Object of the Week Feb 19, 2012 - Thommes' Nebula revealed

Thommes' Nebula
New Reflection Nebula

06 57 22.2 -08 23 18
Mag unknown

An image taken by Jim Thommes of the nebula LBN 1022 in Monoceros (http://www.jthommes.com/Astro/LBN1022.htm) on November 21, 2009 revealed a new compact reflection nebula surrounding V900 Mon, a recently discovered eruptive variable. The nebula is only barely visible on earlier (POSS) images, so is reminiscent of Jay McNeil's discovery. In addition, Thommes' image showed an intriguing jet or flow to the southwest.

The nascent star has just been shown to be a member of the rare class of FU Orionis stars. The paper can be read at www.ifa.hawaii.edu/users/reipurth/PREPRINTS/ms_V900Mon.pdf

Last night (February 18th), I had an opportunity to take a look at the nebula, along with Jimi Lowrey and Jim Chandler, using Lowrey's 48-inch. Thommes' nebula was immediately picked up by Jimi at 285x as a fairly faint, small, round glow, roughly 15" in diameter along with a brighter nearby nebula (see below). At 488x and 814x, the jet was clearly visible as a tail or extension streaming to the southwest and making the nebula appear elongated at least 2:1.

Sharing the same field as Thommes' Nebula is RNO 78 (Red Nebulous Object from Martin Cohen's list of 150 objects in dark clouds), a brighter compact nebula just 3' NNW with a star at the east edge. Using 488x, the nebula was irregular in appearance and three additional stars or knots were resolved within the glow.

Thommes' Nebula was relatively prominent in the 48" and is certainly visible in much smaller scopes -- take a look and let's hear what you find!

Attachment 91

GIVE IT A GO AND LET US KNOW

GOOD LUCK AND GOOD VIEWING

Steve Gottlieb

This is one COOL object I was really surprised at how bright it was. I wonder what is the smallest scope that can see it is?

I highly recommend that you put this one on your observing list !

Steve,

Great object for this weeks OOTW!

Do you suspect you could pick this up with your 18"? From the images it looks as though you probably could as it looks fairly bright. What about the jet?

Thanks Steve - this object will be on my list the next time I make it out.

I had read about it already on CloudyNights and I put this YSO immediately on my to do list.

As most of these objects are RNs, they look easier on the images than they are at the eyepiece :-(

At the Winter Star Party last week, I stayed mostly with my scope and those of my friends, but I gave the coordinates of Thomme's Nebula to Alan and showed him how to be sure it was the correct blob and not the other one nearby. He was observing with someone's 25-inch f/4 with a 13mm Nagler. They had no trouble seeing it.

Sue

I have to bring up again this thread on Thommes Nebula.

Last night, I was looking at McNeil's Nebula in M78, which was, as usual, very faint. I remembered to look as well at Thommes Nebula, which was unexpectedly prominent. Though the seeing was mediocre, the YSO appeared as a clearly non-stellar direct vision object with my 22" and similar with a friends 14". At times, it appeared elongated with a tail pointing approximately south, possibly the jet-like structure mentioned by Steve.

This is clearly one of the brighter young stellar objects.

I also had a chance to take a look again at Thommes Nebula (first view in Jimi's scope) with my 24-inch last weekend and was quite impressed. It was surprisingly easy to pick up at 175x as a fairly faint, round glow <20" diameter. Appeared similar to a small, 14th magnitude galaxy. At 225x, it seemed ~15" diameter with a faint extension to the south or southwest, increasing the size to 25"x15".

If you take a look at this field, you'll immediately notice the reflection nebula RNO 78 just 3' NNW. It appeared moderately bright, fairly small, 20" diameter. A star is at the east edge, barely beyond the glow of RNO 78 and there appeared to be a star embedded in the glow. This little known reflection nebula has a fairly high surface brightness!