scholarly journals Star Formation and Galactic Evolution: From Protogalaxies to Starbursts

1987 ◽  
Vol 115 ◽  
pp. 663-689 ◽  
Author(s):  
Joseph Silk
Keyword(s):  
Star Formation ◽  
Physical Mechanism ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Mass Function ◽  
Initial Mass Function ◽  
Galactic Evolution ◽  
Solar Neighborhood ◽  
Formation Theory ◽  
Formation Efficiency

Three topics in star formation theory are reviewed: the initial mass function, the star formation efficiency, and the star formation rate. A physical mechanism for bimodal star formation is developed. Applications are made to the solar neighborhood, to the inner galaxy, to starburst galaxies, and to past star formation in protodisks and in protoellipticals. Implications are drawn for galactic morphology, for chemical evolution, and for the present density of stellar remnants.

scholarly journals Bimodal Star Formation and Remnant-Dominated Galactic Models

1987 ◽  
Vol 117 ◽  
pp. 413-413
Author(s):  
Richard B. Larson
Keyword(s):  
Star Formation ◽  
Formation Rate ◽  
Mass Function ◽  
Current Data ◽  
Initial Mass Function ◽  
Solar Neighborhood ◽  
Gas Content ◽  
High Mass ◽  
Stellar Content ◽  
Stellar Initial Mass Function

Current data on the luminosity function of nearby stars allow the possibility that the stellar initial mass function (IMF) is double-peaked and that the star formation rate (SFR) has decreased substantially with time. It is then possible to account for all of the unseen mass in the solar vicinity as stellar remnants. A model for the solar neighborhood has been constructed in which the IMF is bimodal, the SFR is constant for the low-mass mode and strongly decreasing for the high-mass mode, and the mass in remnants is equal to the column density of unseen matter; this model is found to be consistent with all of the available constraints on the evolution and stellar content of the solar neighborhood. In particular, the observed chemical evolution is satisfactorily reproduced without infall. The total SFR in the model decreases roughly with the 1.4 power of the gas content, which is more plausible than the nearly constant SFR required by models with a monotonic IMF.

scholarly journals Star Formation of Star Clusters in the SMC and their Adjoining Fields

1986 ◽  
Vol 116 ◽  
pp. 101-102
Author(s):  
M. Kontizas ◽  
E. Kontizas
Keyword(s):  
Star Formation ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Star Clusters ◽  
Mass Function ◽  
Spectroscopic Studies ◽  
Initial Mass Function ◽  
The West ◽  
West Side ◽  
Halo Population

Photometric and recent spectroscopic studies of the SMC have shown that the differences observed in the SMC clusters and those of our Galaxy could be attibuted to differences in metallicity, star formation rate and/or the Initial Mass Function (IMF) (Humphries, 1983). The studied clusters NGC152 and KRON3 are located at the west side of the bar of the SMC and their adjoining fields represent the halo population of this galaxy.

scholarly journals Modes of star formation from Herschel

2012 ◽  
Vol 8 (S292) ◽  
pp. 87-90
Author(s):  
L. Testi ◽  
E. Bressert ◽  
S. Longmore
Keyword(s):  
Star Formation ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Mass Function ◽  
Initial Mass Function ◽  
Dense Gas ◽  
Nearby Star ◽  
Star Forming ◽  
Star Forming Regions ◽  
Massive Cluster

AbstractWe summarize some of the results obtained from Herschel surveys of nearby star forming regions and the Galactic plane. We show that in the nearby star forming regions the starless core spatial surface density distribution is very similar to that of the young stellar objects. This, taken together with the similarity between the core mass function and the initial mass function for stars and the relationship between the amount of dense gas and star formation rate, suggest that the cloud fragmentation process defines the global outcome of star formation. This “simple” view of star formation may not hold on all scales. In particular dynamical interactions are expected to become important at the conditions required to form young massive clusters. We describe the successes of a simple criterion to identify young massive cluster precursors in our Galaxy based on (sub-)millimeter wide area surveys. We further show that in the location of our Galaxy where the best candidate for a precursor of a young massive cluster is found, the “simple” scaling relationship between dense gas and star formation rate appear to break down. We suggest that in regions where the conditions approach those of the central molecular zone of our Galaxy it may be necessary to revise the scaling laws for star formation.

scholarly journals How feedback shapes galaxies: an analytic model

2019 ◽  
Vol 491 (4) ◽  
pp. 5083-5100
Author(s):  
Jaime Salcido ◽  
Richard G Bower ◽  
Tom Theuns
Keyword(s):  
Dark Matter ◽  
Star Formation ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Mass Function ◽  
Stellar Mass ◽  
Mass Relation ◽  
Analytic Model ◽  
The Galaxy ◽  
Formation Efficiency

ABSTRACT We introduce a simple analytic model of galaxy formation that links the growth of dark matter haloes in a cosmological background to the build-up of stellar mass within them. The model aims to identify the physical processes that drive the galaxy-halo co-evolution through cosmic time. The model restricts the role of baryonic astrophysics to setting the relation between galaxies and their haloes. Using this approach, galaxy properties can be directly predicted from the growth of their host dark matter haloes. We explore models in which the effective star formation efficiency within haloes is a function of mass (or virial temperature) and independent of time. Despite its simplicity, the model reproduces self-consistently the shape and evolution of the cosmic star formation rate density, the specific star formation rate of galaxies, and the galaxy stellar mass function, both at the present time and at high redshifts. By systematically varying the effective star formation efficiency in the model, we explore the emergence of the characteristic shape of the galaxy stellar mass function. The origin of the observed double Schechter function at low redshifts is naturally explained by two efficiency regimes in the stellar to halo mass relation, namely, a stellar feedback regulated stage, and a supermassive black hole regulated stage. By providing a set of analytic differential equations, the model can be easily extended and inverted, allowing the roles and impact of astrophysics and cosmology to be explored and understood.

scholarly journals Calibration of Star-Formation Rate Measurements Across the Electromagnetic Spectrum

2012 ◽  
Vol 10 (H16) ◽  
pp. 495-527
Author(s):  
V. Buat ◽  
J. Braine ◽  
D. A. Dale ◽  
A. Hornschemeier ◽  
B. Lehmer ◽  
...  
Keyword(s):  
Star Formation ◽  
Radiative Transfer ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Mass Function ◽  
Initial Mass Function ◽  
Stellar Atmospheres ◽  
Electromagnetic Spectrum ◽  
X Rays ◽  
Multi Wavelength

AbstractStar-formation is one of the main processes that shape galaxies, and together with black-hole accretion activity the two agents of energy production in galaxies. It is important on a range of scales from star clusters/OB associations to galaxy-wide and even group/cluster scales. Recently, studies of star-formation in sub-galactic and galaxy-wide scales have met significant advances owing to: (a) developments in the theory of stellar evolution, stellar atmospheres, and radiative transfer in the interstellar medium; (b) the availability of more sensitive and higher resolution data; and (c) observations in previously poorly charted wavebands (e.g. Ultraviolet, Infrared, and X-rays). These data allow us to study more galaxies at ever-increasing distances and nearby galaxies in greater detail, and different modes of star formation activity such as massive star formation and low level continuous star formation in a variety of environments. In this contribution we summarize recent results in the fields of multi-wavelength calibrations of star-formation rate indicators, the Stellar Initial Mass function, and radiative transfer and modeling of the Spectrale Energy Disrtributions of galaxies.

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