Inferring the evolutionary stages of the internal structures of NGC 7538 S and IRS1 from chemistry

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Volume 593 (September 2016)

A&A, 593 (2016) A46

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Table 1

Properties of continuum substructures in IRS1 and NGC 7538 S, identified in Fig. 1.


Source		RA	Dec	Peak flux I_ν	Size (θ^d)	T _rot	N _{H_2,1} ^e,g	N _{H_2,2} ^f,g	M ^m	Alternative
		[J2000]	[J2000]	(mJy / beam)	(″×″, PA°)	(K)	(10²³ cm^-2)	(10²³ cm^-2)	(M_⊙)	designations
		23^h13^m	61°


IRS1	IRS1-peak			1945.1 ± 182.3	0.49″ × 0.43″, 13°	214 ± 66^h	− ^k	44.07 ± 31.51	− ^k
IRS1	IRS1-mmS			126.4 ± 3.1	0.61″ × 0.37″, 87°	162 ± 14ⁱ	− ^k	− ^l	− ^k	SW extension^a


	MM1			32.2 ± 1.1	0.87″ × 0.64″, 153°	172 ± 23 ⁱ	16.90 ± 2.52	16.50 ± 1.91	3.28 ± 0.52	1a:SMA3^b, CARMA S_A1^c
S										1b:SMA4^b, CARMA S_A2^c
										1c:SMA5^b


	MM2			25.7 ± 0.8	1.08″ × 0.59″, 166°	137 ± 14 ⁱ	17.05 ± 2.11	2.70 ± 0.19	2.54 ± 0.30	2:SMA2^b, S_B^c


	MM3			27.0 ± 1.1	0.68″ × 0.49″, 170°	50 ^j	52.49 ± 2.14	0.29 ± 0.01	≤ 6.58	3:SMA1^b, S_C^c


	JetN			σ = 0.12	−	150 ^j	≤ 0.27	2.54 ± 0.01	−


	JetS			σ = 0.27	−	150 ^j	≤ 0.61	3.33 ± 0.03	−

Notes.

^(a)

Zhu et al. (2013).

^(b)

Naranjo-Romero et al. (2012).

^(c)

Wright et al. (2012).

^(d)

Projection size is fitted with 2D Gaussian.

^(e)

H₂ column densities are calculated from the continuum using Eq. (1). The uncertainties come from the measurement of the continuum fluxes and the calculation of temperatures.

^(f)

H₂ column densities are calculated from C¹⁸O conversion. The uncertainties come from the Gaussian fit to C¹⁸O (2 → 1) and the excitation temperatures.

^(g)

The column density estimates in MM1–MM3 from dust continuum are thought more reliable than that derived from C¹⁸O conversion (see Appendix ).

^(h)

Temperature lower limit is taken by assuming the same as in IRS1-mmS, and upper limit is taken from Goddi et al. (2015; see details in Sect. 5.1).

⁽ⁱ⁾

Temperature derived from rotation diagram of CH₃CN in Fig. 4.

^(j)

Temperature assumed based on estimation from Sandell & Wright (2010).

^(k)

Continuum is dominated by free-free emission at 219 GHz.

^(l)

Column density could not be obtained because C¹⁸O (2 → 1) shows P-Cygni profile.

^(m)

Mass on scale of 0.01 pc is derived from Eq. (2), based on total flux reported in Beuther et al. (2012), which is corrected for free-free contribution and with >90% missing flux.

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