Messier 75
Template:Short description Template:Use dmy dates Template:Infobox globular cluster
Messier 75 or M75, also known as NGC 6864, is a globular cluster of stars in the southern constellation Sagittarius.Template:Efn It was discovered by Pierre Méchain in 1780 and included in Charles Messier's catalog of comet-like objects that same year.<ref name=Frommert2007/>
M75 is about 67,500<ref name=Koch2018/> light years away from Earth and is 14,700<ref name=Bergh2012/> light years away from, and on the opposite side of, the Galactic Center.<ref name=Corwin2003/> Its apparent size on the sky translates to a true radius of 67 light years.<ref name=trig/> 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 Template:Val.<ref name=Koch2018/> The absolute magnitude of M75 is about −8.5, equating to 180,000 times more luminous than the Sun (Template:Lo).<ref name=Frommert2007/>
The cluster has a half-light radius of Template:Convert<ref name=Bergh2012/> with a core radius of about Template:Convert and appears not to have undergone core collapse yet. The mass density at the core is Template:Val·pc−3.Template:Efn<ref name=Ramos2012/> There are 38 RR Lyrae variable stars and the cluster appears to be Oosterhoff-intermediate in terms of metallicity.<ref name=Corwin2003/> 62 candidate blue stragglers have been identified in the cluster field, with 60% being in the core region.<ref name=Ramos2012/>
Messier 75 is part of the Gaia Sausage, the hypothesized remains of a dwarf galaxy that merged with the Milky Way.<ref name=Myeong2018/> 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 Template:Convert.<ref name=Koch2018/>
GalleryEdit
- Messier 75 -hst11628 10 08723 43-Lasinh ABR555B438log.png
Messier 75 – wide field view
- M75map.png
Map showing location of M75
See alsoEdit
References and footnotesEdit
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External linksEdit
Template:Sky Template:Portal bar Template:Messier objects Template:Ngc70