Bibcode
Samarasinha, Nalin H.; Mueller, B. E. A.; Hadamcik, E.; Lin, Z. Y.; Meech, K. J.; Tozzi, G. P.; Tricarico, P.; Waniak, W.; A'Hearn, M. F.; Bonev, T.; Borisov, G.; Brucato, J. R.; Drahus, M.; Epifani, E. M.; Farnham, T. L.; Gersch, A.; Hainaut, O. R.; Ip, W. H.; Lara, L. M.; Levasseur-Regourd, A. C.; Licandro, J.; Patriarchi, P.; Pittichova, J.; Sen, A. K.; Tanga, P.; Thomas, P.
Referencia bibliográfica
American Astronomical Society, DPS meeting #44, #506.03
Fecha de publicación:
10
2012
Número de citas
1
Número de citas referidas
1
Descripción
The target of the NASA DIXI mission, comet 103P/Hartley 2 is in a
non-principal-axis (NPA) rotational state that was observed to be
varying with time. However, there is still no consensus on the specific
NPA rotational state during the 103P/Hartley 2 encounter by DIXI. We
analyze the continuum features observed in ground-based images
bracketing the time of the DIXI encounter taken from a number of
observatories located at different time zones to provide a dense
temporal coverage. The continuum features are present at nearly all
rotational phases (for the published periodicities of 18-hours and
55-hours). Therefore, we suggest the following possibilities for the
origin of the continuum features and the implications. (a) If the
features are originating from fixed source regions on the nucleus,
short-axis-mode NPA states are more likely than the long-axis-mode NPA
states, as the position angles of the observed features are restricted
to a small range ( 65 degrees) in the sunlit side. (b) If the features
are due to the aggregate effect of the sunward emission from the
nucleus, then the continuum features cannot be used to exclude a
particular mode of NPA rotation. However, the correct rotational model
together with the activity model should be able to reproduce the
observed coma features as a function of time. Dynamically, the moments
of inertia of the near-prolate nucleus based on the shape model place
severe constraints on the range of short-axis-mode states that are
feasible. We will explore how non-uniform density distributions would
affect the plausible NPA states and how they contrast with the case of
uniform density. We will discuss both our analysis of the
multi-observatory continuum images as well as the implications of
non-uniform density distributions on the rotational state.