Searching for trans ethyl methyl ether in Orion KL

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Volume 582 (October 2015)

A&A, 582 (2015) L1

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Table 1

Column densities and ratios.

Species	N_g.s. (×10¹⁵) [cm^-2]	N Ratio

CH₃OCH₃ (DME)	600 ± 120 ^a^b
CH₃CH₂OCH₃ (tEME)	≤ 4.0 ± 0.8 ^a	DME/tEME ≥ 150
CH₃CH₂OCH₂CH₃	≤ 1.0 ± 0.2 ^a	DME/Tt-DEE ≥ 600
(Tt-DEE)^†		tEME/Tt-DEE ≥ 4
CH₃OCHCH₂	≤ 0.5 ± 0.1 ^a	DME/cis-MVE ≥ 1200
(cis-MVE)^††		tEME/cis-MVE ≥ 9
CH₃OCOH (MF)	240 ± 50 ^a^b^c
CH₃CH₂OCOH (EF)	2.0 ± 0.4 ^a^d	MF/EF ≃ 120
CH₃OH (MetOH)	2700 ± 500 ^b^e^f
CH₃CH₂OH (EtOH)	60 ± 10 ^b^d^e	MetOH/EtOH ≃ 45
Gt-CH₃CH₂CH₂OH	1.0 ± 0.2 ^e	MetOH/PropOH ≃ 2700
(PropOH)		EtOH/PropOH ≃ 60

Notes.

^(†)

trans-trans diethyl ether.

^(††)

cis methyl vinyl ether.

^(a)

Position A; same physical parameters of the ALMA tEME model (see Sect. 3.1).

^(b)

Three kinetic temperatures: 50 ± 10, 150 ± 30, and 250 ± 75 K.

^(c)

b type lines fitted (a type lines are optically thick); another component has been included to properly fit the observed line profiles (v_LSR = +9 km s^-1, Δv = 4 km s^-1, T_K = 150 ± 30 K, N_g.s = (1.0 ± 0.2) × 10¹⁷ cm^-2).

^(d)

trans+gauche.

^(e)

Position B; assuming the same physical parameters of the ALMA Gt-n-propanol model (see Sect. 3.2).

^(f)

¹²C/¹³C = 45 (Tercero et al. 2010).

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