by Ann » Thu Jul 25, 2013 6:21 am
The Trifid is a glorious nebula which looks great in almost all RGB images. Today's picture is certainly splendid.
The Trifid nebula can actually be compared with the Orion Nebula in that it has its own
"Trapezium cluster". The Trifid, like the Orion Nebula, is powered by a small, tight group of central stars. As is the case in the Orion Nebula, one star alone is so hot and bright that it does most of the ionizing of the nebula all of its own. The
Theta-1 C Orionis of the Trifid Nebula is called HD 164492.
The Trifid consists of a red emission nebula surrounded by a blue reflection nebula. This seems unusual, but the unusual thing about the Trifid is probably just that its surrounding reflection nebula is so bright and obvious.
The Cocoon nebula is interestingly similar to the Trifid Nebula, even though it is almost certainly smaller and less powerful. But like the Trifid, it is powered by one star alone, and like the Trifid, it consists of a red emission nebula surrounded by a blue reflection nebula.
I have been wondering about the yellow star which appears to be a contributing source to the blue reflection nebula of the Trifid. The star is an F-type star, HD 164514, but that is about all I know about it, since it never had its parallax measured by the Hipparcos satellite. In many pictures it looks "untouched" by the reflection nebula surrounding it, as if it was a foreground object. But in R. Jay Gabany's picture to the right, it appears to add its yellowish light to a patch of the red emission nebula. The same effect can be seen, although faintly, in today's APOD.
Ann
The Trifid is a glorious nebula which looks great in almost all RGB images. Today's picture is certainly splendid.
The Trifid nebula can actually be compared with the Orion Nebula in that it has its own [url=http://apod.nasa.gov/apod/ap040618.html]"Trapezium cluster".[/url] The Trifid, like the Orion Nebula, is powered by a small, tight group of central stars. As is the case in the Orion Nebula, one star alone is so hot and bright that it does most of the ionizing of the nebula all of its own. The [url=http://upload.wikimedia.org/wikipedia/commons/thumb/7/75/TrapeziumStars.jpg/250px-TrapeziumStars.jpg]Theta-1 C Orionis[/url] of the Trifid Nebula is called HD 164492.
The Trifid consists of a red emission nebula surrounded by a blue reflection nebula. This seems unusual, but the unusual thing about the Trifid is probably just that its surrounding reflection nebula is so bright and obvious.
[float=left][img2]http://i.dailymail.co.uk/i/pix/2009/03/08/article-1160237-03C83698000005DC-879_468x286.jpg[/img2][c][size=85]Photo: Neil Fleming[/size][/c][/float] The Cocoon nebula is interestingly similar to the Trifid Nebula, even though it is almost certainly smaller and less powerful. But like the Trifid, it is powered by one star alone, and like the Trifid, it consists of a red emission nebula surrounded by a blue reflection nebula.
[float=right][img2]https://sphotos-a.xx.fbcdn.net/hphotos-frc3/s720x720/226855_215208475291478_934141544_n.jpg[/img2][c][size=85]Photo: R. Jay GaBany[/size][/c][/float] I have been wondering about the yellow star which appears to be a contributing source to the blue reflection nebula of the Trifid. The star is an F-type star, HD 164514, but that is about all I know about it, since it never had its parallax measured by the Hipparcos satellite. In many pictures it looks "untouched" by the reflection nebula surrounding it, as if it was a foreground object. But in R. Jay Gabany's picture to the right, it appears to add its yellowish light to a patch of the red emission nebula. The same effect can be seen, although faintly, in today's APOD.
Ann