Astronomy Now Home
Home Magazine Resources Store

On Sale Now!

The October 2014 issue of Astronomy Now is on sale! Order direct from our store (free 1st class post & to UK addresses). Astronomy Now is the only astronomy magazine specially designed to be read on tablets and phones. Download the app from Google Play Store or the Apple App Store.

Top Stories

Earthshine used to test life detection method
...By imagining the Earth as an exoplanet, scientists observing our planet's reflected light on the Moon with ESO's Very Large Telescope have demonstrated a way to detect life on other worlds...

Solid buckyballs discovered in space
...Astronomers using NASA’s Spitzer Space Telescope have detected a particular type of molecule, given the nickname “buckyball”, in a solid form for the first time...

Steamy water-world gets the Hubble treatment
...Hubble Space Telescope observations of a 7 Earth-mass planet find an unusual water-rich world swathed in a thick, steamy atmosphere...

Are heavyweight stars
born like our Sun?

Posted: 29 January 2010

Bookmark and Share

Obscured by dust, catching the rapid formation of massive stars in the act is nigh on impossible, but new Gemini observations hint that these stellar heavyweights may be born in a similar way to lightweights like our Sun.

“The problem is that when the most massive stars form it happens very quickly compared to stars like our Sun, and by the time they break free of their natal clouds they are already the finished article,” says Ben Davies of the University of Leeds, UK, and the Rochester Institute of Technology. “If you want to see a massive star in the process of forming, you need to be able to see through the obscuring clouds to where the action is.”

Artist’s conception of W33A showing the accretion disc (yellow/orange), torus (dark ring around disc) and bi-polar outflow jets (blue) within the dense clouds of its stellar nursery. Image: Gemini Observatory, artwork by Lynette Cook.

Existing theories for massive star formation include scaled-up versions of low mass star formation, or a completely different physical process altogether. Now, new observations that combine adaptive optics – which removes the blur of the Earth's atmosphere – with sensitive infrared spectroscopic observations afforded by the Near-Infrared Integral Field Spectrograph (NIFS) on the Frederick C. Gillett Gemini North telescope on Hawaii’s Mauna Kea, have allowed astronomers to penetrate the thick dust clouds surrounding massive protostar W33A that lies12,000 light-years away toward the constellation of Sagittarius.

“While the optical light is attenuated by about a factor of 10,000, [meaning it is completely obscured in optical light as seen by the human eye] much of the infrared light can pass through the intervening material. This affords us a glimpse of what is happening deep inside W33A’s natal cloud,” says Davies. “We were not only able to resolve the inner nebula on small spatial scales, but also probe its dynamics by measuring the Doppler-shift of light from the glowing gas to determine its velocity and how it flows around the forming star. This is an amazingly powerful tool for understanding the inner workings of how stars actually form.”

Team member Melvin Hoare, also of the University of Leeds, adds that what they saw was “reassuringly familiar, like nice cup of tea!”

The proto-star is already ten times more massive than our Sun, and is rapidly putting on weight. The observations also hint at an accretion disc embedded within a torus of gas and dust, and the astronomers see material being blasted away from the forming star's poles at speeds of up to 300 kilometres per second. “These features are all common to the formation process found in much smaller stars,” states Davies.

Previous studies of W33A – nicknamed a Massive Young Stellar Object – only hinted at its dynamic nature, and the level of detail offered by combining adaptive optics with spectroscopy has surely set a precedent for the future of massive star formation studies.

Colin Aspin of the Institute for Astronomy at the University of Hawaii adds, “This result provides us with one of the first clues that high-mass stars form in similar ways to their low-mass counterparts and shows the power of integral-field near-infrared spectroscopy as a way of probing the youngest phases of stellar evolution.”

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.