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Proceedings Paper

A starshade for JWST: science goals and optimization
Author(s): Rémi Soummer; Webster Cash; Robert A. Brown; Ian Jordan; Aki Roberge; Tiffany Glassman; Amy Lo; Sara Seager; Laurent Pueyo
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Paper Abstract

The James Webb Space Telescope will be an extraordinary observatory, providing a huge range of exciting new astrophysical results. However, by itself it will not be capable of directly imaging planets in the habitable zone of nearby stars, one of the most fascinating goals of astronomy for the coming decade. In this paper we discuss the New Worlds Probe (NWP) concept whereby we use an external occulter (or starshade) to cast a shadow from the star onto the telescope, therefore canceling the direct star light while the light from a planet is not affected. This concept enables JWST to take images and spectra of extrasolar planets with sufficient contrast and inner working angle to be able to discover planets down to the size of the Earth in the habitable zone around nearby stars. JWST's instruments are appropriate to achieve low resolution spectroscopy (R ≅ 40) of these planets, and address a series of fundamental questions: are there planets in the habitable zone around nearby stars? What is the composition of their atmosphere? What are the brightness and structures of exozodiacal disks around nearby stars? What is the mass and composition of currently known giant planets? In this paper we study the starshade optimization for JWST given the instrumental constraints, and show that the modest optical quality of the telescope at short wavelength does not impact the possibility of using a starshade. We propose a solution to enable imaging and spectroscopy using target acquisition filters. We discuss possible time allocation among science goals based on exposure time estimates and total available observing time. The starshade can be launched up to 3 years after JWST and rendezvous with the telescope in orbit around L2.

Paper Details

Date Published: 19 August 2009
PDF: 15 pages
Proc. SPIE 7440, Techniques and Instrumentation for Detection of Exoplanets IV, 74400A (19 August 2009); doi: 10.1117/12.826702
Show Author Affiliations
Rémi Soummer, Space Telescope Science Institute (United States)
Webster Cash, Univ. of Colorado at Boulder (United States)
Robert A. Brown, Space Telescope Science Institute (United States)
Ian Jordan, Computer Sciences Corp. (United States)
Space Telescope Science Institute (United States)
Aki Roberge, NASA Goddard Space Flight Ctr. (United States)
Tiffany Glassman, Northrop Grumman Corp. (United States)
Amy Lo, Northrop Grumman Corp. (United States)
Sara Seager, Massachusetts Institute of Technology (United States)
Laurent Pueyo, Jet Propulsion Lab. (United States)

Published in SPIE Proceedings Vol. 7440:
Techniques and Instrumentation for Detection of Exoplanets IV
Stuart B. Shaklan, Editor(s)

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