scholarly journals Case Studies of Mass Transfer and Star Formation in Galaxy Collisions

2004 ◽  
Vol 217 ◽  
pp. 400-405
Author(s):  
Curtis Struck
Keyword(s):  
Mass Transfer ◽  
Star Formation ◽  
Case Studies ◽  
Structural Parameters ◽  
Dynamical Models ◽  
Star Forming ◽  
Star Forming Regions ◽  
Individual Star ◽  
Galaxy Collisions

The amount, timing and ultimate location of mass transfer and induced star formation in galaxy collisions are sensitive functions of orbital and galaxy structural parameters. I discuss the role of detailed case studies and describe the results for two systems, Arp 284 and NGC 2207/IC 2163, that have been studied with both multiwaveband observations, and detailed dynamical models. The models yield the mass transfer and compressional histories of the encounters and the “probable causes” or triggers of individual star-forming regions.

scholarly journals The Role of Magnetic Fields in Star Forming Regions

1990 ◽  
Vol 140 ◽  
pp. 259-267
Author(s):  
L Mestel
Keyword(s):  
Magnetic Field ◽  
Star Formation ◽  
Magnetic Fields ◽  
The Self ◽  
Galactic Magnetic Field ◽  
Star Forming ◽  
Star Forming Regions

The flux from the galactic magnetic field alters radically the appropriate description of the equilibrium, collapse and fragmentation of the self-gravitating gas clouds that are the locale of star formation.

scholarly journals Probing Individual Star Forming Regions Within Strongly Lensed Galaxies at z > 1

2014 ◽  
Vol 10 (S309) ◽  
pp. 251-254
Author(s):  
Matthew B. Bayliss ◽  
Jane R. Rigby ◽  
Keren Sharon ◽  
Michael D. Gladders ◽  
Eva Wuyts
Keyword(s):  
Star Formation ◽  
Gravitational Lensing ◽  
Velocity Structure ◽  
Spectroscopic Studies ◽  
Uv Spectra ◽  
Star Forming ◽  
Star Forming Regions ◽  
Wide Range ◽  
Individual Star ◽  
Multi Wavelength

AbstractStar formation occurs on physical scales corresponding to individual star forming regions, typically of order ∼100 parsecs in size, but current observational facilities cannot resolve these scales within field galaxies beyond the local universe. However, the magnification from strong gravitational lensing allows us to measure the properties of these discrete star forming regions within galaxies in the distant universe. New results from multi-wavelength spectroscopic studies of a sample of extremely bright, highly magnified lensed galaxies are revealing the complexity of star formation on sub-galaxy scales during the era of peak star formation in the universe. We find a wide range of properties in the rest-frame UV spectra of individual galaxies, as well as in spectra that originate from different star forming regions within the same galaxy. Large variations in the strengths and velocity structure of Lyman-alpha and strong P Cygni lines such as C IV, and MgII provide new insights into the astrophysical relationships between extremely massive stars, the elemental abundances and physical properties of the nebular gas those stars ionize, and the galactic-scale outflows they power.

scholarly journals The role of Galactic H II regions in the formation of filaments

2020 ◽  
Vol 638 ◽  
pp. A7 ◽  
Author(s):  
A. Zavagno ◽  
Ph. André ◽  
F. Schuller ◽  
N. Peretto ◽  
Y. Shimajiri ◽  
...  
Keyword(s):  
Star Formation ◽  
Profile Analysis ◽  
Spatial Scales ◽  
Intensity Profile ◽  
Mass Star ◽  
Star Forming ◽  
Star Forming Regions ◽  
Dense Shell ◽  
The Impact

Context. Massive stars and their associated ionized (H II) regions could play a key role in the formation and evolution of filaments that host star formation. However, the properties of filaments that interact with H II regions are still poorly known. Aims. To investigate the impact of H II regions on the formation of filaments, we imaged the Galactic H II region RCW 120 and its surroundings where active star formation takes place and where the role of ionization feedback on the star formation process has already been studied. Methods. We used the large-format bolometer camera ArTéMiS on the APEX telescope and combined the high-resolution ArTéMiS data at 350 and 450 μm with Herschel-SPIRE/HOBYS data at 350 and 500 μm to ensure good sensitivity to a broad range of spatial scales. This allowed us to study the dense gas distribution around RCW 120 with a resolution of 8′′ or 0.05 pc at a distance of 1.34 kpc. Results. Our study allows us to trace the median radial intensity profile of the dense shell of RCW 120. This profile is asymmetric, indicating a clear compression from the H II region on the inner part of the shell. The profile is observed to be similarly asymmetric on both lateral sides of the shell, indicating a homogeneous compression over the surface. On the contrary, the profile analysis of a radial filament associated with the shell, but located outside of it, reveals a symmetric profile, suggesting that the compression from the ionized region is limited to the dense shell. The mean intensity profile of the internal part of the shell is well fitted by a Plummer-like profile with a deconvolved Gaussian full width at half maximum of 0.09 pc, as observed for filaments in low-mass star-forming regions. Conclusions. Using ArTéMiS data combined with Herschel-SPIRE data, we found evidence for compression from the inner part of the RCW 120 ionized region on the surrounding dense shell. This compression is accompanied with a significant (factor 5) increase of the local column density. This study suggests that compression exerted by H II regions may play a key role in the formation of filaments and may further act on their hosted star formation. ArTéMiS data also suggest that RCW 120 might be a 3D ring, rather than a spherical structure.

scholarly journals The Spatially-Resolved Star Formation History of the M31 Disk from Resolved Stellar Populations

2014 ◽  
Vol 10 (S309) ◽  
pp. 57-60
Author(s):  
Alexia R. Lewis ◽  
Julianne J. Dalcanton ◽  
Andrew E. Dolphin ◽  
Daniel R. Weisz ◽  
Benjamin F. Williams ◽  
...  
Keyword(s):  
Star Formation ◽  
Stellar Populations ◽  
Star Formation History ◽  
Star Forming ◽  
Spatially Resolved ◽  
Star Forming Regions ◽  
Star Formation Activity ◽  
Individual Star ◽  
Star Formation Histories ◽  
Optical Color

AbstractThe Panchromatic Hubble Andromeda Treasury (PHAT) is an HST multi-cycle treasury program that has mapped the resolved stellar populations of ∼1/3 of the disk of M31 from the UV through the near-IR. This data provides color and luminosity information for more than 150 million stars. Using stellar evolution models, we model the optical color-magnitude diagram to derive spatially-resolved recent star formation histories (SFHs) over large areas of M31 with 100 pc resolution. These include individual star-forming regions as well as quiescent portions of the disk. With these gridded SFHs, we create movies of star formation activity to study the evolution of individual star-forming events across the disk. We analyze the structure of star formation and examine the relation between star formation and gas throughout the disk and particularly in the 10-kpc star-forming ring. We find that the ring has been continuously forming stars for at least 500 Myr. As the only large disk galaxy that is close enough to obtain the photometry for this type of spatially-resolved SFH mapping, M31 plays an important role in our understanding of the evolution of an L* galaxy.

scholarly journals warpfield population synthesis: the physics of (extra-)Galactic star formation and feedback-driven cloud structure and emission from sub-to-kpc scales

2020 ◽  
Vol 498 (3) ◽  
pp. 3193-3214 ◽  
Author(s):  
Eric W Pellegrini ◽  
Stefan Reissl ◽  
Daniel Rahner ◽  
Ralf S Klessen ◽  
Simon C O Glover ◽  
...  
Keyword(s):  
Star Formation ◽  
Phase Distribution ◽  
Formation Rate ◽  
Dynamical Evolution ◽  
Multipole Expansion ◽  
Star Forming ◽  
Star Forming Regions ◽  
Individual Star ◽  
Novel Method ◽  
Cloud Evolution

ABSTRACT We present a novel method to model galactic-scale star formation and emission of star clusters and a multiphase interstellar medium (ISM). We combine global parameters, including star formation rate and metallicity, with the 1D cloud evolution code warpfield to model the sources of feedback within a star-forming galaxy. Within individual star-forming regions, we include stellar evolution, stellar winds, radiation pressure, and supernovae, all coupled to the dynamical evolution of the 1D parental cloud in a highly non-linear fashion. Heating of the diffuse galactic gas and dust is calculated self-consistently with the age-, mass-, and density-dependent escape fractions of photons from these fully resolved local star-forming regions. We construct the interstellar radiation field, and we employ the multifrequency radiative transfer code polaris to produce synthetic emission maps for a one-to-one comparison with observations. We apply this to a cosmological simulation of a Milky-Way-like galaxy built-up in a high-resolution MHD simulation of cosmic structure formation. From this, we produce the multiscale/phase distribution of ISM density and temperature and present a synthesized all-sky H  α map. We use a multipole expansion to show that the resulting maps reproduce all observed statistical emission characteristics. Next, we predict [S iii] 9530 Å, a key emission line that will be observed in several large forthcoming surveys. It suffers less extinction than other lines and provides information about star formation in very dense environments that are otherwise observationally inaccessible optically. Finally, we explore the effects of differential extinction, and discuss the consequences for the interpretation of H α emission at different viewing angles by an extragalactic observer.

scholarly journals Cloud–cloud collisions and triggered star formation

2020 ◽  
Author(s):  
Yasuo Fukui ◽  
Asao Habe ◽  
Tsuyoshi Inoue ◽  
Rei Enokiya ◽  
Kengo Tachihara
Keyword(s):  
Star Formation ◽  
Cluster Formation ◽  
High Mass ◽  
Mass Star ◽  
Star Forming ◽  
Star Forming Regions ◽  
Ngc 6334 ◽  
Almost All ◽  
Massive Cluster

Abstract Star formation is a fundamental process for galactic evolution. One issue over the last several decades has been determining whether star formation is induced by external triggers or self-regulated in a closed system. The role of an external trigger, which can effectively collect mass in a small volume, has attracted particular attention in connection with the formation of massive stellar clusters, which in extreme cases may lead to starbursts. Recent observations have revealed massive cluster formation triggered by cloud–cloud collisions in nearby interacting galaxies, including the Magellanic system and the Antennae Galaxies as well as almost all well-known high-mass star-forming regions in the Milky Way, such as RCW 120, M 20, M 42, NGC 6334, etc. Theoretical efforts are going into the foundation for the mass compression that causes massive cluster/star formation. Here, we review the recent progress on cloud–cloud collisions and the triggered star-cluster formation, and discuss future prospects for this area of study.

scholarly journals The Circumstellar Environment of Embedded Massive Stars

2002 ◽  
Vol 12 ◽  
pp. 143-145 ◽  
Author(s):  
Lee G. Mundy ◽  
Friedrich Wyrowski ◽  
Sarah Watt
Keyword(s):  
Massive Star ◽  
Massive Stars ◽  
Low Mass Stars ◽  
Submillimeter Wavelength ◽  
Star Forming ◽  
Star Forming Regions ◽  
Low Mass ◽  
Circumstellar Environments ◽  
Near Future

Millimeter and submillimeter wavelength images of massive star-forming regions are uncovering the natal material distribution and revealing the complexities of their circumstellar environments on size scales from parsecs to 100’s of AU. Progress in these areas has been slower than for low-mass stars because massive stars are more distant, and because they are gregarious siblings with different evolutionary stages that can co-exist even within a core. Nevertheless, observational goals for the near future include the characterization of an early evolutionary sequence for massive stars, determination if the accretion process and formation sequence for massive stars is similar to that of low-mass stars, and understanding of the role of triggering events in massive star formation.

scholarly journals THE STAR-FORMATION-RATE-DENSITY RELATION AT 0.6

2011 ◽  
Vol 735 (1) ◽  
pp. 53 ◽  
Author(s):  
Shannon G. Patel ◽  
Daniel D. Kelson ◽  
Bradford P. Holden ◽  
Marijn Franx ◽  
Garth D. Illingworth
Keyword(s):  
Star Formation ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Star Forming ◽  
Density Relation

scholarly journals The Connection between Molecular Gas and Star Formation in XUV Disks

2016 ◽  
Vol 11 (S321) ◽  
pp. 214-216
Author(s):  
Linda C. Watson
Keyword(s):  
Star Formation ◽  
Molecular Hydrogen ◽  
Optical Disk ◽  
Molecular Gas ◽  
Star Forming ◽  
Star Forming Regions

AbstractWe found that star-forming regions in extended ultraviolet (XUV) disks are generally consistent with the molecular-hydrogen Kennicutt-Schmidt law that applies within the inner, optical disk. This is true for star formation rates based on Hα + 24 μm data or FUV + 24 μm data. We estimated that the star-forming regions have ages of 1 − 7 Myr and propose that the presence or absence of molecular gas provides an additional “clock” that may help distinguish between aging and stochasticity as the explanation for the low Hα-to-FUV flux ratios in XUV disks. This contribution is a summary of the work originally presented in Watson et al. (2016).

scholarly journals Survey of ortho-H2D+ in high-mass star-forming regions

2020 ◽  
Vol 644 ◽  
pp. A34
Author(s):  
G. Sabatini ◽  
S. Bovino ◽  
A. Giannetti ◽  
F. Wyrowski ◽  
M. A. Órdenes ◽  
...  
Keyword(s):  
Star Formation ◽  
Formation Process ◽  
Strong Dependence ◽  
Cosmic Ray ◽  
High Mass ◽  
Clear Correlation ◽  
Mass Star ◽  
Large Sample ◽  
Star Forming ◽  
Star Forming Regions

Context. Deuteration has been suggested to be a reliable chemical clock of star-forming regions due to its strong dependence on density and temperature changes during cloud contraction. In particular, the H3+ isotopologues (e.g. ortho-H2D+) seem to act as good proxies of the evolutionary stages of the star formation process. While this has been widely explored in low-mass star-forming regions, in the high-mass counterparts only a few studies have been pursued, and the reliability of deuteration as a chemical clock remains inconclusive. Aims. We present a large sample of o-H2D+ observations in high-mass star-forming regions and discuss possible empirical correlations with relevant physical quantities to assess its role as a chronometer of star-forming regions through different evolutionary stages. Methods. APEX observations of the ground-state transition of o-H2D+ were analysed in a large sample of high-mass clumps selected from the ATLASGAL survey at different evolutionary stages. Column densities and beam-averaged abundances of o-H2D+ with respect to H2, X(o-H2D+), were obtained by modelling the spectra under the assumption of local thermodynamic equilibrium. Results. We detect 16 sources in o-H2D+ and find clear correlations between X(o-H2D+) and the clump bolometric luminosity and the dust temperature, while only a mild correlation is found with the CO-depletion factor. In addition, we see a clear correlation with the luminosity-to-mass ratio, which is known to trace the evolution of the star formation process. This would indicate that the deuterated forms of H3+ are more abundant in the very early stages of the star formation process and that deuteration is influenced by the time evolution of the clumps. In this respect, our findings would suggest that the X(o-H2D+) abundance is mainly affected by the thermal changes rather than density changes in the gas. We have employed these findings together with observations of H13CO+, DCO+, and C17O to provide an estimate of the cosmic-ray ionisation rate in a sub-sample of eight clumps based on recent analytical work. Conclusions. Our study presents the largest sample of o-H2D+ in star-forming regions to date. The results confirm that the deuteration process is strongly affected by temperature and suggests that o-H2D+ can be considered a reliable chemical clock during the star formation processes, as proved by its strong temporal dependence.

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