Category Archives: Deep Sky Observing

RS Ophiuchi- a rare occasion

Posted on by September 6, 2021

Life seems to be chugging along when suddenly there’s a thermonuclear eruption somewhere far far away. By far away I mean 5000ly!
What’s happening there?

A white dwarf star and a red giant are orbiting one another and maybe too close for comfort. The white dwarf siphons off material from the red giant star and developes a dense atmosphere which consists mainly of hydrogen. The newly accreted atmosphere is thermally heated by the hot white dwarf.  With this extra mass, gravity increases and the white dwarf becomes compressed which causes it to ignite.
I’ve read that only 10 recurrent novae have been identified. So what I’m following here is quite rare
To get a visual comparison, I’ve been setting up missions to RS Ophiuchi on the same telescope at Slooh and more or less at the same time of night. Cloudy weather was persistent but just as well because the Moon might have been too bright and in close proximity on those cloudy nights.
I did not give up and last night, conditions were perfect and I got a beautiful follow-up image. There’s no doubt, RS Oph is dimming and will go into slumber mode again.

To do an accurate comparison, I have not processed or cropped these images.

Gum 50 & Trumpler 23

Posted on by July 21, 2021

While working through South African astronomer, Magda Streicher’s, list of delightful asterisms to enjoy the pretty in the night sky, I have come across some very interesting deep-sky objects in the nearby regions of the sky.

I noticed a pinkish-reddish object to the north of asterism, Streicher 34. I ran the co-ordinates in Aladin Sky Atlas and identified this as Gum 50. Then another surprise! I also found the faint but destinctive open cluster, Trumpler 23 northeast of Gum 50. The cluster has an interesting shape and almost looks connected to Gum 50 by a string of stars. Could they be somehow connected?
If only I could understand what’s been written in scientific papers by Y M and Y P Georgelin and Veta Avedisova, I would have a clearer idea.

At one stage Avedisova placed Gum 50 and Trumpler 23 in the same star forming region. After measuring distances and determining spectral classes of the stars, the Georgelins cast doubt on whether the cluster was associated with Gum 50, which goes by RCW 99 as well.