Table 1
Observational and spectroscopic parameters related to the molecular lines presented in this work.
| Serpens filament | Serpens South | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Transition | Frequency (MHz) | Eu/k (K) | A (s−1) | µ (D) | nc(H2) (cm−3) | θbean (″) | ηmb/ηf | σ (mK) | δυ (km s−1) | σ (mK) | δυ (km s−1) | Telescope |
| (1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) | (9) | (10) | (11) | (12) | (13) |
| HCNH+ J= 1 − 0 | 74111.302(3) | 3.6 | 1.4 × 10−7 | 0.29 | 2.0 × 102 | 33 | 0.87 | – | – | 51 | 0.20 | IRAM-30 m |
| HCNH+ J = 2 − 1 | 148 221.450(17) | 10.7 | 1.3 × 10−6 | 0.29 | 1.7× 103 | 18 | 0.78 | 21 | 0.21 | 58 | 0.21 | IRAM-30 m |
| HCNH+ J = 3 − 2 | 222329.277(8) | 21.3 | 4.9 × 10−6 | 0.29 | 5.2 × 103 | 27 | 0.80 | 28 | 0.08 | 20 | 0.08 | APEX |
| H13CN J = 1 − 0 | 86 339.921(1) | 4.1 | 2.2 × 10−5 | 2.99 | 5.3 × 105 | 28 | 0.85 | 22 | 0.17 | 24 | 0.68 | IRAM-30 m |
| HN13C J = 1 − 0 | 87 090.825(4) | 4.2 | 1.9 × 10−5 | 2.70 | 1.4× 105 | 28 | 0.85 | 18 | 0.17 | 26 | 0.67 | IRAM-30 m |
| H13CO+ J = 1 − 0 | 86 754.288(5) | 4.2 | 3.9 × 10−5 | 3.90 | 6.2 × 104 | 28 | 0.85 | 40 | 0.17 | 27 | 0.68 | IRAM-30 m |
| N2H+ J = 1 − 0 | 93 173.398(1) | 4.5 | 3.6 × 10−5 | 3.40 | 6.1 × 104 | 26 | 0.84 | 19 | 0.16 | 26 | 0.63 | IRAM-30 m |
Notes. (1) Observed transition. All transitions were observed in on-the-fly mode except for HCNH+ (3−2), which was observed as a single pointing toward Serpens South. (2) Rest frequency taken from the Cologne Database for Molecular Spectroscopy (CDMS, https://cdms.ast.ro.uni-koeln.de/; Endres et al. 2016). Uncertainties in the last digits are given in parentheses. For the observed lines, only the frequency of the strongest HFS component is listed. (3) Upper energy level of the observed transition. (4) Einstein A coefficient. (5) Dipole moment from CDMS (Endres et al. 2016). (6) Optically thin H2 critical density at a kinetic temperature of 10 K. The critical densities of HCNH+ transitions are calculated using the collisional rate coefficients from Bop & Lique (2023) and Eq. (4) in Shirley (2015). For the other lines, the values are directly taken from Table 1 in Shirley (2015). The critical density of HN13C (1−0) is assumed to be the same as that of HNC (1−0). (7) HPBW. (8) ηf and ηmb are the forward efficiency and main beam efficiency, respectively. (9) RMS level at the smoothed angular resolution of 36″.3. (10) Velocity channel spacing. (11) RMS level at the smoothed angular resolution of 36″.3. For pointed HCNH+ (3−2) observations in Serpens South, the RMS level is estimated at the original angular resolution of 27″. (12) Velocity channel spacing. (13) Telescope.
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