SETI [ASTRO] Key Mechanism For Star Formation Found?

Larry Klaes (
Wed, 02 Jun 1999 15:26:17 -0400

>X-Authentication-Warning: majordom set sender to owner-astro using -f >Date: Wed, 2 Jun 1999 15:12:05 GMT >From: Ron Baalke <> >To: >Subject: [ASTRO] Key Mechanism For Star Formation Found? >Sender: >Reply-To: Ron Baalke <> > >ESA Science News > > >02 Jun 1999 > >Key mechanism for star formation found? > >What causes new stars to form inside clouds of gas and dust in space? A >team of astronomers using the European Space Agency's infrared space >observatory, ISO, believes they have taken a big step towards answering >this question. They announced today in Chicago (US), at the American >Astronomical Society meeting, the first ever space-based detection of >weak magnetic fields in a distant region in which stars are being formed. >The differences between these magnetic fields and those from regions >with no star formation have revealed what could be the key factor in >triggering the birth of new stars. > >The team, led by Dan Clemens, from Boston University Institute for >Astrophysical Research, examined a distant cloud of gas and dust called >GF9, located about 1300 light years away. It shows a filamentary or >wispy appearance, with dark "globules" distributed along its length. The >new observation with ISO focused on two of these dark globules, one in >which a young star is forming and one in which no new stars are currently >forming. > >The results show that the magnetic fields in the star-forming region are >more ordered and aligned than in the star-free region. It is this alignment >of the weak magnetic fields that astronomers suspect is the key ingredient >needed for gas clouds to become star-forming clouds. > >"The finding is very important", says ESA astronomer Ren=E9 Laureijs at the >ISO Data Centre in Villafranca (Spain), who last week chaired a workshop >on this topic attended by Clemens. "It shows that our theories describing >star-forming clouds are incomplete. People expected that the magnetic >fields would follow the same pattern of the gas and dust filaments >observable in the cloud, but we now know that the magnetic fields >have a different, unexpected direction. Because of the weakness of the >magnetic fields it has been a very difficult detection, made possible >thanks to the sensitivity of ESA's ISO telescope" > >The observations were made with the photopolarimeter ISOPHOT, one >of the four instruments on board ISO. The polarimeter module of >ISOPHOT worked rather similarly to the way in which polaroid >sunglasses block light which has been polarized (caused to vibrate >in the same direction) by reflection off metal or water. In the dust >and gas cloud GF9 the light is polarized by grains of dust, which act >as tiny magnets that alter the way the light propagates. By measuring >the direction of this polarized light the ISO polarimeter could also >sense the direction of the faint magnetic fields in GF9. > >As Clemens explains, "the dust grains respond to the magnetic field by >spinning around the lines of magnetic force, and we sense those dust >grains through the polarized infrared light they emit". > >The data show that the magnetic fields detected toward the star-forming >globule in GF9 are surprisingly uniform and parallel, while in the star-less >globule the magnetic field lines are tangled and disordered. Astronomers >think that tangled magnetic field lines may be an important source of >support that keeps some clouds from collapsing to form new stars. > >This new discovery was made possible because of the great improvement >in sensitivity to infrared light brought about by the cooled ISO telescope >and its location above the Earth's atmosphere. Clemens believes more >space missions with infrared polarimetric capabilities are needed. >"Similar studies of other nearby star-forming clouds will have to await >development of a new generation of small, highly capable cooled telescope >missions", he says. > >Footnote on ISO > >ESA's infrared space observatory, ISO, was placed in orbit in November >1995, by an Ariane 44P launcher from the European Spaceport in Kourou, >French Guiana. Its operational phase lasted till 16 May 1998, almost a >year longer than expected. As an unprecedented observatory for infrared >astronomy, able to examine cool and hidden places in the Universe, ISO >made nearly 30,000 scientific observations. These are now available >to the scientific community via the ISO Archive >( at the ISO Data Centre, in Villafranca, >near Madrid, Spain. > >For more information: > >ESA Public Relations Division >Tel: +33(0) Fax:+33(0) > >Martin F. Kessler >ISO Project Scientist >Tel.: +34 91 813 1253 > >Ren=E9 Laureijs >ISO Data Centre in Villafranca (Madrid, Spain) >Tel: +34 91 813 1367 > >Other science contact points: > >Dan Clemens >Director of the Boston University Institute for Astrophysical Research >Tel: +1 617 353 6140 > >The ISO photopolarimeter, ISOPHOT, was built by a large international team >led by Dietrich Lemke, MPI Fuer Astronomie, Heidelberg >Tel: +49 6221.528.259 > >USEFUL LINKS FOR THIS STORY > >ISO science website > > >[NOTE: An illustration supporting this article is available at >] > > >

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