Southern Pinwheel is cosmic cracker


Tonight’s the night that the skies of Britain are filled with fireworks as people celebrate Guy Fawkes’ bid to blow up Parliament in 1605. But for really spectacular fireworks, just look at this cracker of an image from the new camera fitted to the Hubble space telescope.

It shows a myriad of new stars bursting into existence in a cosmic catherine wheel of a spiral galaxy called Messier 83 (M83).

The galaxy is commonly known as the Southern Pinwheel among amateur astronomers and lies 15 million light-years away in the constellation of Hydra, the water snake.

Star birth is happening at a faster rate in M83 than in our own Milky Way galaxy, particularly in its heart. Hubble’s new instrument, the Wide Field Camera 3 fitted by shuttle astronauts in May, reveals hundreds of young star clusters, ancient swarms of globular star clusters, plus hundreds of thousands of individual stars, mainly blue supergiants and red supergiants.

The camera views the universe in a wide range of wavelengths, from ultraviolet to near-infrared, revealing stars at different stages of their life. It shows that the newest generations of stars are forming largely in clusters on the edges of dark lanes of dust in the spiral arms. Only a few million years old, these young stars stand out as bubbles of brightly glowing reddish hydrogen gas.

The young stars’ fierce winds of charged particles eventually blow away the gas, revealing bright blue star clusters aged from about one million to 10 million years. Older-still populations of stars are not as blue.

A bar of stars, gas, and dust can be seen slicing across the core of the galaxy and may be provoking most of the star birth in the galaxy’s core, say astronomers. Also visible are the remains of about 60 supernova blasts – five times more than were known to exist.


Related Posts