Howell using infrared camera to observe Kilauea lava flows. Robert R. Howell
Emeritus Professor
Dept. of Geology & Geophysics
University of Wyoming

Education & Employment

B.Sc. Physics, University of Michigan, 1974
Ph.D. Planetary Sciences, University of Arizona, 1980
Assistant Astronomer, University of Hawaii, 1980-1986
Assistant Professor, University of Wyoming, 1986-1992
Associate Professor, University of Wyoming, 1992-2018
Emeritus Professor, University of Wyoming, 2018-present

Back to Top

Spring 2018 Classes

Fall 2017 Classes

Previous Classes

Back to Top

Research Interests

Volcanism on Jupiter's Moon Io
Io is the most volcanically active body in the solar system. It provides a unique laboratory for the study of volcanism under unusual conditions, for the study of the process of "tidal heating" in the outer solar system, and also for the study of planetary magnetospheres -- in this case derived from volcanically released sulfur dioxide. Observations from the earth can complement the observations being made by the Galileo spacecraft currently in Jupiter orbit. In the infrared a significant portion of the light from Io comes from the volcanic hotspots. Infrared monitoring can therefore be used to study the location, duration, and other characteristics of the volcanoes.  As part of this general effort, infrared measurements of terrestrial lava flows are also being modelled.
 
Infrared Observations of Terrestrial Analogs to Io's volcanism
As part of a team of Io scientists I've been using infrared instrumentation to observe terrestrial lava lakes which may be analogs of those on Io. See the publications below for an article on Vanuatu's Ambrym lava lake as well as articles on Vanuatu's Yasur volcano. Part of the support for that work came from Planeta Extrema on Brazil's Globo Television. There is an episode of that program documenting our work (in Portuguese) on YouTube at Vanuatu Planeta Extremo.
 
Stellar Occultations by Lucy-Target-Asteroids, and by Pluto
Lightcurves of a star's brightness as it passes behind (is occulted by) an asteroid give the size and shape of that asteroid, and occultations by planets give information about the structure of their atmospheres. I've been participating in the occultation program run by Marc Buie of Southwest Research Institute (SwRI) to determine sizes and shapes of the Trojan asteroids which the Lucy spacecraft will fly by in a few years. That information is critical to planning the spacecraft observations. The PBS program Nova recently had an episode Star Chasers of Senegal describing one such observing campaign (although not one I was involved in). Occultations are also used to detect and characterize asteroid satellites. I've also been involved in a SwRI program to observe occultations by Pluto to characterize and measure the long-term evolution of its atmosphere.
 
Infrared Instrumentation
The observations described above rely for the most part upon infrared instruments built at Wyoming. The early speckle work and the lunar occultations were carried out with a specially optimized single-channel InSb detector. Later observations were obtained with a small format InSb camera built for high speed 3-5 micron work. I finished that camera (IoCam1) while on sabbatical at Lowell Observatory during the 1996/1997 academic year.  It was used at the Wyoming 92" and the Lowell 72" telescopes. I have also developed small portable very-near-infrared (0.65–0.95µm) systems for field observations of terrestrial volcanoes.
 
High Angular Resolution Astronomy
The angular resolution obtained by ground-based telescopes is usually limited by the "seeing" caused by turbulence in the earth's atmosphere, but special techniques can be used to overcome this limitation. One technique, known as "speckle interferometry", makes use of multiple high-speed images of the object and a comparison star, coupled with Fourier analysis of the images. It is being used at Wyoming to study the volcanism on Io, as well as the processes taking place in regions surrounding recently formed stars and also stars undergoing mass loss. Another technique relies upon photometry obtained during occultations by the moon or by other bodies. Lunar occultations have been used at Wyoming to measure the binary frequency of T Tauri stars and to search for disks surrounding such stars. Occultations of Io by Jupiter allow us to measure the location of faint volcanic hotspots. Occultations of Io by the other Galilean satellites provide the highest possible spatial resolution. A series of such mutual events occurs every six years.
 
X-Ray Observations of Planetary Objects
Observations by the Chandra X-Ray Observatory have detected emission from the Galilean Satellites Io, Europa, and Ganymede.  The radiation, primarily in the oxygen K-alpha line, is most likely caused by high energy particles from the Jupiter magnetosphere impacting the satellite surfaces.  The process is, on a very large scale, similar to that which takes place in the electron and ion microprobes commonly used to study the elemental composition of geologic materials.  While measurements have not yet detected emission lines from other elements, the process has the potential for providing our first reliable estimates of the composition of these objects.  Modeling efforts are underway to predict the expected fluxes for other common elements, and to more fully model the observed oxygen emission.
 

Io Observing Techniques, and observing results

Back to Top

Preprints and Recent Papers

Back to Top

Field Trips (with pictures)

Back to Top

Other Interests

Back to Top

What's New

Back to Top

Useful Links

Back to Top

Contact Information

EMail:	rhowell@uwyo.edu
Phone:	(307) 314-5149
Dept.:	(307) 766-3386
Fax:	(307) 766-6679
Mail:
  Department of Geology & Geophysics
  University of Wyoming
  1000 E. University Ave.
  Laramie, WY  82071
Shipping (UPS, FedEx, etc.):
  Department of Geology & Geophysics
  16th and Gibbon
  Laramie, WY  82071

Dept. of Geology & Geophysics

University of Wyoming

Back to Top

Last revised: 2024_07_03 16:55