New Star Survey Sheds Light On The Evolution Of Galaxies

The survey, which publishes its initial findings today in theMonthly Notices of the Royal Astronomical Society, uses the latest highresolution instruments to seek out stars and nebulae in the early andlate phases of their evolution, stages that are rarely observed becausethey are so short-lived. Lead researcher Professor Janet Drew Opens innew window, of the Department of Physics at Imperial College London,says:

"These are crucial evolutionary stages in the growth and death ofplanetary systems, and many of the major unsolved problems in stellarevolution are to do with the fact that we have had relatively fewexamples to work with.

"The last time the northern Milky Way was searched in a concertedway was the 1960s, using much smaller telescopes and now obsoletedetection methods. This new survey has the potential to greatly expandour understanding of how our own Solar System came to be and what itwill become."

The UK, Dutch and Spanish team is using the 2.5 metre Isaac NewtonTelescope (INT) to detect stars and bodies of gas that emit strongly atthe wavelength of red light called H alpha. H alpha is emitted byexcited atoms of hydrogen, allowing scientists to pick out both young,potential planet-building systems and old objects that will soon becomecompact white dwarfs or supernova explosions.

These are particularly important in understanding the evolution ofgalaxies, since youthful stars help to shape the growth of planetarysystems while those in old age recycle energy and chemically enrichedmatter back into the galactic environment as they collapse.

The new survey reaches beyond the sun's orbit around the centre ofthe Milky Way to a radius of 30 kiloparsecs (kpc) around 90,000 lightyears. Currently almost nothing is known about the star populationsbeyond a distance of about 15 kpc. Professor Drew adds:

"At the moment, very little is known about the far reaches of theMilky Way's disc there's still uncertainty in its spiral arm structure,and we don't really know where the stars run out. Recent technicaldevelopments, which have boosted both the efficiency of large-scaleastronomical surveys and their quality in a major way, mean we now havethe opportunity to survey the galaxy we live in at hugely improvedsensitivity."

The team expects to complete its observations in late 2006 with atotal of around 80 million objects catalogued. Current images can beviewed at astro.ic.ac.uk/Research/Halpha/North/gallery.shtml