Image of the day 09/02/2016

ARP273 consists of the interacting pair of UGC1810 (larger) and UGC1813 (smaller). This pair lies 300mly distant in Andromeda. The pairing gets the “Rose” nickname from the obvious appearance of a rose blossom and stem. Research suggests the smaller, UGC1813 actually passed through UGC1810 at some time in the not so distant past.

UGC1810 (larger galaxy)
The gravitational tidal forces unraveled the outer arm and created numerous clumps of star-forming material that takes on the blue tint of massive young stars. Visible at the bottom (in this view) of this arm is a suspected third galaxy which, in the Hubble image, shows a distinct nucleus and perhaps some spiral arms. It is difficult to make out in this image, or Hubble’s for that matter.

UGC1813 (smaller galaxy)
This one appears to be a barred spiral that lost its arms in the merger. The central bar is also home to massive star forming regions which lends more evidence to the recent collision theory. That, and the fact that there is a tidal tail connecting the two spanning tens of thousands of light years. The tail extends on the opposite side of UGC1813 also. This is likely the remnant of a once-coherent spiral structure.

This ranks up as one of my favorite galaxy pairs, though it only measures 1.7 x 0.6 arcminutes! Continuing along in my quest for tiny objects, this was another one where I tried 2x drizzle stacking to increase my resolution. I fully processed it and then in the end, I scaled it back to capture resolution and cropped it in significantly for presentation.

I’m pretty happy with the result but there are some serious challenges here that were hard to deal with.

Rev A - Original Process
Rev B - Pulls back some of the halos of the large stars