Are infrared dark clouds really quiescent?

S. Feng; H. Beuther; Q. Zhang; Th. Henning; H. Linz; S. Ragan; R. Smith

doi:10.1051/0004-6361/201526864

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Volume 592 (August 2016)

A&A, 592 (2016) A21

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Table 5

Parameters from 30 m and APEX observations and estimates based on two hypotheses of fragmentation (thermal Jeans fragmentation and turbulent Jeans fragmentation).

Source	Δυ ^a	σ _obs ^a	T _{30 m}	σ _th	σ _Nth	n _c ^b	λ _th−J ^c	M _th−J ^c	λ _Nth−J ^d	M _Nth−J ^d	λ _cl ^e^g	M _cl ^e^g	(M/l)_cl ^e^g	(M/l)_ATLAS ^f^g	Con.^h
	(km s^-1)	(km s^-1)	(K)	(km s^-1)	(km s^-1)	(10⁵ cm^-3)	(pc)	(M_⊙)	(pc)	(M_⊙)	(pc)	(M_⊙)	M_⊙ pc^-1	M_⊙ pc^-1

			12	0.14	1.29 ± 0.03	1.07	0.07	1.16	0.45	291	1.57	1240		1690 ± 481
G28.34 S	3.07 ± 0.06	1.30 ± 0.03	15	0.15	1.29 ± 0.03	0.72	0.10	1.97	0.55	354	1.91	1510	788	1146 ± 326	0.63 ± 0.04
			18	0.17	1.29 ± 0.03	0.54	0.12	2.99	0.63	409	2.21	1740		858 ± 244

			12	0.14	0.84 ± 0.03	0.79	0.08	1.34	0.34	94.60	–	–	–	–
18530	2.01 ± 0.06	0.85 ± 0.03	15	0.15	0.84 ± 0.03	0.54	0.11	2.28	0.41	115	–	–	–	–	0.62 ± 0.04
			18	0.17	0.84 ± 0.03	0.40	0.14	3.47	0.48	133	–	–	–	–

			12	0.14	0.86 ± 0.04	0.85	0.08	1.30	0.34	97.10	–	–	–	–
18306	2.05 ± 0.10	0.87 ± 0.04	15	0.15	0.86 ± 0.04	0.57	0.11	2.21	0.41	118	–	–	–	–	0.64 ± 0.07
			18	0.17	0.85 ± 0.04	0.43	0.14	3.36	0.47	136	–	–	–	–

			12	0.14	0.88 ± 0.04	0.52	0.10	1.67	0.44	132	1.54	561		391 ± 34
18308	2.09 ± 0.09	0.89 ± 0.04	15	0.15	0.87 ± 0.04	0.35	0.14	2.83	0.53	160	1.87	681	365	265 ± 23	0.60 ± 0.07
			18	0.17	0.87 ± 0.04	0.26	0.18	4.30	0.62	185	2.16	787		198 ± 17

Notes.

^(a)

Measured from H¹³CO⁺ (1 → 0) in a 40′′× 40′′ region (from [20′′, 20′′] to [−20′′, −20′′] offset, corresponding to ~1.5 × 10⁵ AU) obtained from 30 m observations.

^(b)

n_c is measured from ATLASGAL dust emission at 870 μm.

^(c)

Thermal Jeans length (λ_th−J) and mass (M_th−J) are predicted from ATLASGAL dust emission at 870 μm.

^(d)

Turbulent Jeans length (λ_Nth−J) and mass (M_Nth−J) are predicted from 30 m observations on H¹³CO⁺ (1 → 0).

^(e)

The critical mass and length of cylindrical fragmentation are predicted from 30 m observations on the velocity dispersion of H¹³CO⁺ (1 → 0), Eqs. (12)–(14).

^(f)

The linear mass densities at different dust temperatures (assuming T_ATLAS = T_{30 m}) are predicted from ATLASGAL dust emission at 870 μm.

^(g)

The values in IRDC 18306 and IRDC 18308 are not given, because the fragments in each source do not align well along the large-scale filamentary direction.

^(h)

Concentration of the gas in the filamentary scale is estimated from ATLASGAL dust emission at 870 μm (temperature independent).

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