Astronomers make celestial = discovery

High-resolution infrared images of the dusty pinwheel = nebulae are=20 shown inset overlaid on a Hubble Space Telescope image of = the=20 Quintuplet cluster. Each of the five bright red stars is now = thought=20 to be a pinwheel nebula.

Submitted by Peter Tuthill (Sydney = University), Keck=20 Observatory, and Donald Figer = (RIT).

For the first time, scientists have identified the cluster of=20 Quintuplet stars in the Milky Way=92s galactic center, next to the = super=20 massive black hole, as massive binary stars nearing the end of = their life=20 cycle, solving a mystery that had dogged astronomers for more than = 15=20 years.

The nature of the stars was not entirely clear until now. In a = paper=20 published in the Aug. 18 issue of Science, co-authors Peter = Tuthill of the=20 University of Sydney and Donald Figer of RIT=92s Chester F. = Carlson Center=20 for Imaging Science, show that the Quintuplet cluster consists of = young=20 massive binary stars that produce large amounts of dust. Their = data reveal=20 that five bright red stars are nearing the end of their = =93short=94 lives of=20 approximately 5 million years. These quickly evolving stars burn = fast and=20 bright, but die younger than fainter stars, which live for = billions of=20 years. The study captures the Quintuplet stars just before = disintegrating=20 in supernovae explosions.

Using advanced imaging techniques on the world=92s biggest = telescope at=20 the W.M. Keck Observatory in Hawaii, the scientists captured the = stars at=20 the highest attainable resolution for the instrument, far = exceeding the=20 capability of the Hubble Space Telescope, which imaged the cluster = a=20 decade ago. The extra-resolution gives scientists a new glimpse of = the=20 dust plumes surrounding the stars and the swirling spirals Tuthill = likened=20 to pinwheels when he identified the first one in 1999 elsewhere in = the=20 galaxy.

=93Only a few pinwheels are known in the galaxy,=94 Figer says. = =93The point=20 is, we=92ve found five all next to each other in the same cluster. = No one=20 has seen anything like this before.=94

According to Figer, the swirling dust in pinwheel stars is key = to the=20 presence of the most evolved massive stars and points to the = presence of=20 pairs of stars. The geometry of the plume allows scientists to = measure the=20 properties of the binary stars, including the orbital period and=20 distance.

=93The only way that pinwheels can form is if they have two = stars,=20 swirling around each other. The stars are so close that their = winds=20 collide, forming dust in a spiral shape, just like water sprayed = from a=20 garden hose of a twirling sprinkler,=94 Figer says. =93A single = star wouldn=92t=20 be able to produce the dust and wouldn=92t have the spiral = outflow.=94

An earlier study by Figer in 1996 claimed the Quintuplet = cluster=20 consists of evolved massive stars that produce dust. Figer=92s = research=20 could not be confirmed until now with the use of the Keck = telescope.

Figer joined RIT late last year as part of a New York State = Office of=20 Science, Technology and Academic Research Faculty Development = grant to=20 build the Rochester Imaging Detector Laboratory.

Other scientists involved with the study include John Monnier = of=20 University of Michigan, Angelle Tanner of the Jet Propulsion = Laboratory,=20 Andrea Ghez of University of California and William Danchi of NASA = Goddard=20 Space Center.

Susan Gawlowicz=20

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