1I/`Oumuamua As Debris of Dwarf Interstellar Comet That Disintegrated Before Perihelion. (arXiv:1901.08704v1 [astro-ph.EP])
<a href="http://arxiv.org/find/astro-ph/1/au:+Sekanina_Z/0/1/0/all/0/1">Zdenek Sekanina</a>
Intrinsically faint comets in nearly-parabolic orbits with perihelion
distances much smaller than 1 AU exhibit strong propensity for suddenly
disintegrating at a time not long before perihelion, as shown by Bortle (1991).
Evidence from available observations of such comets suggests that the
disintegration event usually begins with an outburst and that the debris is
typically a massive cloud of dust grains that survives over a limited period of
time. Recent CCD observations revealed, however, that also surviving could be a
sizable fragment, resembling a devolatilized aggregate of loosely-bound dust
grains that may have exotic shape, peculiar rotational properties, and
extremely high porosity, all acquired in the course of the disintegration
event. Given that the brightness of 1I/`Oumuamua’s parent could not possibly
equal or exceed the Bortle survival limit, there are reasons to believe that it
suffered the same fate as do the frail comets. The post-perihelion observations
then do not refer to the object that was entering the inner Solar System in
early 2017, as is tacitly assumed, but to its debris. Comparison with C/2017 S3
suggests that, as a monstrous fluffy dust aggregate released in the course of
the recent explosive event, `Oumuamua should be of strongly irregular shape,
tumbling, not outgassing, and subjected to effects of solar radiation pressure,
consistent with observation. The unknown timing of the disintegration event may
compromise studies of the parent’s home stellar system. Limited search for
possible images of the object to constrain the time of the (probably minor)
outburst is recommended.
Intrinsically faint comets in nearly-parabolic orbits with perihelion
distances much smaller than 1 AU exhibit strong propensity for suddenly
disintegrating at a time not long before perihelion, as shown by Bortle (1991).
Evidence from available observations of such comets suggests that the
disintegration event usually begins with an outburst and that the debris is
typically a massive cloud of dust grains that survives over a limited period of
time. Recent CCD observations revealed, however, that also surviving could be a
sizable fragment, resembling a devolatilized aggregate of loosely-bound dust
grains that may have exotic shape, peculiar rotational properties, and
extremely high porosity, all acquired in the course of the disintegration
event. Given that the brightness of 1I/`Oumuamua’s parent could not possibly
equal or exceed the Bortle survival limit, there are reasons to believe that it
suffered the same fate as do the frail comets. The post-perihelion observations
then do not refer to the object that was entering the inner Solar System in
early 2017, as is tacitly assumed, but to its debris. Comparison with C/2017 S3
suggests that, as a monstrous fluffy dust aggregate released in the course of
the recent explosive event, `Oumuamua should be of strongly irregular shape,
tumbling, not outgassing, and subjected to effects of solar radiation pressure,
consistent with observation. The unknown timing of the disintegration event may
compromise studies of the parent’s home stellar system. Limited search for
possible images of the object to constrain the time of the (probably minor)
outburst is recommended.
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