Astronomy Now Online
Home Magazine Resources Store

Top Stories

MESSENGER reveals more of Mercury’s secrets

...the MESSENGER spacecraft successfully completed its second flyby of Mercury, unveiling another 30 percent of the planet’s surface...

read more

Evolving galaxies shed gas and fireballs

...astronomers studying the Coma Cluster of galaxies have discovered that galactic collisions are powerful enough to strip a galaxy of its gas and fling star-forming fireballs out into space...

read more

Small asteroid burns up in Earth’s atmosphere

...according to predictions, a three metre wide asteroid exploded in the Earth’s atmosphere at 0246 UT above northern Sudan on Tuesday...

read more

Spaceflight Now +

Subscribe to Spaceflight Now Plus for access to our extensive video collections!
How do I sign up?
Video archive

STS-120 day 2 highlights

Flight Day 2 of Discovery's mission focused on heat shield inspections. This movie shows the day's highlights.


STS-120 day 1 highlights

The highlights from shuttle Discovery's launch day are packaged into this movie.


STS-118: Highlights

The STS-118 crew, including Barbara Morgan, narrates its mission highlights film and answers questions in this post-flight presentation.

 Full presentation
 Mission film

STS-120: Rollout to pad

Space shuttle Discovery rolls out of the Vehicle Assembly Building and travels to launch pad 39A for its STS-120 mission.


Dawn leaves Earth

NASA's Dawn space probe launches aboard a Delta 2-Heavy rocket from Cape Canaveral to explore two worlds in the asteroid belt.

 Full coverage

Dawn: Launch preview

These briefings preview the launch and science objectives of NASA's Dawn asteroid orbiter.

 Launch | Science

Become a subscriber
More video

A multi-wavelength portrait of stellar birth

Posted: October 09, 2008

By combining observations at different wavelengths from telescopes on the ground and in space, astronomers have taken a fresh look at the history of star formation in a galaxy residing in the Small Magellanic Cloud.

NGC 346 is the brightest star forming region in the Small Magellanic Cloud, an irregular dwarf galaxy that orbits the Milky Way at a distance of 210,000 light years. "NGC 346 is a real astronomical zoo," says Dimitrios Gouliermis of the Max Planck Institute for Astronomy in Heidelberg, Germany. "When we combined data at various wavelengths, we were able to tease apart what's going on in different parts of this intriguing region."

This colourful portrait of NGC 346 shows that stellar formation is triggered by both wind and radiation from massive stars. Radiation triggered star formation has occurred in the centre of the image, with compressed material visible as the arc-shaped red-orange filament. Wind triggered formation is at play in the isolated pink blob at the top of the image and to the right of the stellar 'bubble' surrounding the bright white stars. Image: NASA/JPL-Caltech/ESA/ESO/MPIA.

The colourful portrait was made by combining infrared, visible and X-ray light from NASA's Spitzer Space Telescope, ESO's New Technology Telescope (NTT) and the European Space Agency's XMM-Newton orbiting X-ray telescope, respectively. The visible-light images allowed astronomers to resolve glowing gas while the multi-wavelength image reveals new insights into the mechanisms of stellar formation.

The image reveals that small stars are scattered throughout the whole of NGC 346, with the most massive stars residing in its centre. It is thought that these massive stars and most of the small ones formed at the same time out of one dense cloud, while other less massive stars were created later through a process called ‘triggered star formation’. This results from intense radiation from massive stars that eat away at the surrounding dusty cloud, triggering the expansion of gas and creating shock waves that compress nearby dust and gas into new stars, in this case within the region bound by red-orange filaments in the centre of the image.

But another set of younger low-mass stars in the region, seen as a pinkish blob at the top of the image, cannot be explained by this mechanism. "We were particularly interested to know what caused this seemingly isolated group of stars to form," says Gouliermis. The multi-wavelength data holds the answer: the trigger was a very massive star that blasted apart in a supernova explosion about 50,000 years ago. But instead of radiation, fierce winds from the dying star slammed the gas and dust together, forcing the creation of new stars.

While the remains of this massive star cannot be seen in the image, a ghostly reminder can be seen as a bubble surrounding the large white spot (which is actually a trilogy of stars) with a blue halo in the upper left of the image.

The finding demonstrates that both wind- and radiation-induced triggered star formation are at play in the same cloud, showing astronomers that stellar nurseries are far more complicated than originally thought, and comprising different competitive or collaborative mechanisms.

The Planets
From tiny Mercury to distant Neptune and Pluto, The Planets profiles each of the Solar System's members in depth, featuring the latest imagery from space missions. The tallest mountains, the deepest canyons, the strongest winds, raging atmospheric storms, terrain studded with craters and vast worlds of ice are just some of the sights you'll see on this 100-page tour of the planets.

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.

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!


© 2014 Pole Star Publications Ltd.