Owl Nebula
Planetary Nebula in Ursa Major

Click here for higher-resolution versions: 1288x1288 (66-2/3%)  1932X1932 (Full Resolution)


M97, the bright blue-green object at the center of the image, is a moderate-sized (about 3.4 arcminutes in diameter), fairly bright (magnitude 10 according to most sources) planetary nebula, the type of nebula which it is generally thought our Sun will produce as nuclear fusion slows and then dies in its core, and it expels its outer layers of gas (the star itself ultimately shrinks to become a "white dwarf"; the progenitor star, according to Wikipedia, now has 55–60% of our Sun's mass in a sphere with less than 1% of our Sun's diameter--it's really dense!, 41–148 times the brightness of our Sun, and an effective temperature of 123,000 K--compared to our Sun's 5800 K temperature). M97 is estimated to be anywhere from about 1300 light years from us, to over 10,000 light years from us; the most common numbers are around 2,000 or a little more, which would make it a little less than one light years across. It is commonly known as the "Owl Nebula," because an early observer of the nebula drew it to resemble an owl (note the two "eyes" inside the nebula).

The main color is a result of the strong emissions of doubly-ionized oxygen atoms (OIII); the red is from the emissions of hydrogen ions (hydrogen alpha). The faint outer shell seems to be entirely OIII, since it doesn't show up at all in the Ha images.

I always love how almost any view of the heavens will show so many background galaxies, and this is no exception. If you examine the highest-resolution version, you can see many tiny galaxies mixed in among the stars (they're the ones that are either quite oblong or faint and blurry, so generally a galaxy). Of course, these are huge things, tens of thousands of light years across, with billions upon billions of stars in each one, but they're so far away they barely show at all.


Technical Information:

LRGBOIIIHa: 345:180:120:180:300:240 (Luminance layer consists of blend of luminance and OIII data; red channel consists of a blend of the red and Ha data; green consists of a blend of green and OIII data, and blue consists of a blend of blue and OII data); all subexposures unbinned.

Equipment: RC Optical Systems 14.5 inch Ritchey–Chrétien carbon fiber truss telescope, with ion-milled optics, at about f/9, and an SBIG STX-16803 with internal filter wheel (SBIG filter set), guided by an SBIG AO-X, all riding on a Bisque Paramount ME German Equatorial Mount.

Image Acquisition/Camera Control: Maxim DL, controlled with ACP/Scheduler, working in concert with TheSky X.

Processing: All images calibrated (darks and dawn flats), aligned, and combined in Pixinsight. Color combine in Pixinsight. Some finish work (background neutralization, color calibration and gradient removal) done in Pixinsight; some finish work (adjustment of contrast, Smart Sharpen of the luminance layer, and Neat Image noise reduction) was done in Photoshop CC.

Location: Data acquired remotely from Deep Sky West Remote Observatory, Rowe, New Mexico, USA.

Date: Images taken on many nights in June 2019. Image posted July 5, 2019.

Date: Image scale of full-resolution image: 0.56 arcseconds per pixel.

CCD Chip temperature: -25C

Copyright 2019 Mark de Regt

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