Messier 37

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title: "Messier 37" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["open-clusters", "auriga", "messier-objects", "ngc-objects", "perseus-arm", "astronomical-objects-discovered-in-1654"] description: "Open cluster in the constellation Auriga" topic_path: "general/open-clusters" source: "https://en.wikipedia.org/wiki/Messier_37" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Open cluster in the constellation Auriga ::

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

Field	Value
name	Messier 37
image	[[File:M37 Mazur full.jpg
caption	Open cluster Messier 37 in Auriga
epoch	J2000.0
constellation	Auriga
ra
dec
dist_ly	4.511 kly
appmag_v	6.2
size_v	24′
mass_msol	1,500
radius_ly	10-13 ly
age	346.7 to 550 Ma
names	NGC 2099
::

| name = Messier 37 | image = [[File:M37 Mazur full.jpg|300px]] | caption = Open cluster Messier 37 in Auriga | epoch = J2000.0 | constellation = Auriga | ra = | dec = | dist_ly = 4.511 kly | appmag_v = 6.2 | size_v = 24′ | mass_kg = | mass_msol = 1,500 | radius_ly = 10-13 ly | v_hb = | age = 346.7 to 550 Ma | notes = | names = NGC 2099

Messier 37 (also known as M37, NGC 2099, or the Salt and Pepper Cluster) is the brightest and richest open cluster in the constellation Auriga. It was discovered by the Italian astronomer Giovanni Battista Hodierna before 1654. M37 was missed by French astronomer Guillaume Le Gentil when he rediscovered M36 and M38 in 1749. French astronomer Charles Messier independently rediscovered M37 in September 1764 but all three of these clusters were recorded by Hodierna. It is classified as Trumpler type I,1,r or I,2,r.

M37 exists in the antipodal direction, opposite from the Galactic Center as seen from Earth, so is in one of the nearby outer arms.

At its estimated distance of around 4,500 ly from Earth, the cluster's angular diameter of 24 arcminutes corresponds to a physical extent of about 20 -. The tidal radius of the cluster, where external gravitational perturbations begin to have a significant influence on the orbits of its member stars, is about 46 -. This cluster is following an orbit through the Milky Way with a period of 219.3 Ma and an eccentricity of 0.22. This will bring it as close as 19.6 kly to, and as distant as 30.7 kly from, the Galactic Center. It reaches a peak distance above the galactic plane of 0.29 kly and will cross the plane with a period of 31.7 Ma.

Sky charts

| title= | width=250 | height=250 | align=center | File:M37 charta.png|M37 appears as the central yellow dot in this large-scale (close range), detailed map | File:M37map.png|Small-scale (outline) map. Cocchierre (Italian) translates to Auriga.

References

References

1. (2022). "The Planetary Nebula in the 500 Myr Old Open Cluster M37". The Astrophysical Journal Letters.
2. (November 2009). "The orbits of open clusters in the Galaxy". [[Monthly Notices of the Royal Astronomical Society]].
3. (February 2010). "Chemical abundance analysis of the open clusters Cr 110, NGC 2099 (M 37), NGC 2420, NGC 7789, and M 67 (NGC 2682)". [[Astronomy and Astrophysics]].
4. (January 2009). "Deep MMT Transit Survey of the Open Cluster M37. III. Stellar Rotation at 550 Myr". [[The Astrophysical Journal]].
5. (January 2008). "Tidal radii and masses of open clusters". Astronomy and Astrophysics.

::callout[type=info title="Wikipedia Source"] This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page. ::