Search Publications
Photospheric Shear Flows along the Magnetic Neutral Line of Active Region 10486 prior to an X10 Flare
Xu, Yan; Cao, Wenda; Yang, Guo +3 more
We present high spatial resolution observations of proper motions in the solar NOAA Active Region 10486 using a high-order adaptive optics system, frame selection, and speckle-masking image reconstruction. The data were obtained with the Dunn Solar Telescope of the National Solar Observatory/Sacramento Peak on 2003 October 29. The resolution of th…
A CNO Dichotomy among O2 Giant Spectra in the Magellanic Clouds
Walborn, Nolan R.; Massey, Philip; Howarth, Ian D. +4 more
From a survey of the 3400 Å region in the earliest O-type spectra, we have found that two of the four O2 giants observed in the Large Magellanic Cloud have O IV lines there that are stronger than the N IV lines, while the other two have the opposite. A Small Magellanic Cloud counterpart also has N IV stronger than O IV. Inspection of the blue spec…
Comparison of Solar Subsurface Flows Assessed by Ring and Time-Distance Analyses
Gizon, Laurent; Duvall, Thomas L., Jr.; Toomre, Juri +2 more
The solar near-surface shear layer exhibits a rich medley of flows that are now being measured by a variety of local helioseismic techniques. We present comparisons of the horizontal flows obtained with two of these techniques, ring and time-distance analyses, applied to Michelson Doppler Imager (MDI) Dynamics Program data from the years 1998 and …
M31 Globular Cluster X-Ray Sources: XMM-Newton and Chandra Results
Trudolyubov, Sergey; Priedhorsky, William
We present the results of an M31 globular cluster (GC) X-ray source survey, based on the data of XMM-Newton and Chandra observations covering ~6100 arcmin2 of M31. We detected 43 X-ray sources coincident with GC candidates from various optical surveys. The inferred isotropic X-ray luminosities of GC sources lie between ~1035 …
Smashing the Guitar: An Evolving Neutron Star Bow Shock
Chatterjee, S.; Cordes, J. M.
The Guitar Nebula is a spectacular example of an Hα bow shock nebula produced by the interaction of a neutron star with its environment. The radio pulsar B2224+65 is traveling at ~800-1600 km s-1 (for a distance of 1-2 kpc), placing it on the high-velocity tail of the pulsar velocity distribution. Here we report time evolution in the sh…
A Chandra View of the Morphological and Spectral Evolution of Supernova Remnant 1987A
Zhekov, Svetozar A.; Garmire, Gordon P.; Park, Sangwook +2 more
We present an update on the results of our monitoring observations of the X-ray remnant of supernova (SN) 1987A with Chandra. As of 2002 December, we have performed a total of seven observations of SN 1987A, which allows us to monitor the details of the earliest stage of the supernova remnant evolution in X-rays. The high angular resolution images…
Recycling of the Solar Corona's Magnetic Field
Longcope, D. W.; Priest, E. R.; Parnell, C. E. +1 more
Magnetic fields play a dominant role in the atmospheres of the Sun and other Sun-like stars. Outside sunspot regions, the photosphere of the so-called quiet Sun contains myriads of small-scale magnetic concentrations, with strengths ranging from the detection limit of ~1016 Mx up to ~3×1020 Mx. The tireless motion of these ma…
ESO 3060170: A Massive Fossil Galaxy Group with a Heated Gas Core?
Hornstrup, A.; Vikhlinin, A.; Forman, W. +3 more
We present a detailed study of the ESO 3060170 galaxy group, combining Chandra, XMM-Newton, and optical observations. The system is found to be a fossil galaxy group. The group X-ray emission is composed of a central, dense, cool core (10 kpc in radius) and an isothermal medium beyond the central 10 kpc. The region between 10 and 50 kpc (the cooli…
Fe II/Mg II Emission-Line Ratios of QSOs. II. z > 6 Objects
Doi, Mamoru; Yoshii, Yuzuru; Motohara, Kentaro +4 more
Near-infrared spectra of four QSOs located at z>6 are obtained with the OH-airglow suppressor mounted on the Subaru telescope. The Fe II/Mg II emission-line ratios of these QSOs are examined by the same fitting algorithm as in our previous study of z<5.3 QSOs. The fitting results show that two out of the four z>6 QSOs have significant Fe …
A Survey for Water Maser Emission toward Planetary Nebulae: New Detection in IRAS 17347-3139
Miranda, Luis F.; Anglada, Guillem; de Gregorio-Monsalvo, Itziar +4 more
We report on a water maser survey toward a sample of 27 planetary nebulae (PNe) using the Robledo de Chavela and Medicina single-dish antennas, as well as the Very Large Array (VLA). Two detections have been obtained: the already known water maser emission in K3-35, and a new cluster of masers in IRAS 17347-3139. This low rate of detections is com…