Hubble Sees Red Giant Blow a Bubble
Camelopardalis,
or U Cam for short, is a star nearing the end of its life. As stars run
low on fuel, they become unstable. Every few thousand years, U Cam
coughs out a nearly spherical shell of gas as a layer of helium around
its core begins to fuse. The gas ejected in the star’s latest eruption
is clearly visible in this picture as a faint bubble of gas surrounding
the star.
U Cam is an example of a carbon star, a rare type of
star with an atmosphere that contains more carbon than oxygen. Due to
its low surface gravity, typically as much as half of the total mass of a
carbon star may be lost by way of powerful stellar winds. Located in
the constellation of Camelopardalis (The Giraffe), near the North
Celestial Pole, U Cam itself is much smaller than it appears in this
Hubble image. In fact, the star would easily fit within a single pixel
at the center of the image. Its brightness, however, is enough to
saturate the camera's receptors, making the star look much larger than
it is.
The shell of gas, which is both much larger and much
fainter than its parent star, is visible in intricate detail in Hubble’s
portrait. This phenomenon is often quite irregular and unstable, but
the shell of gas expelled from U Cam is almost perfectly spherical.
Image Credit: ESA/NASA
NASA
Guillermo Gonzalo Sánchez Achutegui
ayabaca@gmail.com
ayabaca@hotmail.com
ayabaca@yahoo.com
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