Looking Up: A puff of color in the depths of space
Astrophotographer Ted Wolfe has successfully moved his telescope from Naples to the Atacama Desert in northern Chile. The entire set-up is now operated from here in the U.S., but the scope itself is in Chile. His pictures of colliding galaxies, dying stars, supernovas, glowing nebulas, etc., are published in the leading national magazines in the field of astronomy. Exhibits of his pictures have appeared in numerous science museums, universities and institutions — including a 20-month show featuring a large number of his images at the Kennedy Space Center. A full collection of his pictures are on permanent display at the Center for Space Studies at the University of Florida.
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Welcome to a very colorful place where new stars are being born to populate our galaxy. Such regions, found here and there throughout the Milky Way, are the essential life blood that promotes a galaxy's vigor and longevity.
This one is called the "Trifid Nebula" or officially, M20. This is yet another outstanding subject found in the star-rich fields of the constellation Sagittarius, toward the center of the Milky Way.
The name "Trifid" means "divided into three lobes." This refers to the prominent sections in the pink nebula, which appear as three separate entities in a telescope. However, in astrophotos, as can be seen here, the dark lanes appear to carve out four distinct sections.
Due to its brightness, at magnitude 6.3, the Trifid has long been a favorite target for amateur astronomers with telescopes or binoculars. In fact, the whole of Sagittarius, which resembles a teacup in appearance, is worthy of slow sweeping with binoculars or a small telescope on a dark summer night.
M20 was discovered by the redoubtable Charles Messier on the night of June 5, 1764, as he searched the sky over Paris for comets. There is a lot going on in the region and Messier mentioned the great nebula itself only in passing, as an "envelope of nebulosity."
The object is particularly appealing from southern latitudes, and the astronomer John Herschel coined the name "Trifid Nebula" when he observed it from his observatory in South Africa in the early 19th century.
It is often difficult to precisely measure the distance to a nebula. The best accepted distance to this one seems to be about 5,200 light years, which means it is not all that far away from us.
What is happening here?
There are pockets (nebulas) of dust mixed with hot gas spotted throughout the galaxy. They are spaced out from each other at large distances forming a kind of patchwork array. Inside these nebulas, small clumps of material undergo temperature drops. This causes the material to condense and contract. Once the contraction reaches a certain point, gravity compresses the center and a nuclear reaction is ignited in response to the pressure.
This is the birth of a star. In fact, many, many stars are born in this fashion throughout the nebula. Different stars have different effects on the surrounding gas and dust. So they light up their birthplace with different colors.
The reason that the top part of the nebula is glowing pink is because there is a clutch of extremely bright "O" type stars packed tightly in the center. In this picture you can see them bunched so tightly that they look like one, bright, very large white star.
This powerful clutch of stars is pouring out a prodigious amount of energy and exciting the atoms in the gas and dust around them (a process know as "ionization"). This causes the main body of the Trifid Nebula to emit energy and glow pink.
Note that the bottom region is blue. This is caused by another type of newly-born star called a class "B" star. They are not powerful enough to ionize their environment, but their blue glow bounces off the tops of the clouds of gas and dust, reflecting the blue color back. Note: The bright, yellow/white star in the center is a foreground star, not part of the nebula.
Lastly, note the dark lanes themselves that are inside the main, pink section of the Trifid. These are made up of very dense dust.
More new stars will be born out of the material in these dark lanes. In fact, NASA's Spitzer Infrared Telescope discovered 120 more newborn stars and 30 embyronic stars in the Trifid Nebula, which can't be seen in visible light images like the one above. They are, for now, buried in the dust.
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Ted is a member of the Everglades Astronomical Society. Organized in 1981 it serves the Naples community, providing information in all aspects of amateur astronomy. Its goals include educating the general public, school children and other groups to the wonders of the universe. The society meets at 7 p.m. every second Tuesday of the month at the Norris Center (public invited). Regular viewing visits to a special, dark sky site in the Everglades are held each month, allowing the general public to observe the night sky through telescopes, under pristine conditions. For more information, visit the website at http://naples.net/clubs/eas. A Blu-ray disc for viewing on TV is now available which features 70 of Ted's deep space images with original background music. For more information, go to www.naples.net/clubs/eas/sales.html.