Herschel highlights hidden stars

One year ago, ESA’s Herschel space observatory was launched on a mission to explore the infrared Universe. Now safely orbiting about 1.5 million km from Earth, Herschel is beginning to reveal previously hidden details of star formation. New images show thousands of distant galaxies furiously building stars and beautiful, star-forming clouds scattered across the Milky Way.

Herschel is the largest astronomical observatory ever to be placed into space, with a main mirror four times wider than any previous infrared space telescope. This enables it to study the cold, star-forming clouds of our Galaxy in greater detail than ever before. One of these regions, known as RCW 120, contains a newly born star which looks set to become a supergiant within the next few hundred thousand years.

Already 8 to 10 times heavier than the Sun, the infant is surrounded by a huge cloud of gas and dust on which it can feed and grow. Scientists don’t understand how stars swell to 150 solar masses, so RCW 120 will be watched carefully to see how such supergiants form.

Another new Herschel image shows how material in the Milky Way comes together to form stars. The ‘seeds’ first appear inside streamers of glowing dust and gas, forming chains of stellar nurseries, tens of light years long. Beyond our Milky Way, Herschel has measured infrared light from thousands of other galaxies, spread across billions of light years.

By studying the brightness of these pinpricks of light, it has shown that stars were forming 10-15 times faster in the past than they are today. Herschel has also detected matter that does not occur naturally on Earth - water molecules that have been split by powerful radiation and given an electric charge.