(IAAC) [ASTRO] M20 - The Trifid Nebula : the @stro object for the week of 03/13/2000

------- Forwarded Message
From: "Roger Herzler" <rherzler@CTS.COM>
Date: Wed, 15 Mar 2000 09:51:43 -0800
Subject: [ASTRO] M20 - The Trifid Nebula : the @stro object for the week of 
@stro object of the week
drafted by the @stro pages
the week of 03/13/2000
highlighted this week: M20 - The Trifid Nebula
The Trifid Nebula became "M20" in Charles Messier's catalog, but it got its
"Trifid" name when it was viewed by John Herschel who noticed the appearance
of "tri" or three different segments separated by dust lanes. It is also
part of the NGC catalog with a designation of NGC 6514. The estimated
distances to the Trifid vary widely between 2000 and 5200 light-years away.
Emission nebula are nebula that are visible because of radiation from nearby
stars exciting the gas in the nebula. Reflection nebula are nebula that are
visible because they are reflecting the light of nearby stars. The Trifid
Nebula is consists of both emission and reflection nebulae. The red areas
visible in the image are the emission nebula portion and are powered by a
bright triple star system named CC24537. The blue areas are visible as a
result of light reflected from a nearby O-Type star.
On a night of excellent seeing and dark skies the Trifid Nebula is reputed
to be visible to the naked eye, but it will surely show up in modest sized
telescope. Right now is the best time of year to undertake the "Messier
Marathon", which is a marathon to locate and observe all of the objects in
Messier's catalog. For more on the marathon check out the SEDS Messier
Marathon webpage.
Current information for M20 (North America):
Rise: 1h 48m 57s
Set: 6h 31m 57s
R.A.: 18:02
Dec.: -23:02
Magnitude: 6.3
Constellation: Sagittarius
more info from SEDS on the Trifid Nebula...
more info from Bill Arnett's site...
more info on the Messier Marathon...
Image of the Trifid Nebula:
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