Timothy D. Brandt

A STATISTICAL ANALYSIS OF SEEDS AND OTHER HIGH-CONTRAST EXOPLANET SURVEYS: MASSIVE PLANETS OR LOW-MASS BROWN DWARFS?*

We conduct a statistical analysis of a combined sample of direct imaging data, totalling nearly 250 stars. The stars cover a wide range of ages and spectral types, and include five detections (κ And b, two ∼60 M {sub J} brown dwarf companions in the Pleiades, PZ Tel B, and CD–35 2722B). For some analyses we add a currently unpublished set of SEEDS observations, including the detections GJ 504b and GJ 758B. We conduct a uniform, Bayesian analysis of all stellar ages using both membership in a kinematic moving group and activity/rotation age indicators. We then present a new statistical method for computing the likelihood of a substellar distribution function. By performing most of the integrals analytically, we achieve an enormous speedup over brute-force Monte Carlo. We use this method to place upper limits on the maximum semimajor axis of the distribution function derived from radial-velocity planets, finding model-dependent values of ∼30-100 AU. Finally, we model the entire substellar sample, from massive brown dwarfs to a theoretically motivated cutoff at ∼5 M {sub J}, with a single power-law distribution. We find that p(M, a)∝M {sup –0.65} {sup ±} {sup 0.60} a {sup –0.85} {sup ±} {sup 0.39} (1σ errors) providesmorexa0» an adequate fit to our data, with 1.0%-3.1% (68% confidence) of stars hosting 5-70 M {sub J} companions between 10 and 100 AU. This suggests that many of the directly imaged exoplanets known, including most (if not all) of the low-mass companions in our sample, formed by fragmentation in a cloud or disk, and represent the low-mass tail of the brown dwarfs.«xa0less

RECOVERY OF THE CANDIDATE PROTOPLANET HD 100546 b WITH GEMINI/NICI AND DETECTION OF ADDITIONAL (PLANET-INDUCED?) DISK STRUCTURE AT SMALL SEPARATIONS

We report the first independent, second-epoch (re-)detection of a directly-imaged protoplanet candidate. Using

THE AGE AND AGE SPREAD OF THE PRAESEPE AND HYADES CLUSTERS: A CONSISTENT, ∼800 Myr PICTURE FROM ROTATING STELLAR MODELS

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BAYESIAN AGES FOR EARLY-TYPE STARS FROM ISOCHRONES INCLUDING ROTATION, AND A POSSIBLE OLD AGE FOR THE HYADES

high-contrast imaging of HD 100546 taken with the Near-Infrared Coronagraph and Imager (NICI) on Gemini South, we recover `HD 100546 b with a position and brightness consistent with the original VLT/NaCo detection from Quanz et al, although data obtained after 2013 will be required to decisively demonstrate common proper motion. HD 100546 b may be spatially resolved, up to

Rotating Stellar Models Can Account for the Extended Main-sequence Turnoffs in Intermediate-age Clusters

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The architecture of the LkCa 15 transitional disk revealed by high-contrast imaging

12-13 AU in diameter, and is embedded in a finger of thermal IR bright, polarized emission extending inwards to at least 0.3. Standard hot-start models imply a mass of

Detailed structure of the outer disk around HD 169142 with polarized light in H-band

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The Structure of Pre-transitional Protoplanetary Disks. II. Azimuthal Asymmetries, Different Radial Distributions of Large and Small Dust Grains in PDS 70

15

Prospects for detecting oxygen, water, and chlorophyll on an exo-Earth

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The SEEDS High-Contrast Imaging Survey of Exoplanets Around Young Stellar Objects

. But if HD 100546 b is newly formed or made visible by a circumplanetary disk, both of which are plausible, its mass is significantly lower (e.g. 1--7