Colloquia

2019 HotSci at STScI

Wed 28 Aug 2019
Location:

Space Telescope Science Institute (STScI)
3700 San Martin Drive
Baltimore, MD 21218

Time:

2:45 PM - 4:00 PM

Contact Information:

Have questions? Please contact Martha Devaud.

Description:

Featuring Bonnie Meinke on Identifying collisions in Saturn’s Rings by observing the sub-cm particle distribution and Susana Deustua on HST as a particle detector.

Notes:

All talks are held on Wednesdays in the STScI John N. Bahcall Auditorium at 3:00 p.m. preceded by refreshments at 2:45 p.m.

Name: Bonnie Meinke
Title: Identifying collisions in Saturn’s Rings by observing the sub-cm particle distribution
Abstract: I present the analysis of solar occultation data from Cassini's Ultraviolet Imaging Spectrograph (UVIS) in order to measure the particle size distribution in Saturn’s F ring. My team has analyzed 16 solar occultations in UVIS EUV data, with emphasis on features produced by diffraction by micron-sized particles in Saturn’s F ring and the light diffracted by the particles in the ring during the occultation to determine the size distribution of sub-centimeter ring particles. The detections of small particles in the UVIS data are indicative of ongoing collisions in the F ring. I will discuss the correlation of small particle detections with known and imaged collisional events in the F ring.

Name: Susana Deustua
Title: HST as a particle detector
Abstract: Hubble Space Telescope has been in orbit around Earth since 1990. We exploit the Hubble Space Telescope (HST) as a cosmic ray detector to probe Earth's external magnetic field through analysis of the cosmic ray flux on HST instruments. Using the  100 000+ dark images obtained during HST’s two decades of operation, we  calculate the flux of cosmic rays at an altitude of ~500 km above the terrestrial surface, in order to estimate variations in the external magnetic field, thereby complementing geophysical observatory measurements. The goal is to combine HST results with measurements of solar activity, cosmic ray flux on Earth's surface, and geomagnetic data to tease out external field variations. In this paper I discuss our measurements of the cosmic ray rate and energy distribution from active and legacy HST instruments.

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