類太陽恆星

類太陽恆星包括太陽型恆星（solar-type star）、太陽相似體（solar analog）、孿生太陽（solar twin）等，是與太陽特別相似的那些恆星。這樣的分類是有階層性的，孿生是與太陽最接近的，其次是相似體，最後是太陽型^[1]。觀察這些恆星最重要的是能更好的理解太陽與其他恆星相關的各種性質，特別是恆星與行星的適居性。

與太陽相似的

這三種與太陽相似度類型的定義，反映出天文觀測技術的演變。起初，太陽型恆星的定義只是考慮與太陽最接近的相似性。然後，觀測技術的改善可以提供更精確的關鍵測量，像是溫度，可以篩檢出與太陽更為相似的恆星。最後，在技術上的改善使精確度持續的提升，孿生太陽是與太陽幾乎完全相同的恆星。

太陽的相似度可以檢查一些得到的數值－像是溫度，可以從色指數推導，較之下，只有太陽的溫度是可以經由直接的測量獲得，是唯一確認無誤的^[1]。對於和太陽不同的恆星，就不會進行交叉的比對^[2]。

太陽型恆星

太陽（左）與相似但規模略小些，活動也較弱的天倉五（右）比較。

這些恆星大致上與太陽相似，它們都是主序星，B-V色指數在0.48至0.80之間，而太陽的B-V色指數為0.65。或者，可以使用基於光譜類型的定義，如從F8 V至K2 V，這將對應於0.50至1.00的B-V色指數^[1]。這樣的類太陽恆星清單將會相當廣泛，大約有10%的恆星會適合這樣的定義^{[來源請求]}。

太陽型恆星顯示它們的自轉速率和色球活動（如鈣的H和K線的發射）與日冕活動（例如X射線輻射）之間有高度的相關性^{[來源請求]}。當太陽型恆星因為主序星生命期中的磁製動而降低自轉速率，這些也與年齡有粗略的相關性。Mamajek和Hillenbrand (2008)^[3]曾經以它們的色球活動為基礎（通過衡量鈣的H和K發射譜線）估計距離在16秒差距內的108顆太陽型（F8V — K2V）主序恆星的年齡。

下表列出基於目前的測量，在50光年的距離內，類太陽恆星中滿足太陽型恆星的樣品。

太陽型恆星的例子
恆星名稱	J2000座標^[4]		距離^[4] (ly)	恆星分類^[4]	溫度 (K)	金屬量 (dex)	註解
恆星名稱	赤經	赤緯	距離^[4] (ly)	恆星分類^[4]	溫度 (K)	金屬量 (dex)	註解
波江座ε	03^h 32^m 55.8^s	-09° 27′ 29.7″	10.5	K2V	5,153	–0.11	^[5]
鯨魚座τ	01^h 44^m 04.1^s	-15° 56′ 15″	11.9	G8V	5,344	–0.52	^[6]
波江座40A	04^h 15^m 16.3^s	-07° 39′ 10″	16.5	K1V	5,126	–0.31	^[6]
波江座82	03^h 19^m 55.7^s	-43° 04′ 11.2″	19.8	G8V	5,338	–0.54	^[7]
孔雀座δ	20^h 08^m 43.6^s	-66° 10′ 55″	19.9	G8IV	5,604	+0.33	^[5]
HR 7722	20^h 15^m 17.4^s	-27° 01′ 59″	28.8	K2V	5,166	–0.04	^[5]
格利澤86A	02^h 10^m 25.9^s	-50° 49′ 25″	35.2	G9V	5,163	-0.24	^[6]
雙魚座54	00^h 39^m 21.8^s	+21° 15′ 02″	36.1	K0V	5,129	+0.19	^[7]
御夫座V538	05^h 41^m 20.3^s	+53° 28′ 51.8″	39.9	K1V	3,500-5,000	-0.20	^[7]
HD 14412	02^h 18^m 58.5^s	-25° 56′ 45″	41.3	G5V	5,432	-0.46	^[7]
HR 4587	12^h 00^m 44.3^s	-10° 26′ 45.7″	42.1	G8IV	5,538	0.18	^[7]
HD 172051	18^h 38^m 53.4^s	-21° 03′ 07″	42.7	G5V	5,610	-0.32	^[7]
武仙座72	17^h 20^m 39.6^s	+32° 28′ 04″	46.9	G0V	5,662	-0.37	^[7]
HD 196761	20^h 40^m 11.8^s	-23° 46′ 26″	46.9	G8V	5,415	-0.31	^[5]
豺狼座Nu²	15^h 21^m 48.1^s	-48° 19′ 03″	47.5	G4V	5,664	-0.34	^[5]

太陽相似體

這些恆星是在光度計的測量下與太陽相似，有以下的性質：

與太陽的溫度差異在500 K以內（大約在5,200至6,300K）
金屬量是太陽的50—200%（± 0.3 dex），意味着這些恆星的原行星盤有類似於太陽的塵埃數量，可以讓行星形成。
沒有靠近的伴星（軌道週期為十天或更短），因為這樣的伴星會激化恆星的活動。

類太陽恆星不能滿足更嚴謹的孿生太陽標準，在50光年距離之內的類太陽恆星以距離的遞增列於下表：

恆星名稱	J2000座標^[4]		距離^[4] (ly)	恆星分類^[4]	溫度 (K)	金屬量 (dex)	註解
恆星名稱	赤經	赤緯	距離^[4] (ly)	恆星分類^[4]	溫度 (K)	金屬量 (dex)	註解
半人馬座α A	14^h 39^m 36.5^s	-60° 50′ 02″	4.37	G2V	5,847	+0.24	^[8]
半人馬座α B	14^h 39^m 35.0^s	-60° 50′ 14″	4.37	K1V	5,316	+0.25	^[8]
蛇夫座70 A	18^h 05^m 27.3^s	+02° 30′ 00″	16.6	K0V	5,314	–0.02	^[9]
天龍座σ	19^h 32^m 21.6^s	+69° 39′ 40″	18.8	K0V	5,297	–0.20	^[10]
仙后座ηA	00^h 49^m 06.3^s	+57° 48′ 55″	19.4	G0V	5,941	–0.17	^[11]
雙魚座107	01^h 42^m 29.8^s	+20° 16′ 07″	24.4	K1V	5,242	–0.04	^[7]^[12]
獵犬座β	12^h 33^m 44.5^s	+41° 21′ 27″	27.4	G0V	5,930	-0.30	^[7]
室女座61	13^h 18^m 24.3^s	-18° 18′ 40″	27.8	G5V	5,558	–0.02	^[5]
杜鵑座ζ	00^h 20^m 04.3^s	–64° 52′ 29″	28.0	F9.5V	5,956	–0.14	^[6]
獵戶座ψ¹ A	05^h 54^m 23.0^s	+20° 16′ 34″	28.3	G0V	5,902	–0.16	^[7]
后髮座β	13^h 11^m 52.4^s	+27° 52′ 41″	29.8	G0V	5,970	–0.06	^[7]
HR 4523A	11^h 46^m 31.1^s	–40° 30′ 01″	30.1	G5V	5,629	–0.29	^[5]
大熊座61	11^h 41^m 03.0^s	+34° 12′ 06″	31.1	G8V	5,483	–0.12	^[7]
HR 4458A	11^h 34^m 29.5^s	–32° 49′ 53″	31.1	K0V	5,629	–0.29	^[5]
HR 511	01^h 47^m 44.8^s	+63° 51′ 09″	32.8	K0V	5,333	+0.05	^[7]
蒼蠅座α	06^h 10^m 14.5^s	–74° 45′ 11″	33.1	G5V	5,594	+0.10	^[6]
網罟座ζ¹	03^h 17^m 46.2^s	-62° 34′ 31″	39.5	G3-5V	5,733	-0.22	^[6]
網罟座ζ²	03^h 18^m 12.8^s	-62° 30′ 23″	39.5	G2V	5,843	-0.23	^[6]
巨蟹座55	08^h 52^m 35.81^s	+28° 19′ 51″	40.3	G8V	5,235	+0.25	^[11]
HD 69830	08^h 18^m 23.9^s	-12° 37′ 56″	40.6	K0V	5,410	-0.03	^[6]
HD 10307	01^h 41^m 47.1^s	+42° 36′ 48″	41.2	G1.5V	5,848	-0.05	^[7]
HD 147513	16^h 24^m 01.3^s	-39° 11′ 35″	42.0	G1V	5,858	+0.03	^[5]
波江座58	04^h 47^m 36.3^s	-16° 56′ 04″	43.3	G3V	5,868	+0.02	^[6]
仙女座εA	01^h 36^m 47.8^s	+41° 24′ 20″	44.0	F8V	6,212	+0.13	^[6]
HD 211415 A	22^h 18^m 15.6^s	–53° 37′ 37″	44.4	G1-3V	5,890	-0.17	^[6]
大熊座47	10^h 59^m 28.0^s	+40° 25′ 49″	45.9	G1V	5,954	+0.06	^[6]
天爐座αA	03^h 12^m 04.3^s	-28° 59′ 21″	46.0	F6V	6,275	-0.19	^[6]
巨蛇座φA	15^h 44^m 01.8^s	+02° 30′ 55″	47.9	G5V	5,636	-0.03	^[7]
HD 84117	09^h 42^m 14.4^s	–23° 54′ 56″	48.5	F8V	6,167	–0.03	^[6]
HD 4391	00^h 45^m 45.6^s	–47° 33′ 07″	48.6	G3V	5,878	–0.03	^[6]
小獅座20	10^h 01^m 00.7^s	+31° 55′ 25″	49.1	G3 V	5,741	+0.20	^[7]
鳳凰座ν	01^h 15^m 11.1^s	–45° 31′ 54″	49.3	F8V	6,140	+0.18	^[6]
飛馬座51	22^h 57^m 28.0^s	+20° 46′ 08″	50.9	G2.5IVa	5,804	+0.20	^[6]

孿生太陽

這些恆星與太陽更為相似，它們要具備以下的性質^[1]：

與太陽的溫度差異小於50K（大約是5720至5830K）。
金屬量為太陽的89—112% （± 0.05 dex），意味着這些恆星的原行星盤會有幾乎同的塵埃量以形成行星。
沒有恆星的伴星，因為太陽本身是孤獨的。
與太陽的年齡差距在10億年內（大約35億至56億）

以下是已知滿足這些條件，最接近孿生太陽的恆星（太陽被列入以便進行比較）：

恆星名稱	J2000座標^[4]		距離^[4] (ly)	恆星分類^[4]	溫度 (K)	金屬量 (dex)	年齡 (十億年)	註解
恆星名稱	赤經	赤緯	距離^[4] (ly)	恆星分類^[4]	溫度 (K)	金屬量 (dex)	年齡 (十億年)	註解
太陽	—	—	0.00	G2V	5,778	+0.00	4.6	^[13]
天蠍座18	16^h 15^m 37.3^s	–08° 22′ 06″	45.1	G2Va	5,835	+0.04	4.2	^[14]
HD 44594	06^h 20^m 06.1^s	-48° 44′ 29″	84	G3V	5,840	+0.15	4.1	^[15]
HD 150248			88	G2	5,750	-0.04	6.2	^[16]
HD 164595			91	G2	5,790	-0.04	4.5	^[16]
HD 195034	20^h 28^m 11.8^s	+22° 07′ 44″	92	G5	5,760	-0.04	2.9	^[17]
HD 117939			98	G3	5,765	-0.10	6.1	^[16]
HD 138573	15^h 32^m 43.7^s	+10° 58′ 06″	101	G5IV-V	5,750	0.0	5.6	^[18]^[16]
HD 142093	15^h 52^m 00.6^s	+15° 14′ 09″	103	G2V	5,841	–0.15	1.3	^[18]
HD 71334			124	G2	5,710	-0.06	5.1	^[16]
HD 98618	11^h 21^m 29.1^s	+58° 29′ 04″	126	G5V	5,851	+0.03	4.2	^[14]
HD 98649			137	G3	5,775	-0.02	4.7	^[16]
HD 134664			140	G3	5,820	0.13	2.6	^[16]
HD 143436	16^h 00^m 18.8^s	+00° 08′ 13″	141	G0	5,768	+0.00	3.8	^[18]
HD 129357	14^h 41^m 22.4^s	+29° 03′ 32″	154	G2V	5,749	–0.02	8.2	^[18]
HD 118598			160	G2	5,755	0.02	4.3	^[16]
HD 133600	15^h 05^m 13.2^s	+06° 17′ 24″	171	G0	5,808	+0.02	6.3	^[14]
HD 115382			176	G1	5,775	-0.08	6.1	^[16]
Goromladen			200	G2V	5,778	0.00	4.6
HD 101364	11^h 40^m 28.5^s	+69° 00′ 31″	208	G5V	5,795	+0.02	3.5	^[14]^[19]
BD +15 3364			209	G2	5,785	0.07	3.8	^[16]
HD 197027	20^h 41^m 54.6^s	-27° 12′ 57.4″	250	G3V	5,723	-0.013	8.2	^[20]
YBP 1194	08^h 51^m 00.807^s	+11° 48′ 52.76″	2934	G5V	5,780	+0.023	4.2	^[21]

一些其他的恆星有時也會被題為孿生太陽的候選者，尤其是：常陳四（獵犬座β，請參閱Turnbull和Tarter）、雙子座37 （參見Turnbull和Tarter）和天鵝座16 B（Porto de Mello et al. 2000）。然而，這三顆的溫度和/或光度都太高了，不能成為真正的孿生太陽。而且，常陳四和天樽增一（雙子座37）的金屬量與孿生太陽相較也都太低。最後，奚仲四B（天鵝座16 B ）是分離得很遠的聯星系統，並且要做為孿生太陽，年齡也太大了（至少已有70-80億歲）。常陳四比較適合歸類在前述的太陽相似體。

適居性

孿生太陽的另一種定義是適居恆星 －一顆恆星的性質特別適合類似地球的行星。這些性質包括穩定性、質量、年齡、金屬量和鄰近的夥伴。

年齡至少30億歲
位於在主序帶上
是非變異性的恆星
擁有類地行星
支援動力學穩定的適居帶

這需要恆星在主序帶上停留的時間至少在30億年以上，質量不能超過1.5倍的太陽質量，對應到最熱的光譜型態為F5V。這樣的恆星，在主序帶的壽命結束時，絕對星等可以達到2.5等，或是太陽的8.55倍^[22]。

在理想的情況下，非變異性是指變異性低於1%，但在實際上達到3%依然是可接受的範圍內。一顆恆星的適居帶會由於伴星與軌道的離心率，造成輻照度的變異，也是一個問題^[22]。

在多星系統中的類地行星，由於含有三顆或更多恆星的系統，是不可能有長期穩定的軌道。在聯星系統中，穩定的軌道是兩種型式之一：S型（衛星或是拱星）軌道是環繞其中一顆恆星；和P型（行星或聯星）軌道，環繞着整個聯星系統。離心木星也可能幹擾適居帶中的行星軌道^[22]。

金屬量至少是太陽的40%（[Fe/H] = -0.4）是形成類似地球的行星所必要的條件。高金屬量與熱木星的形成有着密切關聯性，但這與生命無絕對的關係。像是一些氣體巨行星最終有環繞着自己的軌道適居帶，也可能有類似地球的衛星^[22]。

一個類似此種恆星的例子是HD 70642^[23]。

參考資料

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^ Williams, D.R. Sun Fact Sheet. NASA. 2004 [2009-06-23]. （原始內容存檔於2010-07-15）.
^ ^14.0 ^14.1 ^14.2 ^14.3 Meléndez, Jorge; Ramírez, Iván. HIP 56948: A Solar Twin with a Low Lithium Abundance. The Astrophysical Journal. November 2007, 669 (2): L89–L92. Bibcode:2007ApJ...669L..89M. arXiv:0709.4290  . doi:10.1086/523942.
^ Sousa, S. G.; Fernandes, J.; Israelian, G.; Santos, N. C. Higher depletion of lithium in planet host stars: no age and mass effect. Astronomy and Astrophysics. March 2010, 512: L5. Bibcode:2010A&A...512L...5S. arXiv:1003.0405  . doi:10.1051/0004-6361/201014125.
^ ^16.00 ^16.01 ^16.02 ^16.03 ^16.04 ^16.05 ^16.06 ^16.07 ^16.08 ^16.09 Porto de Mello, G. F.; da Silva, R.; da Silva, L. & de Nader, R. V. A photometric and spectroscopic survey of solar twin stars within 50 parsecs of the Sun; I. Atmospheric parameters and color similarity to the Sun. Astronomy and Astrophysics. March 2014, 563: A52. Bibcode:2014A&A...563A..52P. S2CID 119111150. arXiv:1312.7571  . doi:10.1051/0004-6361/201322277.
^ Takeda, Yoichi; Tajitsu, Akito. High-Dispersion Spectroscopic Study of Solar Twins: HIP 56948, HIP 79672, and HIP 100963. Publications of the Astronomical Society of Japan. 2009, 61 (3): 471–478. Bibcode:2009PASJ...61..471T. arXiv:0901.2509  . doi:10.1093/pasj/61.3.471.
^ ^18.0 ^18.1 ^18.2 ^18.3 King, Jeremy R.; Boesgaard, Ann M.; Schuler, Simon C. Keck HIRES Spectroscopy of Four Candidate Solar Twins. The Astronomical Journal. November 2005, 130 (5): 2318–2325. Bibcode:2005AJ....130.2318K. arXiv:astro-ph/0508004  . doi:10.1086/452640.
^ Vázquez, M.; Pallé, E.; Rodríguez, P. Montañés. Is Our Environment Special?. The Earth as a Distant Planet: A Rosetta Stone for the Search of Earth-Like Worlds. Astronomy and Astrophysics Library. Springer New York. 2010: 391–418. ISBN 978-1-4419-1683-9. doi:10.1007/978-1-4419-1684-6. See table 9.1.
^ Monroe, T. R.; et al. High Precision Abundances of the Old Solar Twin HIP 102152: Insights on Li Depletion from the Oldest Sun. The Astrophysical Journal Letters. 2013, 774 (2): 22. Bibcode:2013ApJ...774L..32M. S2CID 56111132. arXiv:1308.5744  . doi:10.1088/2041-8205/774/2/L32.
^ A. Önehag; A. Korn; B. Gustafsson; E. Stempels; D. A. VandenBerg. M67-1194, an unusually Sun-like solar twin in M67. Astronomy and Astrophysics. 2011, 528: A85. Bibcode:2011A&A...528A..85O. S2CID 119116626. arXiv:1009.4579  . doi:10.1051/0004-6361/201015138.
^ ^22.0 ^22.1 ^22.2 ^22.3 Turnbull, M. C.; Tarter, J. C. Target Selection for SETI. I. A Catalog of Nearby Habitable Stellar Systems. The Astrophysical Journal Supplement Series. 2002, 145: 181. Bibcode:2003ApJS..145..181T. arXiv:astro-ph/0210675  . doi:10.1086/345779.
^ Solar System 'twin' found. BBC News. 2003-07-03 [2014-08-11]. （原始內容存檔於2008-01-24）.

進階讀物

G. W. Lockwood & B. A. Skiff. The Photometric Variability of Sun-like Stars: Observations and Results, 1984—1995. The Astrophysical Journal. 1997, 485 (2): 789–811. Bibcode:1997ApJ...485..789L. doi:10.1086/304453.
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M. C. Turnbull & J. C. Tarter. Target Selection for SETI. II. Tycho-2 Dwarfs, Old Open Clusters, and the Nearest 100 Stars. The Astrophysical Journal Supplement Series. 2003, 149 (2): 423–436. Bibcode:2003ApJS..149..423T. doi:10.1086/379320.
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J. D. Jr do Nascimento, M. Castro, J. Meléndez, M. Bazot, S. Théado, G. F. Porto de Mello. Age and mass of solar twins constrained by lithium abundance. Astronomy and Astrophysics. 2009, 501 (1): 687–694. Bibcode:2009A&A...501..687D. arXiv:0904.3580  . doi:10.1051/0004-6361/200911935.

[soderblum_king1998-1] 1.0 ^1.1 ^1.2 ^1.3 Soderblom, David R.; King, Jeremy R. Solar-Type Stars: Basic Information on Their Classification and Characterization. Jeffrey C. Hall (編). Solar Analogs: Characteristics and Optimum Candidates. The Second Annual Lowell Observatory Fall Workshop - October 5-7, 1997. Lowell Observatory: 41–60. 1998 [2 March 2013]. Bibcode:1998saco.conf...41S. （原始內容存檔於2021-01-07）.

[2] D. R. Soderblom; J. R. King. Solar-Type Stars: Basic Information on Their Classification and Characterization. Solar Analogs : Characteristics and Optimum Candidates. 1998 [2008-02-26]. （原始內容存檔於2009-05-24）.

[apj687_1264-3] E. E. Mamajek; L. A. Hillenbrand. Improved Age Estimation for Solar-Type Dwarfs Using Activity-Rotation Diagnostics. Astrophysical Journal. 2008, 687 (2): 1264. Bibcode:2008ApJ...687.1264M. arXiv:0807.1686  . doi:10.1086/591785.

[SIMBAD-4] 4.0 ^4.1 ^4.2 ^4.3 ^4.4 ^4.5 ^4.6 ^4.7 ^4.8 SIMBAD Astronomical Database. SIMBAD. Centre de Données astronomiques de Strasbourg. [2009-01-14]. （原始內容存檔於2019-05-30）.

[aaa487-5] 5.0 ^5.1 ^5.2 ^5.3 ^5.4 ^5.5 ^5.6 ^5.7 ^5.8 Sousa, S. G.; et al. Spectroscopic parameters for 451 stars in the HARPS GTO planet search program. Stellar [Fe/H] and the frequency of exo-Neptunes. Astronomy and Astrophysics. August 2008, 487 (1): 373–381. Bibcode:2008A&A...487..373S. arXiv:0805.4826  . doi:10.1051/0004-6361:200809698. See VizieR catalogue J/A+A/487/373 （頁面存檔備份，存於互聯網檔案館）.

[aaa425-6] 6.00 ^6.01 ^6.02 ^6.03 ^6.04 ^6.05 ^6.06 ^6.07 ^6.08 ^6.09 ^6.10 ^6.11 ^6.12 ^6.13 ^6.14 ^6.15 ^6.16 Santos, N. C.; Israelian, G.; Randich, S.; García López, R. J.; Rebolo, R. Beryllium anomalies in solar-type field stars. Astronomy and Astrophysics. October 2004, 425 (3): 1013–1027. Bibcode:2004A&A...425.1013S. arXiv:astro-ph/0408109  . doi:10.1051/0004-6361:20040510.

[geneva3-7] 7.00 ^7.01 ^7.02 ^7.03 ^7.04 ^7.05 ^7.06 ^7.07 ^7.08 ^7.09 ^7.10 ^7.11 ^7.12 ^7.13 ^7.14 ^7.15 Holmberg J., Nordstrom B., Andersen J. The Geneva-Copenhagen survey of the solar neighbourhood. III. Improved distances, ages, and kinematics. Astronomy and Astrophysics. July 2009, 501 (3): 941–947. Bibcode:2009A&A...501..941H. arXiv:0811.3982  . doi:10.1051/0004-6361/200811191. See Vizier catalogue V/130 （頁面存檔備份，存於互聯網檔案館）.

[aaa488_2-8] 8.0 ^8.1 Porto de Mello, G. F.; Lyra, W.; Keller, G. R. The Alpha Centauri binary system. Atmospheric parameters and element abundances. Astronomy and Astrophysics. September 2008, 488 (2): 653–666. Bibcode:2008A&A...488..653P. arXiv:0804.3712  . doi:10.1051/0004-6361:200810031.

[mnras382_4-9] Casagrande, Luca; Flynn, Chris; Portinari, Laura; Girardi, Leo; Jimenez, Raul. The helium abundance and ?Y/?Z in lower main-sequence stars. Monthly Notices of the Royal Astronomical Society. December 2007, 382 (4): 1516–1540. Bibcode:2007MNRAS.382.1516C. arXiv:astro-ph/0703766  . doi:10.1111/j.1365-2966.2007.12512.x.

[apj683_1-10] Boyajian, Tabetha S.; et al. Angular Diameters of the G Subdwarf µ Cassiopeiae A and the K Dwarfs s Draconis and HR 511 from Interferometric Measurements with the CHARA Array. The Astrophysical Journal. August 2008, 683 (1): 424–432. Bibcode:2008ApJ...683..424B. S2CID 8886682. arXiv:0804.2719  . doi:10.1086/589554.

[apjss159_1-11] 11.0 ^11.1 Valenti, Jeff A.; Fischer, Debra A. Spectroscopic Properties of Cool Stars (SPOCS). I. 1040 F, G, and K Dwarfs from Keck, Lick, and AAT Planet Search Programs. The Astrophysical Journal Supplement Series. July 2005, 159 (1): 141–166. Bibcode:2005ApJS..159..141V. doi:10.1086/430500. See VizieR catalogue J/ApJS/159/141 （頁面存檔備份，存於互聯網檔案館）.

[aaa411_3-12] Kovtyukh, V. V.; Soubiran, C.; Belik, S. I.; Gorlova, N. I. High precision effective temperatures for 181 F-K dwarfs from line-depth ratios. Astronomy and Astrophysics. 2003, 411 (3): 559–564. Bibcode:2003A&A...411..559K. arXiv:astro-ph/0308429  . doi:10.1051/0004-6361:20031378.

[nssdc-13] Williams, D.R. Sun Fact Sheet. NASA. 2004 [2009-06-23]. （原始內容存檔於2010-07-15）.

[apj669_2-14] 14.0 ^14.1 ^14.2 ^14.3 Meléndez, Jorge; Ramírez, Iván. HIP 56948: A Solar Twin with a Low Lithium Abundance. The Astrophysical Journal. November 2007, 669 (2): L89–L92. Bibcode:2007ApJ...669L..89M. arXiv:0709.4290  . doi:10.1086/523942.

[aaa512_L5-15] Sousa, S. G.; Fernandes, J.; Israelian, G.; Santos, N. C. Higher depletion of lithium in planet host stars: no age and mass effect. Astronomy and Astrophysics. March 2010, 512: L5. Bibcode:2010A&A...512L...5S. arXiv:1003.0405  . doi:10.1051/0004-6361/201014125.

[aaa563_A52-16] 16.00 ^16.01 ^16.02 ^16.03 ^16.04 ^16.05 ^16.06 ^16.07 ^16.08 ^16.09 Porto de Mello, G. F.; da Silva, R.; da Silva, L. & de Nader, R. V. A photometric and spectroscopic survey of solar twin stars within 50 parsecs of the Sun; I. Atmospheric parameters and color similarity to the Sun. Astronomy and Astrophysics. March 2014, 563: A52. Bibcode:2014A&A...563A..52P. S2CID 119111150. arXiv:1312.7571  . doi:10.1051/0004-6361/201322277.

[Takeda2009-17] Takeda, Yoichi; Tajitsu, Akito. High-Dispersion Spectroscopic Study of Solar Twins: HIP 56948, HIP 79672, and HIP 100963. Publications of the Astronomical Society of Japan. 2009, 61 (3): 471–478. Bibcode:2009PASJ...61..471T. arXiv:0901.2509  . doi:10.1093/pasj/61.3.471.

[apj130_5-18] 18.0 ^18.1 ^18.2 ^18.3 King, Jeremy R.; Boesgaard, Ann M.; Schuler, Simon C. Keck HIRES Spectroscopy of Four Candidate Solar Twins. The Astronomical Journal. November 2005, 130 (5): 2318–2325. Bibcode:2005AJ....130.2318K. arXiv:astro-ph/0508004  . doi:10.1086/452640.

[vazquez_et_al_2010-19] Vázquez, M.; Pallé, E.; Rodríguez, P. Montañés. Is Our Environment Special?. The Earth as a Distant Planet: A Rosetta Stone for the Search of Earth-Like Worlds. Astronomy and Astrophysics Library. Springer New York. 2010: 391–418. ISBN 978-1-4419-1683-9. doi:10.1007/978-1-4419-1684-6. See table 9.1.

[Monroe2013-20] Monroe, T. R.; et al. High Precision Abundances of the Old Solar Twin HIP 102152: Insights on Li Depletion from the Oldest Sun. The Astrophysical Journal Letters. 2013, 774 (2): 22. Bibcode:2013ApJ...774L..32M. S2CID 56111132. arXiv:1308.5744  . doi:10.1088/2041-8205/774/2/L32.

[M67-1194-21] A. Önehag; A. Korn; B. Gustafsson; E. Stempels; D. A. VandenBerg. M67-1194, an unusually Sun-like solar twin in M67. Astronomy and Astrophysics. 2011, 528: A85. Bibcode:2011A&A...528A..85O. S2CID 119116626. arXiv:1009.4579  . doi:10.1051/0004-6361/201015138.

[Turnbull2002-22] 22.0 ^22.1 ^22.2 ^22.3 Turnbull, M. C.; Tarter, J. C. Target Selection for SETI. I. A Catalog of Nearby Habitable Stellar Systems. The Astrophysical Journal Supplement Series. 2002, 145: 181. Bibcode:2003ApJS..145..181T. arXiv:astro-ph/0210675  . doi:10.1086/345779.

[23] Solar System 'twin' found. BBC News. 2003-07-03 [2014-08-11]. （原始內容存檔於2008-01-24）.

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