The constellation of the Giraffe is a large region that extends between the north star and the constellation Auriga, it is visible all year from the northern hemisphere. It contains no remarkable star, but Hubble has noticed. Hubble saw a giant bubble emitted by a star at end of life.
U Cam is the star.
When the stars lack of fuel, they become unstable.
U Cam expels every few thousand years, a nearly spherical shell of gas.
When a helium layer of the core begins to fuse, it ejects into space a tenuous envelope of gas.
The gas ejected in the eruption of the star is clearly visible in this Hubble telescope image.
A light 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 the low surface gravity of such stars, the powerful stellar winds sweep regularly atmospheres of carbon and oxygen. These stars can lose, every cough, half of their mass, blown by winds of their own.
U Cam is located in the constellation of the Giraffe (Camelopardalis), near the north celestial pole.
It is visible in this scene, or rather, it was his brilliance that we see, U Cam is actually much smaller than it looks on the Hubble image. If it is represented here, it would occupy one small pixel in the center of the image.
But its brightness is sufficient to saturate the receptor Advanced Camera for Surveys Hubble, making the star much larger than it is.
However the gas shell, which is both much larger and much lower than its parent star, is visible in every detail. These phenomena that occur in dying stars, are often highly irregular and unstable, but the shell of gas expelled from U Cam is almost perfectly spherical.
Scientists call these events supernova explosions impostor, because they seem similar to supernovae, but they stop just before you completely destroy their star. Image credit: ESA / Hubble, NASA and H. Olofsson (Onsala Space Observatory).
| || |
Image: Camelopardalis U, or U Cam is a star at the end of his life. it starts to run out of fuel, unstable, it ejects into space a tenuous envelope of gas.
Telescope image NASA / ESA Hubble Space.