March 4, 2020

NGC 2442 & some companions (2019)


NGC 2442 is in the constellation Volans.  It is not visible from Texas at all---too far south.  This data came from a remote observatory in Australia, gathered by an amateur whose standards for data are as high as mine or higher.

NGC 2442 is about 56 million light years away.  It has obviously been disturbed by something.  According to more than one study, that something is probably AM 0738-692, the galaxy to the left (also known as PGC 21457).  The small galaxy appears to have come from the right and moved to the left just above NGC 2442, probably within the last 300,000 years.  This passage disturbed the larger galaxy, and eventually the smaller one will swing back, crash again, and eventually combine with NGC 2442.  At least that is predicted by this study: https://arxiv.org/pdf/astro-ph/9701015.pdf.

Another study suggests another cause and posts a deep image showing that NGC 2442's unusual arm extends much further than the other:
https://arxiv.org/pdf/astro-ph/0103099.pdf
Here's the photo from that study:
https://arxiv.org/PS_cache/astro-ph/ps/0103/0103099v1.f2.jpg
I can make my data do some of that:

A later study detected an intergalactic gas cloud in the area of NGC 2442.  It's possible that the gas cloud has come from NGC 2442 as part of its interactions.
https://iopscience.iop.org/article/10.1086/321453/pdf

Lots of other little galaxies are floating about, including some that I could not identify.

This is 21x1200" with a 17 Planewave CDK and SBIG 11000m camera.