Molecular clouds have a tiny fraction of ions, but high enough to make them to be dynamically sensitive to the presence of the interstellar magnetic field. The role of the magnetic field in the dynamics of the molecular clouds at all scales, and in the process of the star formation, have been a source of vivid debate for the last 3 decades. A relatively strong magnetic filed can prevent...
Protoplanetary disks are thought to form through the gravitational collapse of magne-
tized, rotating dense cores. In this talk, I will review work conducted during an enjoyable
and fruitful collaboration with Daniele Galli on the gravitational collapse phase and the
structure of magnetized protoplanetary disks.
To enable the formation of rotationally supported disks, the magnetic flux...
This talk revisits the mass scales for planets that form through the action of gravitational instability in circumstellar disks. After including the effects of magnetic fields, we show that several alternate ways to specify the mass of forming planets converge to the same result under the constraint that the parental disks are marginally stable (with stability parameter Q=1). Next we show...
In this presentation, I will discuss the magnetic field properties at all spatial scales (cloud, core, disk) of one of the best studied high-mass star-forming regions, the massive protocluster G31.41+0.31. Dust polarization observations of this massive core carried out with the SMA at 870 microns and 1” (3750 au) have revealed one of the most clear examples up to date of an hourglass-shaped...
Among 10% of intermediate mass stars, particularly the group of chemically peculiar Ap/Bp-type stars, have very strong magnetic fields of order 1 kGauss or even above. As the stars are radiative,, the magnetic fields are difficult to explain via a dynamo, but are often considered to possible have an origin of fossil fields from the interstellar medium. In this talk, we assess this possibility,...
Magnetic fields in starless, prestellar cores are crucial for understanding the formation of stars, as these cores mark the initial gravitationally bound stage in the star-formation process. Typically, these cores accumulate gas from their molecular cloud environments until they overcome magneto-turbulent support and collapse into protostellar objects. Traditional studies of magnetic fields in...
Interferometric polarization observations have revealed that magnetic fields are crucial in the star formation process. However, their relative importance in different environments and their role in stellar multiplicity remain poorly understood. The B-field Orion Protostellar Survey (BOPS) recently observed 870 $\mu$m dust polarization observations of 61 young protostars in the Orion molecular...
Only indirect evidence of the role of magnetic braking in regulating gravitational collapse and the formation of circumstellar disks, such as compact disk sizes and the launching of high-velocity collimated protostellar jets, has been found from observational work.
More direct tests of the magnetic braking shaping the angular momentum of the gas in Class 0 protostars are crucially needed to...
The evolution of astrophysical dust during early star formation phases is crucial for understanding planet formation and the magnetic fields have a role in regulating this process. Theoretical models mainly proposed two dominant mechanisms of dust polarization with mm/sub-mm wavelengths; dust alignment due to the magnetic fields (e.g., Lazarian 2007) and self-scattering of dust grains (e.g.,...
Magnetic fields play a dynamically crucial role in massive star formation. Models of massive star formation suggest that the magnetic field could significantly prevent fragmentation, cloud and core collapse, and influence the formation of accretion disks and jets. However, there are many aspects that ultimately lead to the formation of massive stars and star clusters that still remain...
Star formation through the dynamical magnetized collapse remains an active area of astrophysical research. We carry out a comprehensive exploration on the magnetized gravitational collapse of a non-rotating self-gravitating initially spherically symmetric prestellar cloud core using two-dimensional nonideal magnetohydrodynamic simulations incorporating ambipolar diffusion and Ohmic...
At the beginning of the 21st century, the prevailing belief was that primarily super-Alfvénic turbulence could rival gravity in the process of star formation. In the following decade, however, perceptions began to shift as polarized thermal dust emission indicated that cloud-scale magnetic fields were predominantly ordered, suggesting that both turbulence and gravitational contraction were...
The collapse of singular magnetized toroids (Li & Shu 1996) is a natural representation of an early phase in star formation, bridging the prestellar and protostellar phases of the collapse of molecular cloud cores. We revisit the collapse study of Allen et al. (2003), now with explicit nonideal MHD (Ohmic diffusivity $\eta$) and higher resolution using a code able to cover a broader range of...
The formation of astrophysical objects of different nature, from black holes to
gaseous giant planets, involves a disk-jet system, where the disk drives the mass accretion onto a central compact object and the jet is a fast collimated ejection along the disk rotation axis. Magnetohydrodynamic disk winds can provide the
link between mass accretion and ejection, which is essential to ensure...
