Search Publications
Mapping the Structure of the Corona Using Fourier Backprojection Tomography
Morgan, Huw; Habbal, Shadia Rifai; Lugaz, Noé
Estimating the structure, or density distribution, of the solar corona from a set of two-dimensional white-light images made by coronagraphs is a critical challenge in coronal physics. This work describes new data-analysis procedures which are used to create global maps of the coronal structure at heights where the corona becomes approximately rad…
The accretion powered spin-up of GRO J1750-27
Hill, A. B.; Kretschmar, P.; Kuulkers, E. +3 more
The timing properties of the 4.45 s pulsar in the Be X-ray binary system GRO J1750-27 are examined using hard X-ray data from INTEGRAL and Swift during a type II outburst observed during 2008. The orbital parameters of the system are measured and agree well with those found during the last known outburst of the system in 1995. Correcting the effec…
The initial mass function of the rich young cluster NGC 1818 in the Large Magellanic Cloud
de Grijs, R.; Hu, Y.; Baraffe, I. +3 more
We use deep Hubble Space Telescope photometry of the rich, young (~20- to 45-Myr old) star cluster NGC 1818 in the Large Magellanic Cloud to derive its stellar mass function (MF) down to ~0.15Msolar. This represents the deepest robust MF thus far obtained for a stellar system in an extragalactic, low-metallicity ([Fe/H] ~= -0.4dex) envi…
Improved Constraints on the Gravitational Lens Q0957+561. I. Weak Lensing
Schrabback, T.; Keeton, C. R.; Bernstein, G. M. +2 more
Attempts to constrain the Hubble constant using the strong gravitational lens system Q0957+561 are limited by systematic uncertainties in the mass model, since the time delay is known very precisely. One important systematic effect is the mass-sheet degeneracy, which arises because strong lens modeling cannot constrain the presence or absence of a…
Constraints on the Intracluster Dust Emission in the Coma Cluster of Galaxies
Onaka, Takashi; Kaneda, Hidehiro; Kitayama, Tetsu +7 more
We have undertaken a search for the infrared emission from the intracluster dust in the Coma cluster of galaxies by the Multiband Imaging Photometer for Spitzer. Our observations yield the deepest mid and far-infrared images of a galaxy cluster ever achieved. In each of the three bands, we have not detected a signature of the central excess compon…
Timing and Spectral Study of AXJ1745.6-2901 with Suzaku
Maeda, Yoshitomo; Makishima, Kazuo; Koyama, Katsuji +3 more
The eclipsing low-mass X-ray binary AX J1745.6-2901 was observed with Suzaku in its outburst phase. Combining the Chandra observation made 1.5 month earlier than Suzaku, we determined the orbital period to be 30063.76±0.14s. We found deep flux dips prior to the eclipse phase of the orbit. The X-ray spectrum of the persistent phase is described by …
A surviving disk from a galaxy collision at z = 0.4
Yang, Y.; Flores, H.; Hammer, F. +2 more
Context: Spiral galaxies dominate the local galaxy population. Disks are known to be fragile to collisions. Thus it is worthwhile to probe under what conditions a disk can possibly survive such interactions.
Aims: We present a detailed morpho-kinematic study of a massive galaxy with two nuclei,
Suzaku Observation of Diffuse X-Ray Emission from the Open Cluster Westerlund 2: a Hypernova Remnant?
Hayashida, Kiyoshi; Fujita, Yutaka; Takahara, Fumio +1 more
We present an analysis of Suzaku observations of the young open cluster Westerlund 2, which is filled with diffuse X-ray emission. We found that the emission consists of three thermal components, or two thermal and one non-thermal components. The upper limit of the energy flux of the non-thermal component is smaller than that in the TeV band obser…
Relative Kinematics of the Leading Edge and the Prominence in Coronal Mass Ejections
Vršnak, Bojan; Maričić, Darije; Roša, Dragan
We present a statistical analysis of the relationship between the kinematics of the leading edge and the eruptive prominence in coronal mass ejections (CMEs). We study the acceleration phase of 18 CMEs in which kinematics was measured from the pre-eruption stage up to the post-acceleration phase. In all CMEs, the three part structure (the leading …
The "Main Sequence" of Explosive Solar Active Regions: Discovery and Interpretation
Moore, Ronald L.; Gary, G. Allen; Falconer, David A. +1 more
We examine the location and distribution of the production of coronal mass ejections (CMEs) and major flares by sunspot active regions in the phase space of two whole-active-region magnetic quantities measured from 1897 SOHO/MDI magnetograms. These magnetograms track the evolution of 44 active regions across the central disk of radius 0.5 R S…