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Messier 25
Messier 25
	Open cluster Messier 25 in Sagittarius
Observation data (J2000.0 epoch)
Right ascension	18h 31m 47.0s
Declination	−19° 07′ 00″
Distance	2,000 ly (620 pc)
Apparent magnitude (V)	4.6
Apparent dimensions (V)	36′
Physical characteristics
Mass	1,937 M☉ M☉
Radius	6.5 light-years
Estimated age	67.6 million years
Other designations	Messier 25, IC 4725, Cr 382, C 1828–192, Mel 204
Associations
	See also: Open cluster, List of open clusters

Messier 25, also known as IC 4725, is an open cluster of stars in the southern constellation of Sagittarius. The first recorded observation of this cluster was made by Philippe Loys de Chéseaux in 1745 and it was included in Charles Messier's list of nebulous objects in 1764.^[6] The cluster is located near some obscuring features, with a dark lane passing near the center.^[7]

M25 is at a distance of about 2,000 light-years away from Earth and is 67.6 million years old.^[2] The spatial dimension of this cluster is about 13 light-years across. It has an estimated mass of 1,937 M_☉, of which about 24% is interstellar matter.^[4] A Delta Cephei type variable star designated U Sagittarii is a member of this cluster,^[8] as are two red giants, one of which is a binary system.^[9]

New research indicates M25 may constitute a ternary star cluster together with NGC 6716 and Collinder 394.^[10]

References

^ ^a ^b Wu, Zhen-Yu; et al. (November 2009), "The orbits of open clusters in the Galaxy", Monthly Notices of the Royal Astronomical Society, 399 (4): 2146–2164, arXiv:0909.3737, Bibcode:2009MNRAS.399.2146W, doi:10.1111/j.1365-2966.2009.15416.x, S2CID 6066790.
^ ^a ^b ^c ^d Kharchenko, N. V.; et al. (2005), "Astrophysical parameters of Galactic open clusters", Astronomy and Astrophysics, 438 (3): 1163–1173, arXiv:astro-ph/0501674, Bibcode:2005A&A...438.1163K, doi:10.1051/0004-6361:20042523, S2CID 9079873.
^ "Messier 25". SEDS Messier Catalog. Retrieved 21 July 2024.
^ ^a ^b ^c Tadross, A. L.; Marie, M. A.; Osman, A. I.; Hassan, S. M. (2002), "Astrometry of the Open Cluster M25", Astrophysics and Space Science, 282 (4): 607–623, Bibcode:2002Ap&SS.282..607T, doi:10.1023/A:1021137115870, S2CID 117960833.
^ "IC 4725". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved November 12, 2018.
^ Thompson, Robert; Thompson, Barbara (2007), Illustrated Guide to Astronomical Wonders: From Novice to Master Observer, DIY science, O'Reilly Media, Inc., p. 408, ISBN 978-0596526856.
^ Landolt, Arlo U. (February 1964), "The Galactic Cluster M25", Astrophysical Journal Supplement, 8: 352, Bibcode:1964ApJS....8..352L, doi:10.1086/190093.
^ Wampler, J.; et al. (May 1961), "Cepheids in Galactic Clusters. VIII. a Reinvestigation of U SGR in M25 (= IC 4725)", Astrophysical Journal, 133: 895, Bibcode:1961ApJ...133..895W, doi:10.1086/147092.
^ Mermilliod, J. C.; et al. (September 1987), "Membership of cepheids and red giants in 8 open clusters : NGC 129, 6067, 6087, 6649, 6664, IC 4725, LY 6, RU 79", Astronomy and Astrophysics Supplement Series, 70: 389–407, Bibcode:1987A&AS...70..389M.
^ Majaess, D.; et al. (August 2024), "A Rare Cepheid-hosting Open Cluster Triad in Sagittarius", Research Notes of the AAS, 8 (8): 205, doi:10.3847/2515-5172/ad7139.