Free Astronomy Magazine January-February 2022

20 JANUARY-FEBRUARY 2022 ASTRO PUBLISHING Stars in that phase of life eject huge amounts of gas and dust outwards into space, eventually jettisoning their outer layers. In the case of the carbon star CW Leonis, this process has surrounded the star with a dense pall of sooty dust. As the closest carbon star to Earth, CW Leonis gives astronomers the chance to understand the interac- tion between the star and its sur- rounding envelope. This is a particularly interesting ob- ject to study as the envelope of CW CW Leonis glowers from deep within a thick shroud of dust in this image from the NASA/ESA Hub- ble Space Telescope. Lying roughly 400 light-years from Earth in the constellation Leo, CW LEonis is a car- bon star — a luminous type of red giant star with a carbon-rich atmos- phere. The dense clouds of sooty gas and dust engulfing this dying star were created as the outer layers of CW Leonis itself were thrown out into the void. When small to intermediate-mass stars run out of hydrogen fuel in their cores, the outwards pressure that balances the crush of gravity within their cores falls out of equi- librium, causing the star to start col- lapsing. As the core collapses, the shell of plasma surrounding the core becomes hot enough to begin fus- ing hydrogen, generating enough heat to dramatically expand the outer layers of the star and turn it into a bloated red giant. A striking observation of the carbon star CW Leonis by NASA/ESA Bethany Downer