Star Formation in Molecular Clouds

Shu, Frank H.

doi:10.1007/978-94-009-5291-1_112

Cited by 9 publications

(3 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It also plays an important rôle in star formation processes (e.g. Shu 1985;Beck et al 1996;Ferrière 2001). Furthermore, observations of the detailed structure of the magnetic field can provide constraints for Galactic dynamo models (Han et al 1997).…”

Section: Introductionmentioning

confidence: 99%

Multi-frequency polarimetry of the Galactic radio background around 350 MHz

Haverkorn

Katgert²,

Bruyn³

2003

A&A

View full text Add to dashboard Cite

Abstract. With the Westerbork Synthesis Radio Telescope (WSRT), multi-frequency polarimetric images were taken of the diffuse radio synchrotron background in a ∼5 • × 7 • region centered on (l, b) = (161 • , 16 • ) in the constellation of Auriga. The observations were done simultaneously in 5 frequency bands, from 341 MHz to 375 MHz, and have a resolution of ∼5.0 × 5.0 cosec δ. The polarized intensity P and polarization angle φ show ubiquitous structure on arcminute and degree scales, with polarized brightness temperatures up to about 13 K. On the other hand, no structure at all is observed in total intensity I to an rms limit of 1.3 K, indicating that the structure in the polarized radiation must be due to Faraday rotation and depolarization mostly in the warm component of the nearby Galactic interstellar medium (ISM). Different depolarization processes create structure in polarized intensity P. Beam depolarization creates "depolarization canals" of one beam wide, while depth depolarization is thought to be responsible for creating most of the structure on scales larger than a beam width. Rotation measures (RM) can be reliably determined, and are in the range −17 < ∼ RM < ∼ 10 rad m −2 with a non-zero average RM 0 ≈ −3.4 rad m −2 . The distribution of RMs on the sky shows both abrupt changes on the scales of the beam and a gradient in the direction of positive Galactic longitude of ∼1 rad m −2 per degree. The gradient and average RM are consistent with a regular magnetic field of ∼1 µG which has a pitch angle of p = −14 • . There are 13 extragalactic sources in the field for which RMs could be derived, and those have |RM| < ∼ 13 rad m −2 , with an estimated intrinsic source contribution of ∼3.6 rad m −2 . The RMs of the extragalactic sources show a gradient that is about 3 times larger than the gradient in the RMs of the diffuse emission and that is approximately in Galactic latitude. This difference is ascribed to a vastly different effective length of the line of sight. The RMs of the extragalactic sources also show a sign reversal which implies a reversal of the magnetic field across the region on scales larger than about ten degrees. The observations are interpreted in terms of a simple single-cell-size model of the warm ISM which contains gas and magnetic fields, with a polarized background. The observations are best fitted with a cell size of 10 to 20 pc and a ratio of random to regular magnetic fields B ran /B reg ≈ 0.7 ± 0.5. The polarization horizon, beyond which most diffuse polarized emission is depolarized, is estimated to be at a distance of about 600 pc.

show abstract

Section: Introductionmentioning

confidence: 99%

Multi-frequency polarimetry of the Galactic radio background around 350 MHz

Haverkorn

Katgert²,

Bruyn³

2003

A&A

View full text Add to dashboard Cite

show abstract

“…The formation of more massive stars could require substantially different accretion/ejection processes. For the mass accretion rates predicted by theory (e.g., [14]), the accretion time becomes longer than the protostar contraction time for masses ≥8 M ⊙ . At this point, the star reaches the ZAMS and, as a consequence, its radiation pressure would be sufficient to halt the inflow [17], thus preventing further increase of the stellar mass.…”

Section: Introductionmentioning

confidence: 93%

High-Mass Star Formation and Maser VLBI

Moscadelli¹

2015

Proceedings of 12th European VLBI Network Symposium and Users Meeting — PoS(EVN 2014)

View full text Add to dashboard Cite

“…Hayashi [1] has discussed the problem of evolution of protostars and discusses the different phase of formation of protostar in connection with variation of temperature and density. Shu et al [2] have investigated the problem of star formation in molecular clouds and concluded that the star formation occurs mainly in four phases. In this problem, the self-gravitational instability of dust and gas plays important role.…”

Section: Introductionmentioning

confidence: 99%

Effect of Radiative Heat-Loss Function and Finite Larmor Radius Corrections on Jeans Instability of Viscous Thermally Conducting Self-Gravitating Astrophysical Plasma

Kaothekar

Chhajlani

2012

ISRN Astronomy and Astrophysics

View full text Add to dashboard Cite

The effect of radiative heat-loss function and finite ion Larmor radius (FLR) corrections on the self-gravitational instability of infinite homogeneous viscous plasma has been investigated incorporating the effects of thermal conductivity and finite electrical resistivity for the formation of a star in astrophysical plasma. The general dispersion relation is derived using the normal mode analysis method with the help of relevant linearized perturbation equations of the problem. Furthermore the wave propagation along and perpendicular to the direction of external magnetic field has been discussed. Stability of the medium is discussed by applying Routh Hurwitz's criterion. We find that the presence of radiative heat-loss function and thermal conductivity modify the fundamental Jeans criterion of gravitational instability into radiative instability criterion. From the curves we see that temperature dependent heat-loss function, FLR corrections and viscosity have stabilizing effect, while density dependent heat-loss function has destabilizing effect on the growth rate of self-gravitational instability. Our result shows that the FLR corrections and radiative heat-loss functions affect the star formation.

show abstract

Star Formation in Molecular Clouds

Cited by 9 publications

References 26 publications

Multi-frequency polarimetry of the Galactic radio background around 350 MHz

Multi-frequency polarimetry of the Galactic radio background around 350 MHz

High-Mass Star Formation and Maser VLBI

Effect of Radiative Heat-Loss Function and Finite Larmor Radius Corrections on Jeans Instability of Viscous Thermally Conducting Self-Gravitating Astrophysical Plasma

Contact Info

Product

Resources

About