======================================================================== G C N E W S * Newsflash * - The Newsletter for Galactic Center Research - gcnews@aoc.nrao.edu http://www.aoc.nrao.edu/~gcnews ======================================================================== Vol. 25, No. 2 Aug 10, 2006 Recently submitted papers: -------------------------- 1) The Intrinsic Size of Sagittarius A* from 0.35 cm to 6 cm (Bower et al., ApJL) 2) GCIRS16SW: a massive eclipsing binary in the Galactic Center (Martins et al., ApJL) ------------------------------------------------------------------------ Email : gbower@astro.berkeley.edu Title : The Intrinsic Size of Sagittarius A* from 0.35 cm to 6 cm Author(s): Geoffrey C. Bower^1, W.M. Goss^2, Heino Falcke^3, Donald C. Backer^1, Yoram Lithwick^4 Institute: (1) Astronomy Department & Radio Astronomy Laboratory, University of California, Berkeley, CA 94720 (2) National Radio Astronomy Observatory, P.O. Box 0, Socorro NM 87801, U.S.A. (3) ASTRON, Postbus 2, 7990 AA Dwingeloo, The Netherlands and Department of Astrophysics, Radboud Universiteit Nijmegen, Postbus 9010, 6500 GL Nijmegen, The Netherlands (4) CITA, University of Toronto, 60 St. George Street, Toronto, Ontario, M5S 3H8 Paper : ApJL in press EPrint : astro-ph/0608004 Abstract: We present new high-resolution observations of Sagittarius A* at wavelengths of 17.4 to 23.8 cm with the Very Large Array in A configuration with the Pie Town Very Long Baseline Array antenna. We use the measured sizes to calibrate the interstellar scattering law and find that the major axis size of the scattering law is smaller by 6% than previous estimates. Using the new scattering law, we are able to determine the intrinsic size of Sgr A* at wavelengths from 0.35 cm to 6 cm using existing results from the VLBA. The new law increases the intrinsic size at 0.7 cm by 20% and < 5% at 0.35 cm. The intrinsic size is 13^+7_-3 Schwarzschild radii at 0.35 cm and is proportional to lambda ^ gamma , where gamma is in the range 1.3 to 1.7. ------------------------------------------------------------------------ Email : martins@mpe.mpg.de Title : GCIRS16SW: a massive eclipsing binary in the Galactic Center Author(s): F. Martins^1, S. Trippe^1, T. Paumard^1, T. Ott^1, R. Genzel^1,2, G. Rauw^3, F. Eisenhauer^1, S. Gillessen^1, H. Maness^4, R. Abuter^5 Institute: (1) MPE, Postfach 1312, D-85741, Garching, Germany (2) Department of Physics, University of California, CA 94720, Berkeley, USA (3) Institut d'Astrophysique et de Geophysique, Universite de Liege, Allee du 6 Aout 17, Bat. B5c, 4000 Liege, Belgium (4) Department of Astronomy, University of California, CA 94720, Berkeley, USA (5) ESO, Karl-Schwarzschild-Str. 2, D-85748 Garching, Germany Paper : ApJL, accepted EPrint : astro-ph/0608215 Abstract: We report on the spectroscopic monitoring of GCIRS16SW, an Ofpe/WN9 star and LBV candidate in the central parsec of the Galaxy. SINFONI observations show strong daily spectroscopic changes in the K band. Radial velocities are derived from the He i 2.112 mu m line complex and vary regularly with a period of 19.45 days, indicating that the star is most likely an eclipsing binary. Under various assumptions, we are able to derive a mass of 50 \msun for each component. ------------------------------------------------------------------------ (Older versions of the Newsflash can be found at the gcnews web-page) ======================================================================== Edited by Sera Markoff, Loránt Sjouwerman, Joseph Lazio, Cornelia Lang, Rainer Schödel, Robin Herrnstein - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - For Abstract submission please follow the instructions which are at http://www.aoc.nrao.edu/~gcnews/home/submission.shtml ========================================================================