Search Publications
A Young Brown Dwarf Companion to DH Tauri
Kobayashi, Naoto; Usuda, Tomonori; Pyo, Tae-Soo +20 more
We present the detection of a young brown dwarf companion, DH Tau B, associated with the classical T Tauri star DH Tau. Near-infrared coronagraphic observations with CIAO on the Subaru Telescope have revealed DH Tau B with H=15 mag located 2.3" (330 AU) away from the primary, DH Tau A. Comparing its position with a Hubble Space Telescope archive i…
A Chandra Study of the Multicomponent X-Ray Emission from the X-shaped Radio Galaxy 3C 403
Hardcastle, M. J.; Worrall, D. M.; Murray, S. S. +1 more
We present results from a 49.4 ks Chandra ACIS-S observation of the nearby (z=0.059) X-shaped FR type II (FR II) radio galaxy 3C 403. This is the first Chandra observation of an X-shaped radio galaxy, and one of the goals of this pioneering study is to determine the relationship between the X-ray-emitting gas and the X-shaped radio morphology. We …
An X-Ray Variable Millisecond Pulsar in the Globular Cluster 47 Tucanae: Closing the Link to Low-Mass X-Ray Binaries
Bogdanov, Slavko; van den Berg, Maureen; Grindlay, Jonathan E.
We report the discovery of peculiar X-ray spectral variability in the binary radio millisecond pulsar PSR J0024-7204W in the globular cluster 47 Tuc. The observed emission consists of a dominant nonthermal component, which is eclipsed for a portion of the orbit, and a thermal component, which appears to be persistent. We propose that the nontherma…
Moving Magnetic Features around Sunspots
Shine, Richard A.; Hagenaar, Hermance J.
We study statistical properties of small-scale magnetic features around sunspots using time sequences of high-resolution magnetograms of eight sunspots made with the Michelson Doppler Imager (MDI) on board SOHO. Flow maps around the spots are also derived from cross-correlation analysis of MDI continuum or TRACE white light and used for comparison…
Magnetic Reconnection Flux and Coronal Mass Ejection Velocity
Qiu, Jiong; Yurchyshyn, Vasyl B.
We explore the relationship between the total reconnection flux ψrec estimated from flare observations and the velocity VCME of coronal mass ejections (CMEs) observed with the Large Angle and Spectrometric Coronagraph (LASCO) Experiment. Our study includes 13 events with varying magnetic configurations in source regions. It i…
Stellar Disk Truncations at High z: Probing Inside-Out Galaxy Formation
Trujillo, Ignacio; Pohlen, Michael
We have conducted a systematic search for stellar disk truncations in disklike galaxies at intermediate redshift (z<1.1) using the Hubble Ultra Deep Field data. We use the position of the truncation as a direct estimator of the size of the stellar disk. After accounting for the surface brightness evolution of the galaxies, our results suggest t…
Evidence of Primordial Clustering around the QSO SDSS J1030+0524 at z=6.28
Panagia, N.; Djorgovski, S. G.; Stern, D. +7 more
We present tentative evidence of primordial clustering, manifested as an excess of color-selected objects in the field of the QSO SDSS J1030+0524 at redshift z=6.28. We have selected objects red in i775-z850 on the basis of Hubble Space Telescope Advanced Camera for Surveys imaging of a field centered on the QSO. Compared to …
Statistics of Active Region Complexity: A Large-Scale Fractal Dimension Survey
Gallagher, Peter T.; McAteer, R. T. James; Ireland, Jack
A quantification of the magnetic complexity of active regions using a fractal dimension measure is presented. This fully automated approach uses full-disk MDI magnetograms of active regions from a large data set (2742 days of the SOHO mission, 9342 active region images) to compare the calculated fractal dimension of each region to both its Mount W…
An XMM-Newton View of the Soft Gamma Repeater SGR 1806-20: Long-Term Variability in the Pre-Giant Flare Epoch
Tiengo, A.; Götz, D.; Mereghetti, S. +7 more
The low-energy (<10 keV) X-ray emission of the soft gamma repeater SGR 1806-20 has been studied by means of four XMM-Newton observations carried out in the last two years, the latest performed in response to a strong sequence of hard X-ray bursts observed on 2004 October 5. The source was caught in different states of activity; over the 2003-20…
Constraints on z~10 Galaxies from the Deepest Hubble Space Telescope NICMOS Fields
Bouwens, R. J.; Illingworth, G. D.; Thompson, R. I. +1 more
We use all available fields with deep NICMOS imaging to search for J110-dropouts (H160,AB<~28) at z~10. Our primary data set for this search is the two J110+H160 NICMOS fields taken in parallel with the Advanced Camera for Surveys (ACS) Hubble Ultra Deep Field (UDF). The 5 σ limiting magnitudes were ~…