September 27, 2012
Gemini Observatory Takes Sharpest Ground-Based Images Ever Of Pluto And Charon
Lawrence LeBlond for redOrbit.com - Your Universe Online
Pluto, the dwarf planet (ex-number-nine), and its larger companion Charon, recently posed for astronomers. Using the high-resolution Gemini North 8-meter telescope along with reconstructive speckle imaging, astronomers were able to capture the twin extrasolar planetary system, providing the sharpest ground-based images of the deep-space dwellers.The images prove that ground-based speckle imaging is a powerful tool for exoplanet discoveries. The data received also verified previous orbital characteristics for the twin system and revealed precise diameters for each.
“The Pluto-Charon result is of timely interest to those of us wanting to understand the orbital dynamics of this pair for the 2015 encounter by NASA's New Horizons spacecraft,” said Steve Howell of the NASA Ames Research Center, who led the study.
Howell also noted that NASA´s Kepler mission, a very powerful space-based exoplanet discovery telescope, will benefit greatly from speckle imaging techniques. Speckle imaging with the Gemini telescope will provide Kepler´s follow-up program an increase in its ability to hunt down exoplanets and validate the existence of Earth-like planets.
In essence, by implementing Gemini´s technique, Kepler´s observations would increase by a 3- to 4-magnitude in sensitivity, or about a 50-fold increase in sensitivity over observations that can be made with Gemini alone.
“This is an enormous gain in the effort underway to confirm small Earth-size planets,” Howell added.
The images were made possible by mounting the Differential Speckle Survey Instrument (DSSI) on the Gemini telescope.
“This was a fantastic opportunity to bring DSSI to Gemini North this past July,” said Elliott Horch, of Southern Connecticut State University, coauthor of the Gemini study. “In just a little over half an hour of Pluto observations, collecting light with the large Gemini mirror, we obtained the best resolution ever with the DSSI instrument —— it was stunning!”
The team explained, as an example, that the resolution obtained from their observations corresponds to separating a pair of car headlights in Rhode Island from California. To achieve this level of definition, Gemini had to take a large number of quick “snapshots” of Pluto and Charon, which were then reconstructed by the Gemini team into a single image. Of course, blurring effects and ever-changing speckled artifacts caused by turbulence in the atmosphere also had to be accounted for, which the team was able to cancel out to some extent.
The work was funded in part by the National Science Foundation and NASA´s Kepler discovery mission. The study will be published in the journal Publications of the Astronomical Society of the Pacific in October 2012.