Open Access
Table 6
Properties of comet 8P/Tuttle derived from our Spitzer Space Telescope observations.
| Nucleus | |
| Shape | Two spheres in contact (binary) |
| Size of each sphere | 2.7 ± 0.1 km and 1.1 ± 0.1 km (radii) |
| Pole orientation | RA = 285 ± 12° and Dec = +20 ± 5° |
| Geometric albedo | 0.042 ± 0.008 (R-band) |
| Roughness and thermal inertia | |
| Valid combinations | η = 0.7 and I = 0–100 J K−1 m−2 s−1∕2 |
| or η = 0.8 and I = 0 J K−1 m−2 s−1∕2 | |
| Production rates | |
Water  |
1.1 ± 0.2 × 1028 s−1 (1.6 AU pre-peri.) |
| Active fraction | ≈9% |
| Dust ɛfρ | 310 ± 34 cm (1.6 AU pre-perihelion) |
| 325 ± 36 cm (2.2 AU post-perihelion) | |
| Dust properties | |
| Tdust | 258 ± 10 K (1.6 AU pre-perihelion) |
| Grain size | ≈10 μm (diameter) |
| Composition | Amorphous pyroxene |
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