none

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

Connect with NRAO

The National Radio Astronomy Observatory and Green Bank Observatory are facilities of the U.S. National Science Foundation operated under cooperative agreement by Associated Universities, Inc.

Founded in 1956, the NRAO provides state-of-the-art radio telescope facilities for use by the international scientific community. NRAO telescopes are open to all astronomers regardless of institutional or national affiliation. Observing time on NRAO telescopes is available on a competitive basis to qualified scientists after evaluation of research proposals on the basis of scientific merit, the capability of the instruments to do the work, and the availability of the telescope during the requested time. NRAO also provides both formal and informal programs in education and public outreach for teachers, students, the general public, and the media.

The National Science Foundation (NSF) is an independent federal agency created by Congress in 1950 "to promote the progress of science; to advance the national health, prosperity, and welfare; to secure the national defense..."

AUI collaborates with the scientific community and research sponsors to plan, build, and operate cutting-edge facilities. We cultivate excellence, deliver value, enhance education, and engage the public.