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2015 Annual Science Report

NASA Goddard Space Flight Center Reporting  |  JAN 2015 – DEC 2015

Circumstellar Debris and Planetesimals in Exoplanetary Systems

Project Summary

GCA astronomer Marc Kuchner studies the dynamics of debris disks, extrasolar analogs to the Kuiper Belt and the asteroid belt in our solar system, using NASA’s supercomputers. He develops numerical models of the orbits and the interactions of the planetesimals in these disks for use in interpreting images of them made with the Hubble Telescope and other NASA observatories. Together, the images and models teach us about how planetary systems form and evolve – the context within which processes affecting our Solar System are evaluated and extended to exo-planetary systems. An important goal is to extend these studies to a wider range of proto-planetary systems, thereby expanding the range of diversity within which the Solar System must be interpreted. Kuchner’s second initiative targets that objective.

Accordingly, Kuchner invited the public to help him discover new planetary systems through a new website, launched in 2014. At, volunteers view data from NASA’s Wide-field Infrared Survey Explorer (WISE) mission and three other surveys. WISE measured more than 745 million objects, representing the most comprehensive survey of the sky at mid-infrared wavelengths ever taken. Among these objects, thousands of planetary systems await discovery – recognizable by the dusty disks that surround them. But galaxies, interstellar dust clouds and asteroids also glow in the infrared, which stymies automated efforts to identify these disks. At Disk, the volunteers find the disks by watching 10-second videos of objects seen by WISE, then classifying them by clicking on a selection of buttons on their screens.

4 Institutions
3 Teams
5 Publications
3 Field Sites
Field Sites

Project Progress

The Disk Detective project is now 27% complete. It has identified more than 3000 objects of interest, and is preparing its first paper for publication with a list of 39 new disk candidates. Kuchner led several new initiatives to follow up the best targets from the project: observing programs on the Tillinghast telescope at Whipple Observatory, ROBO-AO at Mt. Palomar, the duPont telescope, CASLEO Observatory, the James Clerk Maxwell Telescope, Gemini Planet Imager, and SOFIA.

Kuchner’s disk modeling efforts resulted in some interesting new results as well. It is widely known that debris rings often shine brighter on the side nearest the star they orbit, a phenomenon called “pericenter glow”. Kuchner’s team discovered that at long wavelengths, this effect is reversed. So for example, recent ALMA images of the debris ring around Fomalhaut should be reinterpreted as showing “apocenter glow”.

    Marc Kuchner Marc Kuchner
    Project Investigator
    Erika Nesvold

    Margaret Pan

    Hanno Rein

    Steven Silverberg

    Objective 1.1
    Formation and evolution of habitable planets.

    Objective 1.2
    Indirect and direct astronomical observations of extrasolar habitable planets.