PI: Marshall Perrin
mperrin@stsci.edu; http://www.stsci.edu/~mperrin/; Office is Muller N412; 410 338 4789.
Project duration: 1 year, with much potential to grow into a thesis project
Project Abstract:
Intro: STScI's Extrasolar Planetary Systems Imaging Group carries out a wide range of leading efforts in high contrast imaging of nearby exoplanets and circumstellar disks, using state-of-the-art methods from ground and space. Our team, consisting of a dozen-plus astronomers, technical staff, students and postdocs, has several opportunities for new students.
Thousands of exoplanets have now been detected and studied by indirect means (e.g. transits and radial velocity detections), but only a relatively small handful of planets have yet been directly imaged, seen as separate points of light resolved from their parent stars. Since even the brightest planets are far fainter than their parent stars, direct detection requires combining sophisticated specialized optical systems (coronagraphs) plus advanced image processing methods. Currently, the leading US facility for exoplanet imaging is the Gemini Planet Imager (GPI), an AO coronagraphic instrument at Gemini South developed in part by our team for observations of exoplanets and circumstellar disks. The Hubble Space Telescope's STIS coronagraph remains the most sensitive coronagraph for faint circumstellar dusty disks, though can't see quite as close to a star as GPI can. And soon, JWST will be the next major step in direct imaging of exoplanets, offering orders of magnitude deeper sensitivity in the thermal infrared, a wavelength region that can provide access to key spectral diagnostics of exoplanet atmospheres.
Project 1: Studying Young Circumstellar Disks with Hubble and GPI. An ongoing HST program by our team has been using the STIS coronagraph to obtain optical scattered-light imaging of circumstellar debris disks, dusty belts around nearby stars. By imaging disks we can study the makeup and evolution of nearby stellar systems, and sometimes draw conclusions about the presence or properties of planets that cannot yet be seen. In some cases we can also obtain near-infrared images and polarimetry using GPI, for better angular resolution to see finer detail, and broader wavelength coverage that helps place constraints on the physical properties of circumstellar dust. We currently have new, fresh-from-the-telescope observations on half a dozen circumstellar disks, ready for analysis and interpretation to understand the properties of these nearby planetary systems. For examples of work in this area by recent JHU graduates see Ren et al. 2019 or Wolff et al. 2017. STScI experts in debris disk observations eager to work with students include Drs. Marshall Perrin, Chris Stark, John Debes, and Christine Chen.
Project 2: Preparing for Exoplanet Imaging with JWST. At STScI, several of us in the Extrasolar Planetary Systems Imaging Group will be leading some of the very first coronagraphic observations of exoplanets and circumstellar disks with JWST, via guaranteed time and early release science observations that will take place in the first year of JWST's operations. In preparation for that, we are developing detailed simulations, testing and perfecting our image processing and data analysis tools, and in general getting ready to "hit the ground running" with JWST. In this coming year (2019-2020), a student could work with Drs. Marshall Perrin, Laurent Pueyo, Julien Girard, and Chris Stark on generating detailed simulations of expected JWST observations (using existing software tools to prepare mock observations while varying the simulated exoplanet atmospheric properties, and using the latest models for observatory and telescope performance); we will then process and analyze the data using our team's world-leading exoplanetary data processing toolkit, assess how well we can measure the input exoplanet properties, and iterate to refine and 'tune up' our methods to work as well as possible on the expected properties of JWST data. In conjunction with existing ongoing efforts we expect this would lead to coauthorship on a publication around summer of 2020 giving updated predictions for JWST's exoplanetary imaging discovery parameter space. There will also be opportunities in spring 2020 to collaborate in proposals to JWST Cycle 1. This effort will help set up a student to lead scientific discoveries with JWST in the near future once it is operation, and be part of one of the teams conducting some of the its very first discoveries.
