Open AccessCollapse and fragmentation of rotating magnetized clouds – I. Magnetic flux–spin relation
Author(s) -
Machida Masahiro N.,
Matsumoto Tomoaki,
Tomisaka Kohji,
Hanawa Tomoyuki
Publication year - 2005
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2005.09297.x
Subject(s) - physics , magnetic flux , core (optical fiber) , flux (metallurgy) , angular velocity , magnetic field , astrophysics , magnetic cloud , atomic physics , computational physics , classical mechanics , optics , quantum mechanics , coronal mass ejection , materials science , solar wind , metallurgy
We discuss the evolution of the magnetic flux density and angular velocity in a molecular cloud core, on the basis of three‐dimensional numerical simulations, in which a rotating magnetized cloud fragments and collapses to form a very dense optically thick core of >5 × 10 10 cm −3 . As the density increases towards the formation of the optically thick core, the magnetic flux density and angular velocity converge towards a single relationship between the two quantities. If the core is magnetically dominated its magnetic flux density approaches 1.5( n /5 × 10 10 cm −3 ) 1/2 mG , while if the core is rotationally dominated the angular velocity approaches 2.57 × 10 −3 ( n /5 × 10 10 cm −3 ) 1/2 yr −1 , where n is the density of the gas. We also find that the ratio of the angular velocity to the magnetic flux density remains nearly constant until the density exceeds 5 × 10 10 cm −3 . Fragmentation of the very dense core and emergence of outflows from fragments will be shown in the subsequent paper.