發現時間 | 2016年8月24日 | |
| 發現者 | ||
| 發現方法 | 都卜勒光譜學 | |
| 發現地點 | 欧洲南方天文台 | |
| 發表論文 | 確認 | |
| 其他名稱 | ||
半人馬座α Cb（Alpha Centauri Cb）, Proxima b, GL 551 b, HIP 70890 b
| ||
| 數據庫參考 | ||
| 太陽系外行星 百科全書 | data | |
| SIMBAD | data | |
比鄰星b（Proxima Centauri b 或 Proxima b[3][4]）是一顆位於距離太陽最近的其他恆星，紅矮星比鄰星適居帶內的太陽系外行星[5]。該行星距離地球約4.2光年（1.3秒差距），在天球上位於半人馬座 。比鄰星b是已知距離太陽系最近的系外行星，也是已知距離最近的適居帶內系外行星。該行星是由觀測母恆星光譜譜線週期性移動狀況的徑向速度法發現。根據觀測資料，該天體相對於地球的運動速度大約5 km/h [1]。
Characteristics
Mass, radius and temperature
Proxima Centauri b may be an Earth-sized planet. It has a minimum mass of 1.27 M🜨.[1] The actual mass depends on the unknown orbital inclination, and there is a 90% chance the actual mass is below 3 M🜨.[6] The radius is at least 1.1 R🜨, assuming a rocky composition and a density equal to that of the Earth. However, it could be larger if it has a lower density than the Earth, or a mass higher than the minimum mass.[7] The planet has an equilibrium temperature of 234 K（−39 °C；−38 °F）.[1]
Host star
The planet orbits a (M-type) red dwarf star named Proxima Centauri. The star has a mass of 0.12 M☉ and a radius of 0.14 R☉.[1] It has a surface temperature of 3042 K[8] and is 4.85 billion years old.[9] In comparison, the Sun is 4.6 billion years old[10] and has a surface temperature of 5778 K.[11] Proxima Centauri rotates once every ~83 days,[12] and has a luminosity about 0.0015 times that of the Sun.[1]
The star's apparent magnitude, or how bright it appears from Earth's perspective, is 11.13.[13] Even though it is the closest star to the Sun, because of its low luminosity, it is not visible to the unaided eye (and even with small binoculars) from Earth.
Orbit
Proxima Centauri b orbits its host star every 11.186 days with a semi-major axis distance of approximately 0.05 AU (comparatively, Mercury's semi-major axis distance from the Sun is 0.39 AU).[1] At this distance, the stellar flux Proxima Centauri b receives is about 65% of the amount the Earth receives from the Sun. However, Proxima Centauri b receives about 400 times more X-ray flux than the Earth.[1]
Habitability
The exoplanet was announced orbiting within the habitable zone of Proxima Centauri, the region where, with the correct conditions and atmospheric properties, liquid water may exist on the surface of the planet. Its host star is a red dwarf, with about a tenth of the mass of the Sun. As a result, stars like Proxima Centauri have the ability to live up to 3–4 trillion years, 300–400 times longer than the Sun will live.[14]
The planet is close enough to its star that it might be tidally locked;[15] a state in which a planet's orbital period and rotational period fall into sync.[16] If the planet's orbital eccentricity is 0, this could result in synchronous rotation, with one side permanently facing towards the star, while the opposite side is permanently dark.[17][18] However, between these two extreme areas, there would be a region of habitability – called the terminator line, where the temperatures may be suitable (about 273 K（0 °C；32 °F）) for liquid water to exist. Proxima Centauri b's orbital eccentricity is not known with certainty, only that it is below 0.35; potentially high enough to produce a 3:2 orbit resonance similar to that which the planet Mercury has with the Sun. The European Southern Observatory predicts a far more clement environment would result from such a configuration, with average temperatures similar to those on Earth.[19] Additionally, a much larger portion of the planet may be habitable if it supports a thick enough atmosphere to transfer heat to the side facing away from the star.[16]
Discovery
Proxima Centauri b was discovered by a European Southern Observatory team[9] led by Guillem Anglada-Escudé of Queen Mary University of London. The discovery was reported in Nature on 24 August 2016.[1][15][20] The measurements were done using two spectrographs, HARPS at La Silla Observatory and UVES on the 8-meter Very Large Telescope.[1] The first indication of a planet was found in 2013.[12] The peak radial velocity of the host star combined with the orbital period allowed for the minimum mass of the exoplanet to be calculated.
Before the official discovery, the planet was suspected to exist for at least a few weeks during a period time when a small fragment of an announcement from the ESO was leaked online, and the news circulated quickly. The European Southern Observatory denied any involvement in the leak or the discovery. However, after increasing pressure the ESO eventually decided to hold an online press conference regarding if the planet existed.[21]
參見
參考資料
- ^ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 Anglada-Escudé, Guillem; Amado, Pedro J.; Barnes, John; Berdiñas, Zaira M.; Butler, R. Paul; Coleman, Gavin A. L.; de la Cueva, Ignacio; Dreizler, Stefan; Endl, Michael; Giesers, Benjamin; Jeffers, Sandra V.; Jenkins, James S.; Jones, Hugh R. A.; Kiraga, Marcin; Kürster, Martin; López-González, Marίa J.; Marvin, Christopher J.; Morales, Nicolás; Morin, Julien; Nelson, Richard P.; Ortiz, José L.; Ofir, Aviv; Paardekooper, Sijme-Jan; Reiners, Ansgar; Rodríguez, Eloy; Rodrίguez-López, Cristina; Sarmiento, Luis F.; Strachan, John P.; Tsapras, Yiannis; Tuomi, Mikko; Zechmeister, Mathias. A terrestrial planet candidate in a temperate orbit around Proxima Centauri. Nature. 25 August 2016, 536 (7617): 437–440. ISSN 0028-0836. doi:10.1038/nature19106 （英语）.
- ^ Torres, C. A. O.; Quast, G. R.; Da Silva, L.; De La Reza, R.; Melo, C. H. F.; Sterzik, M. Search for associations containing young stars (SACY). I. Sample and searching method. Astronomy and Astrophysics. December 2006, 460 (3): 695–708. Bibcode:2006A&A...460..695T. arXiv:astro-ph/0609258
. doi:10.1051/0004-6361:20065602.
- ^ Earth-like planet discovered orbiting sun's neighbor. CNN. 24 August 2016 [24 August 2016].
A planet named Proxima b has been discovered orbiting the closest star to our sun.
- ^ Davis, Nicola. Discovery of potentially Earth-like planet Proxima b raises hopes for life. The Guardian. 24 August 2016 [24 August 2016].
- ^ Chang, Kenneth. One Star Over, a Planet That Might Be Another Earth. New York Times. 24 August 2016 [24 August 2016].
- ^ Marchis, Franck. Proxima Centauri b: Have we just found Earth’s cousin right on our doorstep?. The Planetary Society. August 24, 2016 [August 24, 2016].
- ^ A Potentially Habitable World in Our Nearest Star. Planetary Habitability Laboratory. August 24, 2016.
- ^ Ségransan, D.; Kervella, P.; Forveille, T.; Queloz, D. First radius measurements of very low mass stars with the VLTI. Astronomy and Astrophysics. 2003, 397 (3): L5–L8. Bibcode:2003A&A...397L...5S. arXiv:astro-ph/0211647 . doi:10.1051/0004-6361:20021714.
- ^ 9.0 9.1 Mathewson, Samantha. Proxima b By the Numbers: Possibly Earth-Like World at the Next Star Over. Space.com. August 24, 2016 [August 25, 2016].
- ^ Fraser Cain. How Old is the Sun?. Universe Today. 16 September 2008 [19 February 2011].
- ^ Fraser Cain. Temperature of the Sun. Universe Today. 15 September 2008 [19 February 2011].
- ^ 12.0 12.1 Proxima b is our neighbor… better get used to it!. Pale Red Dot. August 24, 2016 [August 24, 2016].
- ^ Jao, Wei-Chun; Henry, Todd J.; Subasavage, John P.; Winters, Jennifer G.; Gies, Douglas R.; Riedel, Adric R.; Ianna, Philip A. The Solar Neighborhood. XXXI. Discovery of an Unusual Red+White Dwarf Binary at ~25 pc via Astrometry and UV Imaging. The Astronomical Journal. 2014, 147 (1): 21. Bibcode:2014AJ....147...21J. ISSN 0004-6256. arXiv:1310.4746 . doi:10.1088/0004-6256/147/1/21.
- ^ Adams, Fred C.; Laughlin, Gregory; Graves, Genevieve J. M. Red Dwarfs and the End of the Main Sequence. Gravitational Collapse: From Massive Stars to Planets. Revista Mexicana de Astronomía y Astrofísica: 46–49. Bibcode:2004RMxAC..22...46A.
- ^ 15.0 15.1 Witze, Alexandra. Earth-sized planet around nearby star is astronomy dream come true. Nature. 24 August 2016: 381–382 [24 August 2016]. doi:10.1038/nature.2016.20445.
- ^ 16.0 16.1 Singal, Ashok K. Life on a tidally-locked planet. Planex Newsletter, Vol. , Issue , 8 (01). 2014, 4 (2). arXiv:1405.1025 .
- ^ Barnes, Rory (编), Formation and Evolution of Exoplanets, John Wiley & Sons: 248, 2010, ISBN 3527408967.
- ^ Heller, R.; Leconte, J.; Barnes, R. Tidal obliquity evolution of potentially habitable planets. Astronomy & Astrophysics. April 2011, 528: 16. Bibcode:2011A&A...528A..27H. arXiv:1101.2156 . doi:10.1051/0004-6361/201015809. A27.
- ^ Numerical simulation of possible surface temperatures on Proxima b (synchronous rotation). ESO. 2016 [2016-08-24].
- ^ Anglada-Escudé, Guillem; Amado, Pedro J.; Barnes, John; Berdiñas, Zaira M.; Butler, R. Paul; Coleman, Gavin A. L.; de la Cueva, Ignacio; Dreizler, Stefan; Endl, Michael; Giesers, Benjamin; Jeffers, Sandra V.; Jenkins, James S.; Jones, Hugh R. A.; Kiraga, Marcin; Kürster, Martin; López-González, María J.; Marvin, Christopher J.; Morales, Nicolás; Morin, Julien; Nelson, Richard P.; Ortiz, José L.; Ofir, Aviv; Paardekooper, Sijme-Jan; Reiners, Ansgar; Rodríguez, Eloy; Rodríguez-López, Cristina; Sarmiento, Luis F.; Strachan, John P.; Tsapras, Yiannis; Tuomi, Mikko; Zechmeister, Mathias. A terrestrial planet candidate in a temperate orbit around Proxima Centauri (PDF). eos.org. European Southern Observatory. 2016-07-13 [2016-08-24].
- ^ Earth-Like Planet Around Proxima Centauri Discovered. Universe Today. 17 August 2016 [24 August 2016].
外部連結
- A search for Earth-like planets around Proxima Centauri
- The habitability of Proxima Centauri b - Pale Red Dot website for future updates
- ESOcast 87: Pale Red Dot Results
- Interviews with Pale Red Dot scientists
- Press Conference at ESO HQ
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