Astrophoto: The Crescent Nebula by Nicolas Outters
Written by R. Jay Gabany
Nothing lasts forever. Even the stars in space have a beginning and an end. The length of time that a star shines is based on the amount of material and energy it contains which is also referred to as its mass. Stars shine by changing its lightest material into something heavier. This initially begins by converting hydrogen into helium through a process called nuclear fusion. It also releases massive amounts of energy which we see as (sun or) star light. But every star has a finite amount of hydrogen and once it is depleted the star's fate is based on the mass of what it still possesses.
For over five billion years, our Sun has maintained an equilibrium between the weight of its material falling inward and the outward push of the nuclear fusion at its interior. Every second of every day since it first started shining, four hundred million tons of hydrogen has been converted into helium in a continuous, self-contained hydrogen bomb explosion of unbelievable proportions. Thankfully, it's located about 95 million miles away at the center of our solar system.
But this can't go on forever, either in our Sun or any other that twinkles in the heavens. Eventually, the hydrogen becomes exhausted and the location where fusion takes place will start to move outward from the star's center. All the helium that has been manufactured will become the new fuel for ongoing nuclear reactions as the star next converts it into heavier elements like carbon and oxygen. Stars that are many times more massive than the Sun can eventually produce so much heavy material that the exterior of the star becomes cooled and huge solar winds begin to blow it into surrounding space where it forms a wraith-like shell or nebula. This usually begins to happen in the later stages of the star's existence and is a foreshadow of the star's eventual cataclysmic destruction.
The image that accompanies this article is of a place in space about 5,000 light years from Earth towards the northern constellation Cygnus. The colors in this image are not as they would actually appear to our eyes, however. They show what this area looks like based on what the scene is made of through a process called color mapping. Mapped color pictures are created by placing special dark filters in front of the camera. Each filter has been tuned to only let the light from one element pass to the imaging chip. In this picture red was used to color the presence of hydrogen, green was selected to give oxygen its own tint and blue was assigned as the hue for sulfur. This is one way that astronomers can understand what something is made of even though it is very far away and in the distant past.
The bright, compact and waffled-looking area near the middle of this image is called the Crescent Nebula. It was produced about 250,000 years ago by the stellar winds blowing material off the surface of the bright star near its center (please be sure to take a look at the larger image for a better view). These winds and the star matter they carried eventually collided with a shell blown off it's surface at some earlier period. As new and old material mixed in the blowing wind, denser pockets of matter were formed thus giving this nebula its complex appearance. The star that is responsible is in the last part of its existence and because is about 20 times more massive than our Sun, it will, some day, end in an titanic explosion called a supernova.
This amazing image was produced by Nicolas Outters from his private imaging location called the Orange Observatory, located near Geneva, Switzerland at an altitude of 1068 meters. Nicolas produced this picture with a four inch wide-angle telescope. His total exposure time, from June 4 through June 12, 2006 was almost 25 hours!
Do you have photos you'd like to share? Post them to the Universe Today astrophotography forum or email them, and we might feature one in Universe Today.
Written by R. Jay GaBany
Filed under: Astrophotos
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