Messier 36 - The Pinwheel Cluster

Welcome back to Messier Monday! In our ongoing tribute to the great Tammy Plotner, we take a look at the Pinweel Cluster, otherwise known as Messier 36. Enjoy!

During the 18th century, famed French astronomer

Charles Messier

noted the presence of several "nebulous objects" in the night sky. Having originally mistaken them for comets, he began compiling a list of them so that others would not make the same mistake he did. In time, this list (known as the

Messier Catalog

) would come to include 100 of the most fabulous objects in the night sky.

Included in this list is the open star cluster Messier 36, also known as the Pinwheel Cluster. This cluster is so-named because of its association with the Auriga constellation (aka. "the Charioteer"). Though similar in size and make-up to the

Pleiades Cluster

(Messier 45), the Pinwheel Cluster is actually ten times farther away from Earth - and one of the most distant of any clusters catalogued by Messier.

What You Are Looking At:

Located a little more than 4000 light years from our solar system, this group of about 60 stars spans across about 14 light years of space. As you are studying it, you'll notice one star which seems brighter than the rest... With good reason! Its a spectral type B2 and about 360 more luminous than our Sun. Many of the cluster members here are also B-type stars and rapid rotators.

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Close-up of the central region of Messier 36. Credit: Wikisky

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This means that 25 million year old Messier 36 shares a lot in common with another nearby star cluster, the Pleiades. By taking a deep look at young clusters with stars of varying ages, astronomers are able to how long circumstellar disks may last - giving us a clue as to whether or not planet-forming stars may lay within them.

As Karl E. Haisch, Jr. (et al), wrote in a 2001 study "

Disk Frequencies and Lifetimes in Young Clusters

ut, can M36 hold surprises? You betcha'. As Bo Reipurth stated in a 2008 study titled "

Star Formation and Molecular Clouds towards the Galactic Anti-Center

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2MASS Atlas Image Mosaic of the open star cluster Messier 36. Credit: NASA/IPAC/Caltech/University of Massachusetts

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And the search for planet-building stars within M36 hasn't stopped yet. The Spitzer Space telescope will also be investigating it, thanks to a proposal made by George Rieke:

History of Observation:

The presence of this awesome star cluster was first recorded by Giovanni Batista Hodierna before 1654 and re-discovered by Le Gentil in 1749. However, it was Charles Messier who took the time to carefully record its position for future generations:

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M36 Open Cluster. Credit: NOAO/AURA/NSF

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It would be observed again by Caroline, William and John Herschel who would be the first to note the double star in M36's center. Although none of their notes are particularly glowing on this awesome star cluster, Admiral Symth does come to the historic rescue!

Locating Messier 36:

Locating Messier 36 is relatively easy once you understand the constellation of

Auriga

. Looking roughly like a pentagon in shape, start by identifying the brightest of these stars - Capella. Due south of it is the second brightest star which shares its border with Beta Tauri, El Nath. By aiming binoculars at El Nath, go north about 1/3 the distance between the two and enjoy all the stars!

You will note two very conspicuous clusters of stars in this area, and so did Le Gentil in 1749. Binoculars will reveal the pair in the same field, as will telescopes using lowest power. The dimmest of these is the M38, and will appear vaguely cruciform in shape. At roughly 4200 light years away, larger aperture will be needed to resolve the 100 or so fainter members. About 2 1/2 degrees to the southeast (about a finger width) you will see the much brighter M36.

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The location of M36 in the Auriga constellation. Credit: IAU and Sky and Telescope Magazine (Roger Sinnott & Rick Fienberg)

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More easily resolved in binoculars and small scopes, this "jewel box" galactic cluster is quite young and about 100 light years closer. If you continue roughly on the same trajectory about another 4 degrees southeast you will find open cluster M37. This galactic cluster will appear almost nebula-like to binoculars and very small telescopes – but comes to perfect resolution with larger instruments.

While all three open star clusters make fine choices for moonlit or light polluted skies, remember that high sky light means less faint stars which can be resolved - robbing each cluster of some of its beauty. Messier 36 is intermediate brightness of the trio and you'll quite enjoy its "X" shape and many pairings of stars!

Has the central double changed with time? Why not observe for yourself and see!

Object Name: Messier 36
Alternative Designations: M36, NGC 1960, Pinwheel Cluster
Object Type: Galactic Open Star Cluster
Constellation: Auriga
Right Ascension: 05 : 36.1 (h:m)
Declination: +34 : 08 (deg:m)
Distance: 4.1 (kly)
Visual Brightness: 6.3 (mag)
Apparent Dimension: 12.0 (arc min)

We have written many interesting articles about Messier Objects here at Universe Today. Here's Tammy Plotner's

Introduction to the Messier Objects

, ,

M1 – The Crab Nebula

M8 – The Lagoon Nebula

, and David Dickison's articles on the

2013

and

2014

Messier Marathons.

Be to sure to check out our complete

Messier Catalog

. And for more information, check out the

SEDS Messier Database

Sources: