Protostellar disk formation and transport of angular momentum during magnetized core collapse

By M. Joos, P. Hennebelle, Andrea Ciardi. 2012

238 citations recorded by the source corpus.

Context. Theoretical studies of collapsing clouds have found that even a relatively weak magnetic field may prevent the formation of disks and their fragmentation. However, most previous studies have been limited to cases where the magnetic field and the rotation axis of the cloud are aligned. Aims. We study the transport of angular momentum, and its effects on disk formation, for non-aligned initial configurations and a range of magnetic intensities. Methods. We perform three-dimensional, adaptive mesh, numerical simulations of magnetically supercritical collapsing dense cores using the magneto-hydrodynamic code Ramses. We compute the contributions of all the relevant processes transporting angular momentum, in both the envelope and the region of the disk. We clearly define centrifugally supported disks and thoroughly study their properties. Results. At variance with earlier analyses, we show that the transport of angular momentum acts less efficiently in collapsing cores with non-aligned rotation and magnetic field. Analytically, this result can be understood by taking into account the bending of field lines occurring during the gravitational collapse. For the transport of angular momentum, we conclude that magnetic braking in the mean direction of the magnetic field tends to dominate over both the gravitational and outflow transport of angular momentum. We find that massive disks, containing at least 10% of the initial core mass, can form during the earliest stages of star formation even for mass-to-flux ratios as small as three to five times the critical value. At higher field intensities, the early formation of massive disks is prevented. Conclusions. Given the ubiquity of Class I disks, and because the early formation of massive disks can take place at moderate magnetic intensities, we speculate that for stronger fields, disks will form later, when most of the envelope will have been accreted. In addition, we speculate that some observed early massive disks may actually be outflow cavities, mistaken for disks by projection effects.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/f4774c9608f91d0f03b5065c0f322128f2eb4f7b

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

Citations in the corpus

On the diversity and statistical properties of protostellar discs (2018, background): “If the magnetic field is misaligned with the rotation axis, this can reduce the braking (Hennebelle & Ciardi 2009; Joos et al. 2012; Li et al. 2014).”
The VLA/ALMA Nascent Disk and Multiplicity (VANDAM) Survey of Orion Protostars. II. A Statistical Characterization of Class 0 and Class I Protostellar Disks (2020, background): “Furthermore, nonidealized initial conditions that include turbulence or magnetic fields that are misaligned with respect to the rotation axis can also facilitate the formation of disks (e.g., Hennebelle & Ciardi 2009; Joos et al. 2012; Seifried et al. 2012).”
Ambipolar diffusion in low-mass star formation - I. General comparison with the ideal magnetohydrodynamic case (2015, background): “In cylindrical coordinates, with the z-axis aligned with the mean angular momentum direction vector, the angular momentum flux due to the magnetic field reads (Joos et al. 2012) Fl = − Bθr 4π B .”
Our astrochemical heritage (2012, background): “…et al. (2011), who found rapid growth to ≥100 AU of the circumstellar disk when depletion of the infalling envelope is taken into account, and by Joos et al. (2012), who explored the case of magnetic fields non-aligned with the rotation axis and found less efficient angular momentum transport,…”
TADPOL: A 1.3 mm SURVEY OF DUST POLARIZATION IN STAR-FORMING CORES AND REGIONS (2013, background): “…could have important consequences for the formation of circumstellar disks within rotating envelopes, since preferential misalignment of the B-field and the rotation axis should allow disks to form more easily (Hennebelle & Ciardi 2009; Krasnopolsky et al. 2012; Joos et al. 2012; Li et al. 2013).”
RADIATION MAGNETOHYDRODYNAMIC SIMULATIONS OF PROTOSTELLAR COLLAPSE: NONIDEAL MAGNETOHYDRODYNAMIC EFFECTS AND EARLY FORMATION OF CIRCUMSTELLAR DISKS (2015, background): “Misalignment between magnetic fields and the rotational axis can reduce the efficiency of magnetic braking and enable disk formation when magnetic fields are not too strong (Joos et al. 2012; Krumholz et al. 2013).”
RADIATION MAGNETOHYDRODYNAMIC SIMULATIONS OF PROTOSTELLAR COLLAPSE: PROTOSTELLAR CORE FORMATION (2012, background): “…al. 2008b) and effects of many physical ingredients such as misaligned magnetic fields (Matsumoto & Tomisaka 2004; Machida et al. 2006b; Ciardi & Hennebelle 2010; Joos et al. 2012), metallicities (Machida 2008), and turbulence (Seifried et al. 2012; Santos-Lima et al. 2012) have been investigated.”