December 24, 2015

NGC 1342 (Fall 2015)

NGC 1342 is an open cluster in Perseus.  It's quite large, visually, and I've looked at it a few times, but now I see I've missed the main event.  The cluster is interesting because it is dimmed and reddened by interstellar dust that obscures it.  It makes a very nice image.  The cluster is a couple of thousand light years away.

The bright blue star in the upper left--the left end of the three bright stars--brightens the dust.  One can see just below that star that the blue from the star colors the dust just a bit.  I hypothesize a physical relationship between the two.  The dust, called collectively LDN 1434, has been estimated at around 1100 light years, and that star, V496 Per (type B8), has been estimated at 100 light years in front of that, but some of that dust must lie near the star if light from the star reflects that strongly.  The blue star to the right of V496, called HD 21943 (type B9), is only about 550 light years away and so is merely a foreground object.  The bright, whiter star to the right of that, HD 21809, is only 192 light years distant.

Some background galaxies were picked up in the image thousands of times farther into the distance.

This image is LRGB 36;17;17;17 x 900" from DSW's FSQ.

December 12, 2015

NGC 281 or IC 1590 (Fall 2015)

This lovely nebula is lit up by, once again, a type O multiple star at its center.  In this case, it is HD 5005, a trapezium system of O-type stars on which nearly every ionization front in the nebula seems to center.  Source.  This source names many cluster members as type B, also.

Especially of interest here is the massive cloud of dust in front of the cluster, just to its right.  HD 5005 is eroding this cloud with strong UV radiation, too, but because the cloud is in front of the cluster, it appears as a dark streak with streamers moving away from the cluster of stars.

This image is 20;16;16 x 1800s of SHO from Deep Sky West's FSQ.  I've imaged this object before, several times, and I am proud of higher resolution images here (Ha only) and here (Ha and OIII).

Think this object is cool?  Check out this Hubble shot of the Nebula's center.

December 6, 2015

VdB 142, the Elephant Trunk Nebula (Fall 2015)

This wonderfully large and dramatic scene is caused by the bright multiple star---actually a small cluster of stars unresolvable with this camera setup---at the top left, named HD 206267. One of the cluster stars, HC 206267A, is a multiple star with a combined type O! At least three of the stars in the multiple are type O. Many of the other stars in the cluster are also large and bright. Source. The system puts out fantastic amounts of energy, including X-rays. Our source provides that the cluster is about 3 million years old---very young for a group of stars.

This scene is part of a larger nebula called collectively IC 1396, lit up mostly by HD206267.  It appears in the constellation Cepheus.  This narrowband data is 18;16;16 x1800" of SHO from DSW's FSQ.

December 1, 2015

The Cederblad 214, Sharpless 2-171 Region (Fall 2015)

This amazing space-scape of stars, gas, and dust lies in the constellation Cepheus.  What's going on here?  Just to the left of center a cluster of very young stars has formed out of the dust and gas of the cloud (catalogued Berkeley 59).  The stars are so bright and energetic that they have excited the hydrogen, forcing it to emit red light.  Other elements are glowing, too (oxygen in blue-green, for example), but the hydrogen overwhelms.

In particular, the cluster contains type O stars---rare, very hot stars that burn hotter and bluer than others.  These O-type stars burn hot enough that they emit the UV radiation necessary to ionize the hydrogen, which results in the glow that is captured here.  There are several clues as to which star is causing most of the glow.  First, the brighter nebula is roughly round-ish, and the round shape has a radius.  Second, the nebula contains several "elephant trunks"---dust pillars that are being slowly washed away by the ultraviolet light; at the edges of each pillar is an ionization front where we are looking across a plane of ionized gas.  All the dust pillars share a common "radiant," a point where the UV appears to originate.  Third, at that radiant sits an O-type star that is capable of causing the glow and the washing away.  Spectral studies suggest that this one star is the hottest star within 3,000 light years of us.  It is called BD +66 1673.  I've pointed it out in a close-up below.  This may well be the star that powers the nebula.  Another study reports nine O7- to B3-type stars in the cluster.  Surely they help some, too.  Oh, why aren't the hot O and B stars blue?  Too much dust in the way reddens their color along our line of sight.  Here is the connection between BD +66 1673 and the dust pillars.

The nebula contains some fascinating areas.  I've highlighted some below.

Finally, the view is full of dust clouds that lie in front of everything and block the view of what is behind.
 This wonderful data came from DSW's FSQ and represents 31;21;21;16 x 900" of LRGB,over 22 hours of data.