Does the Debris Disk around HD 32297 Contain Cometary Grains?

We present an adaptive optics imaging detection of the HD 32297 debris disk at L (3.8 microns) obtained with the LBTI/LMIRcam infrared instrument at the LBT. The disk is detected at signal-to-noise per resolution element ~ 3-7.5 from ~ 0.3-1.1 (30-120 AU). The disk at L is bowed, as was seen at shorter wavelengths. This likely indicates the disk is not perfectly edge-on and contains highly forward scattering grains. Interior to ~ 50 AU, the surface brightness at L rises sharply on both sides of the disk, which was also previously seen at Ks band. This evidence together points to the disk containing a second inner component located at $lesssim$ 50 AU. Comparing the color of the outer (50 $< r$/AU $< 120$) portion of the disk at L with archival HST/NICMOS images of the disk at 1-2 microns allows us to test the recently proposed cometary grains model of Donaldson et al. 2013. We find that the model fails to match the disks surface brightness and spectrum simultaneously (reduced chi-square = 17.9). When we modify the density distribution of the model disk, we obtain a better overall fit (reduced chi-square = 2.9). The best fit to all of the data is a pure water ice model (reduced chi-square = 1.06), but additional resolved imaging at 3.1 microns is necessary to constrain how much (if any) water ice exists in the disk, which can then help refine the originally proposed cometary grains model.

The Gray Needle: Large Grains in the HD 15115 Debris Disk from LBT/PISCES/Ks and LBTI/LMIRcam/L Adaptive Optics Imaging

We present diffraction-limited ks band and lprime adaptive optics images of the edge-on debris disk around the nearby F2 star HD 15115, obtained with a single 8.4 m primary mirror at the Large Binocular Telescope. At ks band the disk is detected at signal-to-noise per resolution element (SNRE) about 3-8 from about 1-2fasec 5 (45-113 AU) on the western side, and from about 1.2-2fasec 1 (63-90 AU) on the east. At lprime the disk is detected at SNRE about 2.5 from about 1-1fasec 45 (45-90 AU) on both sides, implying more symmetric disk structure at 3.8 microns . At both wavelengths the disk has a bow-like shape and is offset from the star to the north by a few AU. A surface brightness asymmetry exists between the two sides of the disk at ks band, but not at lprime . The surface brightness at ks band declines inside 1asec (about 45 AU), which may be indicative of a gap in the disk near 1asec. The ks - lprime disk color, after removal of the stellar color, is mostly grey for both sides of the disk. This suggests that scattered light is coming from large dust grains, with 3-10 microns -sized grains on the east side and 1-10 microns dust grains on the west. This may suggest that the west side is composed of smaller dust grains than the east side, which would support the interpretation that the disk is being dynamically affected by interactions with the local interstellar medium.

Direct Imaging Constraints on the Putative Exoplanet 14 Her c

We present results of deep direct imaging of the radial velocity (RV) planet-host star 14 Her (=GJ 614, HD 145675), obtained in the lprime ~band with the Clio-2 camera and the MMT adaptive optics system. This star has one confirmed planet and an unconfirmed outer companion, suggested by residuals in the RV data. The orbital parameters of the unconfirmed object are not well constrained since many mass/semimajor axis configurations can fit the available data. The star has been directly imaged several times, but none of the campaigns has ruled out sub-stellar companions. With about 2.5 hrs of integration, we rule out at 5$sigma$ confidence $gtrsim$ 18 mj ~companions beyond about 25 AU, based on the cite{baraffe} COND mass-luminosity models. Combining our detection limits with fits to the RV data and analytic dynamical analysis, we constrain the orbital parameters of 14 Her c to be: $3 lesssim m/$mj ~$lesssim 42$, $7 lesssim a/$AU $lesssim 25$, and $e lesssim 0.5$. A wealth of information can be obtained from RV/direct imaging overlap, especially with deep imaging as this work shows. The collaboration between RV and direct imaging will become more important in the coming years as the phase space probed by each technique converges. Future studies involving RV/imaging overlap should be sure to consider the effects of a potential planets projected separation, as quoting limits assuming face-on orientation will be misleading.