Subject: GCFLASH - Vol. 4, No. 2 (Nov 7, 1996) ======================================================================== G C N E W S * Newsflash * - The Newsletter for Galactic Center Research - gcnews@astro.umd.edu http://www.astro.umd.edu/~gcnews ======================================================================== Vol. 4, No. 2 Nov 7, 1996 Recently submitted papers: -------------------------- Email : naya@tgrs2.gsfc.nasa.gov Title : Detection of high velocity 26Al towards the Galactic centre Author(s): Juan E. Naya (1,2), Scott D. Barthelmy (1,2), Lyle M. Bartlett (3), Neil Gehrels (1), Marvin Leventhal (4), Ann Parsons (1), Bonnard J. Teegarden (1), & Jack Tueller (1) Institute: (1) NASA/Goddard Space Flight Center, Greenbelt, MD 20771, USA (2) Universities Space Research Association, 7501 Forbes Blvd. #206, Seabrook, MD 20706-2253, USA (3) NAS/NRC Resident Research Associate, Code 718, NASA/GSFC, Greenbelt, MD 20771, USA (4) Dept. of Astronomy, University of Maryland, College Park, MD 20742-2421, USA Paper : Letter to Nature, Nov. 7, 1996 Abstract: Theory predicts that radioactive 26Al (which has a half-life of 0.72 Myr) is released into the interstellar medium by nova and supernova explosions, from winds of massive stars in the Wolf-Rayet phase, and from less-massive stars in very late stages of their evolution (in the Asymtotic Giant Branch phase). Observations of 1809 keV g-ray emission from 26Al can therefore be used as a tracer of Galactic Nucleosynthesis during the past million years. The irregularity of the emission in the plane of the Galaxy suggests that the dominant sources are likely to be massive stars and supernovae; the other predicted sources are older, and therefore expected to be distributed more uniformly. Here we report the detection of the 1809 keV emission line from the direction of the Galactic centre, and we show that the line width is approximately three times that expected from the effect of Doppler broadening due to Galactic rotation. The high velocities inferred from the line width favour an origin of 26Al in supernovae or Wolf-Rayet stars. Moreover, the fact that the 26Al has maintained such high velocities is difficult to reconcile with our current understanding of the propagation of material in the interstellar medium. ------------------------------------------------------------------------ (Older versions of the Newsflash can be found at the gcnews web-page) ======================================================================== Edited by Angela Cotera Heino Falcke (cotera@ipac.caltech.edu) (hfalcke@astro.umd.edu) - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - For Abstract submission please send the (La)Tex file of your paper to gcnews@astro.umd.edu ========================================================================