We present the results of a comprehensive assessment of companions to solartype stars. A sample of 454 stars, including the Sun, was selected from the Hipparcos catalog with π > 40 mas, σ π /π < 0.05, 0.5 ≤ B − V ≤ 1.0 (∼ F6-K3), and constrained by absolute magnitude and color to exclude evolved stars. These criteria are equivalent to selecting all dwarf and subdwarf stars within 25 pc with V -band flux between 0.1 and 10 times that of the Sun, giving us a physical basis for the term "solar-type". New observational aspects of this work include surveys for (1) very close companions with long-baseline interferometry at the Center for High Angular Resolution Astronomy (CHARA) Array, (2) close companions with speckle interferometry, and (3) wide proper motion companions identified by blinking multi-epoch archival images. In addition, we include the results from extensive radial-velocity monitoring programs and evaluate companion information from various catalogs covering many different techniques. The results presented here include four new common proper motion companions discovered by blinking archival images. Additionally, the spectroscopic data searched reveal five new stellar companions. Our synthesis of results from many methods and sources results in a thorough evaluation of stellar and brown dwarf companions to nearby Sun-like stars.

We present interferometric angular diameter measurements of 21 low-mass, Kand M-dwarfs made with the CHARA Array. This sample is enhanced by adding a collection of radii measurements published in the literature to form a total data set of 33 K-M dwarfs with diameters measured to better than 5%. We use these data in combination with the Hipparcos parallax and new measurements of the star's bolometric flux to compute absolute luminosities, linear radii, and effective temperatures for the stars. We develop empirical relations for ∼K0 to M4 mainsequence stars that link the stellar temperature, radius, and luminosity to thebroad-band color index and stellar metallicity [Fe/H]. These relations are valid for metallicities ranging from [Fe/H] = −0.5 to +0.1 dex, and are accurate to ∼2%, ∼5%, and ∼4% for temperature, radius, and luminosity, respectively. Our results show that it is necessary to use metallicity dependent transformations in order to properly convert colors into stellar temperatures, radii, and luminosities. Alternatively, we find no sensitivity to metallicity on relations we construct to the global properties of a star omitting color information e.g., temperature-radius and temperatureluminosity. Thus, we are able to empirically quantify to what order the star's observed color index is impacted by the stellar iron abundance. In addition to the empirical relations, we also provide a representative look-up table via stellar spectral classifications using this collection of data. Robust examinations of single star temperatures and radii compared to evolutionary model predictions on the luminosity -temperature and luminosity -radius planes reveals that models overestimate the temperatures of stars with surface temperatures < 5000 K by ∼ 3%, and underestimate the radii of stars with radii < 0.7 R ⊙ by ∼ 5%. These conclusions additionally suggest that the models over account for the effects that the stellar metallicity may have on the astrophysical properties of an object. By comparing the interferometrically measured radii for the single star population to those of eclipsing binaries, we find that for a given mass, single and binary star radii are indistinguishable. However, we also find that for a given radius, the literature temperatures for binary stars are systematically lower compared to our interferometrically derived temperatures of single stars by ∼ 200 to 300 K. The nature of this offset is dependent on the validation of binary star temperatures; where bringing all measurements to a uniform and correctly calibrated temperature scale is needed to identify any influence stellar activity may have on the physical properties of a star. Lastly, we present a empirically determined HR diagram using fundamental properties presented here in combination with those in Boyajian et al. (2012) for a total of 74 nearby, main-sequence, A-to M-type stars, and define regions of habitability for the potential existence of sub-stellar mass companions in each system.

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Prepared by the LSST Science Collaborations, with contributions from the LSST Project. PrefaceMajor advances in our understanding of the Universe over the history of astronomy have often arisen from dramatic improvements in our ability to observe the sky to greater depth, in previously unexplored wavebands, with higher precision, or with improved spatial, spectral, or temporal resolution. Aided by rapid progress in information technology, current sky surveys are again changing the way we view and study the Universe, and the next-generation instruments, and the surveys that will be made with them, will maintain this revolutionary progress. Substantial progress in the important scientific problems of the next decade (determining the nature of dark energy and dark matter, studying the evolution of galaxies and the structure of our own Milky Way, opening up the time domain to discover faint variable objects, and mapping both the inner and outer Solar System) all require wide-field repeated deep imaging of the sky in optical bands.The wide-fast-deep science requirement leads to a single wide-field telescope and camera which can repeatedly survey the sky with deep short exposures. The Large Synoptic Survey Telescope (LSST), a dedicated telecope with an effective aperture of 6.7 meters and a field of view of 9.6 deg 2 , will make major contributions to all these scientific areas and more. It will carry out a survey of 20,000 deg 2 of the sky in six broad photometric bands, imaging each region of sky roughly 2000 times (1000 pairs of back-to-back 15-sec exposures) over a ten-year survey lifetime.The LSST project will deliver fully calibrated survey data to the United States scientific community and the public with no proprietary period. Near real-time alerts for transients will also be provided worldwide. A goal is worldwide participation in all data products. The survey will enable comprehensive exploration of the Solar System beyond the Kuiper Belt, new understanding of the structure of our Galaxy and that of the Local Group, and vast opportunities in cosmology and galaxy evolution using data for billions of distant galaxies. Since many of these science programs will involve the use of the world's largest non-proprietary database, a key goal is maximizing the usability of the data. Experience with previous surveys is that often their most exciting scientific results were unanticipated at the time that the survey was designed; we fully expect this to be the case for the LSST as well.The purpose of this Science Book is to examine and document in detail science goals, opportunities, and capabilities that will be provided by the LSST. The book addresses key questions that will be confronted by the LSST survey, and it poses new questions to be addressed by future study. It contains previously available material (including a number of White Papers submitted to the ASTRO2010 Decadal Survey) as well as new results from a year-long campaign of study and evaluation. This book does not attempt to be complete; there are many ...

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We present 0.6È2.5 km, spectra of 27 cool, low-luminosity stars and substellar objects. Based R Z 400 on these and previously published spectra, we develop a preliminary spectral classiÐcation system for L and T dwarfs. For late L and T types the classiÐcation system is based entirely on four spectral indices in the 1È2.5 km interval. Two of these indices are derived from water absorption bands at 1.15 and 1.4 km, the latter of which shows a smooth increase in depth through the L and T sequences and can be used to classify both spectral types. The other two indices make use of methane absorption features in the H and K bands, with the K-band index also applicable to mid-to-late L dwarfs. Continuum indices shortward of 1 km used by previous authors to classify L dwarfs are found to be useful only through mid-L subclasses. We employ the 1.5 km water index and the 2.2 km methane index to complete the L classiÐcation through L9.5 and to link the new system with a modiÐed version of the 2MASS "" color-d ÏÏ index. By correlating the depths of the methane and water absorption features, we establish a T spectral sequence from T0 to T8, based on all four indices, that is a smooth continuation of the L sequence. We reclassify two 2MASS L8 dwarfs as L9 and L9.5 and identify one SDSS object as L9. In the proposed system methane absorption appears in the K band approximately at L8, two subclasses earlier than its appearance in the H band. The L and T spectral classes are distinguished by the absence and presence, respectively, of H-band methane absorption.

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