Best of AOP - Star Clusters


Spilled salt. This is what M14 resembles through a moderate sized telescope under dark skies. This particular cluster is not quite as concentrated in density towards its center. Some clusters such as M15 have a very tight central region.

What is truly interesting about M14 is that this jumble of stars actually helped astronomers put the pieces of a puzzle together. One of the central stars here is very special. It is called a "CH star" because its atmosphere has carbon-hydrogen molecules. Everything heavier than hydrogen, helium, and lithium is basically created in the centers of stars through nuclear fusion or as a by-product of supernovae explosions- the ultimate stellar crucible. Generally small stars do not reveal what heavy elements are contained in their cores until they dredge up these materials near the ends of their lives (and later expel them in the form of a planetary nebula). However this star shown below is not old enough to have done this! Thus astronomers wondered why should CH stars have carbon in their atmospheres?

An answer was soon found when astronomers discovered that all CH stars are part of a binary system. One of the stars, near the end of its life, dredges up its stellar ashes of nuclear fusion and proceeds to expel it into space. Much of this material is dumped onto the other companion. So, although too young to have carbon this companion gets a good helping from its dying friend.

What is so special about finding a CH (binary) star in M14 (or any globular cluster) is that these stars are first generation stars of our universe. There are very few planetary nebulae to be found in globular clusters, so studying the nuclear products of these stars has been difficult. But here, using this CH star astronomers can directly examine the make up of one of these stars by examine the atmosphere of the other!

Star map is navigable within this page.

Last Updated: 25-Jun-2014

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About This Image

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20in RC Optical Systems telescope Operating at f/8.1

Paramount ME Robotic Telescope Mount

SBIG ST10XME CCD camera with color filter wheel

LRGB color production was used to create this image.

Data taken through thin clouds. Due to the clouds the color balance shown here is not exactly by the numbers. I

tried to compensate for the clouds and this is my best guess.

Two iterations of L-R deconvolution (sharpening) algorithm using CCDsharp were applied to the luminance image.

Digital Development (DDP) via Maxim/DL was also used in order to display the very dim and very bright details of

the image simultaneously.

Luminance = 25 minutes binned 1x1

Red = 20 minutes binned 2x2

Green = 20 minutes binned 2x2

Blue = 20 minutes binned 2x2

Minimum credit line: Adam Block/NOAO/AURA/NSF