LPI Seminar Series
LPI seminars will be held on Thursdays.
LPI seminars are held from 3:30–4:30 p.m. in the Lecture Hall at USRA, 3600 Bay Area Boulevard, Houston, Texas. Refreshments are served at 4:30 p.m. For more information, please contact Georgiana Kramer (phone: 281-486-2141; e-mail: email@example.com) or Patricia Craig (phone: 281-486-2144; e-mail: firstname.lastname@example.org). A map of the Clear Lake area is available here. This schedule is subject to revision.
Join the LPI-Seminars mailing list to receive email notifications about upcoming LPI Seminars. To join the mailing list please send an email to:
- Thursday, July 13, 2017 - Lecture Hall, 3:30 PM
James A. Slavin, Department of Climate and Space Science & Engineering, University of Michigan
LPI Seminar: MESSENGER Observations of Mercury’s Dynamic Magnetosphere
Mercury’s magnetosphere is formed by the interaction of the solar wind with its small, ~ 200 nT – RM3, intrinsic magnetic field. The mean altitude of the subsolar magnetopause is only ~ 0.5 RM, but planetary induction currents in Mercury’s highly conducting iron core strongly resist solar wind compression. The weak conductivity of Mercury’s regolith severely limits field-aligned current intensity, but Region 1 currents are measured at low altitudes with magnitudes up to several tens of kilo-Amperes. These currents pass radially through Mercury’s ~ 400 km thick regolith to close across its iron core. Mercury’s surface-bounded exosphere is maintained by sputtering and other surface interactions that eject neutrals from the regolith. While the magnetospheric plasma is primarily of solar wind origin, i.e. H+ and He++, Na+ and other heavy planetary ions derived from the exosphere account for ~ 1 to 10% of ion number density. Magnetic reconnection at the magnetopause is far more frequent and intense than at Earth. “Showers” of 100+ flux transfer events are often observed during a single magnetopause traversal. Indeed, the dayside magnetosphere is sometimes observed to disappear during periods of strong southward interplanetary magnetic fields. Magnetic field loading/unloading of the magnetotail is observed at Mercury similar to that seen at Earth during substorms. Mercury’s substorms are associated with magnetic field dipolarization, energetic electron acceleration and plasmoid ejection, but they last only ~ 2 – 3 min as compared with ~ 1 – 2 hrs for Earth. Future prospects for understanding Mercury’s coupled magnetosphere – exosphere – solid planet as a system with the measurements to be returned by ESA’s BepiColombo mission in 2025 will be discussed.
- Thursday, September 14, 2017 - Lecture Hall, 3:30 PM
Andrea Isella, Rice University
LPI Seminar: Disk sub-structures revealed by ALMA: implications for planet formation.
The Atacama Large Millimeter and sub-millimeter Array (ALMA) has discovered sub-structures in the dust and molecular gas distribution a number of protoplanetary disks. These structures span spatial scales from a few to hundreds of Astronomical Units and are thought to be related to the formation of planets. During my talk I will present some of the most recent ALMA observations of sub-structures in disks and discuss them in the framework of planet formation models.