"Paleomagnetic evidence for an outer solar system meteorite"

It is thought that there were at least two major planetary rearrangements within the rst 1 Gyr of our solar system. Such events are believed to have played a crucial role in shaping the present-day architecture of our solar system as well as possibly those of exoplanetary systems. Within our own solar system, these planetary migrations have been proposed to have brought material that formed beyond the orbit of the gas giants into the inner solar system, possibly explaining the compositional trends across the asteroid belt as well as the makeup of the Trojan asteroids. However, very few robust, accurate or quantitative estimates of the heliocentric distances of the formation of meteorite parent bodies exist. These distance estimates would also provide a means of investigating the range over which the rst solids may have been recycled throughout the solar system by stellar out ows.

Here, we present paleomagnetic evidence that the Tagish Lake meteorite does not contain a stable magnetic remanence. Given the ancient aqueous alteration age of this meteorite (<4 Myr after calcium-aluminum rich [CAI] formation), this absence suggests that the Tagish Lake parent body must have originated from >10-20 AU where the magnetic eld generated by the collapse of the dust and gas within the nebula was <0:15 T. This distance corresponds to radii greater than the orbits of the gas giants prior to Grand Tack, suggesting the Tagish Lake parent body represents the outer disk bodies that now constitute the Kuiper belt and could therefore feasibly be a comet. Tagish Lake contains sparse chondrules and even rare CAIs, indicating that stellar out ows were capable of moving material that formed within 1 AU of the Sun, and within 1 Myr of CAI formation, to distances as far as that of present-day Saturn or Uranus. Finally, our results provide the rst direct, quantitative observation from the meteorite record that a body formed in the outer solar system now resides in the inner solar system, supporting the existence of major planetary migrations that altered the architecture and structure of our solar system.

About the Series

The MIT Planetary Lunch Colloquium Series [PlCS] is a weekly seminar series organized within the EAPS department. Colloquia topics span the range of research interests of the department's planetary sciences research program. The seminars usually take place on Tuesdays from 12-1:30 pm in 54-517 unless otherwise noted (term-time only). Speakers include members of the MIT community and visitors. Talks are intended to appeal to graduate students, postdocs, research scientists, and faculty with a background in planetary science. A light lunch is provided.