scholarly journals FOREST Unbiased Galactic plane Imaging survey with the Nobeyama 45 m telescope (FUGIN): Molecular clouds toward W 33; possible evidence for a cloud–cloud collision triggering O star formation

2018 ◽  
Vol 70 (SP2) ◽  
Author(s):  
Mikito Kohno ◽  
Kazufumi Torii ◽  
Kengo Tachihara ◽  
Tomofumi Umemoto ◽  
Tetsuhiro Minamidani ◽  
...  
Keyword(s):  
Star Formation ◽  
Molecular Clouds ◽  
Galactic Plane

scholarly journals Molecular clouds and star formation toward the Galactic plane within 216.25° ≤l≤ 218.75° and −0.75° ≤b≤ 1.25°

2016 ◽  
Vol 588 ◽  
pp. A104 ◽  
Author(s):  
Y. Gong ◽  
R. Q. Mao ◽  
M. Fang ◽  
S. B. Zhang ◽  
Y. Su ◽  
...  
Keyword(s):  
Star Formation ◽  
Molecular Clouds ◽  
Galactic Plane

scholarly journals A compendium of distances to molecular clouds in the Star Formation Handbook

2020 ◽  
Vol 633 ◽  
pp. A51 ◽  
Author(s):  
Catherine Zucker ◽  
Joshua S. Speagle ◽  
Edward F. Schlafly ◽  
Gregory M. Green ◽  
Douglas P. Finkbeiner ◽  
...  
Keyword(s):  
Star Formation ◽  
Molecular Clouds ◽  
Galactic Plane ◽  
Large Fraction ◽  
Photometric Data ◽  
Solar Neighborhood ◽  
Optical Data ◽  
Distance Measurements ◽  
Dust Clouds ◽  
Future Work

Accurate distances to local molecular clouds are critical for understanding the star and planet formation process, yet distance measurements are often obtained inhomogeneously on a cloud-by-cloud basis. We have recently developed a method that combines stellar photometric data with Gaia DR2 parallax measurements in a Bayesian framework to infer the distances of nearby dust clouds to a typical accuracy of ∼5%. After refining the technique to target lower latitudes and incorporating deep optical data from DECam in the southern Galactic plane, we have derived a catalog of distances to molecular clouds in Reipurth (2008, Star Formation Handbook, Vols. I and II) which contains a large fraction of the molecular material in the solar neighborhood. Comparison with distances derived from maser parallax measurements towards the same clouds shows our method produces consistent distances with ≲10% scatter for clouds across our entire distance spectrum (150 pc−2.5 kpc). We hope this catalog of homogeneous distances will serve as a baseline for future work.

scholarly journals FOREST Unbiased Galactic Plane Imaging Survey with the Nobeyama 45 m telescope (FUGIN). V. Dense gas mass fraction of molecular gas in the Galactic plane

2019 ◽  
Vol 71 (Supplement_1) ◽  
Author(s):  
Kazufumi Torii ◽  
Shinji Fujita ◽  
Atsushi Nishimura ◽  
Kazuki Tokuda ◽  
Mikito Kohno ◽  
...  
Keyword(s):  
Star Formation ◽  
Molecular Clouds ◽  
Galactic Plane ◽  
Formation Rate ◽  
Molecular Gas ◽  
Galactic Rotation ◽  
Dense Gas ◽  
Gas Formation ◽  
Star Formation In Galaxies ◽  
Fractional Mass

Abstract Recent observations of the nearby Galactic molecular clouds indicate that the dense gas in molecular clouds has quasi-universal properties on star formation, and observational studies of extra-galaxies have shown a galactic-scale correlation between the star formation rate (SFR) and the surface density of molecular gas. To reach a comprehensive understanding of both properties, it is important to quantify the fractional mass of dense gas in molecular clouds, fDG. In particular, for the Milky Way (MW) there are no previous studies resolving fDG disk over a scale of several kpc. In this study, fDG was measured over 5 kpc in the first quadrant of the MW, based on the CO J = 1–0 data in l = 10°–50° obtained as part of the FOREST Unbiased Galactic plane Imaging survey with the Nobeyama 45 m telescope (FUGIN) project. The total molecular mass was measured using 12CO, and the dense gas mass was estimated using C18O. The fractional masses, including fDG, in the region within ±30% of the distances to the tangential points of the Galactic rotation (e.g., the Galactic Bar, Far-3 kpc Arm, Norma Arm, Scutum Arm, Sagittarius Arm, and inter-arm regions) were measured. As a result, an averaged fDG of $2.9^{+2.6}_{-2.6}$% was obtained for the entirety of the target region. This low value suggests that dense gas formation is the primary factor in inefficient star formation in galaxies. It was also found that fDG shows large variations depending on the structures in the MW disk. In the Galactic arms, fDG was estimated to be ∼4%–5%, while in the bar and inter-arm regions it was as small as ∼0.1%–0.4%. These results indicate that the formation/destruction processes of the dense gas and their timescales are different for different regions in the MW, leading to differences in Star formation efficiencies.

scholarly journals Stochastic Star Formation and Magnetic Fields

1990 ◽  
Vol 140 ◽  
pp. 257-258
Author(s):  
J. V. Feitzinger ◽  
E. Harfst ◽  
J. Spicker
Keyword(s):  
Star Formation ◽  
Interstellar Medium ◽  
Molecular Clouds ◽  
Large Scale ◽  
Spiral Structure ◽  
Galactic Plane ◽  
Molecular Gas ◽  
Cell Content ◽  
Star Forming ◽  
Flat Rotation Curves

The model of selfpropagating star formation uses local processes (200 pc cell size) in the interstellar medium to simulate the large scale cooperative behaviour of spiral structure in galaxies. The dynamic of the model galaxies is taken into account via the mass distribution and the resulting rotation curve; flat rotation curves are used. The interstellar medium is treated as a multiphase medium with appropriate cooling times and density history. The phases are: molecular gas, cool HI gas, warm intercloud and HII gas and hot coronal fountain gas. A detailed gas reshuffeling between the star forming cells in the plane and outside the galactic plane controls the cell content. Two processes working stochastically are incooperated: the building and the decay of molecular clouds and the star forming events in the molecular clouds.

The Star Formation Activity of Molecular Clouds in the Galactic Plane

2009 ◽  
Vol 5 (H15) ◽  
pp. 795-795
Author(s):  
Joseph C. Mottram ◽  
Christopher M. Brunt
Keyword(s):  
Star Formation ◽  
Molecular Clouds ◽  
Galactic Plane ◽  
Spatial Scales ◽  
Star Forming ◽  
Star Forming Regions ◽  
Automated Method ◽  
Star Formation Activity

AbstractIt is well known that star formation takes place within molecular clouds. However, current observational surveys and investigations usually start by selecting a sample of sites where star formation is ongoing, thus biasing against those clouds and regions with little or no current formation activity. In an attempt to identify samples of clouds both with and without star formation, and to investigate their properties, we present an automated method for associating clouds identified in new 3D CO data with far-IR/sub-mm sources. Given the large number of surveys of the galactic plane currently planned, ongoing or being released, the methods used here may prove instructive in understanding how, where and under what conditions star formation takes place throughout our Galaxy. In addition, this will allow exploration of the properties of star forming regions on a range of spatial scales.

scholarly journals Characteristic scale of star formation – I. Clump formation efficiency on local scales

2020 ◽  
Vol 500 (1) ◽  
pp. 191-210
Author(s):  
D J Eden ◽  
T J T Moore ◽  
R Plume ◽  
A J Rigby ◽  
J S Urquhart ◽  
...  
Keyword(s):  
Star Formation ◽  
Molecular Clouds ◽  
Milky Way ◽  
Galactic Plane ◽  
Power Spectrum Analysis ◽  
Molecular Gas ◽  
Characteristic Scale ◽  
James Clerk Maxwell ◽  
Formation Efficiency ◽  
Spiral Arm

ABSTRACT We have used the ratio of column densities derived independently from the 850-μm continuum James Clerk Maxwell Telescope Plane Survey and the 13CO/C18O (J = 3 → 2) Heterodyne Inner Milky Way Plane Survey to produce maps of the dense-gas mass fraction (DGMF) in two slices of the Galactic plane centred at ℓ = 30° and 40°. The observed DGMF is a metric for the instantaneous clump formation efficiency (CFE) in the molecular gas. We split the two fields into velocity components corresponding to the spiral arms that cross them, and a two-dimensional power-spectrum analysis of the spiral-arm DGMF maps reveals a break in slope at the approximate size scale of molecular clouds. We interpret this as the characteristic scale of the amplitude of variations in the CFE and a constraint on the dominant mechanism regulating the CFE and, hence, the star formation efficiency in CO-traced clouds.

scholarly journals Effects of initial density profiles on massive star cluster formation in giant molecular clouds

2021 ◽  
Author(s):  
Yingtian Chen ◽  
Hui Li ◽  
Mark Vogelsberger
Keyword(s):  
Angular Momentum ◽  
Star Formation ◽  
Molecular Clouds ◽  
Globular Clusters ◽  
Cluster Formation ◽  
Initial Density ◽  
Giant Molecular Clouds ◽  
Density Profiles ◽  
Stellar Feedback ◽  
Gas Accretion

Abstract We perform a suite of hydrodynamic simulations to investigate how initial density profiles of giant molecular clouds (GMCs) affect their subsequent evolution. We find that the star formation duration and integrated star formation efficiency of the whole clouds are not sensitive to the choice of different profiles but are mainly controlled by the interplay between gravitational collapse and stellar feedback. Despite this similarity, GMCs with different profiles show dramatically different modes of star formation. For shallower profiles, GMCs first fragment into many self-gravitation cores and form sub-clusters that distributed throughout the entire clouds. These sub-clusters are later assembled ‘hierarchically’ to central clusters. In contrast, for steeper profiles, a massive cluster is quickly formed at the center of the cloud and then gradually grows its mass via gas accretion. Consequently, central clusters that emerged from clouds with shallower profiles are less massive and show less rotation than those with the steeper profiles. This is because 1) a significant fraction of mass and angular momentum in shallower profiles is stored in the orbital motion of the sub-clusters that are not able to merge into the central clusters 2) frequent hierarchical mergers in the shallower profiles lead to further losses of mass and angular momentum via violent relaxation and tidal disruption. Encouragingly, the degree of cluster rotations in steeper profiles is consistent with recent observations of young and intermediate-age clusters. We speculate that rotating globular clusters are likely formed via an ‘accretion’ mode from centrally-concentrated clouds in the early Universe.

scholarly journals GASTON: Galactic Star Formation with NIKA2. Evidence for the mass growth of star-forming clumps

2021 ◽  
Author(s):  
A J Rigby ◽  
N Peretto ◽  
R Adam ◽  
P Ade ◽  
M Anderson ◽  
...  
Keyword(s):  
Star Formation ◽  
Large Scale ◽  
Galactic Plane ◽  
High Sensitivity ◽  
High Mass ◽  
Evolutionary Stage ◽  
Mass Star ◽  
Mass Growth ◽  
Star Forming ◽  
Compact Source

Abstract Determining the mechanism by which high-mass stars are formed is essential for our understanding of the energy budget and chemical evolution of galaxies. By using the New IRAM KIDs Array 2 (NIKA2) camera on the Institut de Radio Astronomie Millimétrique (IRAM) 30-m telescope, we have conducted high-sensitivity and large-scale mapping of a fraction of the Galactic plane in order to search for signatures of the transition between the high- and low-mass star-forming modes. Here, we present the first results from the Galactic Star Formation with NIKA2 (GASTON) project, a Large Programme at the IRAM 30-m telescope which is mapping ≈2 deg2 of the inner Galactic plane (GP), centred on ℓ = 23${_{.}^{\circ}}$9, b = 0${_{.}^{\circ}}$05, as well as targets in Taurus and Ophiuchus in 1.15 and 2.00 mm continuum wavebands. In this paper we present the first of the GASTON GP data taken, and present initial science results. We conduct an extraction of structures from the 1.15 mm maps using a dendrogram analysis and, by comparison to the compact source catalogues from Herschel survey data, we identify a population of 321 previously-undetected clumps. Approximately 80 per cent of these new clumps are 70 μm-quiet, and may be considered as starless candidates. We find that this new population of clumps are less massive and cooler, on average, than clumps that have already been identified. Further, by classifying the full sample of clumps based upon their infrared-bright fraction – an indicator of evolutionary stage – we find evidence for clump mass growth, supporting models of clump-fed high-mass star formation.

scholarly journals Molecular Clouds and Star Formation Rate in Disk Galaxies

2016 ◽  
Vol 25 (3) ◽  
Author(s):  
E. O. Vasiliev ◽  
S. A. Khoperskov ◽  
A. V. Khoperskov
Keyword(s):  
Star Formation ◽  
Molecular Clouds ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Disk Galaxies

AbstractWe use

Detection of Molecular Clouds in the Magellanic Bridge: Candidate Star Formation Sites in a Nearby Low-Metallicity System

2006 ◽  
Vol 643 (2) ◽  
pp. L107-L110 ◽  
Author(s):  
N. Mizuno ◽  
E. Muller ◽  
H. Maeda ◽  
A. Kawamura ◽  
T. Minamidani ◽  
...  
Keyword(s):  
Star Formation ◽  
Molecular Clouds ◽  
Low Metallicity
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