Search Publications
Persistent rings in and around Jupiter’s anticyclones - Observations and theory
de Pater, Imke; Wong, Michael H.; Luszcz-Cook, Statia +5 more
We present observations and theoretical calculations to derive the vertical structure of and secondary circulation in jovian vortices, a necessary piece of information to ultimately explain the red color in the annular ring inside Jupiter's Oval BA. The observations were taken with the near-infrared detector NIRC2 coupled to the adaptive optics sy…
Pluto and Charon with the Hubble Space Telescope. I. Monitoring Global Change and Improved Surface Properties from Light Curves
Stern, S. Alan; Young, Leslie A.; Buie, Marc W. +2 more
We present new light-curve measurements of Pluto and Charon taken with the Advanced Camera for Surveys High-resolution Camera on the Hubble Space Telescope. The observations were collected from 2002 June to 2003 June at 12 distinct sub-Earth longitudes over a range of solar phase angle 0fdg36-1fdg74—a larger range than previously measured. The new…
The Velocity Distribution of Nearby Stars from Hipparcos Data. II. The Nature of the Low-velocity Moving Groups
Bovy, Jo; Hogg, David W.
The velocity distribution of nearby stars (lsim100 pc) contains many overdensities or "moving groups," clumps of comoving stars, that are inconsistent with the standard assumption of an axisymmetric, time-independent, and steady-state Galaxy. We study the age and metallicity properties of the low-velocity moving groups based on the reconstruction …
Probing evolutionary mechanisms in galaxy clusters: neutral atomic hydrogen in Abell1367
Hardcastle, M. J.; Croston, J. H.; Boselli, A. +6 more
We present Very Large Array HI imaging data for a field in the NW of the galaxy cluster Abell 1367 (z =0.02) in an attempt to probe the effect environment has on the interstellar medium of late-type spiral galaxies. Several galaxies, like CGCG 097-087, show pronounced tails and asymmetries, and seven out of 10 show significant, several kpc offsets…
The Quiet Solar Atmosphere Observed and Simulated in Na I D1
Leenaarts, J.; Carlsson, M.; Hansteen, V. +2 more
The Na I D1 line in the solar spectrum is sometimes attributed to the solar chromosphere. We study its formation in quiet-Sun network and internetwork. We first present high-resolution profile-resolved images taken in this line with the imaging spectrometer Interferometric Bidimensional Spectrometer at the Dunn Solar Telescope and compa…
Mapping the Distribution of Electron Temperature and Fe Charge States in the Corona with Total Solar Eclipse Observations
Rušin, V.; Druckmüller, M.; Esser, R. +7 more
The inference of electron temperature from the ratio of the intensities of emission lines in the solar corona is valid only when the plasma is collisional. Once collisionless, thermodynamic ionization equilibrium no longer holds, and the inference of an electron temperature and its gradient from such measurements is no longer valid. At the helioce…
Dynamics of isolated magnetic bright points derived from Hinode/SOT G-band observations
Veronig, A.; Utz, D.; Hanslmeier, A. +3 more
Context. Small-scale magnetic fields in the solar photosphere can be identified in high-resolution magnetograms or in the G-band as magnetic bright points (MBPs). Rapid motions of these fields can cause magneto-hydrodynamical waves and can also lead to nanoflares by magnetic field braiding and twisting. The MBP velocity distribution is a crucial p…
The Chandra M101 Megasecond: Diffuse Emission
Kuntz, K. D.; Snowden, S. L.
Because M101 is nearly face-on, it provides an excellent laboratory in which to study the distribution of X-ray-emitting gas in a typical late-type spiral galaxy. We obtained a Chandra observation with a cumulative exposure of roughly 1 Ms to study the diffuse X-ray emission in M101. The bulk of the X-ray emission is correlated with the star forma…
Spatial Seismology of a Large Coronal Loop Arcade from TRACE and EIT Observations of its Transverse Oscillations
Foullon, C.; Verwichte, E.; Van Doorsselaere, T.
We present a study of transverse loop oscillations in a large coronal loop arcade, using observations from the Transition Region And Coronal Explorer (TRACE) and Extreme-ultraviolet Imaging Telescope (EIT). For the first time we reveal the presence of long-period transverse oscillations with periods between 24 minutes and 3 hr. One loop bundle, 69…
Proper-motion Study of the Magellanic Clouds Using SPM Material
Casetti-Dinescu, Dana I.; Girard, Terrence M.; Korchagin, Vladimir I. +8 more
Absolute proper motions are determined for stars and galaxies to V = 17.5 over a 450 deg2 area that encloses both Magellanic Clouds. The proper motions are based on photographic and CCD observations of the Yale/San Juan Southern Proper Motion program, which span a baseline of 40 years. Multiple, local relative proper-motion measures are…