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NGC 891 & M32
Erin Tanis & Dalton Meyaard

NGC 891 M32
NGC 891 Galaxy- Erin Tanis M 32- Dalton Meyaard

The NGC 891 and M32, or Messier 32, are both galaxies in the Andromeda constellation. A galaxy, according to The Cosmic Perspective Fundamentals, is a "collection of anywhere from a few hundred million to more than a trillion stars, all bound together by dust" (G-5). Messier 32 is an elliptical galaxy, characterized by its spherical shape, whereas NGC 891 is a spiral galaxy, marked by its tendril-like arms.

Spiral galaxies consist of a disk, a halo, and a bulge, with old stars at the center. Similar to the Milky Way, the image of this galaxy is presumed to appear very much like our own galaxy as viewed from its side. NGC 891 was discovered in 1784 by William Herschel . It is roughly 27 million ly away from the Milky Way with an apparent dimension of 13.5 x 2.8 arc minutes (Frommert).

Discovered by Le Gentil in 1749, M32 is roughly 2.59 million light years away. It is a satellite galaxy to M31, the Andromeda Galaxy, which is causing the light to appear in the right portion of the image. It is considered a dwarf elliptical galaxy, meaning that is smaller than typical elliptical galaxies. Its dimensions are approximately 8x6 arcminutes. As an elliptical galaxy, it would considered old, and lacks any new star production, but there are signs that there has been star production in the recent past (Rudenko).

Beyond both being galaxies, M32 and NGC 891 have a few other similarities. For example, unlike irregular galaxies, they share a certain structure to them, with their stars existing on a plain of orbit. They also both have the color yellow, which indicates an older stellar population, as the color yellow would be produced by older stars.

The two galaxies also share some differences. NGC 891 has a spiral structure while M32 has a more spherical shape. Futhermore, while they both have the color yellow, NGC 891 alone contains some blue. This would indicate that there is still star formation in those areas the galaxy. M32 lacks this blue tinge, indicating that there is no longer star formation.

References:

Frommet, Hartmut. "NGC 891." Students for the Exploration and Development of Space. <http://messier.seds.org/xtra/ngc/n0891.html>

Nemiroff, Robert. "Astronomy Picture of the Day." NASA. <http://apod.nasa.gov/apod/ap990919.html>

Frommert, Hartmut. "M32." Students for the Exploration and Development of Space. <http://messier.seds.org/m/m032.html>

Rudenko, Pavlo; Worthey, Guy; Mateo, Mario (2009). "Intermediate age clusters in the field containing M31 and M32 stars". The Astronomical Journal 138  <http://adsabs.harvard.edu/abs/2009AJ....138.1985R>

 

Object NGC 891 Messier 32
Right Ascension (J2000) '02 22 33.00' 00:42:41.8
Declination (J2000) '+42 20 49.9' +40 51' 55''
Filters used B (Blue), C (Clear), R (Red), V (Green) B (Blue), C (Clear), R (Red), V (Green)
Exposure time per filter B (180s), V (150s), and R (150s); C (180s) B (560s), V (200s), R (140s), C (300s)
Image dimension 1092x736 pixels; 23.8x16.1 arcminutes 1092x736 pixels; 23.8x16.1 arcminutes
Date/time observed V, R, C September 29, 2015, 7:17 UT; R October 15, 2015, 9:33 UT B, V, R, C October 14, 2015, 3:14 UT

 

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