Friday, March 19, 2010

Partly Cloudy in Taurus

When it comes to astronomical imaging, I've professed my attraction to hunting down dark nebulae, clouds of dust and gas that are not glowing or reflecting starlight like their luminous counterparts, but rather are seen mostly by silhouette against a rich star field. I posted one of my favorite fields about 14 months ago in Taurus near the Pleiades star cluster. In another post from last October, I was examining an image of the same field with a wider lens, and thought I saw some small clouds near the Hyades, the vee-shaped star cluster that makes up the "face" of the constellation Taurus the bull. I needed to take some long exposure sequences to build up the faint images that might be there... The picture of interest is shown at left, with a label pointing to the objects in question. North is up in this exposure.

The Hyades star cluster is the closest cluster to us, 150 light years distance. The bright red supergiant star Aldebaran is unassociated with the cluster and closer to us, only 65 light years away. All the pics I've seen do not show any dark nebulae near the cluster, nor to any of my amateur star charts.


Over the last month, I've gotten out 3 times taking some exposures of the Hyades with a 135mm Nikon lens. As we progress towards Spring, Taurus is getting lower in the west, so time was getting short this observing season, and now with the moon climbing into the evening sky, the window is pretty much closed for now. I got about 2 hours of total exposure when you add together all the 3 minute exposures. Yes, there are a couple of dark clouds, and like the Taurus dark clouds in the uppermost link above, they appear to be faintly illuminated by starlight. And one of the clouds appears to have a small glowing nebula within it. Since many of these clouds are condensing to form stars, there might be a proto-star illuminating it from within... Shown are the nearly full image at left, and a closeup of the largest clouds to the right. North is to the right in these exposures


I'll have to do a little more research with professional star maps to find out the identities. It is fun to find these little-known objects with a telephoto lens and consumer camera these days...

The Latest:
Thanks to a hint from a TAAA member, the two major dark nebulae have been identified, as well as the glowing cloud within. Click the pic here for labels. They are members of a catalog from Beverly Lynds, who I actually have worked with a time or two when I was at Kitt Peak back in the early '80s. She went through the Palomar Sky Survey (in the 1960s) and cataloged all bright and dark nebulae, and came up with the LBN and LDN lists (for Lynds Bright & Dark Nebulae). So the two clouds easiest to spot are LDN 1543 and LDN 1551. The little glowing cloud inside LDN 1551 is Sharpless 239 (SH2-239), and it is, in fact, a proto-star forming region. Also found on the Internet is a spectacular image of the little glowing cloud in red light with an 8" telescope and nearly 12 hours (!) of exposure. I'm only recording the inner bright region, but the enlarged pic with the 135mm lens above shows the oval shape shown in much higher detail in the CCD image. Mystery over as to what it is, but still fun searching the little guys out!

2 comments:

David A. Harvey said...

Very cool Dean! What equipment did you use for the various shots?

Dave

Dean said...

Hi Dave-
The top wide field was with a 50mm, the other is with a 135mm with various crop and levels, all old Nikon glass with adaptor.
-Dean