Collapse and Fragmentation of Molecular Cloud Cores. VII. Magnetic Fields and Multiple Protostar Formation

2002 ◽  
Vol 568 (2) ◽  
pp. 743-753 ◽  
Author(s):  
Alan P. Boss
Keyword(s):  
Magnetic Fields ◽  
Molecular Cloud ◽  
Cloud Cores

scholarly journals Magnetic Fields in Molecular Cloud Cores

1990 ◽  
Vol 140 ◽  
pp. 291-292
Author(s):  
Z.P. Zhou ◽  
X.W. Zheng
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Circular Polarization ◽  
Molecular Cloud ◽  
Zeeman Splitting ◽  
Hii Regions ◽  
Observational Evidence ◽  
Hii Region ◽  
Vlbi Observations ◽  
Cloud Cores

Strong circular polarization of OH masers at 1665 and 1667 MHz lines has been observed towards the molecular cloud cores associated with HII regions. Magnetic field strengths of a few mG are derived from the Zeeman splitting of OH lines. For instance, a magnetic field of about 4 mG in the masing region of W3(OH) has been estimated by OH-line Zeeman splitting (Davies, 1974). VLBI observations show that the OH maser spots project onto or very close to the surface of associated compact HII regions (Reid et al., 1986). The observational evidence demonstrates that the scales of OH maser components surrounding a compact HII region (R ~ 1016 cm) are about 1014 cm in diameter with an amplification pathlength of ~1015 cm. Hence the magnetic fields determined by the Zeeman splitting of OH maser lines appear partly very close to the associated HII region. Elitzur (1979) has theoretically obtained similar results as above.

scholarly journals Aperture synthesis CS and 98 GHz continuum observations of protostellar IRAS sources in Taurus

1991 ◽  
Vol 147 ◽  
pp. 353-356
Author(s):  
N. Ohashi ◽  
R. Kawabe ◽  
M. Hayashi ◽  
M. Ishiguro
Keyword(s):  
Molecular Cloud ◽  
Total Mass ◽  
T Tauri Stars ◽  
Continuum Emission ◽  
Beam Size ◽  
Dust Grains ◽  
Dynamical Mass ◽  
T Tauri ◽  
Cloud Cores ◽  
The Continuum

The CS (J = 2 — 1) line and 98 GHz continuum emission have been observed for 11 protostellar IRAS sources in the Taurus molecular cloud with resolutions of 2.6″−8.8″ (360 AU—1200 AU) using the Nobeyama Millimeter Array (NMA). The CS emission is detected only toward embedded sources, while the continuum emission from dust grains is detected only toward visible T Tauri stars except for one embedded source, L1551-IRS5. This suggests that the dust grains around the embedded sources do not centrally concentrate enough to be detected with our sensitivity (∼4 m Jy r.m.s), while dust grains in disks around the T Tauri stars have enough total mass to be detected with the NMA. The molecular cloud cores around the embedded sources are moderately extended and dense enough to be detected in CS, while gas disks around the T Tauri are not detected because the radius of such gas disks may be smaller than 70 (50 K/Tex) AU. These results imply that the total amount of matter within the NMA beam size must increase when the central objects evolve into T Tauri stars from embedded sources, suggesting that the compact and highly dense disks around T Tauri stars are formed by the dynamical mass accretion during the embedded protostar phase.

scholarly journals Chemical variation in molecular cloud cores in the Orion A Cloud. III

2014 ◽  
Vol 66 (6) ◽  
pp. 119 ◽  
Author(s):  
Satoshi Ohashi ◽  
Ken'ichi Tatematsu ◽  
Minho Choi ◽  
Miju Kang ◽  
Tomofumi Umemoto ◽  
...  
Keyword(s):  
Molecular Cloud ◽  
Chemical Variation ◽  
Cloud Cores
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