Reddest Star

[beka]

Hi All,

Being mostly a visual observer, I am now beginning to venture more and more into astrophotography (mainly because of increasing light pollution). After some tinkering I managed to set up a learning rig consisting of my NexStar 102SLT, Canon 700D and Astroberry INDI server. I can set this up on my balcony, and once I have aligned and focused the telescope, I can  control it remotely over WiFi from KStars on my laptop (and from the comfort of my bed).

This way I took some subs of M36 to see what I can achieve with this modest setup, and while processing with Siril, detected what I first thought was an artifact - a tiny red dot next to the cluster. I had attempted to take some darks but did not intend to use them as I had overlooked setting the ISO on the camera. Now I checked these and could not see any hot spots. Kind of intrigued I checked the region on Stellarium (I had not downloaded catalogs on KStars for fainter stars) and had difficulty matching up the star fields. It looked like Stellarium was missing one of the stars near this object, and the red dot was also absent.

I then did some Internet digging and found the red dot to be the carbon star A* OW Aur. I had read about carbon stars before but had never seen anything this red on my previous images, so this started me off on a quest to see if this was the reddest star known 🙂. This was easier said than done but after a while I managed to figure out that it has a color index of 5.5, and as it turns out it seems the crown for the title of the reddest star known might belong to V* DY Cru with an index of 5.8 . This list of the reddest stars in the sky does not include A* OW Aur,  but it would have ranked 4th or 5th reddest if it did.

The image is from 18 10 second subs at ISO 800, and Bortle 5 site - A* OW Aur in red circle.

Thanks for reading!

 

 

Edited March 7, 2022 by beka
Wrong Image

[CCD-Freak]

Here is a good list of RED carbon stars to check out.