Open Access
Table 1
Parameters for the solar wind and comet for the three simulation runs and for comet 67P as encountered by the Rosetta spacecraft at 3 au.
| Parameter | Symbol [unit] | 67P | Simulation | ||
|---|---|---|---|---|---|
| run A | run B | run C | |||
| Heliocentric distance | R [au] | 3.0 | |||
| Scale factor | 400 | 400 | 200 | ||
| Nucleus radius | rn [m] | 2 × 103 | 5 | 5 | 10 |
| Max radius Haser | r1 [m] | 850 | 850 | 1.08 × 103 | |
| Zero density radius | r2 [m] | 930 | 930 | 1.18 × 103 | |
| Water production rate | Q [s−1] | 8.75 × 1025 | 2.19 × 1023 | 2.19 × 1023 | 4.37 × 1023 |
| Water ionisation rate | νi [s−1 ] | 3.68 × 10−8 | 3. 68 × 10−8 | 3.68 × 10−8 | 3. 68 × 10−8 |
| Water speed | u [km s−1] | 0.6 | 0.6 | 0.6 | 0.6 |
| Ionisation excess energy | Ek [eV] | 15 | 15 | 15 | 15 |
| SW number density | n0 [cm−3 ] | 0.78 | 0.78 | 0.78 | 0.78 |
| SW electron temperature | kB Te,0 [eV] | 6.21 | 6.21 | 6.21 | 6.21 |
| SW proton temperature |  |
3.31 | 3.31 | 3.31 | 3.31 |
| SW bulk speed | u0 [km s−1 ] | 430 | 430 | 430 | 430 |
| B-field magnitude | B0 [nT] | 5 | 1.98 × 103 | (0.8−2) × 103 | 990 |
| Water ion density max. |  |
300 | 88 | 88 | 88 |
| Electron mass | m/me | 1 | 20 | 20 | 20 |
| Proton to electron mass ratio | mp/me | 1836 | 91.8 | 91.8 | 91.8 |
| H2O+ to proton mass ratio |  |
17.9 | 17.9 | 17.9 | 17.9 |
| Electron cyclotron freq. | fce [Hz] | 139 | 2.78 × 103 | (1.1−2.8) × 103 | 1.39 × 103 |
| Electron plasma freq. max. | fpe [Hz] | 1.6 × 105 | 1.9 × 104 | 1.9 × 104 | 1.9 × 104 |
| H2O+ plasma freq. max. | fpi [Hz] | 855 | 460 | 460 | 460 |
| H2O+ cyclotron freq. | fci [Hz] | 4.23 × 10−3 | 1.69 | 0.68−1.7 | 0.85 |
| Simulation cube side | Nx | 240 | 240 | 304 | |
| Grid cell size | ∆x [m] | 8 | 8 | 8 | |
| Time step | ∆t [s] | 3 × 10−6 | 3 × 10−6 | 3 × 10−6 | |
Notes. The Rosetta values are estimates based on the literature (Edberg et al. 2015; Hansen et al. 2016; Goetz et al. 2017), and the simulation parameters correspond to the initial state.
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