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Astronomical Observatory: Cool Images

Astr212 Galaxy Projects, Spring 2005

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M87 Giant Elliptical Galaxy, Matt Cosnek


The M87 galaxy, the bright object on the middle left, is an enormous E1 elliptical galaxy located at the center
of the Virgo Cluster, roughly 60 million light years from us. Discovered by Charles Messier in 1781, M87 is
much larger than our Milky Way galaxy. To compare the two, M87 contains about 15,000 globular clusters,
while the Milky Way has only 150 to 200 globulars. M87 is also about 2.7 trillion times the mass of the sun.
M87's size is due to the fact that it has merged with so many other galaxies. A phenomenon known as
galactic cannibalism. Also shown in the picture are galaxies NGC4486B (type C galaxy located at top middle),
NGC4478 (E1 galaxy located at bottom right), NGC4986A (type C galaxy located below M87), and NGC4476
(S0 galaxy located at far right).

M87 is unique because of a jet that extends from its center (Emphasized in the picture below). The jet
extends for thousands of light years and consists of gas that is shot out from a super-massive black hole at
M87's center.



The above Radio picture shows the Radio lobes of M87. The radio lobes are approximately 80 kpc from end
to end. The image below is a close up on the red area of the Radio lobe picture. It shows the super massive
black hole at the center and the jet extending from it.


The X-Ray image below of M87's jet shows the synchrotron radiation, which is emitted by energetic electrons spiraling around magnetic field lines.


The graph below is a light profile of M87. The light profile shows the pixel brightness as the radius increases
along the major axis of M87. The equation at the top of the graph represents the portion from 18 to 30
[Radius (kpc)}^(1/4). This can be used to find the effective radius of M87, 7.4 kpc with an uncertainty of 158
pc. The effective radius represents the area where half the light from M87 is emitted. Along with the light
profile for the minor axis of M87, an ellipticity of 2.335 was calculated.


Elmegreen, D.M. 1998, Galaxies and Galactic Structure (New Jersey: Prentice Hall)

Nemiroff, R. and Bonnell, J., Elliptical Galaxy M87 1995, Astronomy Picture of the Day

Owen, F., Biretta, J., Eilek, J., M87 as a Radio Galaxy, Jan. 1999

Students for the Exploration and Development of Space, M87, Jan. 2000

Students for the Exploration and Development of Space, X-Ray image of M87, Sept 2001.

Observation Details
RA (J2000) 12:30:49.43
Dec (J2000) +12:23:27.7
This is in the constellation Coma. North is up and East is to the left.
Scale The image is 21.5 by 14.5 arcmin, which is 375,200 by 253,000 light years at the distance of M87.
Exposure time per filter
25 x 60s
16 x 300s
8 x 300s
8 x 300s
Dates of observation
2005 Feb.8
2005 Mar.8
2005 Mar. 10
2005 Apr.6
Processing details: Images were dark subtracted and flat-fielded to remove noise. The images from each filter were then combined to produce a high sensitivity image in each filter. All 4 images were combined to produce a color image, and a non-linear (gamma) transform was applied to bring out faint detail in the filaments without saturating the bright, middle region.






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