Search Publications
Short large-amplitude magnetic structures (SLAMS) at Venus
Coates, A. J.; Barabash, S.; Zhang, T. L. +5 more
We present the first observation of magnetic fluctuations consistent with short large-amplitude magnetic structures (SLAMS) in the foreshock of the planet Venus. Three monolithic magnetic field spikes were observed by the Venus Express on 11 April 2009. The structures were ∼1.5-11 s in duration, had magnetic compression ratios between ∼3 and 6, an…
The Panchromatic Hubble Andromeda Treasury. II. Tracing the Inner M31 Halo with Blue Horizontal Branch Stars
Bell, Eric F.; Williams, Benjamin F.; Gilbert, Karoline M. +7 more
We attempt to constrain the shape of M31's inner stellar halo by tracing the surface density of blue horizontal branch (BHB) stars at galactocentric distances ranging from 2 kpc to 35 kpc. Our measurements make use of resolved stellar photometry from a section of the Panchromatic Hubble Andromeda Treasury survey, supplemented by several archival H…
On Signatures of Twisted Magnetic Flux Tube Emergence
van Driel-Gesztelyi, L.; Vargas Domínguez, S.; MacTaggart, D. +2 more
Recent studies of NOAA active region 10953, by Okamoto et al. (Astrophys. J. Lett.673, 215, 2008; Astrophys. J.697, 913, 2009), have interpreted photospheric observations of changing widths of the polarities and reversal of the horizontal magnetic field component as signatures of the emergence of a twisted flux tube within the active region and al…
Peak emission altitude of Saturn's H3+ aurora
Baines, Kevin H.; Brown, Robert H.; Melin, Henrik +3 more
Here we present the first detailed measurement of the altitudinal profile of H3+ emission within Saturn's ionosphere, made using images taken by the VIMS instrument on Cassini on 11-12 October 2006, during a chance alignment between the visible limb of the planet and the position of the main auroral emission. Using this, we s…
Flash Mixing on the White Dwarf Cooling Curve: Spectroscopic Confirmation in NGC 2808
Brown, Thomas M.; Hubeny, Ivan; Sweigart, Allen V. +3 more
We present new Hubble Space Telescope far-UV spectroscopy of two dozen hot evolved stars in NGC 2808, a massive globular cluster with a large population of "blue-hook" (BHk) stars. The BHk stars are found in ultraviolet color-magnitude diagrams of the most massive globular clusters, where they fall at luminosities immediately below the hot end of …
Seasonal Disappearance of Far-infrared Haze in Titan's Stratosphere
Calcutt, S. B.; de Kok, R.; Flasar, F. M. +9 more
A far-infrared emission band attributed to volatile or refractory haze in Titan's stratosphere has been decreasing in intensity since Cassini's arrival in 2004. The 220 cm-1 feature, first seen by the Voyager Infrared Interferometer Spectrometer, has only been found in Titan's winter polar region. The emission peaks at about 140 km alti…
Observations of a Two-stage Solar Eruptive Event (SEE): Evidence for Secondary Heating
Veronig, Astrid; Chamberlin, Phillip C.; Su, Yang +4 more
We present RHESSI, SDO/AIA, SOHO/LASCO, STEREO, and GOES observations of a partially occulted solar eruptive event that occurred at the southwest limb on 2011 March 8. The GOES X-ray light curve shows two peaks separated by almost 2 hr that we interpret as two stages of a single event associated with the delayed eruption of a coronal mass ejection…
A Link to the Past: Using Markov Chain Monte Carlo Fitting to Constrain Fundamental Parameters of High-redshift Galaxies
Koekemoer, Anton; Malhotra, Sangeeta; Rhoads, James +4 more
We have developed a new method for fitting spectral energy distributions (SEDs) to identify and constrain the physical properties of high-redshift (4 < z < 8) galaxies. Our approach uses an implementation of Bayesian based Markov Chain Monte Carlo that we have dubbed "πMC2." It allows us to compare observations to arbitrarily comp…
Analysis of a Fragmenting Sunspot Using Hinode Observations
Venkatakrishnan, P.; Ravindra, B.; Mathew, Shibu K. +3 more
We employ high-resolution filtergrams and polarimetric measurements from Hinode to follow the evolution of a sunspot for eight days starting on 2007 June 28. The imaging data were corrected for intensity gradients, projection effects, and instrumental stray light prior to the analysis. The observations show the formation of a light bridge at one c…
Dust levitation as a major resurfacing process on the surface of a saturnian icy satellite, Atlas
Hirata, Naoyuki; Miyamoto, Hideaki
A small inner satellite of Saturn, Atlas, has an enigmatic saucer-like shape explained by an accumulation of particles from A-ring of Saturn. However, its unusual smooth surface remains unexplained. Gardening through continuous particle impact events cannot be a unique explanation for the smoothness, because Prometheus does not exhibit a similar s…