Trifid Nebula, Star Factory

The Trifid Nebula is one of the most popular objects to be viewed and photographed by amateurs like me, but if you are in mid North America you have to be quick, it isn’t up for long. In mid-August it doesn’t get fully dark where my observatory is in Torrey, Utah until 10 PM. At that time the nebula is due south, right at the meridian, and at its highest point in the sky for the night at a low 26 degrees altitude (90 degrees is straight up). Boulder Mountain is south of Torrey and it is as dark as it gets in that direction, so it is a good place and time to photograph the object. But by 1 AM the Trifid is getting below 20 degrees altitude, getting close to the mountain and running into too much atmospheric interference near the horizon. The trick is to get some moonless, cloudless nights at these few critical hours. Mid-August worked out this year.

Deep-sky object, Trifid Nebula
Trifid Nebula in Sagittarius, HαRGB, August 2020
Sky plot
Just above the “teapot,” the field radius of the attached image = 0.5 degrees

In truly dark skies the Trifid can be seen with the naked eye. I have read of professional astronomers who live further north in skies with more light pollution who say that they have never seen it. To them it is too low in the south and lost in the haze of the horizon. But from Torrey on a moonless night and after full astronomical dark, it is easy enough to spot. The teapot asterism of Sagittarius is just below it. The “steam” of the Milky Way rises out of the teapot’s spout but just far enough to the east so that the Trifid stands out in contrast to a darker sky. Telescopes and cameras are a lot of fun, but in some ways they are cheating, Seeing an object free of technology is always compelling.

The Trifid Nebula was first observed and recorded by Europeans around 1747. Messier, the comet hunter, catalogued it as M20 in June of 1764. John Herschel, the great astronomer Sir William Herschel’s son, was the first to call it the “Trifid” describing it as ” . . . consisting of 3 bright and irregularly formed nebulous masses, graduating away insensibly externally, but coming up to a great intensity of light at their interior edges where they enclose and surround a sort of 3-forked rift or vacant area, abruptly and uncouthly crooked and quite void of nebulous light . . . A beautiful triple star is situated precisely on the edge of one of these nebulous masses just where the interior vacancy forks into two channels.” Remember this is 150 years before the invention of film and camera and all done by eye through a hand run telescope. I am a little jealous of that. In my image you can see a distorted looking large star at the center of the red part of the nebula that is the triple star.

When looking at the Trifid one is looking toward the center of the Milky Way and viewing one of the richest parts of the celestial sphere. Messier catalogued more objects here than anywhere else. There are open clusters, globular clusters, star clouds and numerous nebula like the Trifid and nearby Lagoon Nebula (M8). The Trifid and Lagoon are about the same distance from earth, around 4,100 light years, and may be related immense clouds of gas. The Trifid is another triple in that it is an emission nebula which is ionized hydrogen gas creating the red colors, a reflection nebula, which is the blue colors lit up by the bright, young, big blue stars in the nebula, and a dark nebula which makes up the three dark lanes in the brightest red region. These bright blue stars were, in astronomical time, recently formed by the gasses surrounding them and the region continues to operate as a star factory.

You can see the astrophotography details below a larger version of this image by clicking the picture above or here.

-Mark Bailey

7 thoughts on “Trifid Nebula, Star Factory

  1. Ggreybeard

    A lovely image of M20 and thanks for all the information.

    Regarding that triple star, my own images are inconclusive, but one source I rely on indicates that it is a “Sextuple star”, with each of the three stars being a double. I’m not sure if that is verified elsewhere. 🙂

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    1. Mark Bailey Post author

      Sextuple, interesting! A triple double. I wasn’t sure if it was conclusive whether it was a double or triple. The mystery deepens. Have you looked by eye? 🤔

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  2. Mark Bailey Post author

    Aha. I used Burnhams to get the history I quoted. I didn’t notice he said he saw 6 stars with a 36″ at Lick. I can’t quite figure out how to read the table there. What do A-F refer to?

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