Distribution Of Giant Molecular Clouds Research Articles

Gibbs point process model for young star clusters in M33

ABSTRACT We demonstrate the power of Gibbs point process models from the spatial statistics literature when applied to studies of resolved galaxies. We conduct a rigorous analysis of the spatial distributions of objects in the star formation complexes of M33, including giant molecular clouds (GMCs) and young stellar cluster candidates (YSCCs). We choose a hierarchical model structure from GMCs to YSCCs based on the natural formation hierarchy between them. This approach circumvents the limitations of the empirical two-point correlation function analysis by naturally accounting for the inhomogeneity present in the distribution of YSCCs. We also investigate the effects of GMCs’ properties on their spatial distributions. We confirm that the distribution of GMCs and YSCCs are highly correlated. We found that the spatial distributions of YSCCs reaches a peak of clustering pattern at ∼250 pc scale compared to a Poisson process. This clustering mainly occurs in regions where the galactocentric distance ≳4.5 kpc. Furthermore, the galactocentric distance of GMCs and their mass have strong positive effects on the correlation strength between GMCs and YSCCs. We outline some possible implications of these findings for our understanding of the cluster formation process.

Accretion in the Center of the Milky Way

AbstractWe have analyzed the distribution of giant molecular clouds and their radial velocities in the inner ~ 300 pc of the Milky Way in order to deduce the characteristic properties of its large scale motion. We find radial inflow of matter towards the Galactic Center of ~ 10−2 M⊙/yr. Moreover, we have determined the position of individual clouds along the line of sight.

Submillimeter continuum survey of the Galactic center

view Abstract Citations (116) References (67) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Submillimeter Continuum Survey of the Galactic Center Lis, D. C. ; Carlstrom, J. E. Abstract We have conducted a survey of the 800 micron continuum emission from an approximately 1.5 deg x 0.2 deg area around the Galactic center with the objective to study the distribution of high-density material in the nuclear disk and to investigate the contribution of high-mass star formation to the luminosity and ionization of this region. Toward known high-mass star-forming regions, such as Sgr B2 and Sgr C, the large-scale distribution of the submillimeter continuum emission, which traces the temperature-weighted column density of dust, correlates well with the distribution of the radio continuum and far-infrared emission. However, in the Sgr A complex and the vicinity of the radio arc the correlation between the distribution of Giant Molecular Clouds (GMC) cores traced by the dust emission and those of compact far-infrared sources and compact H II regions is poor. This may indicate that many of the dust cores detected in our survey are heated by the diffuse external radiation field rather than embedded young stars. In particular, there is no evidence for embedded far-infrared sources or compact H II regions associated with the dust cores located in a dust ridge which bridges the radio arc and Sgr B1. These dust cores may be unusually cold. The two major sites of high-mass star formation in the nuclear disk, Sgr B2 and Sgr C, appear to coincide with the location of the inner Lindblad resonance. This region has been suggested as a location of enhanced star formation in circumnuclear regions of a number of barred galaxies. Publication: The Astrophysical Journal Pub Date: March 1994 DOI: 10.1086/173882 Bibcode: 1994ApJ...424..189L Keywords: Continuums; Disk Galaxies; Interstellar Matter; Molecular Clouds; Star Formation; Emission Spectra; Line Spectra; Stellar Luminosity; Astrophysics; GALAXY: CENTER; ISM: CLOUDS; ISM: INDIVIDUAL NAME: SAGITTARIUS A; ISM: INDIVIDUAL NAME: SAGITTARIUS B; ISM: INDIVIDUAL NAME: SAGITTARIUS C; STARS: FORMATION full text sources ADS | data products SIMBAD (9)

Accretion of gaseous disks of galaxies. II. Allowance for viscosity in a disk consisting of giant molecular clouds

The evolution of the distribution of giant molecular clouds in galaxies under the influence of dynamical friction on stars and viscosity is calculated in the approximation of a collisionless gas. It is shown that in principle the joint action of the viscosity and the dynamical friction can lead to the formation of the ring-shaped distribution of giant molecular clouds in the Galaxy with a maximum at 6-7 kpc from the center during a time of the order of a few billion years.

Accretion of gaseous disks of galaxies. I. Influence of dynamical friction on the large-scale H2 distribution

The influence of dynamical friction on stars on the global distribution of giant molecular clouds in galaxies is calculated in different model approximations. It is shown that in their Galaxy dynamical friction alone cannot lead to the formation of the observed ring-shaped distribution of the giant molecular clouds during a time comparable with the age of the disk of the Galaxy.

Formation of Giant Molecular Clouds by Coagulation of Small Molecular Clouds in a Spiral Gravitational Potential

The formation process of giant molecular clouds (GMCs) is investigated from the standpoint of the coagulation theory of molecular clouds. Small clouds collide with each other and grow to become massive ones. Ultimately they form GMCs with a finite lifetime. The occurrence of star formation in a GMC destroys it and consequently small clouds are formed again. We study the time evolution of the clouds which move through a spiral gravitational potential by an N-body simulation. Then the ensemble of clouds responds to the spiral potential and forms a spiral structure similar to that produced by hydrodynamical galactic shock. It is shown that GMCs are formed in the spiral arm region by collisions between clouds. The distribution of GMCs indicates their short lifetime, of the order of a few times 107 years.