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Table 2
Purpose and use of the millimeter molecular lines.
| Line | Frequ. [GHz] | ncrit (10 K) [cm−3] | Ref. | Advantages | Disadvantages | Used for(a) |
|---|---|---|---|---|---|---|
| 12CO(2–1) | 230.538 | 1 × 101 | 1 | Abundant, low ncrit best (only?) tracer of outflow | Often optically thick, Self-absorption by envelope Does not trace the outflow Self-absorption by envelope Traces only inner part of disk Self-absorption by envelope Barely detected | Mass estimate of outflow, velocity field of disk and outflow Velocity field of disk |
| 13CO(1–0) | 110.201 | 8 × 102 | 1 | Low ncrit mostly optically thin | Does not trace the outflow Self-absorption by envelope | Velocity field of inner disk |
| HCO+ (1–0) | 89.189 | 4.5 × 104 | 2 | High ncrit, strong line | Traces only inner part of disk Self-absorption by envelope | Velocity field of inner disk |
| H13CO+ (1–0) | 86.754 | 4.1 × 104 | 2 | High ncrit, optically thin | Barely detected | Not used |
| HCO+ (3–2) | 267.558 | 1.4 × 106 | 2 | High ncrit, not excited in env. No self-abs. by envelope | Traces only inner part of disk | Velocity field of inner disk |
Notes. (α)We only list the use in this paper. For other targets and conditions, these lines may also be used for other purposes.
References. (1) Bešlić et al. (2021); (2) Shirley (2015).
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