Thursday, November 09, 2006

Orion the Hunter


What's up with Orion, now very clear in the western sky around 5:00-6:ooam? I got a good look at Betelgeuse , (60,000 times brighter than our sun! One of two first magnitude Super-Giants) this morning in the upper left of the constellation- (Orion's right shoulder) But there's something more and it's on Orion's Sword!

Orion (the Hunter) climbs the sky. Orion's belt, Mintaka at right, Alnilam in the center, and Alnitak at left, runs through the middle of the picture. Betelgeuse is the bright reddish star at upper left, Rigel the bright star at lower right, Bellatrix the star to the right of center above the belt. Saiph is centered near the lower edge of the picture below the belt. Orion's head is marked by the trio of stars at the top of the picture just left of center, the brightest of which is Meissa. The the red glow in the middle of Orion's Sword is the Orion Nebula, which is lit by Theta-1 Ori.
The pink circle in the image is of a star with two circling planets.


The Orion Nebula, which appears to surround the central star in
Orion's Sword , is a vast cloud of interstellar gas and dust some
20 light years across that is lit by a quartet of hot stars (the Trapezium) at its apparent center. Some 1500 light years away, the Trapezium and Nebula lie in front of a cold, dusty "giant molecular cloud" that hosts regions of intense star formation. The stars of the Trapezium electrify a blister on the front edge of the molecular cloud, which makes it glow.

More technically, energetic ultraviolet starlight (most of which
comes from Theta-1 Orionis C) ionizes a portion of the molecular
cloud, that is, it strips electrons from the nebula's atoms, which
are mostly hydrogen. When the charged ions recapture the free electrons, the energy is given back up as (in part) optical light in the form of emission lines.

This image of the Orion nebula, taken by NASA's Spitzer and Hubble Space Telescopes and released November 7, 2006, shows an infrared and visible-light composite that indicates that a 'gang' of four monstrously massive stars at the center of the
cloud may be the main culprits of mayhem in the
familiar Orion constellation. The stars are collectively
called the 'Trapezium' and can be communally identified
as the yellow smudge near the center of the
image. Swirls of green in Hubble's ultraviolet and
visible-light view reveal hydrogen and sulfur gas that have been heated and ionized by intense ultraviolet radiation from the Trapezium's stars.

Great stuff in the Cosmos!

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