NASA's Spitzer Space Telescope may have uncovered the youngest pair of brown dwarfs ever seen, a discovery that could help solve the mystery of how these cosmic misfits are formed.

Brown dwarfs fall between planets and stars in terms of their temperature and mass; they are cooler and more lightweight than stars but more massive and warmer than planets. Answering the question of 'do brown dwarfs form like planets or like stars?' is one that is much debated by astronomers. Often called failed stars because they are unable to trigger nuclear fusion in their cores, they are difficult to detect because they are much less luminous then their fully fledged stellar counterparts. To complicate matters further, they also evolve relatively rapidly, making it difficult to capture them in the first throes of youth when they heat up the nearby gas and dust.

By using Spitzer’s heat-sensitive infrared vision, an international team of astronomers found a so-called “proto-brown dwarf” while it was still cocooned in its natal star-forming region in the dark cloud Barnard 213. “We decided to go several steps back in the process when brown dwarfs are really hidden,” says David Barrado of the Centro de Astrobiologia in Madrid. “During this step they would have an opaque envelope, a cocoon, and they would be easier to identify due to their strong infrared excesses. We have used this property to identify them. This is where Spitzer plays an important role because Spitzer can have a look inside these clouds. Without it this wouldn’t have been possible.”

Spitzer’s longer-wavelength infrared camera penetrated the dusty star-forming cloud to observe a baby brown dwarf named SSTB213 J041757. The observation was confirmed with near-infrared imaging from the Calar Alto Observatory in Spain, which revealed not one, but two faint, cool brown dwarfs.

Ploughing through archived data and following up with telescopic measurements from around the world yielded more information about the dusty cocoon in which the proto-brown dwarfs are embedded, enabling the astronomers to build up a picture of the conditions prevailing inside the cloud.

“We were able to estimate that these two objects are the faintest and coolest discovered so far,” says Barrado. The findings potentially solve the mystery about whether brown dwarfs form more like stars or planets. The authors conclude that they form like low-mass stars, the evidence based on their observations of the change in brightness of the objects at various wavelengths that matches that of other very young, low-mass stars.

While further study will confirm whether these two celestial objects are in fact proto brown dwarfs, they are the best candidates so far. “It is a story that has been unfolding piece by piece,” says Barrado. ”Sometimes nature takes its time to give up its secrets.”

The observations were made before Spitzer ran out of its liquid coolant in May 2009, and were backed up with data from the Caltech Submillimeter Observatory in Hawaii, the Calar Alto Observatory in Spain, the Very Large Telescope in Chile and the Very Large Array in New Mexico. Decade-old data was also pulled from the Canadian Astronomy Data Centre archives to provide measurements of how the two objects are moving in the sky. The full details of the study are presented in a paper by Barrado et al in the Astronomy & Astrophysics journal.

Our latest 132-page Astronomy Now special edition is an extravaganza of astronomy for the year ahead, with a complete 30-page guide to observing the planets, moon, meteor showers, two solar eclipses, and the deep sky in 2010.
 U.K. STORE
 E.U. STORE
 U.S. & WORLDWIDE STORE

Hubble Reborn
Hubble Reborn takes the reader on a journey through the Universe with spectacular full-colour pictures of galaxies, nebulae, planets and stars as seen through Hubble's eyes, along the way telling the dramatic story of the space telescope, including interviews with key scientists and astronauts.
 U.K. STORE
 E.U. STORE
 U.S. & WORLDWIDE STORE

3D Universe
Witness the most awesome sights of the Universe as they were meant to be seen in this 100-page extravaganza of planets, galaxies and star-scapes, all in 3D!
 U.K. STORE
 E.U. STORE
 U.S. & WORLDWIDE STORE

This special publication features the photography of British astro-imager Nik Szymanek and covers a range of photographic methods from basic to advanced. Beautiful pictures of the night sky can be obtained with a simple camera and tripod before tackling more difficult projects, such as guided astrophotography through the telescope and CCD imaging.
 U.K. STORE
 E.U. STORE
 U.S. & WORLDWIDE STORE

Explore the Universe with these new versions of the award-winning Starry Night Software. Available now from the Astronomy Now Store.
 U.K. STORE
 E.U. STORE
 U.S. & WORLDWIDE STORE

Astronomy Now is pleased to announce the publication of Exploring Mars. The very best images of Mars taken by orbiting spacecraft and NASA's Spirit and Opportunity rovers fill up the 98 glossy pages of this special edition!
 U.K. STORE
 E.U. STORE
 U.S. & WORLDWIDE STORE

This new poster features some of the best pictures from NASA's amazing Mars Exploration Rovers Spirit and Opportunity.
 U.K. STORE
 E.U. STORE
 U.S. & WORLDWIDE STORE