Herschel space telescope pierces giant star bubble

A colossal star many times the mass of our own Sun is seen growing in a bubble of excited gas just pictured by the Herschel space observatory.

The image of the bubble, known as RCW 120, has been released a few days ahead of the European telescope's first birthday in orbit.

Herschel's infrared detectors are tuned to see the cold materials that give birth to stars.

Pictures like RCW 120 will help explain how really giant ones are made.

The monster in this picture is seen as the small white blob on the bottom edge of the bubble.

The "baby" star is perhaps a few tens of thousands of years old and has yet to ignite the nuclear furnace that will form at its core. But it is some eight to 10 times the mass of our Sun and is surrounded by about 200 times as much material.

If more of that gas and dust continues to fall in on the star, the object has the potential to become one of the Milky Way Galaxy's true giants, and it will go on to have a profound influence on its environment.

"It's the massive stars that control the dynamical and chemical evolution of the galaxy," explained Herschel scientist Dr Annie Zavagno from the Laboratoire d'Astrophysique de Marseille.

THE HERSCHEL SPACE TELESCOPE The telescope is sited over a million km from Earth Its instruments sense far-infrared and sub-millimetre radiation Its 3.5m diameter mirror is the largest ever flown in space Herschel can probe clouds of gas and dust to see stars being born It will investigate how galaxies have evolved through time The mission will end when its helium refrigerant boils off Seeking the cold cosmos

"It's the massive stars that create the heavy elements like iron and they are able to put them in the interstellar medium. And because they end their lives in supernova explosions, they also inject a lot of energy into the galaxy," she told BBC News.

The baby owes its existence to another, unseen star, the radiation from which has sculpted the exquisite shape of the bubble. By pushing away this shroud of gas and dust, it has raised the density of matter in new locations, triggering a fresh round of starbirth.

Present theories of star formation struggle to explain how objects larger than about 10 solar masses can exist. The fierce light they emit should blast away their birth clouds, limiting their growth.

And yet, astronomers know of stars that are 120 times the mass of our Sun.

The unique capabilities of Herschel - it works in the far-infrared and sub-millimetre range (55 to 672 microns) - mean it can see physical processes that are beyond the vision of other telescopes.

Hubble, for example, which senses visible and near-infrared light, is blind to the details in this picture.

Scientists hope Herschel's vision can give them the information they need to correct their models.

The European Space Agency's billion-euro observatory was sent into orbit on an Ariane rocket on 14 May last year.

It is positioned far from Earth to give it an unobstructed view of deep space.

Nasa's Kepler planet-hunter detects five worlds

Nasa's Kepler Space Telescope has detected its first five exoplanets, or planets beyond our Solar System.

The observatory, which was launched last year to find other Earths, made the discoveries in its first few weeks of science operations.

Although the new worlds are all bigger than our Neptune, the US space agency says the haul shows the telescope is working well and is very sensitive.

The exoplanets have been given the names Kepler 4b, 5b, 6b, 7b and 8b.

They were announced at an American Astronomical Society meeting in Washington DC.

The planets range in size from an object that has a radius four times that of Earth, to worlds much bigger than even our Jupiter.

And they all circle very close to their parent stars, following orbits that range from about 3.2 to 4.9 days.

This proximity and the fact that the host stars are themselves much hotter than our Sun means Kepler's new exoplanets experience an intense roasting.

Intriguing density

Estimated temperatures go from about 1,200C to 1,650C (2,200F to 3,000F).

"The planets we found are all hotter than molten lava; they all simply glow with their temperatures," said Bill Borucki, Kepler's lead scientist from Nasa's Ames Research Center in Moffett Field, California.

THE KEPLER SPACE TELESCOPE Will study more than 100,000 suns Continuously for 4 to 6+ years Tuned to see Earth-size planets Will target the habitable zone Will also see Mars to Jupiter sizes

"In fact the upper two are hotter than molten iron and looking at them might be like looking at a blast furnace. They are very bright in their own right and certainly no place to look for life."

Kepler 7b will intrigue many scientists. It is one of the lowest-density exoplanets (about 0.17 grams per cubic centimetre) yet discovered.

"The average density of this planet with its core is about the same as Styrofoam," explained Dr Borucki. "So it's an amazingly light planet, something I'm sure theoreticians will be delighted to look at in terms of trying to understand [its] structure."

Kepler blasted into space atop a Delta II rocket from Cape Canaveral Air Force Station on 6 March, 2009.

It is equipped with the largest camera ever launched into space. The telescope's mission is to continuously and simultaneously observe more than 100,000 stars.

It senses the presence of planets by looking for a tiny "shadowing" effect when one of them passes in front of its parent star.

'Water worlds'

Kepler's detectors, built by UK firm e2v, have extraordinary sensitivity.

Nasa says that if the observatory were to look down at a small town on Earth at night from space, it would be able to detect the dimming of a porch light as somebody passed in front of it.

Artist's impression: Four of the five are bigger than a Jupiter

The space agency hopes this sensitivity will lead it to planets that are not only Earth-size but which orbit their stars at distances more favourable to life, where liquid water might potentially reside on their surfaces.

The mission's scientists told the AAS meeting that Kepler had measured hundreds of possible planet signatures but that these needed further investigation to establish their true nature.

To confirm the existence of the most ideal Earth-like planets would take a few years, they warned.

In the meantime, all detections will help scientists improve their statistics on the distributions of planet size and orbital period.

The follow-up observations needed to confirm the new exoplanets' existence used a suite of ground-based facilities including the Keck I telescope in Hawaii.