海後星

29 Amphitrite
	海後星的VLT圖像
發現
發現者	阿爾貝特·馬特
發現地	倫敦
發現日期	1854年3月1日
編號
命名依據	安菲特里忒 ; （希臘神話）
其它名稱	A899 NG
小行星分類	主小行星帶 · (中部); 背景
形容詞	Amphitritean /ˌæmfɪtrɪˈtiːən/, /ˌæmfɪˈtraɪtiən/
軌道參數
	曆元 2018年3月23日（JD 2458200.5）
	不確定參數 0
觀測弧	162.83 年（59,472 日）
遠日點	2.7400 AU
近日點	2.3712 AU
半長軸	2.5556 AU
離心率	0.0722
軌道週期	4.09 年（1,492日）
平近點角	187.97°
軌道傾角	6.0823°
角距離	0° 14m 28.68s / 日
升交點黃經	356.37°
近日點參數	63.036°
物理特徵
大小	233 km × 212 km × 193 km
扁率	0.18
質量	(12.7±2.0)×1018 kg ; (11.8±?)×1018 kg
平均密度	2.86±0.45 g/cm3; 2.36±0.26 g/cm3
自轉週期	5.3921 h
幾何反照率	0.194; 0.157±0.035; 0.1793±0.012; 0.195; 0.216±0.043
光譜類型	S
絕對星等(H)	5.85; 5.99; 6.0

海後星（29 Amphitrite）是最大的S-型小行星之一，直徑約200公里（120英里），可能是繼司法星、婚神星、虹神星和大力神星之後的第五大小行星。

發現

海後星由阿爾伯特·馬爾特於1854年3月1日在倫敦攝政公園的私人南別墅天文台發現。這是馬爾特發現的唯一一顆小行星。天文台的擁有者喬治·畢曉普（George Bishop）為這顆小行星命名，取自希臘神話中的海洋女神安菲特里忒的名字命名。這顆小行星的歷史符號是貝殼和星星；在Unicode 17.0 中，它的編碼為U+1CECF 𜻏 ()。^[14]^[15]

物理特徵

海後星軌道比其他較大的小行星更接近圓形，傾斜度也較小。事實上，它是迄今為止發現的所有小行星中軌道最圓的。正因因此，海後星的亮度從未像虹神星或韶神星那樣明亮，尤其是因為它比這些小行星離太陽更遠。在有利的沖日條件下，海後星的星等可達到 +8.6 左右，但通常接近雙筒望遠鏡的可見極限，約為+9.5等^[16]^[17]。

詹姆斯·貝爾（James Baer）和史蒂芬·R·切斯利（Steven R. Chesley）在2007年的研究估計海後星的質量為1.9 ×10¹⁹千克^[18]。而來自貝爾最新的研究估計它的質量為1.18 ×10¹⁹千克^[7]。

根據愛德華·F·特德斯科收集的光變曲線數據，海後星可能存在一顆衛星^[19]^[20]。1988年，人們利用毛納基山天文台的UH88望遠鏡搜尋這顆小行星周圍的衛星或塵埃，但一無所獲^[21]。

注釋

^ 從最大縱橫比得出的展平(c/a): $f=1-{\frac {c}{a}}$ , where (c/a) = 6999820000000000000♠0.82±0.03.^[8]

參考來源

^ ^1.0 ^1.1 ^1.2 29 Amphitrite. Minor Planet Center. [1 June 2018].
^ Schmadel, Lutz D. (29) Amphitrite. Dictionary of Minor Planet Names – (29) Amphitrite. Springer Berlin Heidelberg. 2007: 18. ISBN 978-3-540-00238-3. doi:10.1007/978-3-540-29925-7_30.
^ ^3.0 ^3.1 ^3.2 JPL Small-Body Database Browser: 29 Amphitrite (2018-05-23 last obs.). Jet Propulsion Laboratory. [1 June 2018].
^ ^4.0 ^4.1 Asteroid (29) Amphitrite. AstDyS-2, Asteroids – Dynamic Site. [25 May 2018].
^ ^5.0 ^5.1 ^5.2 Asteroid 29 Amphitrite. Small Bodies Data Ferret. [1 June 2018].
^ Noah Webster (1884) A Practical Dictionary of the English Language
^ ^7.0 ^7.1 ^7.2 ^7.3 Jim Baer. Recent Asteroid Mass Determinations. Personal Website. 2008 [27 November 2008]. （原始內容存檔於2 July 2013）.
^ ^8.0 ^8.1 ^8.2 ^8.3 P. Vernazza; et al. VLT/SPHERE imaging survey of the largest main-belt asteroids: Final results and synthesis. Astronomy & Astrophysics. 2021, 54 (A56).
^ LCDB Data for (29) Amphitrite. Asteroid Lightcurve Database (LCDB). [1 June 2018].
^ Mainzer, A.; Grav, T.; Masiero, J.; Hand, E.; Bauer, J.; Tholen, D.; et al. NEOWISE Studies of Spectrophotometrically Classified Asteroids: Preliminary Results. The Astrophysical Journal. November 2011, 741 (2): 25. Bibcode:2011ApJ...741...90M. S2CID 118700974. arXiv:1109.6407 . doi:10.1088/0004-637X/741/2/90. (catalog)
^ Tedesco, E. F.; Noah, P. V.; Noah, M.; Price, S. D. IRAS Minor Planet Survey V6.0. NASA Planetary Data System. October 2004, 12: IRAS–A–FPA–3–RDR–IMPS–V6.0 [22 October 2019]. Bibcode:2004PDSS...12.....T.
^ Usui, Fumihiko; Kuroda, Daisuke; Müller, Thomas G.; Hasegawa, Sunao; Ishiguro, Masateru; Ootsubo, Takafumi; et al. Asteroid Catalog Using Akari: AKARI/IRC Mid-Infrared Asteroid Survey. Publications of the Astronomical Society of Japan. October 2011, 63 (5): 1117–1138. Bibcode:2011PASJ...63.1117U. doi:10.1093/pasj/63.5.1117. (online, AcuA catalog p. 153)
^ Masiero, Joseph R.; Grav, T.; Mainzer, A. K.; Nugent, C. R.; Bauer, J. M.; Stevenson, R.; et al. Main-belt Asteroids with WISE/NEOWISE: Near-infrared Albedos. The Astrophysical Journal. August 2014, 791 (2): 11. Bibcode:2014ApJ...791..121M. S2CID 119293330. arXiv:1406.6645 . doi:10.1088/0004-637X/791/2/121.
^ Bala, Gavin Jared; Miller, Kirk. Unicode request for historical asteroid symbols (PDF). unicode.org. Unicode. 18 September 2023 [26 September 2023].
^ Unicode. Proposed New Characters: The Pipeline. unicode.org. The Unicode Consortium. [6 November 2023].
^ Nautical Almanac Office. The Astronomical Almanac for the Year 2014. Government Printing Office. 2013: 2. ISBN 9780707741420 （英語）.
^ Wayne Orchiston. John Tebbutt: Rebuilding and Strengthening the Foundations of Australian Astronomy. Springer. 2016: 359. ISBN 9783319445212.
^ Baer, James; Steven R. Chesley. Astrometric masses of 21 asteroids, and an integrated asteroid ephemeris. Celestial Mechanics and Dynamical Astronomy. 2008, 100 (2008): 27–42. Bibcode:2008CeMDA.100...27B. doi:10.1007/s10569-007-9103-8 .
^ Tedesco, E. F. Binary Asteroids: Evidence for Their Existence from Lightcurves. Science. New Series. March 1979, 203 (4383): 905–907. Bibcode:1979Sci...203..905T. PMID 17771729. S2CID 19431574. doi:10.1126/science.203.4383.905.
^ van Flandern, T. C.; Tedesco, E. F.; Binzel, R. P. Satellites of asteroids. Asteroids. Tucson, AZ: University of Arizona Press: 443–465. 1979. Bibcode:1979aste.book..443V.
^ Gradie, J.; Flynn, L., A Search for Satellites and Dust Belts Around Asteroids: Negative Results, Abstracts of the Lunar and Planetary Science Conference 19, March 1988, 19: 405–406, Bibcode:1988LPI....19..405G

外部連結

發現情況：編號小行星 (1)-(5000) – 小行星中心
海後星 at AstDyS-2, Asteroids—Dynamic Site
- Ephemeris · Observation prediction · Orbital info · Proper elements · Observational info
海後星 at the JPL Small-Body Database
- Close approach · Discovery · Ephemeris · Orbit diagram · Orbital elements · Physical parameters

[9] 從最大縱橫比得出的展平(c/a): $f=1-{\frac {c}{a}}$ , where (c/a) = 6999820000000000000♠0.82±0.03.^[8]

[MPC-object-1] 1.0 ^1.1 ^1.2 29 Amphitrite. Minor Planet Center. [1 June 2018].

[springer-2] Schmadel, Lutz D. (29) Amphitrite. Dictionary of Minor Planet Names – (29) Amphitrite. Springer Berlin Heidelberg. 2007: 18. ISBN 978-3-540-00238-3. doi:10.1007/978-3-540-29925-7_30.

[jpldata-3] 3.0 ^3.1 ^3.2 JPL Small-Body Database Browser: 29 Amphitrite (2018-05-23 last obs.). Jet Propulsion Laboratory. [1 June 2018].

[AstDys-object-4] 4.0 ^4.1 Asteroid (29) Amphitrite. AstDyS-2, Asteroids – Dynamic Site. [25 May 2018].

[Ferret-5] 5.0 ^5.1 ^5.2 Asteroid 29 Amphitrite. Small Bodies Data Ferret. [1 June 2018].

[6] Noah Webster (1884) A Practical Dictionary of the English Language

[Baer-7] 7.0 ^7.1 ^7.2 ^7.3 Jim Baer. Recent Asteroid Mass Determinations. Personal Website. 2008 [27 November 2008]. （原始內容存檔於2 July 2013）.

[VLT-8] 8.0 ^8.1 ^8.2 ^8.3 P. Vernazza; et al. VLT/SPHERE imaging survey of the largest main-belt asteroids: Final results and synthesis. Astronomy & Astrophysics. 2021, 54 (A56).

[lcdb-10] LCDB Data for (29) Amphitrite. Asteroid Lightcurve Database (LCDB). [1 June 2018].

[WISE-11] Mainzer, A.; Grav, T.; Masiero, J.; Hand, E.; Bauer, J.; Tholen, D.; et al. NEOWISE Studies of Spectrophotometrically Classified Asteroids: Preliminary Results. The Astrophysical Journal. November 2011, 741 (2): 25. Bibcode:2011ApJ...741...90M. S2CID 118700974. arXiv:1109.6407 . doi:10.1088/0004-637X/741/2/90. (catalog)

[SIMPS-12] Tedesco, E. F.; Noah, P. V.; Noah, M.; Price, S. D. IRAS Minor Planet Survey V6.0. NASA Planetary Data System. October 2004, 12: IRAS–A–FPA–3–RDR–IMPS–V6.0 [22 October 2019]. Bibcode:2004PDSS...12.....T.

[AKARI-13] Usui, Fumihiko; Kuroda, Daisuke; Müller, Thomas G.; Hasegawa, Sunao; Ishiguro, Masateru; Ootsubo, Takafumi; et al. Asteroid Catalog Using Akari: AKARI/IRC Mid-Infrared Asteroid Survey. Publications of the Astronomical Society of Japan. October 2011, 63 (5): 1117–1138. Bibcode:2011PASJ...63.1117U. doi:10.1093/pasj/63.5.1117. (online, AcuA catalog p. 153)

[Masiero-2014-14] Masiero, Joseph R.; Grav, T.; Mainzer, A. K.; Nugent, C. R.; Bauer, J. M.; Stevenson, R.; et al. Main-belt Asteroids with WISE/NEOWISE: Near-infrared Albedos. The Astrophysical Journal. August 2014, 791 (2): 11. Bibcode:2014ApJ...791..121M. S2CID 119293330. arXiv:1406.6645 . doi:10.1088/0004-637X/791/2/121.

[astunicode-15] Bala, Gavin Jared; Miller, Kirk. Unicode request for historical asteroid symbols (PDF). unicode.org. Unicode. 18 September 2023 [26 September 2023].

[pipeline-16] Unicode. Proposed New Characters: The Pipeline. unicode.org. The Unicode Consortium. [6 November 2023].

[17] Nautical Almanac Office. The Astronomical Almanac for the Year 2014. Government Printing Office. 2013: 2. ISBN 9780707741420 （英語）.

[18] Wayne Orchiston. John Tebbutt: Rebuilding and Strengthening the Foundations of Australian Astronomy. Springer. 2016: 359. ISBN 9783319445212.

[Baer2007-19] Baer, James; Steven R. Chesley. Astrometric masses of 21 asteroids, and an integrated asteroid ephemeris. Celestial Mechanics and Dynamical Astronomy. 2008, 100 (2008): 27–42. Bibcode:2008CeMDA.100...27B. doi:10.1007/s10569-007-9103-8 .

[20] Tedesco, E. F. Binary Asteroids: Evidence for Their Existence from Lightcurves. Science. New Series. March 1979, 203 (4383): 905–907. Bibcode:1979Sci...203..905T. PMID 17771729. S2CID 19431574. doi:10.1126/science.203.4383.905.

[21] van Flandern, T. C.; Tedesco, E. F.; Binzel, R. P. Satellites of asteroids. Asteroids. Tucson, AZ: University of Arizona Press: 443–465. 1979. Bibcode:1979aste.book..443V.

[Gradie1988-22] Gradie, J.; Flynn, L., A Search for Satellites and Dust Belts Around Asteroids: Negative Results, Abstracts of the Lunar and Planetary Science Conference 19, March 1988, 19: 405–406, Bibcode:1988LPI....19..405G

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