Query : 2016A&A...586A.126L

2016A&A...586A.126L - Astronomy and Astrophysics, volume 586A, 126-126 (2016/2-1)

A rotating helical filament in the L1251 dark cloud.


Abstract (from CDS):

We derive the physical properties of a filament discovered in the dark cometary-shaped cloud L1251. Mapping observations in the NH3(1, 1) and (2, 2) inversion lines, encompassing 300 positions toward L1251, were performed with the Effelsberg 100-m telescope at a spatial resolution of 40'' and a spectral resolution of 0.045km/s. The filament L1251A consists of three condensations (α, β, and γ) of elongated morphology, which are combined in a long and narrow structure covering a 38'x3' angular range (∼3.3pcx0.3pc). Comparing the kinematics with the more extended envelope (∼61'x33') emitting in 13CO, we find that: (1) the angular velocity of the envelope around the horizontal axis E-W is ΩEWCO≃-2x10–14rad/s (the line-of-sight velocity is more negative to the north); (2) approximately one half of the filament (combined α and β condensations) exhibits counter-rotation with ΩEWαβ≃2x10–14rad/s; (3) one third of the filament (the γ condensation) co-rotates with ΩEWγ≃-2x10–14rad/s; (4) the central part of the filament between these two kinematically distinct regions does not show any rotation around this axis; (5) the whole filament revolves slowly around the vertical axis S-N with ΩSNtot≃7x10–15rad/s. The opposite chirality (dextral and sinistral) of the αβ and γ condensations indicates magnetic field helicities of two types, negative and positive, which were most probably caused by dynamo mechanisms. We estimated the magnetic Reynolds number Rm≳600 and the Rossby number R<1, which means that dynamo action is important.

Abstract Copyright:

Journal keyword(s): ISM: clouds - ISM: molecules - ISM: kinematics and dynamics - radio lines: ISM - techniques: spectroscopic - line: profiles

Simbad objects: 6

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Number of rows : 6
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
1 GAL 029.96-00.02 Y*O 18 46 03.7 -02 39 21           ~ 339 1
2 LDN 1247 DNe 22 21.9 +75 06           ~ 16 0
3 LDN 1251A DNe 22 30 31.8 +75 14 17           ~ 73 2
4 LDN 1251 DNe 22 36.1 +75 16           ~ 100 0
5 LDN 1215 DNe 22 51.9 +62 06           ~ 7 0
6 NAME Cep Flare MoC 23 34 +72.0           ~ 109 0

    Equat.    Gal    SGal    Ecl

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