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Rotational and Radial Velocities for a Sample of 761 HIPPARCOS Giants and the Role of Binarity
Latham, David W.; Stefanik, Robert P.; Massarotti, Alessandro +1 more
We present rotational and radial velocities for a sample of 761 giants selected from the Hipparcos Catalogue to lie within 100 pc of the Sun. Our original goal was to examine stellar rotation in field giants using spectroscopic line broadening to look for evidence of excess rotation that could be attributed to planets that were engulfed as the par…
Nonlinear Force-Free Modeling of Coronal Magnetic Fields. II. Modeling a Filament Arcade and Simulated Chromospheric and Photospheric Vector Fields
Wiegelmann, Thomas; Schrijver, Carolus J.; Valori, Gherardo +6 more
We compare a variety of nonlinear force-free field (NLFFF) extrapolation algorithms, including optimization, magneto-frictional, and Grad - Rubin-like codes, applied to a solar-like reference model. The model used to test the algorithms includes realistic photospheric Lorentz forces and a complex field including a weakly twisted, right helical flu…
Outflows at the Edges of Active Regions: Contribution to Solar Wind Formation?
Young, P. R.; Mandrini, C. H.; van Driel-Gesztelyi, L. +5 more
The formation of the slow solar wind has been debated for many years. In this Letter we show evidence of persistent outflow at the edges of an active region as measured by the EUV Imaging Spectrometer on board Hinode. The Doppler velocity ranged between 20 and 50 km s-1 and was consistent with a steady flow seen in the X-Ray Telescope. …
M dwarfs: effective temperatures, radii and metallicities
Casagrande, Luca; Flynn, Chris; Bessell, Michael
We empirically determine effective temperatures and bolometric luminosities for a large sample of nearby M dwarfs, for which high accuracy optical and infrared photometry is available. We introduce a new technique which exploits the flux ratio in different bands as a proxy of both effective temperature and metallicity. Our temperature scale for la…
The Sloan Lens ACS Survey. VII. Elliptical Galaxy Scaling Laws from Direct Observational Mass Measurements
Treu, Tommaso; Schlegel, David J.; Gavazzi, Raphaël +5 more
We use a sample of 53 massive early-type strong gravitational lens galaxies with well-measured redshifts (ranging from z = 0.06 to 0.36) and stellar velocity dispersions (between 175 and 400 km s-1) from the Sloan Lens ACS (SLACS) Survey to derive numerous empirical scaling relations. The ratio between central stellar velocity dispersio…
Cosmic X-Ray Background and Earth Albedo Spectra with Swift BAT
Greiner, J.; Strong, A. W.; Ajello, M. +8 more
We use Swift BAT Earth occultation data at different geomagnetic latitudes to derive a sensitive measurement of the cosmic X-ray background (CXB) and of the Earth albedo emission in the 15-200 keV band. We compare our CXB spectrum with recent (INTEGRAL, BeppoSAX) and past results (HEAO-1) and find good agreement. Using an independent measurement o…
Optical and Near-Infrared Observations of the Highly Reddened, Rapidly Expanding Type Ia Supernova SN 2006X in M100
Filippenko, Alexei V.; Foley, Ryan J.; Li, Weidong +14 more
We present extensive optical (UBVRI), near-infrared (JK) light curves and optical spectroscopy of the Type Ia supernova SN 2006X in the nearby galaxy NGC 4321 (M100). Our observations suggest that either SN 2006X has an intrinsically peculiar color evolution or it is highly reddened [E(B - V)host = 1.42 +/- 0.04 mag ] with RV…
Acceleration in Fast Halo CMEs and Synchronized Flare HXR Bursts
Temmer, M.; Veronig, A. M.; Maričić, D. +4 more
We study two well-observed, fast halo CMEs, covering the full CME kinematics including the initiation and impulsive acceleration phase, and their associated flares. We find a close synchronization between the CME acceleration profile and the flare energy release as indicated by the RHESSI hard X-ray flux onsets, as well as peaks occur simultaneous…
The Very Low Albedo of an Extrasolar Planet: MOST Space-based Photometry of HD 209458
Moffat, Anthony F. J.; Rucinski, Slavek M.; Seager, Sara +8 more
Measuring the albedo of an extrasolar planet provides insight into its atmospheric composition and its global thermal properties, including heat dissipation and weather patterns. Such a measurement requires very precise photometry of a transiting system, fully sampling many phases of the secondary eclipse. Space-based optical photometry of the tra…
Stellar Proper Motions in the Galactic Bulge from Deep Hubble Space Telescope ACS WFC Photometry
Brown, Thomas M.; Casertano, Stefano; Smith, T. Ed +11 more
We present stellar proper motions in the Galactic bulge from the Sagittarius Window Eclipsing Extrasolar Search (SWEEPS) project using ACS WFC on HST. Proper motions are extracted for more than 180,000 objects, with >81,000 measured to accuracy better than 0.3 mas yr-1 in both coordinates. We report several results based on these mea…