scholarly journals Testing the Paradigm of Low Mass Star Formation

2004 ◽  
Vol 221 ◽  
pp. 201-212
Author(s):  
Lee Hartmann
Keyword(s):  
Star Formation ◽  
Magnetic Fields ◽  
Standard Model ◽  
Molecular Clouds ◽  
Class I ◽  
Stellar Systems ◽  
Mass Star ◽  
Core Formation ◽  
The Standard Model ◽  
Low Mass

Protostellar core formation is probably much more dynamic, and magnetic fields are probably much less important, than has been previously assumed in the standard model of low-mass star formation. This revised picture has important consequences: it is easier to understand the observed rapidity of star formation in molecular clouds; cores are more likely to have structures favoring high infall rates at early times, helping to explain the differences between Class 0 and Class I protostars; and core structure and asymmetry will strongly favor post-collapse fragmentation into binary and multiple stellar systems.

scholarly journals The Mopra DQS survey of the G333 region

2006 ◽  
Vol 2 (S237) ◽  
pp. 404-404
Author(s):  
M. R. Cunningham ◽  
I. Bains ◽  
N. Lo ◽  
T. Wong ◽  
M. G. Burton ◽  
...  
Keyword(s):  
Star Formation ◽  
Magnetic Fields ◽  
Standard Model ◽  
Molecular Clouds ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Star Forming ◽  
Successful Model ◽  
The Standard Model ◽  
Forming Efficiency

Any successful model of star formation must be able to explain the low star forming efficiency of molecular clouds in our Galaxy. If the collapse of gas is regulated only by gravity, then the star formation rate should be orders of magnitude larger than the 1 M per year within our galaxy. The standard model invokes magnetic fields to slow down the rate of collapse, but does not explain star formation in cluster mode, or the lack of observed variations in the chemistry of molecular clouds if they are long-lived entities.

scholarly journals Submillimeter Array Observations of Magnetic Fields in Star Forming Regions

2010 ◽  
Vol 6 (S270) ◽  
pp. 103-106
Author(s):  
R. Rao ◽  
J.-M. Girart ◽  
D. P. Marrone
Keyword(s):  
Magnetic Field ◽  
Star Formation ◽  
Magnetic Fields ◽  
Computational Models ◽  
Dominant Role ◽  
Theoretical Models ◽  
Mass Star ◽  
Star Forming ◽  
Star Forming Regions ◽  
Low Mass

AbstractThere have been a number of theoretical and computational models which state that magnetic fields play an important role in the process of star formation. Competing theories instead postulate that it is turbulence which is dominant and magnetic fields are weak. The recent installation of a polarimetry system at the Submillimeter Array (SMA) has enabled us to conduct observations that could potentially distinguish between the two theories. Some of the nearby low mass star forming regions show hour-glass shaped magnetic field structures that are consistent with theoretical models in which the magnetic field plays a dominant role. However, there are other similar regions where no significant polarization is detected. Future polarimetry observations made by the Submillimeter Array should be able to increase the sample of observed regions. These measurements will allow us to address observationally the important question of the role of magnetic fields and/or turbulence in the process of star formation.

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 Tracing the Mass during Low‐Mass Star Formation. IV. Observations and Modeling of the Submillimeter Continuum Emission from Class I Protostars

2003 ◽  
Vol 145 (1) ◽  
pp. 111-145 ◽  
Author(s):  
Chadwick H. Young ◽  
Yancy L. Shirley ◽  
Neal J. Evans II ◽  
Jonathan M. C. Rawlings
Keyword(s):  
Star Formation ◽  
Class I ◽  
Continuum Emission ◽  
Mass Star ◽  
Low Mass

scholarly journals The detection of class I methanol masers towards regions of low-mass star formation

2006 ◽  
Vol 50 (4) ◽  
pp. 289-297 ◽  
Author(s):  
S. V. Kalenskiĭ ◽  
V. G. Promyslov ◽  
V. I. Slysh ◽  
P. Bergman ◽  
A. Winnberg
Keyword(s):  
Star Formation ◽  
Class I ◽  
Mass Star ◽  
Low Mass ◽  
Methanol Masers

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.

VLA observations of class I methanol masers in the region of low-mass star formation L1157

2010 ◽  
Vol 54 (10) ◽  
pp. 932-939 ◽  
Author(s):  
S. V. Kalenskii ◽  
S. Kurtz ◽  
V. I. Slysh ◽  
P. Hofner ◽  
C. M. Walmsley ◽  
...  
Keyword(s):  
Star Formation ◽  
Class I ◽  
Mass Star ◽  
Low Mass ◽  
Methanol Masers

scholarly journals Class I methanol masers in low-mass star formation regions

2017 ◽  
Vol 13 (S336) ◽  
pp. 33-36
Author(s):  
S. Kalenskii ◽  
S. Kurtz ◽  
P. Hofner ◽  
P. Bergman ◽  
C.M. Walmsley ◽  
...  
Keyword(s):  
Star Formation ◽  
Class I ◽  
Mass Star ◽  
Star Forming ◽  
Star Forming Regions ◽  
Brightness Temperatures ◽  
Push Forward ◽  
Low Mass ◽  
Methanol Masers ◽  
Star Formation Regions

AbstractWe present a review of the properties of Class I methanol masers detected in low-mass star forming regions (LMSFRs). These masers, henceforth called LMMIs, are associated with postshock gas in the lobes of chemically active outflows in LMSFRs NGC1333, NGC2023, HH25, and L1157. LMMIs share the main properties with powerful masers in regions of massive star formation and are a low-luminosity edge of the total Class I maser population. However, the exploration of just these objects may push forward the exploration of Class I masers, since many LMSFRs are located only 200–300 pc from the Sun, making it possible to study associated objects in detail. EVLA observations with a 0.2″ spatial resolution show that the maser images consist of unresolved or barely resolved spots with brightness temperatures up to 5 × 105 K. The results are “marginally” consistent with the turbulent model of maser emission.

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