Messier 75

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title: "Messier 75" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["globular-clusters", "sagittarius-(constellation)", "messier-objects", "ngc-objects", "gaia-enceladus", "astronomical-objects-discovered-in-1780", "discoveries-by-pierre-méchain"] description: "Globular cluster in the constellation Sagittarius" topic_path: "general/globular-clusters" source: "https://en.wikipedia.org/wiki/Messier_75" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Globular cluster in the constellation Sagittarius ::

::data[format=table title="Infobox globular cluster"]

Field	Value
name	Messier 75
image	[[File:Crowded cluster Messier 75.jpg
epoch	J2000
class	I
constellation	Sagittarius
ra
dec
dist_ly	20.9 kpc
appmag_v	8.5
absmag_v	−8.57
size_v
radius_tidal_arcminsec
radius_ly	67 ly
metal_fe	−1.29
names	GCl 116, M75, NGC 6864
::

| name = Messier 75 | image = [[File:Crowded cluster Messier 75.jpg|300px]] | epoch = J2000 | class = I | constellation = Sagittarius | ra = | dec = | dist_ly = 20.9 kpc | appmag_v = 8.5 | absmag_v = −8.57 | size_v = | mass_msol = | radius_tidal_arcminsec = | radius_ly = 67 ly | metal_fe = −1.29 | age = | notes = | names = GCl 116, M75, NGC 6864

Messier 75 or M75, also known as NGC 6864, is a globular cluster of stars in the southern constellation Sagittarius. It was discovered by Pierre Méchain in 1780 and included in Charles Messier's catalog of comet-like objects that same year.

M75 is about 67,500 light years away from Earth and is 14,700 light years away from, and on the opposite side of, the Galactic Center. Its apparent size on the sky translates to a true radius of 67 light years. M75 is classified as class I, meaning it is one of the more densely concentrated globular clusters known. It shows a slow rotation around an axis that is inclined along a position angle of . The absolute magnitude of M75 is about −8.5, equating to 180,000 times more luminous than the Sun ().

The cluster has a half-light radius of 2.80 pc with a core radius of about 0.5 pc and appears not to have undergone core collapse yet. The mass density at the core is ·pc−3. There are 38 RR Lyrae variable stars and the cluster appears to be Oosterhoff-intermediate in terms of metallicity. 62 candidate blue stragglers have been identified in the cluster field, with 60% being in the core region.

Messier 75 is part of the Gaia Sausage, the hypothesized remains of a dwarf galaxy that merged with the Milky Way. It is a halo object with an orbital period of 0.4 billion years to travel around the galaxy on a very pronounced ellipse, specifically eccentricity of 0.87. The apocenter (maximal distance from Earth) is about 17500 pc.

Gallery

Messier 75 -hst11628 10 08723 43-Lasinh ABR555B438log.png|Messier 75 – wide field view M75map.png|Map showing location of M75

References and footnotes

| first1=Hartmut | last1=Frommert | first2=Christine | last2=Kronberg | title=Messier 75 | work=SEDS Messier pages | publisher=Students for the Exploration and Development of Space (SEDS) | date=2 September 2007 | url=http://messier.seds.org/m/m075.html | access-date=2018-12-05 | postscript=. }}

| title=Kinematics of outer halo globular clusters: M 75 and NGC 6426 | last1=Koch | first1=Andreas | last2=Hanke | first2=Michael | last3=Kacharov | first3=Nikolay | display-authors=1 | journal=Astronomy & Astrophysics | volume=616 | id=A74 | pages=9 | date=August 2018 | doi=10.1051/0004-6361/201833110 | postscript=. | bibcode=2018A&A...616A..74K | arxiv=1805.06894 | s2cid=119430366 }}

| title=M75, A Globular Cluster with a Trimodal Horizontal Branch. II. BV photometry of the RR Lyrae Variables | last1=Corwin | first1=T. M. | last2=Catelan | first2=M. | last3=Smith | first3=H. A. | last4=Borissova | first4=J. | last5=Ferraro | first5=F. R. | last6=Raburn | first6=W. S. | journal=The Astronomical Journal | display-authors=1 | volume=125 | issue=5 | pages=2543–2558 | date=May 2003 | doi=10.1086/374232 | bibcode=2003AJ....125.2543C | arxiv=astro-ph/0301542 | s2cid=14043060 | postscript=. }}

| title=Sizes of Galactic Globular Clusters | last1=van den Bergh | first1=Sidney | journal=The Astrophysical Journal | postscript=. | volume=746 | issue=2 | id=189 | pages=4 | date=February 2012 | doi=10.1088/0004-637X/746/2/189 | bibcode=2012ApJ...746..189V | arxiv=1201.3597 | s2cid=250796835 }}

| title=The Unimodal Distribution of Blue Straggler Stars in M75 (NGC 6864) | last1=Contreras Ramos | first1=R. | last2=Ferraro | first2=F. R. | last3=Dalessandro | first3=E. | last4=Lanzoni | first4=B. | last5=Rood | first5=R. T. | display-authors=1 | journal=The Astrophysical Journal | volume=748 | issue=2 | id=91 | pages=9 | date=April 2012 | doi=10.1088/0004-637X/748/2/91 | postscript=. | bibcode=2012ApJ...748...91C | arxiv=1201.4959 | s2cid=118483222 }}

| last1=Shapley | first1=Harlow | last2=Sawyer | first2=Helen B. | title=A Classification of Globular Clusters | journal=Harvard College Observatory Bulletin | volume=849 | issue=849 | pages=11–14 | date=August 1927 | bibcode=1927BHarO.849...11S | postscript=. }}

| last1=C. | first1=Myeong, G. | last2=W. | first2=Evans, N. | last3=V. | first3=Belokurov | last4=L. | first4=Sanders, J. | last5=E. | first5=Koposov, S. | display-authors=1 | title=The Sausage Globular Clusters | journal=The Astrophysical Journal Letters | volume=863 | issue=2 | id=L28 | pages=5 | date=August 2018 | doi=10.3847/2041-8213/aad7f7 | language=en | postscript=. | bibcode=2018ApJ...863L..28M | arxiv=1805.00453 | s2cid=67791285 | doi-access=free }}

| title=NGC 6864 | access-date=2006-11-16

References

1. "Messier 75".
2. From [[trigonometry]]: radius = distance × sin( diameter_angle / 2 ) = 67 ly.

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