Volume 23, March 2006 - Meeting Summaries

[Home] [New Abstracts] [Newsletter] [Newsflash] [Articles] [Conferences] [Subscribers] [Subscription] [Submission]

Meeting summaries - Joe Lazio, Cornelia Lang and Masaaki Sakano

American Astronomical Society

Sgr A* was the target of observations over a wide range of wavelengths:

• Bushouse et al. used the Hubble Space Telescope for a near-IR monitoring campaign (103.02, ``A Multi-Wavelength Study of Sgr A*: Near-IR Variability'').
• Hornstein et al. used the recently commissioned laser-guide star system at the Keck Observatory to observe Sgr A* in the near-IR (78.13, ``Infrared Colors of Sgr A* From HKLM Adaptive Optics Observations'').
• Roberts et al. conducted radio monitoring observations with multiple instruments over more than an order of magnitude in wavelength (103.03, ``A Multi-Wavelength Study of Sgr A*: Radio Continuum Variability'').
• Yusef-Zadeh et al. summarized a series of observations from radio to the high-energy in an effort to arrive at a single, comprehensive explanation for the emission from Sgr A* (103.04, ``A Multi-Wavelength Study of Sgr A*: The Correlation of X-ray, Near-IR and Sub-millimeter Emitting Flares'').

Stars in the GC came in for their share of observations as well:

• Berukoff & Hansen used numerical simulations in an effort to explain the presence of the young stars in the central cluster (181.02, ``Cluster Core Dynamics at the Galactic Center'').
• Haislip & Youdin use numerical simulations to see whether the S stars could have formed in a disk, then be scattered into their current orbits (181.14, ``A Disk Origin for S-Stars in the Galactic Center?'').
• Hewitt et al. reported the possible discovery of a site of forming massive stars (181.01, ``The Sites of Massive Star Formation Toward the Galactic Center Region Using Methanol Masers'').
• Hong et al. considered point-source X-ray emitters, many of which are stars in binaries (181.04, ``X-ray Point Sources in Galactic Center Region Fields'').
• Howard et al. may have found a pulsar wind nebula (181.12, ``Chandra Observations of the Cometary X-Ray Feature at the Galactic Center'').
• Lu et al. used the recently commissioned laser-guide star system at the Keck Observatory to track the motions of various stars in the central cluster (98.06, ``Constraints on Orbits and Origins of Young Stars in the Central Parsec of the Galaxy'').
• Mauerhan et al. found a number of candidate young massive stars in a near-IR survey (181.13, ``A Photometric Search for Young Massive Stars in the Galactic Center'').
• Mikles et al. describe a new compact binary found toward the Galactic center (6.03, ``Galactic Center X-ray Binary Candidate Screams for Attention'').

The first release of (spectacular) Spitzer images merits a category unto itself:

• ``A Mid-Infrared Survey of the Inner 2 * 1.5 Degrees of the Galaxy with Spitzer/IRAC'' (181.05, Stolovy et al.)
• ``Spitzer/IRAC Mid-Infrared Colors of the ISM in the Central 200 pc of the Galaxy'' (181.06, Arendt et al.)
• ``Comparison of Spitzer/IRAC Galactic Center Mid-IR Survey Results with X-ray and Radio Emission Due to High-Energy Processes in the Central 100 Parsecs'' (181.07, Gezari et al.)
• ``Point Sources and Source Subtracted Images in a Spitzer/IRAC Survey of the Galactic Center (181.08, Ramirez et al.)
• ``Massive Star Formation in the Galactic Center as Revealed by Spitzer/IRAC Observations (181.09, Cotera et al.)

The larger environment of the GC was considered from a variety of approaches:

• Boldyrev & Yusef-Zadeh suggested a new mechanism for the generation of the magnetic non-thermal filaments (103.06, ``Turbulent Origin of the Galactic-Center Magnetic Field: Nonthermal Radio Filaments'').
• Law presented his dissertation work on the GC Lobe (103.05, ``A Study of the Galactic Center Lobe'').
• Venturing slightly further away, Martin et al. conducted CO observations of two molecular clouds (181.11, ``AST/RO survey of the Galactic Center: Clumps 1 & 2 in <sup>13</sup>CO(2-1), CO(4-3), and [CI]'').
• Morris et al. found a curious feature which they attribute to a propagating magnetic wave (103.01, ``The Double Helix Nebula: A Torsional Wave Propagating Along the Galactic Center Magnetic Field?'').
• Zhao et al. conducted a multi-wavelength survey of the GC (181.03, ``ChaMPlane Optical Survey in the Galactic Center Region'').

Instruments that either are or will be improving our view of the GC include

• FLAMINGOS-2, a near-infrared wide-field imager and multi-object spectrograph for the Gemini telescopes (Eikenberry et al., 181.10, ``The FLAMINGOS-2 Galactic Center Survey'');
• The Square Kilometer Array (Cordes et al., 137.04, ``Key Science with the Square Kilometer Array: Strong-field Tests of Gravity using Pulsars and Black Holes''); and
• The Sub-millimeter Array (Marrone, 85.07, ``SMA Studies of the Galactic Center Region'').

The Galactic Center: Molecular Clouds to High Energy Phenomena

• Oka reported on CO (J=3-2) and (1-0) observations, in which a high ratio (3-2/1-0) of approximately 0.9 was found. In contrast, the ratio in the disk is approximately 0.5. Very high (3-2/1-0) ratios of approximately 1.5 are found toward some of the CO spots out to a Galactic longitude of 0.8^o. (``The Large Scale CO 3-2 Observations in the Galactic Center by ASTE'')
• Tsuboi reported on the observations of Nobeyama Millimeter Array which have shown that the molecular clouds at +50 km s<sup>-1</sup> are interacting with SNR Sgr A East on their far side. (``The Interaction between Molecular Clouds and SNR Sgr A East'')
• Yamamoto presented the the large scale distribution of molecular clouds toward the Galactic center taken by NANTEN telescope. (``Giant Molecular Clouds toward the Galactic Center'')
• Kudo presented the comparison between 2MASS sources and molecular clouds derived by NANTEN observations. (``Search for the Molecular Clouds associated with 2MASS Clusters in the Galactic Center'')
• Handa reported on SiO (J=1-0 v=0, J=2-1 v=0) and H¹³CO⁺(J=1-0) observations toward the molecular cloud G0.11-0.11, which show that the column density of the molecular cloud is of order of 10²³ cm^-2 and its size is approximately 0.06 pc. The A_V of the cloud is roughly 640-740 mag, and he also described one of the darkest MSX features within the cloud. (``Molecular Cloud G0.11-0.11: Indication of Very High Column Density'')
• Miyazaki and Sudo presented a monitoring program of Sgr A*, at 100 and 140 GHz using Nobeyama Millimeter Array and with 4 cm continuum by e-VLBI and by ATCA. (``Flux Variation of Sgr A* in mm Band'' and ``Optical Network VLBI Observations in Sgr A*'')
• Kohno presented the possibility of an X-ray dominated region in the Galactic center. (``Is There XDR in the Galactic center? The Point of View from Nearby AGNs'')
• Oyama described detailed observations toward the infrared sources associated with a maser source in the Galactic center, taken by VLBA, which indicate the presence of a compact dark mass object whose mass is of order 4 * 10⁵ M_o. (``The Proper Motion of Stars in Very Nearby Galactic Center'')
• Nishiyama reported on deep J, H, and Ks band observations with IRFS/SIRIUS which show that our Galaxy has a double bar from the distribution of the red clumps. In addition, the [Fe/H] distribution estimated from the slope of the red giant branch has no gradient in the region 0<sup>o</sup> < | l | < 7<sup>o</sup> and 1 < |b| < 3<sup>o</sup>. (``Near Infrared Survey in the Galactic Center by IRSF/SIRIUS'')
• Inui and Murakami showed results of the X-ray Suzaku telescope, launched last July, from its observations of the Radio Arc, Sgr A, Sgr B2, and Sgr C. They noted that the 6.4 keV Fe neutral line is extended outside of the giant molecular clouds. (``The Map of the Reflection X-ray in Molecular Clouds Sgr B2'' and ``Fe Observations in X-ray in the Galactic Center'')
• Ebisuzaki discussed formation mechanisms of a super massive black hole by a coalescence of intermediate mass black holes. (``The Settling of Clusters near the Galactic Center and Intermediate Mass Black Hole'')
• Also presenting was A. Yasuda, ``The Physical State of Interstellar Medium in the Galactic Center.''