编辑“︁PSR B1620-26”︁

{{Starbox begin 
| name = PSR B1620−26
}} 
{{Starbox image 
| image = [[Image:Location of pulsar B1620-26.jpg|250px]]
| caption = PSR B1620−26的位置(小藍綠圈標示)
}} 
{{Starbox observe 
| epoch = [[J2000.0]]
| constell = [[天蠍座]](梅西耶天體|M4]])
| ra = {{RA|16|23|38.2218}}<ref name=SIMBAD/>
| dec = {{DEC|−26|31|53.769}}<ref name=SIMBAD/>
| appmag_v = 21.30<ref name=SIMBAD/>
}} 
{{Starbox character 
| class = Pulsar / DB
| b-v = 
| u-b = 
| variable = none
}} 
{{Starbox astrometry 
| radial_v = 
| prop_mo_ra = 
| prop_mo_dec = 
| parallax = 
| p_error = 
| dist_ly = 12,400
| dist_pc = 3,800
| absmag_v = 
}}  
{{Starbox detail 
| age =〜120億
| metal = 
| mass = 1.35 / 0.34
| radius = 
| rotation = 
| luminosity = 
| temperature = 
}} 
{{Starbox catalog 
| names = PSR J1623−2631
}}
{{Starbox reference
|Simbad=PSR+B1620-26
}}
{{Starbox end}}

'''PSR B1620−26'''是位於[[天蠍座]]的[[球狀星團]][[M4 (球狀星團)|M4]]內的[[聯星]]系統，距離3,800[[秒差距]]<ref name=EPEstar>{{cite web |url=http://exoplanet.eu/star.php?st=PSR+B1620-26 |title=Notes for star PSR B1620-26 |author=Jean Schneider |date=2011 |publisher=[[Extrasolar Planets Encyclopaedia]] |access-date=26 September 2011 |archive-date=2012-03-13 |archive-url=https://www.webcitation.org/668nDBSXx?url=http://exoplanet.eu/star.php?st=PSR+B1620-26 |dead-url=no }}</ref><ref name="arzoumanian">{{cite journal | author = Z. Arzoumanian | author2 = K. Joshi | author3 = F. A. Rasio | author4 = S. E. Thorsett | title=Orbital Parameters of the PSR B1620-26 Triple System | journal=Proceedings of the 160th Colloquium of the International Astronomical Union | date=1999 | volume=105 | pages=525 | bibcode=1996ASPC..105..525A |arxiv = astro-ph/9605141 }}</ref><ref name=ESO>{{cite web |url=http://www.eso.org/public/images/m4/ |title=Messier 4 (M4) globular cluster |date=2009 |publisher=[[European Southern Observatory]] |access-date=26 September 2011 |archive-date=2018-09-03 |archive-url=https://web.archive.org/web/20180903082306/https://www.eso.org/public/images/m4/ |dead-url=no }}</ref>。這個系統由一顆[[脈衝星]]( '''PSR B1620−26 A''')和一顆[[白矮星]]( [[WD B1620−26]]或'''PSR B1620−26 B''')組成。截至2000年，該系統還被證實有一顆[[系外行星]]圍繞著這兩顆恆星運行。

== 歷史 ==
聯星系統(''三合星''包括被稱為行星的同伴)就在球狀星團核心之旁。根據估計，這個星團的年齡約為122億年<ref name=aaa143_1>{{cite journal | author=Caputo, F. | author2=Castellani, V. | author3=Quarta, M. L. | title=Reddening, distance modulus and age of the globular cluster NGC 6121 (M4) from the properties of RR Lyrae variables | url=https://archive.org/details/sim_astronomy-and-astrophysics_1985-02_143_1/page/8 | journal=Astronomy and Astrophysics | volume=143| issue=1 |date=February 1985 | pages=8–12 | bibcode=1985A&A...143....8C
}}</ref>。因此，這也是兩顆恆星和行星誕生年齡的估計。

對於這個不尋常的恆星系統命名規則有一個小小的爭議。一方認為命名聯星的A/B約定具有優先權，因此脈衝星命名為PSR B1620−26 A，白矮星伴星為PSR B1620−26 B，行星為[[PSR B1620-26b]]。另一方認為PSR只適用於脈衝星的恆星，而不適用於伴星的白矮星。因此，白矮星應該用WD的慣例命名，即脈衝星是"PSR B1620−26"，白矮星是"WD J1623−266"，行星是"PSR B1620−26 b"。早期的文章使用第一種命名法則，但是星表都使用第二種命名法<ref name=SIMBAD>{{cite simbad|title=PSR B1620-26|access-date=31 January 2018}}</ref><ref name=EPEplanet>{{cite encyclopedia |url=http://exoplanet.eu/planet.php?p1=PSR+B1620-26&p2=b |title=Notes for Planet PSR B1620−2 b |author=Jean Schneider |date=2011 |encyclopedia=[[Extrasolar Planets Encyclopaedia]] |access-date=24 September 2011 |archive-date=2011-11-09 |archive-url=https://web.archive.org/web/20111109025942/http://exoplanet.eu/planet.php?p1=PSR+B1620-26&p2=b |dead-url=no }}</ref>。最近的提議<ref name="hessman">{{cite journal | author = F. V. Hessman | display-authors = 4 | author2 = V. S. Dhillon | author3 = D. E. Winget | author4 = M. R. Schreiber | author5 = K. Horne | author6 = T. R. Marsh | author7 = E. Guenther | author8 = A. Schwope | author9 = U. Heber | title=On the naming convention used for multiple star systems and extrasolar planets | date=2010 | pages=4| bibcode=2010arXiv1012.0707H |arxiv = 1012.0707 }}</ref>提供類似的命名法，以'''PSR B1620−26 (AB)b'''命名行星，括弧中的大寫字母'''A'''和'''B'''識別這是聯星系統的兩顆恆星，後面小寫的'''b'''表示是繞行這兩顆恆星的[[系外行星]]。, 在實務上，細讀上下文可以清楚的表明，是指脈衝星、白矮星、行星，還是整個系統。

== 白矮星 ==
白矮星的質量是0.34[[太陽質量]]；運行軌道對主星傾斜55°<ref name="sigurdsson">{{cite journal | author = S. Sigurdsson | display-authors = 4 | author2 = H. B. Richer | author3 = B. M. Hansen | author4 = I. H. Stairs | author5 = S. E. Thorsett | title=A Young White Dwarf Companion to Pulsar B1620-26: Evidence for Early Planet Formation. | url = https://archive.org/details/sim_science_2003-07-11_301_5630/page/192 | journal=Science | date=2003| volume=301| pages=193–196| bibcode=2003Sci...301..193S |arxiv = astro-ph/0307339 | doi=10.1126/science.1086326 | pmid=12855802 | issue=5630| s2cid = 39446560 }}</ref>。

== 行星系統 ==
[[Image:Jovian planet in globular cluster M4 - calm bystander in stellar drama.jpg|thumb|left|PSR B1620−26系統的演變。]]

PSR B1620−26 b最初是通過它的軌道對其所繞行恆星的軌道產生的都卜勒頻移 (在這種情況下，脈衝星的視脈動週期發生的變化。) 探測到的。

在1990年代初期，由Donald Backer領導的一組天文學家在研究他們所認為的脈衝星聯星時，確認需要第三個天體才能解釋他們所觀察到的都卜勒頻移。在幾年內，這顆行星對脈衝星和白矮星軌道的引力效應已竟被量測出來，從而估計出第三個天體的質量。但這個天體太小了，不可能是恆星。在1993年，{{link-en|Stephen Thorsett}}和它的合作夥伴宣布第三個天體是行星的結論。

{{OrbitboxPlanet begin}}
{{OrbitboxPlanet
| exoplanet = [[PSR B1620-26b|b]]
| mass = 2.5 ± 1
| period = ~36,500
| semimajor = 23
| eccentricity = ''low''
| inclination = 55<sub>−8</sub><sup>+14</sup>
}}
{{Orbitbox end}}

== 相關條目 ==
*[[PSR B1257+12]]
*[[PSR B1620-26b]]
*[[天大将军十一]]（三角座δ）
*[[白矮星]]
*[[中子星]]
*[[脈衝星]]
*[[脈衝星行星]]
*[[太陽系外行星]]
*[[行星系]]

== 參考資料 ==
{{reflist}}

== 外部連結 ==
* [http://www.solstation.com/x-objects/b1620-26.htm '''SolStation''': PSR B1620-26] {{Wayback|url=http://www.solstation.com/x-objects/b1620-26.htm |date=20210127122703 }}
* [http://www.space.com/scienceastronomy/oldest_planet_030710-1.html '''SPACE''': Oldest Known World Conjures Prospect of Ancient Life] {{Wayback|url=http://www.space.com/scienceastronomy/oldest_planet_030710-1.html |date=20030720021737 }}
{{-}}
{{Sky|16|23|38|-|26|31|53|12400}}

{{天蠍座恆星}}

{{DEFAULTSORT:PSR B1620-26}}
[[Category:聯星]]
[[Category:脈衝星]]
[[Category:白矮星]]
[[Category:天蠍座]]
[[Category:聚星的行星系|2]]
[[Category:確認有一顆系外行星的行星系]]