SAS Astronomy Pictures of the Month [December, 2024]
Late Fall Sky - Featuring IC5134 in Cepheus & M15 in Pegasus, as well as spectra from two Wolf-Rayet stars!
Photo by Terry Riopka
This one has it all: the heart of the nebula is the star cluster NGC7129, consisting of a core of 4 bright B stars that illuminate the blue reflection nebula (NGC7133) as well as the smaller yellow reflection cloud LBN497. IC5134 is the encompassing dusty cloud of molecular gas. The entire complex lies about 3300 light years from Earth in the constellation Cepheus. Like NGC1333, this nebula also contains a number of Herbig-Haro objects – bright red clouds of gas ionized by collimated jets of ionized plasma flowing out from young protostars that are detectable only at infrared wavelengths. There are over 100 young protostars in this highly active stellar nursery just waiting to emerge from their cocoons.
I took this image over an entire week from my backyard in Concord MA first week in November, combining 323 3min unguided exposures to give me a 16hr exposure of this beautiful region. As usual, I used my 12″ LX200 Classic Meade on my MyT Paramount with my ASI2600mc cooled camera and processed the image in Pixinsight.
My PI workflow, in case you’re interested: ABE/BXT/SPCC/EzDenoise/ArcSinhStretch, followed by StarNet++ to remove the stars, then separate processing of the nebula regions, reintegration, and final enhancement. Of course, the art is in the enhancement of the nebula regions… I usually spend time preparing various masks for regions I want to blur, with time proportional to the complexity of the regions, then selectively apply and enhance!
Photo by Terry Riopka
This a beautiful globular, bright and compact visually. M15 in Pegasus is about 33,600 light-years distant, and fairly large at 175 light years diameter. M15 is also one of the densest globular clusters known, believed to be in a state of core collapse. In fact, the closer Hubble looks into its center, the more stars are visible, with its density continuing to increase to within 0.06 light years of the core! It is still unclear if the central core of M15 is packed so dense simply because of the mutual gravitational interaction of the stars it is made of, or if it houses a dense, supermassive black hole. M15 also contains 1 of only 4 known planetary nebulae in Milky Way globular clusters.
I combined data from last year with data at the beginning of this month this year, but had issues with my flats, so the processing was a little difficult. I used my same setup as above but with just under 4 hours of exposure time. Here’s a link to my previous attempt over 10 years ago (!) with my 10″ Meade and only 20 minutes of exposure time. I have to admit, there’s something about my older picture I like over this newer one… is it just me, or does my older image look almost 3 dimensional?
David Murray has been experimenting with spectra from Wolf-Rayet stars! Here are two that he acquired, one from WR134 a WRN6 star with blue vertical lines emission reference lines. The second, a spectrum for WR137, a WRC star.