This barred starburst spiral galaxy, also known as NGC 5236 and the Southern Pinwheel Galaxy, is located 16 million light years away in the constellation of Hydra at a declination of -30 degrees. It is a bright magnitude 7.5 galaxy which spans 13 arc-minutes in our apparent view. This corresponds to a diameter of 60,000 light years. Studies have indicated that the galaxy disk appears about 25 degrees from face-on in our view of it.
This is the 6th
brightest galaxy in the sky. We are close enough that the dark dust lanes, blue star clusters, and pink HII star forming regions are visible to us. The core, which hides a supermassive black hole, is very bright. Several distant background galaxies are seen to the left of M83, around 0.7 billion light years away.
The arm structure is hard to trace. It appears to me that it has 2 primary arms, as in a grand design spiral galaxy, with each arm originating from opposite ends of the bar. But there are numerous places – I count at least 5 – where short arm segments branch out from the main arms.
This is a tough object for me to image from my backyard in Texas because of the low altitude of this southern hemisphere object. For a view of what is possible for this object using 25 hours of time with the dream setup of a Planewave 20” scope in Chile, please see the
recent beautiful M83 image from
@John Hayes . The resolution in his image is incredible.
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