SETI [ASTRO] Single Hubble Picture Captures Key Phases In The Stellar Life Cycle


Larry Klaes (lklaes@bbn.com)
Wed, 02 Jun 1999 14:53:28 -0400


>X-Authentication-Warning: brickbat12.mindspring.com: majordom set sender to owner-astro using -f >Date: Tue, 1 Jun 1999 22:39:00 GMT >From: Ron Baalke <BAALKE@kelvin.jpl.nasa.gov> >To: astro@lists.mindspring.com >Subject: [ASTRO] Single Hubble Picture Captures Key Phases In The Stellar Life Cycle >Sender: owner-astro@brickbat12.mindspring.com >Reply-To: Ron Baalke <BAALKE@kelvin.jpl.nasa.gov> > > >University of Washington > >FOR IMMEDIATE RELEASE: June 1, 1999 > >FROM: Vince Stricherz, 206-543-2580, vinces@u.washington.edu > >Single Hubble picture captures key phases in the stellar life cycle > >CHICAGO -- Like a collage of photographs showing a human being from >infancy to old age, a striking new picture unveiled today by a University >of Washington astronomer shows various stages in the life cycle of stars, >all occurring at one time. > >The photograph clearly shows structures that will develop into stars, a >starburst cluster featuring young massive stars, and a blue supergiant in >its last stage before the death throes of becoming a supernova. This single >view, believed to be the first of its kind, illustrates the entire stellar life >cycle, said Eva Grebel, a Hubble postdoctoral fellow in the UW astronomy >department. > >A huge gas cloud that includes two giant gaseous pillars is the most >dominant part of the image. However, the starburst cluster stands out >because winds from its massive stars cleared away the surrounding gas, >giving scientists a much better view of what is occurring inside. > >"We even see stars that are currently being formed in the surroundings of >this very massive cluster," Grebel said. > >She and her colleagues, Wolfgang Brandner of NASA's Jet Propulsion >Laboratory in Pasadena, Calif., and You-Hua Chu of the University of Illinois >at Urbana-Champaign, presented the image at the centennial meeting of the >American Astronomical Society. > >The photograph of the giant galactic nebula NGC 3603 was taken March 5 using >the Wide Field Planetary Camera 2 on the Hubble Space Telescope. The nebula >is about 20,000 light years from Earth (a light year is about 5.88 trillion >miles) and about 26,000 light years from the center of the galaxy, the same >distance as our solar system. > >Bok globules, which appear as small dark masses in the upper right corner of >the photo, could contain one or several forming stars. When such globules >evolve and are near an ionizing source, such as the giant cluster, they can >begin to look like proplyds. > >The term proplyd comes from protoplanetary disk, which is the material >around a forming star that eventually could form a planetary system. It is >believed proplyds consist of a central disk of neutral gas. In the photo, >two proplyds appear as bright yellow objects slightly separated from the >gas cloud in the lower center of the image. > >"By studying these in greater detail, we hope to learn a lot more about the >early life of a star," Grebel said. > >Brandner said the proplyds are 560 billion to 1.7 trillion miles in size. >But he said it is doubtful these developing stars ever will harbor planets >because simulations indicate that within a few tens of thousands of years >the disk of protoplanetary material will be completely ionized and dispersed >because of its closeness to the cluster. > >The central starburst cluster has at least two dozen massive stars, >including O3 stars that, at about 120 times the mass of our sun, are the >most-massive stars known. The massive stars stand out because of their >brightness, but that makes it much less certain how many low-mass stars >are in the cluster because they are hard to see. It is estimated there are >tens of thousands of them. > >Just to the left and slightly above the cluster is the blue supergiant known >as Sher 25. The star is in its last stages before going supernova, though it >could be thousands of years before that happens, Grebel said. A visible ring >around Sher 25 has a diameter of a little more than one light year. > >Also visible in front of the gas cloud are two giant pillars, formed as gas >is beginning to be blown away by powerful winds from massive stars and >from supernova explosions. Eventually the pillars are expected to dissolve, >along with the rest of the gas cloud, Grebel said. > >### > >For more information contact: >Grebel at (206) 685-9010 or grebel@betula.astro.washington.edu >Brandner at (626) 397-7204 or brandner@ipac.caltech.edu >Chu at (217) 333-5535 or chu@astro.uiuc.edu > >During the AAS meeting, messages may be left for any of the researchers at >the AAS pressroom, (312) 294-6607, (312) 294-6608 or (312) 294-6609. > >



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