Search Publications
Identifying Current-Sheet-like Structures in the Solar Wind
Li, G.
In past years, measurements of the solar wind plasma have advanced our understanding of MHD turbulence tremendously. At small scales, the solar wind is believed to be ve`xry multifractal with nonlinear interactions causing an intermittent energy dissipation, leading to possible current-sheet structures. In this Letter, we propose a systematic data…
Outburst of the 2 s Anomalous X-Ray Pulsar 1E 1547.0-5408
Camilo, F.; Ransom, S. M.; Gotthelf, E. V. +2 more
Following our discovery of radio pulsations from the newly recognized anomalous X-ray pulsar (AXP) 1E 1547.0-5408, we initiated X-ray monitoring with the Swift X-ray telescope and obtained a single target-of-opportunity observation with the Newton X-ray Multi-Mirror Mission (XMM-Newton). In comparison with its historic minimum flux of 3 × 10-…
Structure and Kinematics of Molecular Disks in Fast-Rotator Early-Type Galaxies
Cappellari, Michele; Bureau, Martin; Young, Lisa M.
We present interferometric observations resolving the CO emission in the four gas-rich lenticular galaxies NGC 3032, NGC 4150, NGC 4459, and NGC 4526, and we compare the CO distribution and kinematics to those of the stars and ionized gas. Counterrotation documents an external origin for the gas in at least one case (NGC 3032), and the comparisons…
Using Global Simulations to Relate the Three-Part Structure of Coronal Mass Ejections to In Situ Signatures
Riley, Pete; Mikić, Zoran; Lionello, Roberto +1 more
White-light observations of coronal mass ejections (CMEs) often show the classic "three-part" structure consisting of (1) a bright front; (2) a dark cavity; and (3) a bright, compact core. It has proven difficult to unambiguously associate these features with in situ measurements of interplanetary CMEs (ICMEs), in all but a few cases. In this stud…
A Molecular Einstein Ring at z = 4.12: Imaging the Dynamics of a Quasar Host Galaxy Through a Cosmic Lens
Lewis, Geraint F.; Walter, Fabian; Carilli, Christopher L. +4 more
We present high-resolution (0.3'') Very Large Array imaging of the molecular gas in the host galaxy of the high-redshift quasar PSS J2322+1944 (z = 4.12). These observations confirm that the molecular gas (CO) in the host galaxy of this quasar is lensed into a full Einstein ring and reveal the internal gas dynamics in this system. The ring has a d…
Spatial Relationship between Solar Flares and Coronal Mass Ejections
Howard, R. A.; Gopalswamy, N.; Michalek, G. +2 more
We report on the spatial relationship between solar flares and coronal mass ejections (CMEs) observed during 1996-2005 inclusive. We identified 496 flare-CME pairs considering limb flares (distance from central meridian >=45°) with soft X-ray flare size >=C3 level. The CMEs were detected by the Large Angle and Spectrometric Coronagraph (LASC…
Hubble Space Telescope Snapshot Survey of Post-AGB Objects
Szczerba, R.; Meixner, M.; Ueta, T. +3 more
The results of a Hubble Space Telescope (HST) snapshot survey of post-AGB objects are shown. The aim of the survey is to complement existing HST images of protoplanetary nebulae and to connect various types of nebulosities with the physical and chemical properties of their central stars. Nebulosities are detected in 15 of 33 sources. Images and ph…
Thermal X-Rays from Millisecond Pulsars: Constraining the Fundamental Properties of Neutron Stars
Bogdanov, Slavko; Grindlay, Jonathan E.; Rybicki, George B.
We model the X-ray properties of millisecond pulsars (MSPs) by considering hot-spot emission from a weakly magnetized neutron star (NS) covered by a hydrogen atmosphere. We investigate the limitations of using the thermal X-ray pulse profiles of MSPs to constrain the mass-to-radius (M/R) ratio of the NS. The accuracy is strongly dependent on the v…
Magnetogram Measures of Total Nonpotentiality for Prediction of Solar Coronal Mass Ejections from Active Regions of Any Degree of Magnetic Complexity
Falconer, D. A.; Moore, R. L.; Gary, G. A.
For investigating the magnetic causes of coronal mass ejections (CMEs) and for forecasting the CME productivity of active regions, in previous work we have gauged the total nonpotentiality of a whole active region by either of two measures, LSSM and LSGM, two measures of the magnetic field along the main neutral line in a vec…
Solving the Discrepancy between the Seismic and Photospheric Solar Radius
Schmutz, W.; Haberreiter, M.; Kosovichev, A. G.
Two methods are used to observationally determine the solar radius: One is the observation of the intensity profile at the limb; the other one uses f-mode frequencies to derive a "seismic" solar radius which is then corrected to optical depth unity. The two methods are inconsistent and lead to a difference in the solar radius of ~0.3 Mm. Because o…