Searching for, Finding, and Imaging Young Extrasolar Planets with HST/NICMOS

Imaging discovery and subsequent characterization of extrasolar planet (EP) mass companions to stars has been observationally challenging due to the severe planet-to-star contrast ratios. Since the detection of the extrasolar giant planet (EGP) companion to 51 Peg [1], continuing discoveries of 1 – 10 Jupiter mass companions by indirect methods have revealed an unanticipated diversity in mass ranges, dynamical properties, and primary-star characteristics. The past decade has seen an explosion of indirect detections of EGP companions to solar-like stars through radial velocity surveys [2] and more recently, in much smaller numbers, via photometric transits [e.g., 3], microlensing [4] and astrometry [5]. These methods are contributing enormously to this effort, and predicate the Kepler mission’s hopes of transitdetection of lower mass (i.e., terrestrial) planets. Yet, the direct detection of a bona fide EGP by imaging (and spectroscopy) remained elusive as recently developed technical capabilities (i.e., space-based with HST/NICMOS and complementary ground-based adaptive optics observations at longer-wavelength) were to be demonstrated. Today, young EGPs, still thermally emissive from their residual heat of formation can, and no