We discuss contrast limits obtained during a survey of young (<300 Myr), close (<50 pc) stars with the Simultaneous Differential Extrasolar Planet Imager (SDI) implemented at the VLT and the MMT. SDI uses a double Wollaston prism and a quad filter to take images simultaneously at 3 wavelengths surrounding the 1.62 μm methane bandhead found in the spectrum of cool brown dwarfs and gas giants. By performing a difference of images in these filters, speckle noise from the primary can be significantly attenuated, resulting in photon noise limited data. In our survey data, we achieved H band contrasts >25000 (5σ ΔF1(1.575μm)>10 mag, ΔH>10.6 mag for a T6 spectral type) at a separation of 0.5" from the primary star. With this degree of attenuation, we can image (5σ detection) a 2-4 Jupiter mass planet at 5 AU around a 30 Myr star at 10 pc. We are currently completing our survey of young, nearby stars. We have obtained complete datasets for 40 stars in the southern sky (VLT) and 11 stars in the northern sky (MMT). We believe that our SDI images are the highest contrast astronomical images ever made from ground or space for methane rich companions.

Date Published: 4 July 2006
PDF: 10 pages
Proc. SPIE 6272, Advances in Adaptive Optics II, 62722D (4 July 2006); doi: 10.1117/12.671771

Published in SPIE Proceedings Vol. 6272:
Advances in Adaptive Optics II
Brent L. Ellerbroek; Domenico Bonaccini Calia, Editor(s)