In the “Weather on Other Worlds” Spitzer Exploration Science program, we surveyed 44 nearby L3–T8 dwarfs for spot-induced rotational variability. Among single L3–L9.5 dwarfs, we found that 80% are variable at >0.2% in the 3–5 μm wavelength range, while 36% of T0–T8 were variable at >0.4%. Taking into account viewing angle and sensitivity considerations, both of these findings are consistent with spots being present on ~100% of L3–T8 dwarfs. Intriguingly, we find a tentative association (92% confidence) between low surface gravity and high-amplitude variability among L3–L5.5 dwarfs. Although we can not confirm whether lower gravity is also correlated with a higher incidence of variables, the result is promising for the characterization of directly imaged young extrasolar planets through variability.

Using data from the WISE All-Sky Survey, we have found >100 new infrared excess sources around main-sequence Hipparcos stars within 75 pc. Our empirical calibration of WISE photospheric colors and removal of non-trivial false-positive sources are responsible for the high confidence (>99.5%) of detections, while our corrections to saturated W1 and W2 photometry have for the first time allowed us to search for new infrared excess sources around bright field stars in WISE. The careful calibration and filtering of the WISE data have allowed us to probe excess fluxes down to roughly 8% of the photospheric emission at 22μm around saturated stars in WISE. We expect that the increased sensitivity of our survey will not only aid in understanding the evolution of debris disks, but will also benefit future studies using WISE.

We present first imaging results from the PALM-3000 adaptive optics system and PHARO camera on the Hale 5 m telescope. Observations using a vector vortex coronagraph have given us direct detections of the two-ring dusty debris system around the star HD 141569. Our observations reveal the inner clearing in the disk to unprecedentedly small angular separations, and are the most sensitive yet at the H and K bands. We are for the first time able to measure and compare the colors of the scattered light in the inner and outer dust rings, and find that the outer ring is significantly bluer than the inner ring.

We present the detection of stars with infrared (IR) excesses attributed to circumstellar debris disks from the WISE All-Sky Survey at the WISE 12 and 22 μm bandpasses (W3 and W4, respectively). Excess flux at these wavelengths is significant because it traces material in the regions of terrestrial planet formation. We searched for debris disks by cross-matching Hipparcos main sequence stars with the All-Sky Data Release from WISE and seeking excess flux at W3 and W4. Our sample is confined to a volume of 75 pc around the sun, and outside the galactic plane (|b|>5°). Debris disk-bearing stars were identified as 95%-confidence outliers in 2MASS/WISE color distributions, after checking for erroneous photometry and contamination from unrelated nearby objects.