Table 6.

Abundances relative to H₂ in different environments (in units of 10⁻¹⁰).

Molecule	Orion Bar1*	Horsehead		Orion KL		L1157-B17	IRAS 16293-24228	B1-b9
	PDR	PDR2*	Core3*	HC4	CR5	Outflow	Hot corino	Dense core
HCO	1.7	8.4b	< 0.8b	—	< 0.36,g	—	< 2.0	0.2n
HNCO	0.2	—	—	780h	—	605k	1.7	0.7p
H2CO	9.0	2.9c	2.0c	1200h	440h	4000l	7.0	4.6q
H2CS	0.8	—	—	150h	74h	1100l	—	0.9q
t-HCOOH†	0.2a	0.5d	0.1d	800i	—	—	< 3.0	0.1n
CH2NH	0.2	—	—	42h	—	—	< 5.0	—
H2CCO	0.9	1.5d	0.5d	—	51h	—	1.8	0.2n
HC3N	0.07	0.06e	0.08e	81h	—	100l	0.3	3.1r
CH3OH	5.0	1.2f	2.3f	22000h	12000h	115000l	44	31r,s
CH3CN	0.2	2.5e	0.08e	300h	120h	—	1.5	0.4r
CH3CHO	0.8	0.7d	0.2d	9.5i	—	250m	1.0	0.1n
CH3CCH	< 1.0	4.4d	3.0d	24i	1336,i	—	6.5	5.0r

Notes.

^*Abundances with respect to total hydrogen nuclei.

^†To date, the cis conformer of HCOOH has only been detected towards the Orion Bar PDR (Cuadrado et al. 2016), therefore, we only provide the abundances of the trans conformer.

⁽¹⁾This work. Abundances calculated assuming uniform beam filling.

Ref.:

^(a)Cuadrado et al. (2016).

⁽²⁾Low-UV field Horsehead PDR (χ ≈ 60; N_H = 3.8 × 10²² cm⁻²)

⁽³⁾condensation shielded from the UV field (dense core, N_H = 6.4 × 10²² cm⁻²) behind the Horsehead PDR edge.

Ref.:

^(b)Gerin et al. (2009)

^(c)Guzmán et al. (2011)

^(d)Guzmán et al. (2014)

^(e)Gratier et al. (2013)

^(f)Guzmán et al. (2013).

⁽⁴⁾Orion KL Hot Core (HC)

⁽⁵⁾Orion KL Compact Ridge (CR).

⁽⁶⁾Abundances calculated for the Extended Ridge.

Ref.:

^(g)Blake et al. (1987)

^(h)Crockett et al. (2014)

⁽ⁱ⁾B. Tercero, private communication.

⁽⁷⁾Peak B1 in the blue lobe of the L1157.

Ref.:

^(k)Mendoza et al. (2014)

^(l)Bachiller & Pérez Gutiérrez (1997)

^(m)Codella et al. (2015).

⁽⁸⁾Low-mass protostar (hot corino) IRAS 16293-2422. The abundances are computed for a N(H₂) = 2 × 10²³ cm⁻². Abundances averaged over a ~20″ beam (van Dishoeck et al. 1995).

⁽⁹⁾Quiescent dark core Barnard 1-b (B1-b), N(H₂) = 1.3 × 10²³ cm⁻² (see e.g. Hirano et al. 1999; Lis et al. 2002).

Ref.:

⁽ⁿ⁾Cernicharo et al. (2012)

^(p)Marcelino et al. (2009)

^(q)Marcelino et al. (2005)

^(r)N. Marcelino, private communication

^(s)Öberg et al. (2010).