Monday, 3 March 2014

Object of the Month: NGC 2903

There are a few galaxies around the skies of the Northern Hemisphere which Charles Messier somehow missed when he was compiling his famous Messier Catalogue. One of these is the galaxy NGC 2903. Discovered by William Herschel 15 years later, this bright spiral galaxy has an unusual textured core.

Clear image of the galaxy (cropped)

Herschel first observed this galaxy on November the 16th, 1784, publishing his findings in a paper entitled 'Dr. Hershel's Catalogue of One Thousand', in which he describes the object as considerably bright, considerably large and much extended.

With modern technology such as the BRT we are able to see a lot more than the bright, large, extended nebulous area seen by Herschel. We can see that this galaxy, like our own, is a barred spiral galaxy. That is that it has a central bar across it's core, which becomes a spiral further out. On close inspection you can see that the galaxy has a mottled texture caused by areas of dark, cold dust clumped throughout the galaxy. In a lot of spiral galaxies, this dust forms tight 'dust lanes', which follow the spiral arms, but slightly less so here. Beyond the bright, central core the faint arms of the galaxy sweep out into space.

Observations by the Hubble Space Telescope indicate that there is an unusual amount of star formation occurring in a ring around the core of the galaxy. This galaxy is also in a phase when it is creating new globular clusters. The Milky Way has not had the conditions for globular cluster formation for around 12 billion years, which is when all of the globular clusters in our galaxy today originate from.

Observing Tips:

  • Use Galaxy Camera
  • An exposure of 120 000 - 180 000 ms will bring out the faint details in the spiral arms
  • Clear filter gives the least grainy image, but the galaxy is bright enough that colour images should still be acceptable.