Cool Stars 14 - Submitted Abstract # 264
This version created on 05 October 2006

A Survey of Close, Young Stars with SDI at the VLT and MMT


Beth Biller, University of Arizona
Laird Close, University of Arizona
Elena Masciadri, Observatorio Astrofisico di Arcetri
Rainer Lenzen, MPIA-Heidelberg
Wolfgang Brandner, MPIA-Heidelberg
Donald McCarthy, University of Arizona
Thomas Henning, MPIA-Heidelberg
Eric Nielsen, University of Arizona
John Trauger, JPL
Karl Stapelfeldt, JPL
Markus Hartung, ESO

We discuss the results of 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 um 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 and flat-field noise limited data.  In
our survey data, we achieved H band contrasts > 25000  (5sigma Delta
F1(1.575 um) > 10  mag, Delta H > 10.6 mag for a T6 spectral type) at
a separation of 0.5 arcsec from the primary star.  With this degree of
attenuation, we can image (5 sigma detection) a 2-4 Jupiter mass
planet at 5 AU around a 30  Myr star at 10  pc.  We have obtained
complete datasets for ~50  stars.  We believe that our SDI images are
the highest contrast astronomical images ever made from ground or
space for methane rich companions.  We also discuss preliminary
results of an experiment at the High Contrast Imaging Testbed at JPL
using a similar SDI multiwavelength differential imaging scheme
bracketing the Oxygen (A) telluric absorption feature at 0.762 um.

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