NRAO/Socorro Colloquium Series
Michal Drahus
Caltech
Catastrophic Disruptions of Comets
Spontaneous disruption of cometary nuclei is one of the least
understood, but most important aspects of their nature. Attempts to
explain the mysterious phenomenon date back to 1846, when in the middle
of January astronomers were surprised to see periodic comet Biela had
split into two pieces. In the course of time many similar events were
discovered and the breakup rate estimated to be close to one per
century per comet. Breakups are often accompanied by massive outbursts
of brightness, but it is not even clear if it is the outburst that
triggers splitting or the other way around. The fate of split comets is
frequently the same: their fragments continue to break up and quickly
disappear. For example, the two pieces of comet Biela were recovered
during the next return in 1852, but have never been seen again.
Instead, intense meteor showers were observed during the comet's next
expected returns. In spite of this long history and great importance
for the determination of cometary lifetimes, the phenomenon remains
unexplained to date, although several hypotheses have been proposed. In
particular, it has been suggested that the disruption can be caused by
nucleus spin-up powered by outgassing torques, which can drive the
nucleus spin rate beyond the limit of rotational stability. I will
discuss the progress in testing this hypothesis that has happened in
the last decade, and overview possible future studies aimed at solving
this longest-standing problem in cometary science.
March 21, 2014
11:00 am
Array Operations Center Auditorium
All NRAO employees are invited to attend via video, available in Charlottesville 245, Green Bank Auditorium, Tucson N525, and NTC 400.
Local Host: Miller Goss
