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The Large Magellanic Cloud (LMC) has a unique cluster formation history in that nearly all of its globular clusters were formed either $\sim$ 13 Gyr ago or less than $\sim$ 3 Gyr ago. It is not clear what physical mechanism is responsible…
Recent observations of the Small Magellanic Cloud (SMC) have revealed that the HI gas shows a significant amount of rotation (V_c 60 km/s), while no or little rotation is evident for the old stellar populations. We suggest that this unique…
We investigate how the properties of Galactic giant molecular clouds (GMCs) and their denser substructures (clumps) correlate with the local star formation rate. We trace clouds using the $^{12}$CO(3-2) transition, as observed by the CO…
Ongoing accretion of low-metallicity gas onto the disk is a natural prediction of semi-analytical Galactic chemical evolution models. This star formation fuel ameliorates the overproduction of metal-poor G- and K-dwarfs in the solar…
RCW120 is a Galactic HII region having a beautiful ring shape bright in infrared. Our new CO J=1-0 and J=3-2 observations performed with the NANTEN2, Mopra, and ASTE telescopes have revealed that two molecular clouds with a velocity…
We have detected extraplanar cold dust at distances out to > 10 kpc, situated in the halo of the interacting galaxy NGC 4631. The dust emission disk is much thinner than the warped HI disk and new structures emerge. In particular, a giant…
We present 12CO J=1-0 observations from the Caltech Millimeter Array of a field in the nearby spiral galaxy M81. We detect emission from three features that are the size of large giant molecular clouds (GMCs) in the Milky Way Galaxy and…
Sh2-48 is a Galactic HII region located at 3.8 kpc with an O9.5-type star identified at its center. As a part of the FOREST Unbiased Galactic plane Imaging survey using the Nobeyama 45-m telescope (FUGIN) project, we obtained the CO J=1-0…
Using data from the Galactic All-Sky Survey, we have compared the properties and distribution of HI clouds in the disk-halo transition at the tangent points in mirror-symmetric regions of the first quadrant (QI) and fourth quadrant (QIV) of…
The discovery of an HI cloud with peculiar properties at equatorial coordinates (J2000) ra=07h49m, dec=04d30m is presented. The HI object was detected at 21cm using the 300-m NAIC Arecibo telescope. Subsequent follow-up high-resolution…
We have recently identified several high velocity (V < -100 km/s) clouds in the directions of Mrk 509 and PKS 2155-304 that have unusual ionization properties. The clouds exhibit strong C IV absorption with little or no detectable low ion…
Clouds more massive than about $10^5$ M$_\odot$ are potential sites of massive cluster formation. Studying the properties of such clouds in the early stages of their evolution offers an opportunity to test various cluster formation…
New 21cm observations with the Green Bank Telescope show that a significant fraction of the HI in the inner Galaxy's halo 1 kpc from the midplane exists in the form of discrete clouds. Some look very much like a Spitzer ``standard'' diffuse…
The accretion of metal-poor gas sustains galactic star formation. In the Milky Way, this process is fueled by high-velocity clouds (HVCs), yet their fundamental properties have remained elusive in the absence of stellar tracers. Here we…
We present a detailed analysis comparing the velocity fields in molecular clouds and the atomic gas that surrounds them in order to address the origin of the gradients. To that end, we present first-moment intensity-weighted velocity maps…
Complex A is a high-velocity cloud that is traversing through the Galactic halo toward the Milky Way's disk. We combine both new and archival Green Bank Telescope observations to construct a spectroscopically resolved HI~21-cm map of this…
We present the first comparative study of extragalactic GMCs using complete data sets for entire galaxies and a uniform set of reduction and analysis techniques. We present results based on CO observations for the LMC, SMC, M33, M31, IC10…
The formation of molecular clouds out of HI gas is the first step toward star formation. Its metallicity dependence plays a key role to determine star formation through the cosmic history. Previous theoretical studies with detailed chemical…
We have carried out a sample survey in UBVR photometry and proper motions in different directions in the Galaxy, as part of an investigation of galactic structure and evolution. Three fields in the direction of galactic anticentre, centre…
Hierarchical structure formation models predict the existence of large numbers of low velocity dispersion dark halos. Galaxy surveys find far fewer galaxies than predicted by analytical estimates and numerical simulations. In this paper, we…