M48

M 48
M 48
觀測資料 (J2000 曆元)
星座	長蛇座
赤經	08h 13m 43.0s
赤緯	-05° 45′ 00″
距離	2,500 ly（770 pc）
視星等 (V)	5.8
視大小 (V)	30′
物理特徵
質量	2,366+1,109; −755 M☉
半徑	63 ly
估計年齡	450±50 Myr
其他特徵	M48, NGC 2548, Cr 179, H IV-22
	相關條目：疏散星團、NGC天體表

M48或梅西耶48，也以NGC 2548為人所知，是位於天球赤道上的星座，長蛇座的一個疏散星團。它位於長蛇座最西端的邊界附近，靠近麒麟座^[6]，位於長蛇座最亮的星宿一東方偏南，角距離18° 34′^[7]。這個星團是梅西耶在1771年發現的；但就像他在M47中所犯的相同錯誤，它沒有給出正確的位置。他給出的赤經值是正確的，但是赤緯偏離了5度^[8]，因此人們有時會將發現的功勞歸給在1783年看見它的卡羅琳·赫歇爾^[8]，她的姪子約翰·赫歇爾形容它是"一個很好的星團，填補了整個區域；恆星的亮度介於9〜13等，沒有更暗的星，但它所處的整個天空卻奇形怪狀的點綴著無數微小的^[7]。"

在良好的條件下，用肉眼可以直接觀測到M48。它最亮的一顆星是8.3等的HIP 40348^[7]。星團位於離太陽 2,500光年之處^[1]。以恆星等齡線（英語：Stellar isochrone）估計它的年齡是7000400000000000000♠4±1億年，以自轉測年法估計的年齡是7000450000000000000♠4.5±0.5億年；算是相當一致^[4]。這使得他的年齡介於昴宿星團的一億年和畢宿星團的六億五千萬年之間。依據鐵豐度，[Fe/H]]= 3001370000000000000♠−0.063±0.007 dex，金屬豐度若為-1，則表示比太陽少10倍。它比昴宿星團、畢宿星團和鬼宿星團更缺乏金屬元素^[9]。

這個星團的潮汐半徑為63.3 ± 7.8 ly（19.4 ± 2.4 pc）^[3]，至少有438個成員^[10]和質量為7033470490930000000♠2,366 M_☉^[3]。可能是由於和星系盤的相互作用，這個星團的結構呈現塊狀的碎片。現在，這個星團被分為三組，每一組都有自己集體的自行^[10]。

參考資料

^ ^1.0 ^1.1 ^1.2 ^1.3 Wu, Zhen-Yu; et al, The orbits of open clusters in the Galaxy, Monthly Notices of the Royal Astronomical Society, November 2009, 399 (4): 2146–2164, Bibcode:2009MNRAS.399.2146W, arXiv:0909.3737 , doi:10.1111/j.1365-2966.2009.15416.x.
^ ^2.0 ^2.1 Mullaney, James, The Herschel Objects and How to Observe Them, Astronomers' Observing Guides, Springer Science & Business Media: 93, 2007, Bibcode:2007hoho.book.....M, ISBN 978-0387681252.
^ ^3.0 ^3.1 ^3.2 ^3.3 Piskunov, A. E.; et al, Tidal radii and masses of open clusters, Astronomy and Astrophysics, January 2008, 477 (1): 165–172, Bibcode:2008A&A...477..165P, doi:10.1051/0004-6361:20078525 .
^ ^4.0 ^4.1 Barnes, Sydney A.; et al, A color-period diagram for the open cluster M 48 (NGC 2548), and its rotational age, Astronomy & Astrophysics, November 2015, 583: 21, Bibcode:2015A&A...583A..73B, arXiv:1511.00554 , doi:10.1051/0004-6361/201526129, A73.
^ M 48. SIMBAD. 斯特拉斯堡天文資料中心.
^ Sinnott, Roger W.; Perryman, Michael A. C., Millennium Star Atlas 2, Sky Publishing Corporation and the European Space Agency: 810, 1997, ISBN 0-933346-83-2.
^ ^7.0 ^7.1 ^7.2 Adam, Len, Imaging the Messier Objects Remotely from Your Laptop, The Patrick Moore Practical Astronomy Series, Springer: 227, 2018, Bibcode:2018imor.book.....A, ISBN 978-3319653853.
^ ^8.0 ^8.1 Houston, Walter Scott, Deep-Sky Wonders, Sky Publishing Corporation, 2005, ISBN 978-1-931559-23-2.
^ Sun, Qinghui; et al, WIYN Open Cluster Study LXXIX. M48 (NGC 2548) I. Radial Velocities, Rotational Velocities, and Metallicities of Stars in the Open Cluster M48 (NGC 2548), The Astronomical Journal, May 2020, 159 (5): 13, Bibcode:2020AJ....159..220S, arXiv:2004.06812 , doi:10.3847/1538-3881/ab83ef, 220.
^ ^10.0 ^10.1 Vicente, Belén; et al, NGC 2548: clumpy spatial and kinematic structure in an intermediate-age Galactic cluster, Monthly Notices of the Royal Astronomical Society, September 2016, 461 (3): 2519–2526, Bibcode:2016MNRAS.461.2519V, arXiv:1606.06044 , doi:10.1093/mnras/stw1487.

外部連結

Messier 48, SEDS Messier pages （頁面存檔備份，存於網際網路檔案館）
WikiSky上關於M48的內容：DSS2, SDSS, GALEX, IRAS, 氫α, X射線, 天文照片, 天圖, 文章和圖片

[Wu2009a-1] 1.0 ^1.1 ^1.2 ^1.3 Wu, Zhen-Yu; et al, The orbits of open clusters in the Galaxy, Monthly Notices of the Royal Astronomical Society, November 2009, 399 (4): 2146–2164, Bibcode:2009MNRAS.399.2146W, arXiv:0909.3737 , doi:10.1111/j.1365-2966.2009.15416.x.

[Mullaney2007-2] 2.0 ^2.1 Mullaney, James, The Herschel Objects and How to Observe Them, Astronomers' Observing Guides, Springer Science & Business Media: 93, 2007, Bibcode:2007hoho.book.....M, ISBN 978-0387681252.

[Piskunov2008-3] 3.0 ^3.1 ^3.2 ^3.3 Piskunov, A. E.; et al, Tidal radii and masses of open clusters, Astronomy and Astrophysics, January 2008, 477 (1): 165–172, Bibcode:2008A&A...477..165P, doi:10.1051/0004-6361:20078525 .

[Barnes2015-4] 4.0 ^4.1 Barnes, Sydney A.; et al, A color-period diagram for the open cluster M 48 (NGC 2548), and its rotational age, Astronomy & Astrophysics, November 2015, 583: 21, Bibcode:2015A&A...583A..73B, arXiv:1511.00554 , doi:10.1051/0004-6361/201526129, A73.

[SIMBAD-5] M 48. SIMBAD. 斯特拉斯堡天文資料中心.

[Sinnott_Perryman_1997-6] Sinnott, Roger W.; Perryman, Michael A. C., Millennium Star Atlas 2, Sky Publishing Corporation and the European Space Agency: 810, 1997, ISBN 0-933346-83-2.

[Adam2018-7] 7.0 ^7.1 ^7.2 Adam, Len, Imaging the Messier Objects Remotely from Your Laptop, The Patrick Moore Practical Astronomy Series, Springer: 227, 2018, Bibcode:2018imor.book.....A, ISBN 978-3319653853.

[WSH-8] 8.0 ^8.1 Houston, Walter Scott, Deep-Sky Wonders, Sky Publishing Corporation, 2005, ISBN 978-1-931559-23-2.

[Sun_et_al_2020-9] Sun, Qinghui; et al, WIYN Open Cluster Study LXXIX. M48 (NGC 2548) I. Radial Velocities, Rotational Velocities, and Metallicities of Stars in the Open Cluster M48 (NGC 2548), The Astronomical Journal, May 2020, 159 (5): 13, Bibcode:2020AJ....159..220S, arXiv:2004.06812 , doi:10.3847/1538-3881/ab83ef, 220.

[Vicente2016-10] 10.0 ^10.1 Vicente, Belén; et al, NGC 2548: clumpy spatial and kinematic structure in an intermediate-age Galactic cluster, Monthly Notices of the Royal Astronomical Society, September 2016, 461 (3): 2519–2526, Bibcode:2016MNRAS.461.2519V, arXiv:1606.06044 , doi:10.1093/mnras/stw1487.

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