In order to detect variable stars in the well known star forming region, the Orion Nebula Cluster, a series of 22 exposures taken from November 1996 to October 1998, using the ESO 100/152cm Schmidt telescope, covering a field of 5° × 5° was analyzed. The films (Kodak Tech-Pan 4415 emulsions, effective spectral range from ~630 nm to 690 nm) were digitized by the SuperCOSMOS machine, the measurements calibrated to the R magnitude of the USNO B1.0 catalogue and differential photometry was performed throughout the whole field. In the process, a set of 260 stars that remained constant in the 22 films and were well distributed over the field was selected and used as comparison stars for the differential photometry of all the other stars in the field. Diverse statistical studies were performed in order to characterize the type and degree of variability of the objects. The 22 films, all exposed for 30 minutes each, were stacked together at our request by the SuperCOSMOS team, producing perhaps the deepest wide field image of M42 ever taken.

This database (>150 000 objects, mostly stars and ~2% galaxies) is going to be used as a starting point for the Variable Young Stellar Object Survey (VYSOS) project, which consists of 2 fully automated robotic telescopes of 41cm each, one installed on Mauna Loa (Hawaii, USA) and the other at Cerro Armazones (Chile), both using the Pan STARRS set of photometric filters. We discovered thousands of new variable stars within the 5° × 5° region studied. We have variability statistics for all objects and are classifying the variable stars according to the variability type and amplitude. We intend to make this database available via the WEB.

Our goal is to study relatively quiescent dense gas cores, isolated from disruptive stars, to understand the initial conditions of massive star formation. Determining their mass, size, dynamical status, and core mass distribution is a starting point to understand the mechanisms for formation, collapse, and the origin of their IMF. We obtained CSO 350 μm, images of quiescent regions in Orion and detected 51 resolved or nearly resolved molecular cores with masses ranging from 0.1 M to 46 M (Li et al. 2006). The mean mass is 9.8 M, which is one order of magnitude higher than that of the resolved cores in low mass star forming regions, such as Taurus. Our sample includes largely thermally unstable cores, which implies that the cores are supported neither by thermal pressure nor by turbulence, and are probably supercritical. They are likely precursors of protostars.

We have used the FLAMES multi-integral field unit system of the European Southern Observatory (VLT) centered on the cluster MS0451.6-0305 at z = 0.5386 to obtain the spatially resolved kinematics of the cluster members. The spectral data are supported by HST/ACS images that provide immediate morphological information of the cluster galaxies. The relevant structural parameters such as inclination, size, and orientation derived from optical high angular resolution images are compared with those derived from the kinematics. Our final goals are: 1. to derive the Tully-Fisher relation for cluster galaxies with regular kinematics. 2. to obtain the dynamical masses from resolved kinematics and stellar masses from optical images to be compared with local measurements.

The study of dusty discs is an important topic in astrophysics, as they seem to be abundant around different objects and are related to different phenomena. In this poster we present 3D radiative transfer simulations of T Tauri type discs with an inhomogeneous dust distribution to investigate the effect of a clumpy medium on the dust temperature distribution. Our initial results indicate that the structure of the dust temperature distribution is rather insensitive to the structure of the ISM, but nevertheless we find a clear and systematic dependence on the parameters describing the structure of the clumpiness of the dust medium.

In order for the magneto-rotational instability to take place, we need a sufficiently ionized disk. Here, we study, besides viscous dissipation, another heating mechanism for the disk that involves the damping of Alfvén waves due to its interaction with dust grains.

CONDOR, the CO, N+, Deuterium Observations Receiver, is designed to make velocity-resolved observations of the CO, [NII], and p-H2D+ lines in the 1.4 THz (200-240μm) atmospheric windows. CONDOR's first light observations were made with the APEX telescope in November 2005. The CONDOR beam on APEX (at ν = 1.5 THz) was expected to consist of a 4.3″ main beam and a 73″ error beam; this beam structure was verified from scans of Mars. The pointing accuracy, also determined from Mars scans, was better than 7″. The average atmospheric transmission during our Orion observations (elev~57°) was 19 ± 4% along the line-of-sight. A forward efficiency of Feff = 0.8 was determined from sky dips, and observations of the Moon and Mars were used to couple the CONDOR beam to sources of different sizes (ηc = 0.40 and ~0.10, respectively). For more information, see Wiedner et al. 2006.

Intergalactic HII regions, far from the confines of a galactic disk, represent a mode of star formation in low-density gas outside of galaxies. The figure below (left) shows an R-band continuum image of NGC 1533 from the SINGG Hα survey (Meurer et al. 2006) overlaid with HI contours and the location of three intergalactic HII regions discovered by Ryan-Weber et al. (2004). The HI contours are 1.6, 2.0, 2.4, 2.8, 3.2 and 4.0 ×1020 cm−2 and have a resolution of ~1′. ACS/HRC images of the intergalactic HII regions (right) are composites of UV, V, and I bands. The half-light radii of the clusters associated with regions 1, 2, and 5 are 24.7, 21.7, and 17.0 pc, respectively, at the distance to NGC 1533 (21 Mpc; Tonry et al. 2001). Assuming a Salpeter IMF with Mup = 100, Hα/UV ratios indicate a small number of ionizing O stars relative to the total number of UV-emitting O and B stars. These young (4-6 Myr), intergalactic stellar populations lend valuable insight to our understanding of the methods by which star formation is triggered and may even represent the first episodes of star formation in emerging galaxies.

We consider the possibility to study the nature of MHD turbulence in star-forming regions with three different kinds of polarimetric data, namely, the linear polarization of starlight due to extinction by aligned dust grains, the polarized dust thermal radiation at far infrared or submillimeter wavelengths, and the linear polarization of molecular lines due to the Goldreich-Kylafis effect in the anisotropic MHD medium.

The CON+Deuterium Observations Receiver (CONDOR) is a heterodyne receiver that operates between 1250–1530 GHz. Its primary goal is to observe star-forming regions in CO, N+, and H2D+ emission.

The combination of spatial and spectral resolution allow us to use Chandra in the study regions of massive star formation which had been inaccessible even from the ground until the last decade. IRAC and MIPS data from Spitzer can be combined with the X–ray data to provide insight into the presence of a disk and the activity of the star. The total package allows us to better understand the evolution of the clusters. We have an ongoing program to study several young star forming clusters including distant clusters between 1-3 kpc which support O stars, RCW 38, NGC 281 and RCW 108 and well as clusters within a kpc including IRAS 20050+2720 and NGC 1579, which is a small cluster centered on the Be star LkHα101 and is of uncertain distance although the X-ray data help us refine the current distance estimates. Given the space constraints we only discuss RCW 108 below.

We numerically model winds driven by super star clusters (SSC) using the hydrodynamic code ZEUS with the new radiative cooling procedure. The importance of cooling on the wind dynamics depends on the properties of the central cluster: the energy and mass deposition rates Lsc and Ṁsc, and the cluster radius Rsc. Low mass clusters behave adiabatically, and their winds are well described by the solution of Chevalier & Clegg (1985). However, for larger Lsc and Ṁsc and/or smaller Rsc, cooling becomes important, and the wind enters the radiative regime in which the wind temperature quickly drops to 104 K at a small distance away from the cluster (Silich et al., 2004). There is no stationary wind solution for very energetic and compact clusters. This is expressed by the line of the critical luminosity Lcrit shown by the left panel as a function of Rsc.

In the case of SSC above the threshold line, the stagnation point Rst appears inside the cluster. It splits the cluster volume into two parts: the outer one with r > Rst where the wind velocity is always positive, and the inner one r < Rst where it has a complicated time-dependent profile. The mass inserted into the outer region leaves the cluster in a form of quasi-stationary wind, while most of the mass from the inner region either accumulates there or passes the inner boundary and eventually feeds further star formation. The middle figure shows that the stagnation point Rst asymptotically approaches the cluster radius Rsc with the increasing Lsc.

The right figure summarises several of our calculations for a cluster with an Rsc = 10 pc. It shows the amount of the mass Ṁout outflowing from the cluster depending on Lsc. It can be seen that Ṁout grows with Lsc following the power-law fit of the simulations Ṁout ≈ Lsc0.54. However, the fraction of the outflowing mass to the total mass deposited by the cluster Ṁsc decreases with Lsc from 100% for Lsc = Lcrit to several percent for Lsc = 5 × 1044 erg s−1.

Collision between molecular clouds is considered an efficient mechanism to trigger cloud collapse to form stars. Various observations show that the process is taking place in the universe (Vallee 1995; Wang et al. 2004).

We examined observational characteristics of multi-phase turbulent flows in the diffuse interstellar medium (ISM) by calculating atomic and molecular carbon lines. Radiation field maps of C+, C0, and CO line emissions were generated by calculating the non-local thermodynamic equilibrium (nonLTE) level populations and high resolution hydrodynamic simulations of diffuse ISM. By analyzing synthetic line emission, we found a high ratio between the lines of high- and low-excitation energies in the diffuse multi-phase interstellar medium. Our results shows that simultaneous observations of the lines of warm- and cold-gas tracers will be useful in examining the thermal structure, and hence the origin of diffuse interstellar clouds.

Large-scale CO observations with the millimeter/submillimeter telescope NANTEN toward a whole FIR loop-like structure whose angular extent is ~20° × 20° around (l, b) ~(109°, − 45°) in Pegasus have been carried out in the 12CO (J = 1 − 0) at 4′ – 8′ grid spacing and the 12CO emitting region in the 13CO (J=1–0) at 2′ grid spacing. The diameter corresponds to ~25 pc at a distance of 100 pc, adopted from that of the star HD886(B2IV) near the center of the loop.

The new molecular image obtained by NANTEN telescope in the galactic center has revealed the existence of the two loop like structures, loop 1 and loop 2, which have never been seen before toward l = 355° to 358°. The velocities of loop 1 and loop 2 are −180 to −90 km s−1 and −90 and −40 km s−1, respectively, and these two loops have strong velocity gradients. The foot points of the loops show a very broad linewidth of ~40 to 80 km s−1 whose large velocity spans are characteristic of the molecular gas near the galactic center. Therefore, we classified the loops as being located in the galactic center and adopt a distance of 8.5 kpc. Then, the projected lengths of loop 1 and loop 2 were estimated as ~500 and ~300 pc, respectively and velocity gradients corresponds to ~80 km s−1 per 250 pc along loop 1 and ~60 km s−1 per 150 pc along loop 2. The heights of these loops are also estimated as ~220 to ~300 pc from the galactic plane, significantly higher than the typical scale height in the nuclear disk.