GCNEWS
A Newsletter for Galactic Center Research
This Volume was edited by Angela Cotera, Heino Falcke & Sera Markoff
email: gcnews@aoc.nrao.edu
GCNEWS
After talking to a few brave souls who were interested in sponsoring a conference (and after an initial proposal from India evolved into a more general conference), we are pleased to announce that the next Galactic Center conference (workshop?) has found a home and an approximate date. Dr. Matthew Mountain, director of Gemini North has generously agreed to be the primary sponsor of a conference on the big island of Hawaii. We currently anticipate the conference to take place in February of 2002. As soon as the exact location and date have been determined, we will pass this along to you.
The primary organizer for this conference will be François Rigaut, a project scientist with Gemini, and coordinator of the very successful GC Demonstration Science Team (for more information see the feature article in this issue of GCNEWS). Your GCNEWS editors have agreed to provide substantial organizational assistance as François is new to both GC research and conference organization.
At the recent AAS meeting in San Diego a few GC aficionados got together and discussed the GC98 workshop: what worked, what didn't and what we would like to see for this upcoming conference. One proposal that was unanimously supported was reaching out to you, the GC community, for your ideas on what are the most intriguing and important questions facing GC research today. We anticipate soliciting your input in coming months, so start thinking about what questions you would like to see addressed.
The 197th meeting of the AAS in San Diego had a strong GC showing, with many posters in Session 4: The Milky Way Galaxy, as well as other GC-related posters and talks sprinkled throughout the conference. Here we will just give a cursory run-through of the presentations. To see the full abstracts, go to the program at http://www.aas.org/meetings/aas197/program, and follow the links to the session numbers included below with the first author name.
Starting from the big scales and working inwards, the results from several new line mapping and survey programs were reported. The MSC N-to-MIR deep fields presented by Mizuno et al. (4.11) include the GC, as well as an NIR survery for emission-line stars in the Galactic plane (Hoemeier et al. 4.12), which has already turned up one Wolf-Rayet star in the GC. In addition, Christopher et al. (4.07) presented high spatial and spectral resolution images of the central 4 pc in HC0+ and HCN from the Owens Valley mm array, and a CO J=7-6 map of the GC by AST/RO was presented by Kim et al. (4.04) (and see also Ojho et al., this issue).
The nonthermal filaments were a hot topic, as usual, starting with a dissertation talk by C. Lang [28.01] on the Arched Filament complex and environs. She showed that the ionization of the Arched Filament can be entirely accounted for by the Arches Cluster, which she estimates may be as far as 20 pc away in order to explain the observed uniformity. During the questions afterwards, A. Cotera and Lang discussed their respective views on the nearby molecular cloud, and whether it was the source of the star cluster or had moved into the region at a later time. Upcoming velocity comparisons should cast more light on the subject.
LaRosa et al. (4.06) discussed a different group of nonthermal filaments near the GC, which show spectral index variations that are inconsistent with simple aging calculations. And Chandran (4.08, and see this issue) considered the confinement and stability of the vertical ordered magnetic field assumed from these filaments.
Moving in to the central stellar cluster, Gezari et al. (4.01) presented 5 spectral identifications of member stars, while Sand & Ghez (4.10) showed that two familiar players, IRS 16SW and S2-7, are variable. How the central cluster managed to form in the first place is considered Kim (4.09), who presented simulations of dynamical friction as a way to move pre-formed clusters inward.
Some exciting results from the recent Chandra ACIS GC observation were presented by Baganoff et al. (4.02) and Maeda et al. (80.03), who focused on Sgr A* and Sgr A East, respectively. They found a suprisingly soft X-ray source coincident to within 0.35'' of Sgr A*, which seems to be slightly extended and shows a hint of variability. The Sgr A E radio shell is non-luminous in the Chandra range, and is filled with plasma whose line emission suggests a temperature of ~2 keV. The oberabundance of heavy elements supports a SNR origin for this source.
Rounding the inner parsec out, another poster on Sgr A E by Fatuzzo et al. (4.05, and see this issue) suggests it may at some point become a strong source of annihilation radiation. And last but not least, Doeleman et al. (4.03) presented their new 86 GHz observations of Sgr A*, which limit the structure in the N-S direction to < 0.27 mas. They find a best fit to a circular Gaussian brightness distribution.
We look forward to seeing many of these finalized results in our upcoming Volume 13!