All Tables

Table 1: Line parameters for the all the species and data reported in this paper. When two spatial resolutions are indicated, we refer to the HBPW's corresponding to the IRAM 30-m and the SEST telescopes respectively. ^(a) Observed at the CSO. ^(b) Observed at the Effelsberg 100-m telescope. See Sect. 3 for details.
Table 2: Column densities and abundances relative to H₂ (boldface) inferred at positions of interest in the Horsehead, IC 63 and L1688-W. ^(d) 10¹² cm^-2. Units for column densities are in cm^-2 and indicated in superscript for each molecule. Units for abundances are indicated in the first column of each corresponding row. The offsets refer to the positions indicated Figs. 6 and 9.
Table 3: Carbon budget derived in PDRs (this work), diffuse ISM (from Bell et al. 1983; Federman et al. 1994; Shuping et al. 1999; Lucas & Liszt 2000; Roueff et al. 2002; Cernicharo et al. 2002; Rachford et al. 2002) and dark clouds (from Pratap et al. 1997; Bell et al. 1998; Dickens et al. 2000; Turner et al. 2000; Fossé et al. 2001; Fossé 2003). Note that, for a given number of carbon atoms, the molecules found in the different regions may differ (e.g. no C_n carbon clusters in PDRs and dark clouds). For the diffuse ISM, we used the C/H abundance ratio of $1.4\times 10^{-4}$ reported by Cardelli et al. (1996) and assumed an H/H₂ abundance ratio of 0.6 as observed in the $\zeta$ Oph line of sight (e.g. Rachford et al. 2002).
Table 4: Fractional abundances relative to C₂H. The assumed column densities of C₂H are recalled in the first row. CP stands for Cyanopolyyne Peak. References are: ^(a) Pratap et al. 1997, ^(b) Fossé et al. 2001, ^(c) Guélin et al. 1982, ^(d) Fossé 2003, ^(e) Dickens et al. 2000, ^(f) Takano et al. 1998. Since no C₆H and HC₃N measurements were available at the Horsehead IR peak, the corresponding abundances relative to C₂H are given for the hydrocarbon peak.