Messier 32 - the "Le Gentil" Dwarf Elliptical Galaxy

Welcome back to Messier Monday! In our ongoing tribute to the great Tammy Plotner, we take a look at dwarf elliptical galaxy known as Messier 32. 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.

One of these objects is the dwarf elliptical galaxy known as Messier 32 (aka. NGC 221). Located about 2.65 million light-years from Earth, in the direction of the

Andromeda constellation,

this dwarf is actually a satellite galaxy of the massive

Andromeda Galaxy

(M31). Along with Andromeda, the

Milky Way

and the

Triangulum Galaxy

(M33) is a member of the Local Group.

Description:

M32 is an elliptical dwarf galaxy which contains about 3 billion solar masses. While it looks small compared to its massive neighbor, this little guy actually stretches across space some 8,000 light years in diameter. Once you pick it up, you'll notice it's really quite bright on its own - and with very good reason - its nucleus is almost identical to M31. Both contain about 100 million solar masses in rapid motion around a central supermassive object!

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The dwarf elliptical galaxy Messier 32 (Le Gentil). Credit: Wikisky

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As Alister W. Graham wrote in his 2002 study - titled "

Evidence for an outer disk in the Prototype `Compact Elliptical' Galaxy M32

By probing deeply into Messier 32, we've learned this little galaxy is home to mainly mature red and yellow stars. And they're good housekeepers, too... because there's practically no dust or gas to be found. While this seems neat and tidy, it also means there isn't any new star formation going on either, but there are signs of some lively doings in the not too distant past.

Because M32 has shared "space" with neighboring massive M31, the strong tidal field of the larger galaxy may have ripped away what once could have been spiral arms - leaving only its central bulge and triggering starburst in the core. As Kenji Bekki (et al) wrote in their

2001 study

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Messier 31 (the Andromeda Galaxy), along with Messier 32 and Messier 110. Credit: Wikisky

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History of Observation:

M32 was discovered by Guillaume Le Gentil on October 29th, 1749 and became the first elliptical galaxy ever observed. Although it wasn't cataloged by Charles Messier until August 3rd, 1764, he had also seen it some seven years earlier while studying at the Paris Observatory, but his notes had been suppressed. But no matter, for he made sure to include it in his notes with a drawing! As he wrote of the object:

Later, Messier 32 would be examined again, this time by Admiral Symth who said:

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The location of Messier 32 location in the Andromeda constellation. Credit: Roberto Mura

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Locating Messier 32:

Locating M32 is as easy as locating the Andromeda Galaxy, but it will require large binoculars or at least a small telescope to see. Even under moderately light polluted skies the Great Andromeda Galaxy can be easily be found with the unaided eye - if you know where to look. Seasoned amateur astronomers can literally point to the sky and show you the location of M31, but perhaps you have never tried to find it.

Believe it or not, this is an easy galaxy to spot even under the moonlight. Simply identify the large diamond-shaped pattern of stars that is the Great Square of Pegasus. The northernmost star is Alpha, and it is here we will begin our hop. Stay with the northern chain of stars and look four finger widths away from Alpha for an easily seen star.

The next along the chain is about three more finger widths away... And we're almost there. Two more finger widths to the north and you will see a dimmer star that looks like it has something smudgy nearby. Point your binoculars there, because that's no cloud – it's the Andromeda Galaxy!

Now aim your binoculars or telescope its way… Perhaps one of the most outstanding of all galaxies to the novice observer, M31 spans so much sky that it takes up several fields of view in a larger telescope, and even contains its own clusters and nebulae with New General Catalog designations. If you have larger binoculars or a telescope, you will be able to pick up M31's two companions – M32 and M110. Messier 32 is the elliptical galaxy to the south.

Why not stretch your own boundaries? Go observing! Halton Arp included Messier 32 as No. 168 in his Catalogue of Peculiar Galaxies. It's bright, easy and fun! And here are the quick facts on this Messier Object to help you get started:

Object Name: Messier 32
Alternative Designations: M32, NGC 221
Object Type: Type E2, Elliptical Galaxy
Constellation: Andromeda
Right Ascension: 00 : 42.7 (h:m)
Declination: +40 : 52 (deg:m)
Distance: 2900 (kly)
Visual Brightness: 8.1 (mag)
Apparent Dimension: 8x6 (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: