Search Publications
New Members of the TW Hydrae Association, β Pictoris Moving Group, and Tucana/Horologium Association
Zuckerman, B.; Song, Inseok; Bessell, M. S.
We have identified five new members of the TW Hydrae association (TWA), 11 new members of the β Pic moving group, and 11 new Tucana/Horologium association members. These are the three youngest (<~30 Myr) known kinematic stellar groups near the Earth. Newly identified β Pic group members are located mostly in the northern hemisphere, and they ha…
Multiwavelength Observations of Flares on AD Leonis
Hawley, Suzanne L.; Valenti, Jeff A.; Johns-Krull, Christopher M. +9 more
We report results from a multiwavelength observing campaign conducted during 2000 March on the flare star AD Leo. Simultaneous data were obtained from several ground- and space-based observatories, including observations of eight sizable flares. We discuss the correlation of line and continuum emission in the optical and ultraviolet wavelength reg…
Locating the Launching Region of T Tauri Winds: The Case of DG Tauri
Li, Zhi-Yun; Blandford, Roger D.; Krasnopolsky, Ruben +1 more
It is widely believed that T Tauri winds are driven magnetocentrifugally from accretion disks close to the central stars. The exact launching conditions are uncertain. We show that a general relation exists between the poloidal and toroidal velocity components of a magnetocentrifugal wind at large distances and the rotation rate of the launching s…
Galactic Bulges from Hubble Space Telescope Near-Infrared Camera Multi-Object Spectrometer Observations: The Lack of r1/4 Bulges
Balcells, Marc; Graham, Alister W.; Domínguez-Palmero, Lilian +1 more
We use Hubble Space Telescope (HST) near-infrared imaging to explore the shapes of the surface brightness profiles of bulges of S0-Sbc galaxies at high resolution. Modeling extends to the outer bulge via bulge-disk decompositions of combined HST-ground-based profiles. Compact, central unresolved components similar to those reported by others are f…
Alfvénic Turbulence in the Extended Solar Corona: Kinetic Effects and Proton Heating
Cranmer, S. R.; van Ballegooijen, A. A.
We present a model of magnetohydrodynamic (MHD) turbulence in the extended solar corona that contains the effects of collisionless dissipation and anisotropic particle heating. Recent observations have shown that preferential heating and acceleration of positive ions occur in the first few solar radii of the high-speed solar wind. Measurements mad…
A Spectroscopic Survey of Subarcsecond Binaries in the Taurus-Auriga Dark Cloud with the Hubble Space Telescope
Hartigan, Patrick; Kenyon, Scott J.
We report the results of a spectroscopic survey of 20 close T Tauri binaries in the Taurus-Auriga dark cloud where the separations between primaries and their secondaries are less than the typical size of a circumstellar disk around a young star. Analysis of low- and medium-resolution Space Telescope Imaging Spectrograph spectra yields the stellar…
Kinematic Masses of Super-Star Clusters in M82 from High-Resolution Near-Infrared Spectroscopy
Graham, James R.; McCrady, Nate; Gilbert, Andrea M.
Using high-resolution (R~22,000) near-infrared (1.51-1.75 µm) spectra from Keck Observatory, we measure the kinematic masses of two super-star clusters in M82. Cross-correlation of the spectra with template spectra of cool evolved stars gives stellar velocity dispersions of σr=15.9+/-0.8 km s-1 for J0955505+694045 (MGG-…
Chandra Observation of the Cooling Flow Cluster Abell 2052
Sarazin, Craig L.; McNamara, Brian R.; Blanton, Elizabeth L.
We present an analysis of the Chandra X-ray observation of A2052, including large-scale properties of the cluster as well as the central region, which includes the bright radio source 3C 317. We present temperature and abundance profiles using both projected and deprojected spectral analyses. The cluster shows the cooling flow signatures of excess…
A Hubble Space Telescope Survey of Extended [O III] λ5007 Å Emission in a Far-Infrared-Selected Sample of Seyfert Galaxies: Results
Pringle, J. E.; Hutchings, J. B.; Schmitt, H. R. +3 more
We present the results of a Hubble Space Telescope (HST) survey of extended [O III] emission in a sample of 60 nearby Seyfert galaxies (22 Seyfert 1's and 38 Seyfert 2's), selected by mostly isotropic properties. The comparison between the semimajor axis size of their [O III] emitting regions (Rmaj) shows that Seyfert 1's and Seyfert 2'…
Rapid Acceleration of a Coronal Mass Ejection in the Low Corona and Implications for Propagation
Gallagher, Peter T.; Dennis, Brian R.; Lawrence, Gareth R.
A high-velocity coronal mass ejection (CME) associated with the 2002 April 21 X1.5 flare is studied using a unique set of observations from the Transition Region and Coronal Explorer (TRACE), the Ultraviolet Coronagraph Spectrometer (UVCS), and the Large Angle and Spectroscopic Coronagraph (LASCO). The event is first observed as a rapid rise in GO…