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Isochrones for Old (>5 Gyr) Stars and Stellar Populations. I. Models for -2.4 <= [Fe/H] <=+0.6, 0.25 <= Y <= 0.33, and -0.4 <= [α/Fe] <=+0.4

Edvardsson, Bengt; VandenBerg, Don A.; Ferguson, Jason W. +1 more

Canonical grids of stellar evolutionary sequences have been computed for the helium mass-fraction abundances Y = 0.25, 0.29, and 0.33, and for iron abundances that vary from -2.4 to +0.4 (in 0.2 dex increments) when [α/Fe] =+0.4, or for the ranges -2.0 <= [Fe/H] <=+0.6, -1.8 <= [Fe/H] <=+0.6 when [α/Fe] =0.0 and -0.4, respectively. The…

Wide Cool and Ultracool Companions to Nearby Stars from Pan-STARRS 1

Chambers, Kenneth C.; Magnier, Eugene A.; Wainscoat, Richard J. +18 more

We present the discovery of 57 wide (>5'') separation, low-mass (stellar and substellar) companions to stars in the solar neighborhood identified from Pan-STARRS 1 (PS1) data and the spectral classification of 31 previously known companions. Our companions represent a selective subsample of promising candidates and span a range in spectral type…

Transit Confirmation and Improved Stellar and Planet Parameters for the Super-Earth HD 97658 b and its Host Star

Queloz, D.; Demory, B. -O.; Ehrenreich, D. +15 more

Super-Earths transiting nearby bright stars are key objects that simultaneously allow for accurate measurements of both their mass and radius, providing essential constraints on their internal composition. We present here the confirmation, based on Spitzer transit observations, that the super-Earth HD 97658 b transits its host star. HD 97658 is a …

Navy Precision Optical Interferometer Measurements of 10 Stellar Oscillators

van Belle, Gerard T.; Zavala, R. T.; Schmitt, Henrique R. +3 more

Using the Navy Precision Optical Interferometer, we measured the angular diameters of 10 stars that have previously measured solar-like oscillations. Our sample covered a range of evolutionary stages but focused on evolved subgiant and giant stars. We combined our angular diameters with Hipparcos parallaxes to determine the stars' physical radii, …

Deep VLA Images of the HH 124 IRS Radio Cluster and Its Surroundings, and a New Determination of the Distance to NGC 2264

Rodríguez, Luis F.; Loinard, Laurent; Dzib, Sergio A. +1 more

We present new deep (σ ~ 6 µJy) radio images of the HH 124 IRS radio cluster at 4.8 and 7.5 GHz. We detect a total of 50 radio sources, most of them compact. Variability and spectral indices were analyzed in order to determine the nature of the sources and of their radio emission. A proper motion study was also performed for several of these…