Research Article

On the nucleus structure and activity of comet 67P/Churyumov-Gerasimenko

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Science  23 Jan 2015:
Vol. 347, Issue 6220, aaa1044
DOI: 10.1126/science.aaa1044

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  1. Fig. 1 Stereophotogrammetric shape models of comet 67P.

    The blue arrow indicates 67P’s rotation axis z; the red and green arrows display its equatorial x and y axes (x according to the current zero-longitude definition). If the nucleus is homogeneous in density, the axis of minimum moment of inertia is consistent with being in the equatorial plane.

  2. Fig. 2 Gravitational field.

    Left: The effective gravitational potential at the surface, including the centrifugal term due to rotation of the nucleus, is shown looking toward the neck from an intermediate latitude in the northern (positive) hemisphere (between the blue and red arrows in Fig. 1). Right: The slope of the terrain relative to local gravity.

  3. Fig. 3 Geomorphological map of comet 67P.

    Left: Region definition for one face of 67P, showing the Seth region on the body and the smooth Hapi region on the neck. Other regions are defined in more detail by (15). Right: Regional definition looking from the body (foreground) across to the head.

  4. Fig. 4 Jets.

    Jets from the Hapi region as observed on 23 September 2014.

  5. Fig. 5 Map of energy input.

    Left: A map looking at the northern (right-hand rule, positive) pole of 67P showing the total energy received from the Sun per rotation on 6 August 2014. The energy received includes thermal illumination by the surfaces of the comet itself. The base of the neck (Hapi) receives ~15% less energy than the most illuminated region, 3.5 × 106 J m−2 (per rotation). If self-heating were not included, the base of the neck would receive ~30% less total energy. Right: Similar to the left panel but showing total energy received over an entire orbital period in J m−2 (per orbit). This heating varies by only ~50% over the entire surface. Although not shown here, the opposite hemisphere receives essentially the same energy, but at a higher rate over a shorter time.

  6. Fig. 6 Active pits detected in Seth region.

    NAC image acquired on 28 August 2014. Distance to the comet, 60 km; resolution, 1 m/pixel. Enhancing the contrast (right panel) shows fine structures in the shadow of the pit, interpreted as fine jets arising from the pit.

  7. Fig. 7 Nucleus close-ups.

    Top left: The Hathor cliff face is to the right in this view. The aligned linear structures can be clearly seen. The smooth Hapi region is seen at the base of the Hathor cliff. Boulders are prevalent along the long axis of the Hapi region. Bottom left and right: Crack in the Hapi region. The left panel shows the crack (indicated by red arrows) extending across Hapi and beyond. The right panel shows the crack where it has left Hapi and is extending into Anuket, with Seth at the uppermost left and Hapi in the lower left.

  8. Fig. 8 Goosebumps.

    Characteristic scale of all the bumps is ~3 m, extending over >100 m. This example is in the active pit in the Seth region.