We have observed the Galactic Center 50km/s molecular cloud (50MC) with ALMA to search for filamentary structures. In the CS J=2-1 emission line channel maps, we succeeded in identifying 27 molecular cloud filaments using the DisPerSE algorithm. This is the first attempt of filament-finding in the Galactic Center Region. These molecular cloud filaments strongly suggest that the molecular cloud filaments are also ubiquitous in the molecular clouds of the Galactic Center Region.

We found a molecular cloud connecting from the outer region to the “Galactic Center Mini-spiral (GCMS)” which is a bundle of the ionized gas streams adjacent to Sgr A*. The molecular cloud has a filamentary appearance which is prominent in the CS J=2-1 emission line and is continuously connected with the GCMS. The velocity of the molecular cloud is also continuously connected with that of the ionized gas in the GCMS observed in the H42α recombination line. The morphological and kinematic relations suggest that the molecular cloud is falling from the outer region to the vicinity of Sgr A*, being disrupted by the tidal shear of Sgr A* and ionized by UV emission from the Central Cluster. We also found the SiO J=2-1 emission in the boundary area between the filamentary molecular cloud and the GCMS. There seems to exist shocked gas in the boundary area.

Before 2012, Commission 34 was identical to Division VI. The organization and executive officers of the Division and the Commission were the same. At the 2012 General Assembly (GA) in Beijing, the IAU reformed the divisional structure and the previous Division VI which Commission 34 was under was combined with Div VII to form Division H: Interstellar Matter and Local Universe. Ewine van Dishoeck was named by the IAU executive committee as the President of the new Division. Since the Commission structure is to be reformed at the GA of 2015, Commission 34 retains its original name “Interstellar Matter” and joined Commissions 33 and 37 (formally under Division VII) as commissions under the new Division H.

We present results from a high-resolution wide-field imaging observation of the central molecular zone (CMZ) in H13CO+J = (1 − 0) and SiO v=0, J = (2−1) emission lines by using the Nobeyama 45-m telescope in order to depict the high-density molecular gas mass distribution and explore molecular gas affected by interstellar shocks. We found a candidate for ongoing cloud-cloud collision in the Sgr B2 complex. This is identified as a hollow paraboloid-like structure in the l−b−v data cube of both emission lines. The central part of the feature is denser and warmer than the outer envelope and contains a vast amount of shocked molecular gas. These properties are consistent with those expected from simulations of cloud-cloud collisions in the CMZ.

We present the statistical properties of molecular clumps in the Galactic center 50 km s−1 molecular cloud based on observations of the CS J = 1 − 0 emission line with the Nobeyama Millimeter Array. The CMF and size spectrum for the whole cloud can be described by power laws of dN/dM ∝ M−2.6 ± 0.1 and dN/dR ∝ R−5.9±0.3, respectively. The CMF observed in the interacting part with the Sgr A East steepens to dN/dM ∝ M−4.0±0.2. On the other hand, the interaction presumably truncates the size spectrum on the larger side of R ∼ 0.4 pc.

We performed the observation of the flux densities of Sgr A* at 90 and 102 GHz on 6 April 2005 using the Nobeyama Millimeter Array in order to detect the time lag between these frequencies. We constructed light curves covering a few hour with 1 min bin, and the Intra-Day Variability, which had a rising phase and intensity peak, of Sgr A* is clearly seen at both frequencies. We calculated the z-transformed discrete correlation function between the light curves of Sgr A* at 90 and 102 GHz. The derived time lag of the flares at these frequencies was approximately zero, contrary to our expectations based on the previously reported time lag at lower frequencies. If the radio flares of Sgr A* are explained by the expanding plasma model, the light curve at 90 GHz would be delayed with respect to the one at 102 GHz. However, we could not find such a delay with statistical significance in our data.

In 2011 February, a burst of the 22 GHz H2O maser in Orion KL was reported. In order to identify the bursting maser features, we have been carrying out observations of the 22 GHz H2O maser in Orion KL with VERA, a Japanese VLBI network dedicated for astrometry. The bursting maser turns out to consist of two spatially different features at 7.58 and 6.95 km s−1. We determine their absolute positions and find that they are coincident with the shocked molecular gas called the Orion Compact Ridge. We tentatively detect the absolute proper motions of the bursting features toward the southwest direction, perpendicular to the elongation of the maser features. It is most likely that the outflow from the radio source I or another young stellar object interacting with Compact Ridge is a possible origin of the H2O maser burst. We will also carry out observations with ALMA in the cycle 0 period to monitor the submillimeter H2O maser lines in the Orion Compact Ridge region. These follow-up observations will provide novel information on the physical and chemical properties of the mastering region.

Division VI, consisting of one Commission (Commission 34) and two Working Groups (Astrochemistry WG and Planetary Nebulae WG), has 972 members whose theoretical, observational, and experimental research interests cover a wide spectrum of activities associated with the study of the interstellar medium (ISM) in the Universe. As such, the Division has close links with Division VIII, IX, and X. The ISM and stars, the two major visible components of a galaxy, are coupled to each other through star formation, stellar feedback, and gravitational potential; thus, the Division is also closely linked to Division VII.

The business meeting of Division VI was held on Monday 10 October 2009. Apologies had been received in advance from D Breitschwerdt, P Caselli, G Ferland, M Juvela, S Lizano, M Rozyczka, V Tóth, M Tsuboi, J Yang and B-C Koo.

Division VI provides a focus for astronomers studying a wide range of problems related to the physical and chemical properties of interstellar matter in the Milky Way and other galaxies.

This triennium began with an action to re-create the Terms of Reference for the Working Group Global VLBI (WG-GV). These had been lost over the years since the Group was established in 1990. Fortunately, the personal archive of one long-term member yielded a copy of the original memorandum by R. D. Ekers, which was found to coincide quite well with current practice and areas of interest. New Terms of Reference, based on modern conditions, were drafted and accepted by both IAU and URSI.

We performed a mapping observation of the Sunyaev-Zel'dovich effect toward a galaxy cluster, CL0016+16, at 43 GHz using a newly developed 6-beam receiver installed in the Nobeyama 45-m telescope. The temperature decrement of the CMB was measured to be δT*A = −0.49 ± 0.06 mK at the center of the cluster. Fitting the isothermal, spherical-symmetrical β -model to the observed temperature decrement distribution, the S-Z effect at the center is inferred to be δTRJ(0) = −1.0 ± 0.1 mK at the Rayleigh-Jeans limit. This suggests that the Hubble constant is H0{q0 = 0.5} = 67+16−11 km s−1 Mpc−1.

We briefly report the results of polarimetric observations of SiO emission from late-type stars taken with a millimeter polarimeter installed at the Nobeyama 45m telescope. We found that the SiO J = 2 − 1 emission in the v = 0 state from R Cas contains a highly linearly polarized component, followed by the detection of highly linearly polarized emission of the same transition from VY CMa (Shinnaga et al. 1999). The high polarization degree is a strong evidence that the v = 0 emission originates from maser action. We found out that, not only a peculiar supergiant star, but also a Mira variable star is associated with the SiO v = 0 maser.

We have observed three molecular clumps in the Galactic center region in the CS J=2-1 line with the Nobeyama Millimeter Array. We have determined the mass spectrum and other statistical relations for the Galactic center cloud cores. The derived mass spectrum is somewhat steeper than for galactic cloud cores based on molecular line observations. In addition, the spectrum is steeper than that of the large scale Galactic center clumps.

Data : We used the Galactic center region survey data in CS J=1-0 with the Nobeyama 45-m telescope (Tsuboi, Handa, and Ukita 1997).

Cloud Definition : We identified molecular clumps in the positive longitude region of about ∼1deg2 (+0°10′ < l< + 1°42′ and −25′ < b< +25′) within all survey region.

Surely the most striking radio feature in the Galactic center may be a sheaf of straight vertical filaments (VFs, e.g., Yusef-Zadeh, Morris, & Chance 1984) of the radio arc. The VFs are believed to be the manifestations of strong magnetic field lines (≥1mG) which have been illuminated by some local relativistic particle source.

Molecular clouds in the Galactic center region are characterised by their large velocity widths and physical conditions which differ from clouds in the Galactic disk (e.g., Morris 1996). These clouds may not be gravitationally bound, but in equilibrium with the high external pressure in the Galactic bulge (Spergel & Blitz 1992, Oka et al. 1997a).

As a key program of the 45-m telescope at Nobeyama Radio Observatory, we have made high-resolution CO images of the Galactic center region with the 2×2 focal plane array receiver. The data consist of 44,000 12CO and 13,000 13CO spectra taken with 16″ beams spaced by 34″. The 12CO image covers roughly −1.5° ≤ l ≤ +3.4° and −0.6° ≤ b ≤ +0.6° (Oka et al. 1997b)

The kinematics and structures of the molecular clouds probably give us key information for activities in the Galactic center region. CS lines are good tracers of dense molecular clouds. In addition, the lines are expected to be nearly free from the strong contamination of disk molecular clouds because of high critical density, n(H2) ≃ 104cm−3. Thus, we have made survey observations of the Galactic center region in the CS J=1-0 line with the Nobeyama 45-m telescope (Tsuboi, Handa, and Ukita 1997). The beamsize is 34″ and the achieved noise was Trms = 0.25 K/1.6 km s−1 in TMB. Then, we detected the molecular mass of M(H2)CS, thin = (3 − 8) × 107 M⊙ in the Galactic center molecular zone (CMZ), assuming of optically thin, Tex = 30 − 80 K (Güsten 1989), and X(CS) = 1 × 10−8 (Irvine et al. 1987).

Molecular clouds in the Galactic center region are distributed mainly along the Galactic plane and have filamentary shapes with several clumps (Bally et al. 1987, Tsuboi et al. 1989). The “50-km.s−1 molecular cloud (M-0.02-0.07)”, which is located ~3’ east from Sgr A West, is one of most remarkable clumps on these molecular filaments. The intimate relation between this cloud and Sgr A East has been mentioned by many authers (e.g. Ho et al. 1986). Several compact HII regions are located toward the cloud (Ekers et al. 1983). The recombination line velocities correspond to the molecular line velocities in the cloud (Goss et al. 1987). Thus this cloud is one of active star forming regions near the Galactic center.

We observed the 50-km-s−1 molecular cloud in CS J=1-0 emission line (48.991 GHz) using the Nobeyama Millimeter Array (NMA) to reveal the detailed structure of the star forming regions near the Galactic center.