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Characterization of Dusty Debris Disks: The IRAS and Hipparcos Catalogs
Zuckerman, B.; Song, Inseok; McElwain, Michael +1 more
Dusty debris disks around main-sequence stars are signposts for the existence of planetesimals and exoplanets. From cross-correlating Hipparcos stars with the IRAS catalogs, we identify 146 stars within 120 pc of Earth that show excess emission at 60 µm. This search took special precautions to avoid false positives. Our sample is reasonably …
The Distances to Open Clusters from Main-Sequence Fitting. IV. Galactic Cepheids, the LMC, and the Local Distance Scale
Pinsonneault, Marc H.; Terndrup, Donald M.; An, Deokkeun
We derive the basic properties of seven Galactic open clusters containing Cepheids and construct their period-luminosity (P-L) relations. For our cluster main-sequence fitting we extend previous Hyades-based empirical color-temperature corrections to hotter stars using the Pleiades as a template. We use BVICJHKs data to test …
Searching for Earth Analogs Around the Nearest Stars: The Disk Age-Metallicity Relation and the Age Distribution in the Solar Neighborhood
Valenti, Jeff A.; Reid, I. Neill; Turnbull, Margaret C. +2 more
The chemical composition of Earth's atmosphere has undergone substantial evolution over the course of its history. It is possible, even likely, that terrestrial planets in other planetary systems have undergone similar changes; consequently, the age distribution of nearby stars is an important consideration in designing surveys for Earth analogs. …
Color, Rotation, Age, and Chromospheric Activity Correlations in Late-Type Main-Sequence Stars
Cassatella, Angelo; Cardini, Daniela
A study of the rotation-activity-age relationships in a large sample of single late-type main-sequence stars is carried out, based on rotation period data from the literature, on our measurements of the Mg II k line chromospheric flux in IUE high-resolution spectra, and on Hipparcos parallaxes. The analysis of the rotation period data of open clus…
The Planet Host Star γ Cephei: Physical Properties, the Binary Orbit, and the Mass of the Substellar Companion
Torres, Guillermo
The bright, K1 III-IV star γ Cep has been reported previously to have a possibly substellar companion in a ~2.5 yr orbit, as well as an unseen stellar companion at a larger separation. We determine for the first time the three-dimensional orbit of the latter, accounting also for the perturbation from the closer object. We combine new and existing …
Direct Measurement of the Radius and Density of the Transiting Exoplanet HD 189733b with the CHARA Array
Swain, Mark; van Belle, Gerard T.; McAlister, Harold A. +5 more
We have measured the angular diameter of the transiting extrasolar planet host star HD 189733 using the CHARA optical/IR interferometric array. Combining our new angular diameter of 0.377+/-0.024 mas with the Hipparcos parallax leads to a linear radius for the host star of 0.779+/-0.052 Rsolar and a radius for the planet of 1.19+/-0.08 …
EF Chamaeleontis: Warm Dust Orbiting a Nearby 10 Myr Old Star
Zuckerman, B.; Song, Inseok; Rhee, Joseph H.
Most Vega-like stars have far-infrared excess (60 µm or longward in IRAS, ISO, or Spitzer MIPS bands) and contain cold dust (<~150 K) analogous to the Sun's Kuiper Belt region. However, dust in a region more akin to our asteroid belt and thus relevant to the terrestrial planet building process is warm and produces excess emission in mid-i…
The Frequency of Mid-Infrared Excess Sources in Galactic Surveys
Indebetouw, R.; Benjamin, R. A.; Wolfire, M. G. +27 more
We have identified 230 Tycho-2 Spectral Catalog stars that exhibit 8 µm mid-IR extraphotospheric excesses in the MSX and Spitzer GLIMPSE surveys. Of these, 183 are either OB stars earlier than B8 in which the excess plausibly arises from a thermal bremsstrahlung component or evolved stars in which the excess may be explained by an atmospheri…
The Nearby Young Visual Binary HIP 115147 and Its Common Proper Motion Companion LSPM J2322+7847
Makarov, V. V.; Zacharias, N.; Hennessy, G. S. +2 more
We report a late M-type, common proper motion companion to a nearby young visual binary HIP 115147 (V368 Cep), separated by 963" from the primary K0 dwarf. This optically dim star was identified as a candidate high proper motion, nearby dwarf LSPM J2322+7847 by Lépine in 2005. The wide companion is one of the latest post-T Tauri low-mass stars fou…
The Structure and the Distance of Collinder 121 from Hipparcos and Photometry: Resolving the Discrepancy
Makarov, Valeri; Kaltcheva, Nadia
We present further arguments that the Hipparcos parallaxes for some of the clusters and associations represented in the Hipparcos catalog should be used with caution in the study of the Galactic structure. It has already been shown that the discrepancy between the Hipparcos and ground-based parallaxes for several clusters including the Pleiades, C…