| DUST GRAINS | ATOMS | MOLECULES | |||||
|---|---|---|---|---|---|---|---|
wavelengths(µm) | Species | wavelengths(µm) | Species | wavelengths(µm) | Species |
||
| 2.95?, 6.3, 7.1 a | NH3 Ice | 1.88, 2.62, 2.67, 2.76, 4.65, 5.91, 6.6, 7.5, 52.5 | H I | 1.4, 1.8 a | C2 | ||
| 5.2, 5.6, 6.2, 6.9, 7.6, 7.8 | PAH | 3.1, 7.5; 6.6 | Ni I; Ni II | 2.0, 2.6, 7.5 a | C2H2 | ||
| 5.5 a | HCO in Ice | 4.5 | Mg IV, Ar VI (?) | 18 wavelengths to date | CO | ||
| 6.0, 62, 45 a/e | H2O Ice | 5.6 | Mg V | 2.9 a | C2H | ||
| 6.8 a | Hydrocarbon | 6.98 | Ar II | 3.0, 3.5, 7.5 a | HCN | ||
| 19.0 a/e | silicate | 7.63 | Ne III | 5.0 a | C3 | ||
| 24-30+ | MgS (?) | 8.99, 21.8 | Ar III | 8.5 | Si O | ||
| 45, 62 a/e | H2O | 17.9, 26.0 | Fe II | 17.0 | H2 | ||
| 18.7, 33.4 | S III | 53.4, 84.4, 84.6, 119.3, 119.5, 149, 163.1, 164.4, 202 a/e | OH | ||||
| 22.9 | Fe III | 154, 308 | 13CO | ||||
| 24.3 | Ne V | 120.0, 120.2 a/e | 18OH | ||||
| 25.2 | S I | 125, 166, 524 | NH3 | ||||
| 25.9 | O IV | 149.1, 149.4, 203 | CH | ||||
| 34.8 | Si II | 479 | HCl | ||||
| 36.0 | Ne III | 790, 1600 | H2O | ||||
| 51.8, 88.4 | O III | 805 | H2D+ | ||||
| 57.3 | N III | ||||||
| 63.2, 146 | O I | ||||||
| 121.9, 205 | N II | ||||||
| 158 | C II; 13C II | ||||||
| 370, 609 | C I | ||||||
Almost all of these features were first detected from NASA's airborne observatories, and cannot be studied from ground-based sites. Features seen in absorption are indicated with "a", and seen in both emission and absorption with "a/e". Whereas the dust features typically originate in regions cooler than a few hundred degrees Kelvin, the various gaseous lines originate in regions ranging in temperature from ~105K down to ~10K. Thus these infrared spectral features characterize material in all phases of the interstellar medium: solid particles, molecules, neutral atoms, and ionized atoms.
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