The Census of Exoplanets in Visual Binaries: population trends from a volume-limited Gaia DR2 and literature search

We present an extensive search in the literature and Gaia DR2 for visual co-moving binary companions to stars hosting exoplanets and brown dwarfs within 200 pc. We found 218 planet hosts out of 938 to be part of multiple-star systems, with 10 newly discovered binaries and 2 new tertiary stellar components. This represents an overall raw multiplicity rate of 23.2±1.6% for hosts to exoplanets across all spectral types, with multi-planet systems found to have a lower duplicity frequency at the 2.2σ level. We found that more massive hosts are more often in binary configurations, and that planet-bearing stars in multiple systems are predominantly the most massive component of stellar binaries. Investigations of multiplicity as a function of planet mass and separation revealed that giant planets with masses >0.1 MJup are more frequently seen in stellar binaries than small sub-Jovian planets with a 3.6σ difference, a trend enhanced for the most massive (>7 MJup) short-period (0.5 AU). While stellar companion mass appears to have no impact on planet properties, binary separation seems to be an important factor in the resulting structure of planetary systems. Stellar companions on separations <1000 AU can play a role in the formation or evolution of massive close-in planets, while planets in wider binaries show similar properties to planets orbiting single stars. Finally, numerous stellar companions on separations <1-3 arcsec likely remain undiscovered to this date. Continuous efforts to complete our knowledge of stellar multiplicity on separations of tens to hundreds of AU are essential to confirm the reported trends and further our understanding of the roles played by multiplicity on exoplanets

Testing a novel method to map the 3D distribution of gas clouds in intergalactic space

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Physics, June 2011."June 2010." Cataloged from PDF version of thesis.Includes bibliographical references (p. 45-46).We propose a new method to detect intergalactic Lyman a emitter and absorber systems by comparing broadband and narrowband images. The narrowband observations were carried out with the Maryland-Magellan Tunable Filter (MMTF) at central wavelengths of 5120A and 5140A and pointing to the Chandra Deep field South. The broadband images were obtained through the European Southern Observatory public database. Catalogues of galaxies were constructed from all images, taking the R broadband as a reference for locating objects. Via color-color and color-magniude diagrams, and taking the Steidel et al. color selection criteria as a reference, we were able to identify numerous Ly a emission and absorption candidates. This serves as a proof of concept that narrowband absorption could be used to mao the distribution of Lyman limit systems in 3D.by Daniella C. Bardalez Gagliuffi.S.B

Identification of WISE J000100.45+065259.6 as an M8.5+T5 Spectral Binary Candidate

[not part of RNAAS note] We report the discovery of WISE J000100.45+065259.6 as a very low mass star/brown dwarf spectral binary candidate, on the basis of low resolution near-infrared spectroscopy obtained with IRTF/SpeX. Decomposition of the spectrum indicates component types of M8.5+T5 with a predicted $\Delta{J}$ = 3.5. As the majority of confirmed spectral binary candidates to date are very closely-separated systems ($\rho$ $\lesssim$ 3 AU; $P$ $\lesssim$ 15~yr), this source may provide mass measurements across the hydrogen burning limit within the decade.Comment: 3 pages, 1 figure, accepted to Research Notes of the AA

The Orbit of the L dwarf + T dwarf Spectral Binary SDSS J080531.84+481233.0

[abridged] We report four years of radial velocity monitoring observations of SDSS J080531.84+481233.0 that reveal significant and periodic variability, confirming the binary nature of the source. We infer an orbital period of 2.02$\pm$0.03 yr, a semi-major axis of 0.76$^{+0.05}_{-0.06}$ AU, and an eccentricity of 0.46$\pm$0.05, consistent with the amplitude of astrometric variability and prior attempts to resolve the system. Folding in constraints based on the spectral types of the components (L4$\pm$0.7 and T5.5$\pm$1.1), corresponding effective temperatures, and brown dwarf evolutionary models, we further constrain the orbital inclination of this system to be nearly edge-on (90$^o\pm$19$^o$), and deduce a large system mass ratio (M$_2$/M$_1$ = 0.86$^{+0.10}_{-0.12}$), substellar components (M$_1$ = 0.057$^{+0.016}_{-0.014}$ M$_{\odot}$, M$_2$ = 0.048$^{+0.008}_{-0.010}$ M$_{\odot}$), and a relatively old system age (minimum age = 4.0$^{+1.9}_{-1.2}$ Gyr). The measured projected rotational velocity of the primary ($v\sin{i}$ = 34.1$\pm$0.7 km/s) implies that this inactive source is a rapid rotator (period $\lesssim$ 3 hr) and a viable system for testing spin-orbit alignment in very-low-mass multiples. The combination of well-determined component atmospheric properties and masses near and/or below the hydrogen minimum mass make SDSS J0805+4812AB an important system for future tests of brown dwarf evolutionary models.Comment: 15 pages, 11 figures, accepted for publication to Ap

High Resolution Imaging of Very Low Mass Spectral Binaries: Three Resolved Systems and Detection of Orbital Motion in an L/T Transition Binary

We present high resolution Laser Guide Star Adaptive Optics imaging of 43 late-M, L and T dwarf systems with Keck/NIRC2. These include 17 spectral binary candidates, systems whose spectra suggest the presence of a T dwarf secondary. We resolve three systems: 2MASS J1341–3052, SDSS J1511+0607 and SDSS J2052–1609; the first two are resolved for the first time. All three have projected separations <8 AU and estimated periods of 14–80 years. We also report a preliminary orbit determination for SDSS J2052–1609 based on six epochs of resolved astrometry between 2005 and 2010. Among the 14 unresolved spectral binaries, 5 systems were confirmed binaries but remained unresolved, implying a minimum binary fraction of 47_(-11)^(+12) for this sample. Our inability to resolve most of the spectral binaries, including the confirmed binaries, supports the hypothesis that a large fraction of very low mass systems have relatively small separations and are missed with direct imaging