Andrew’s Astronomy Blog

If the previous images of merging galaxies looked rather gentle then this is anything but. Several hundred million years ago, these galaxies were both spirals, rather similar to our own. Now, as the first image shows, they are almost totally disrupted with clumps of new stars ignited by the gravitational interaction.

The second image has been processed to over-expose the galactic cores and show the features that give this pair of galaxies their common name. Two gravity waves have produced long streams of stars, dust and gas stripped from the merging galaxies.

For astonomers wanting to study galactic interaction this pair present an ideal target as they’re are close neighbours at 45 million light years distance.

These images were produced on GRAS-15 and are a combination of 10x 300 second luminance frames binned at 1×1 and 6 each of red, green and blue filtered images binned at 2×2.

Given a very dark clear night, a good pair of binoculars and a set of sharp eyes, it’s possible that you may just be able to see a faint fuzzy blog under the handle of the plough in Canes Venatici. This is ARP 85, the galaxy pairing of Messier 51 & NGC 5195. M51, also known as The Whirlpool,  is one of the finest examples of a spiral galaxy, discovered by Lord Rosse in 1845 who first recognised the spiral structure using his 72 inch reflecting telescope at Birr Castle, Ireland.

For many years it was believed that NGC 5195  was merely on the same line of sight as M51 and further away, however, simulations suggest that NGC 5195 first passed through the disk of M51 some 500 - 600 million years ago travelling towards us before another encounter 50 to 100 million years ago took it back through the spiral. The resulting gravity waves have triggered areas of star formation in the spiral arms of M51.

About 23 million light years away, M51 has a diameter of 76,000 light years and a total mass of about 160 billion suns.

(Click for a larger image)

Imaged on GRAS-001, this is a stack of eleven two minute exposures, processed in IRIS.

Just over a moons width away from M81 lies the galaxy M82, also in Ursa Major. With a really dark sky both are visible in binoculars as faint smudges. In space, the two are about 150,000 light years apart and are part of a galaxy cluster that is about 12 millions light years distant.

A bright moon and high haze limited imaging to bright objects on Tuesday evening  but I did get a picture. I also determined that I had some issues with the imaging process, more on this below.

After the imaging run I noticed that the camera was set to jpeg rather than RAW image quality. After some work I traced this to a ‘fast mode’ setting in the capture software. Now that I’ve isolated this problem, next time out I should get some rather sharper, lower noise images.