scholarly journals The effects of ionizing radiation on star formation in molecular clouds

1991 ◽  
Vol 147 ◽  
pp. 391-393
Author(s):  
F. Bertoldi ◽  
C.F. McKee ◽  
R.I. Klein
Keyword(s):  
Star Formation ◽  
Ionizing Radiation ◽  
Molecular Cloud ◽  
Molecular Clouds ◽  
Massive Star ◽  
Mass Star ◽  
Massive Star Formation ◽  
Before And After ◽  
Low Mass ◽  
Gravitational Stability

The gravitational stability of molecular cloud clumps before and after the onset of massive star formation is discussed. We suggest that the most massive clumps are magnetically supercritical but gravitationally stabilized by the hydromagnetic turbulence caused by FUV photoionization-regulated low-mass star formation in their interiors. The ionizing radiation of an O star can trigger star formation in initially sub- and supercritical clumps.

scholarly journals The effects of ionizing radiation on star formation in molecular clouds

1991 ◽  
Vol 147 ◽  
pp. 391-393
Author(s):  
F. Bertoldi ◽  
C.F. McKee ◽  
R.I. Klein
Keyword(s):  
Star Formation ◽  
Ionizing Radiation ◽  
Molecular Cloud ◽  
Molecular Clouds ◽  
Massive Star ◽  
Mass Star ◽  
Massive Star Formation ◽  
Before And After ◽  
Low Mass ◽  
Gravitational Stability

The gravitational stability of molecular cloud clumps before and after the onset of massive star formation is discussed. We suggest that the most massive clumps are magnetically supercritical but gravitationally stabilized by the hydromagnetic turbulence caused by FUV photoionization-regulated low-mass star formation in their interiors. The ionizing radiation of an O star can trigger star formation in initially sub- and supercritical clumps.

Twinkle little stars: Massive stars are quenched in strong magnetic fields

2018 ◽  
Vol 14 (A30) ◽  
pp. 118-118
Author(s):  
Fatemeh S. Tabatabaei ◽  
M. Almudena Prieto ◽  
Juan A. Fernández-Ontiveros
Keyword(s):  
Star Formation ◽  
Magnetic Fields ◽  
Molecular Clouds ◽  
Massive Star ◽  
Massive Stars ◽  
Radio Continuum ◽  
Small Scale ◽  
Massive Star Formation ◽  
Low Mass ◽  
Formation Efficiency

AbstractThe role of the magnetic fields in the formation and quenching of stars with different mass is unknown. We studied the energy balance and the star formation efficiency in a sample of molecular clouds in the central kpc region of NGC 1097, known to be highly magnetized. Combining the full polarization VLA/radio continuum observations with the HST/Hα, Paα and the SMA/CO lines observations, we separated the thermal and non-thermal synchrotron emission and compared the magnetic, turbulent, and thermal pressures. Most of the molecular clouds are magnetically supported against gravitational collapse needed to form cores of massive stars. The massive star formation efficiency of the clouds also drops with the magnetic field strength, while it is uncorrelated with turbulence (Tabatabaei et al. 2018). The inefficiency of the massive star formation and the low-mass stellar population in the center of NGC 1097 can be explained in the following steps: I) Magnetic fields supporting the molecular clouds prevent the collapse of gas to densities needed to form massive stars. II) These clouds can then be fragmented into smaller pieces due to e.g., stellar feedback, non-linear perturbations and instabilities leading to local, small-scale diffusion of the magnetic fields. III) Self-gravity overcomes and the smaller clouds seed the cores of the low-mass stars.

scholarly journals The role of low-mass star clusters in massive star formation. The Orion case

2013 ◽  
Vol 554 ◽  
pp. A48 ◽  
Author(s):  
V. M. Rivilla ◽  
J. Martín-Pintado ◽  
I. Jiménez-Serra ◽  
A. Rodríguez-Franco
Keyword(s):  
Star Formation ◽  
Massive Star ◽  
Star Clusters ◽  
Mass Star ◽  
Massive Star Formation ◽  
Low Mass

scholarly journals Objective Prism Study of Star Forming Regions

1994 ◽  
Vol 161 ◽  
pp. 470-472
Author(s):  
M. Kun
Keyword(s):  
Star Formation ◽  
Molecular Cloud ◽  
Molecular Clouds ◽  
Wavelength Region ◽  
Mass Star ◽  
Star Forming ◽  
Millimeter Wavelength ◽  
Star Forming Regions ◽  
Low Mass ◽  
Objective Prism

Radio molecular observations in the millimeter wavelength region in the last decade have revealed a number of giant molecular cloud complexes at relatively high galactic latitudes. Examples for such cloud complexes are Cepheus Flare (Lebrun 1986), and Ursa Major and Camelopardalis clouds (Heithausen et al. 1993). Because of their high galactic latitudes, these cloud complexes probably belong to the nearest molecular clouds and among them we may find some nearby regions of low-mass star formation.

scholarly journals Scaled up low-mass star formation in massive star-forming cores in the G333 giant molecular cloud

2016 ◽  
Vol 458 (4) ◽  
pp. 3429-3442 ◽  
Author(s):  
B. Wiles ◽  
N. Lo ◽  
M. P. Redman ◽  
M. R. Cunningham ◽  
P. A. Jones ◽  
...  
Keyword(s):  
Star Formation ◽  
Molecular Cloud ◽  
Massive Star ◽  
Mass Star ◽  
Star Forming ◽  
Giant Molecular Cloud ◽  
Low Mass

scholarly journals Comparison of Low-Mass and High-Mass Star Formation

2015 ◽  
Vol 11 (S315) ◽  
pp. 154-162 ◽  
Author(s):  
Jonathan C. Tan
Keyword(s):  
Star Formation ◽  
Massive Star ◽  
Initial Conditions ◽  
Cluster Formation ◽  
Theoretical Models ◽  
High Mass ◽  
Mass Star ◽  
Massive Star Formation ◽  
Low Mass ◽  
Core Accretion

AbstractI review theoretical models of star formation and how they apply across the stellar mass spectrum. Several distinct theories are under active study for massive star formation, especiallyTurbulent Core Accretion,Competitive AccretionandProtostellar Mergers, leading to distinct observational predictions. These include the types of initial conditions, the structure of infall envelopes, disks and outflows, and the relation of massive star formation to star cluster formation. Even for Core Accretion models, there are several major uncertainties related to the timescale of collapse, the relative importance of different processes for preventing fragmentation in massive cores, and the nature of disks and outflows. I end by discussing some recent observational results that are helping to improve our understanding of these processes.

scholarly journals The elephant in the room: the importance of the details of massive star formation in molecular clouds

2019 ◽  
Vol 488 (2) ◽  
pp. 2970-2975 ◽  
Author(s):  
Michael Y Grudić ◽  
Philip F Hopkins
Keyword(s):  
Star Formation ◽  
Molecular Clouds ◽  
Massive Star ◽  
Initial Conditions ◽  
Mass Function ◽  
Initial Mass Function ◽  
Giant Molecular Clouds ◽  
Massive Star Formation ◽  
Average Mass ◽  
Sampling Schemes

Abstract Most simulations of galaxies and massive giant molecular clouds (GMCs) cannot explicitly resolve the formation (or predict the main-sequence masses) of individual stars. So they must use some prescription for the amount of feedback from an assumed population of massive stars (e.g. sampling the initial mass function, IMF). We perform a methods study of simulations of a star-forming GMC with stellar feedback from UV radiation, varying only the prescription for determining the luminosity of each stellar mass element formed (according to different IMF sampling schemes). We show that different prescriptions can lead to widely varying (factor of ∼3) star formation efficiencies (on GMC scales) even though the average mass-to-light ratios agree. Discreteness of sources is important: radiative feedback from fewer, more-luminous sources has a greater effect for a given total luminosity. These differences can dominate over other, more widely recognized differences between similar literature GMC-scale studies (e.g. numerical methods, cloud initial conditions, presence of magnetic fields). Moreover the differences in these methods are not purely numerical: some make different implicit assumptions about the nature of massive star formation, and this remains deeply uncertain in star formation theory.

scholarly journals Low-mass Star Formation: Observations

2010 ◽  
Vol 6 (S270) ◽  
pp. 25-32 ◽  
Author(s):  
Neal J. Evans
Keyword(s):  
Star Formation ◽  
Molecular Clouds ◽  
Planet Formation ◽  
Mass Star ◽  
Low Mass Stars ◽  
Chemical Changes ◽  
Open Questions ◽  
Low Mass ◽  
Over Time ◽  
The Imf

AbstractI briefly review recent observations of regions forming low mass stars. The discussion is cast in the form of seven questions that have been partially answered, or at least illuminated, by new data. These are the following: where do stars form in molecular clouds; what determines the IMF; how long do the steps of the process take; how efficient is star formation; do any theories explain the data; how are the star and disk built over time; and what chemical changes accompany star and planet formation. I close with a summary and list of open questions.

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