Outgassing induced acceleration of comet 67P/Churyumov-Gerasimenko. (arXiv:1902.02701v1 [astro-ph.EP])
<a href="http://arxiv.org/find/astro-ph/1/au:+Kramer_T/0/1/0/all/0/1">Tobias Kramer</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Laeuter_M/0/1/0/all/0/1">Matthias Laeuter</a>
Cometary activity affects the orbital motion and rotation state due to
sublimation induced forces. The availability of precise orientation and
position data from the Rosetta missions allows one to accurately determine the
outgassing of comet Churyumov-Gerasimenko/67P (67P). From the non-gravitational
acceleration of 67P we recover the diurnal outgassing variations and study a
possible delay of the sublimation response with respect to the peak solar
illumination. We analyze the observed acceleration and evaluate the accuracy of
the commonly used Marsden model for the non-gravitational acceleration. We use
an iterative orbit refinement and Fourier decomposition of the diurnal activity
to derive the outgassing rate. The uncertainties of the data reduction are
established by a sensitivity analysis of an ensemble of best-fit orbits for
comet 67P. We find that the Marsden orbital parameters reproduce parts of the
non-gravitational acceleration but need to be augmented by an analysis of the
nucleus geometry and surface illumination to draw conclusions about the
sublimation process on the surface. The non-gravitational acceleration follows
closely the subsolar latitude (seasonal illumination), with a small thermal lag
angle with respect to local noon around perihelion. In contrast to the
sublimation induced torques, the non-gravitational acceleration does not put
strong constraints on localized active areas on the nucleus.
Cometary activity affects the orbital motion and rotation state due to
sublimation induced forces. The availability of precise orientation and
position data from the Rosetta missions allows one to accurately determine the
outgassing of comet Churyumov-Gerasimenko/67P (67P). From the non-gravitational
acceleration of 67P we recover the diurnal outgassing variations and study a
possible delay of the sublimation response with respect to the peak solar
illumination. We analyze the observed acceleration and evaluate the accuracy of
the commonly used Marsden model for the non-gravitational acceleration. We use
an iterative orbit refinement and Fourier decomposition of the diurnal activity
to derive the outgassing rate. The uncertainties of the data reduction are
established by a sensitivity analysis of an ensemble of best-fit orbits for
comet 67P. We find that the Marsden orbital parameters reproduce parts of the
non-gravitational acceleration but need to be augmented by an analysis of the
nucleus geometry and surface illumination to draw conclusions about the
sublimation process on the surface. The non-gravitational acceleration follows
closely the subsolar latitude (seasonal illumination), with a small thermal lag
angle with respect to local noon around perihelion. In contrast to the
sublimation induced torques, the non-gravitational acceleration does not put
strong constraints on localized active areas on the nucleus.
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