Messier 20, The Trifid Nebula
Optics:  Ritchey–Chrétien 20" F/8.2 (4166mm FL) Processing:  PixInsight, Photoshop
Camera:  SBIG STXL-11000 with Adaptive Optics Date:  September 2021
11 Megapixel (4008 x 2672 16-bit sensor) Location:  Columbus, Texas
Exposure:  LRGB = 670:90:80:100 minutes Imager:  Kent E. Biggs

HERE IT IS! After a month of studying a new image processing program, PixInsight, this is my first attempt through a brand-new image processing workflow. The new workflow has essentially doubled the resolving power of my telescope when compared to the old workflow. It is as if I have just upgraded the telescope to twice its size, with just the purchase of new software, wow! PixInsight is complex but amazing!

This object, Messier 27, aka M27 or NGC 6853, is perhaps the most famous planetary nebula to amateur astronomers. It was the very first planetary nebula discovered in 1764 by Charles Messier. M27 is in the direction of the constellation Vulpecula, the little fox and is a very easy object in a telescope. It has the nickname, The Dumbbell Nebula, due to its resemblance, observed visually, to a dumbbell weight. M27 is too faint to see with the naked eye and is about 3X fainter than the faintest star visible from a dark site. A planetary nebula usually forms late in the life of a star when it starts to throw off material into space due to the imbalance of the inward pressure of gravity and the outward pressures of nuclear fusion.

M27 is about 8 arcminutes in diameter (or 8 x 60 = 480 arcseconds) and 1/4 the diameter of the full moon. Using spectroscopy to measure the shifting of its spectrum due to doppler effect, the rate of expansion is about 2.3 arcseconds per century; it is therefore about 6 arcseconds larger and slightly fainter than at its discovery. Using these values, the computed age of the explosion that caused M27 is half the diameter of the 480 arcseconds width divided by 2.3 arc seconds per century or 240 ÷ 2.3 which is about 100 centuries or 10,000 years ago. Simple math!

Hover over the image above to see annotations for the nebula, its outer shell, and the central white dwarf star. Hover over the image below to see the object without stars, a feature enabled by PixInsight!

The central star is visible even visually through a small telescope. It is a white dwarf and is what remains from the original star that blew off the bright gas 10,000 years ago. M27’s white dwarf star is half the mass of our sun but only 5.5% its size making it very dense indeed. This is due to the force of gravity overcoming any continued nuclear fusion. The central dwarf star has a visual magnitude of 13.9, or about 1500 times fainter than the faintest star visible from a dark site.

M27 has two alternate names: Henize 2-452, PNG 60.8-3.6. Its remainin stats are Type: Planetary Nebula, RA: 19h 59m 36.1s, Dec: +22° 43' 13", Magnitude: 7.5, Size: 8', Magnitude of Central Star: 13.9.