We present the results of a survey of 45 young ( \lesssim 250 Myr ) , close ( \lesssim 50 pc ) stars with the Simultaneous Differential Imager ( SDI ) implemented at the VLT and the MMT for the direct detection of extrasolar planets . based on observations made with the MMT and the ESO VLT at Paranal Observatory under programme ID ’ s 074.C-0548 , 074.C-0549 , and 076.C-0094 As part of the survey , we observed 54 objects total , of which 45 were close , young stars , 2 were somewhat more distant ( < 150 pc ) , very young ( \leq 10 Myr ) stars , 3 were stars with known radial velocity planets , and 4 were older , very nearby ( \leq 20 pc ) solar analogues .
Our SDI devices use a double Wollaston prism and a quad filter to take images simultaneously at 3 wavelengths surrounding the 1.62 \mu m methane absorption bandhead found in the spectrum of cool brown dwarfs and gas giant planets .
By performing a difference of adaptive optics corrected images in these filters , speckle noise from the primary star can be significantly attenuated , resulting in photon ( and flat-field ) noise limited data .
In our VLT data , we achieved H band contrasts \gtrsim 10 mag ( 5 \sigma ) at a separation of 0.5 ” from the primary star on 45 \% of our targets and H band contrasts of \gtrsim 9 mag at a separation of 0.5 ” on 80 \% of our targets .
With this degree of attenuation , we should be able to image ( 5 \sigma detection ) a 5 M _ { Jup } planet 15 AU from a 70 Myr K1 star at 15 pc or a 5 M _ { Jup } planet at 2 AU from a 12 Myr M star at 10 pc .
Our 45 southern targets were observed with the VLT while 11 of our northern targets were observed with the MMT ( 2 objects were observed at both telescopes ) .
We believe that our SDI images are the highest contrast astronomical images ever made from ground or space for methane rich companions \leq 1 ” from their star .
We detected no tentative candidates with S/N > 2 \sigma which behaved consistently like a real object .
Followup observations were conducted on 8 < 2 \sigma candidates ( with separations of 3 - 15.5 AU and masses of 2-10 M _ { Jup } , had they been real ) – none of which were detected at a second epoch .
In the course of our survey , we also discovered 5 new close stellar binary systems with measured separations of 0.14 ” to 0.26 ” .
For the best 20 of our survey stars , we attained 50 \% 5 \sigma completeness for 6-10 M _ { Jup } planets at semi-major axes of 20-40 AU .
Thus , our completeness levels are sufficient to significantly test theoretical planet distributions .
From our survey null result , we can rule out ( at the 98 \% confidence/2.0 \sigma level ) a model planet population using a planet distribution where N ( a ) \propto constant out to a distance of 45 AU ( further model assumptions discussed within ) .