Search Publications
Non-Gaussian Line Profiles in a Large Solar Flare Observed on 2006 December 13
Mariska, J. T.; Hara, H.; Watanabe, T. +4 more
We have studied the characteristics of the non-Gaussian line profile of the Fe XIV 274.20 Å line in and around a flare arcade. We found that broad non-Gaussian line profiles associated with redshifts are observed in the flare arcade. There were two typical types of broad line profiles. One was a distorted line profile caused by multiple flows, and…
A Statistical Study of Solar Active Regions That Produce Extremely Fast Coronal Mass Ejections
Wang, Yuming; Zhang, Jie
We present statistical results on the properties of the solar source regions that produced the 57 fastest (>=1500 km s-1) front-side coronal mass ejections (CMEs) from 1996 June to 2007 January. The properties of these fast-CME-producing regions, 35 in total, are compared with those of all 1143 active regions (ARs) in the period stud…
Toward a Robust Estimate of the Merger Rate Evolution Using Near-IR Photometry
Hammer, Francois; Kembhavi, Ajit K.; Rawat, A. +1 more
We use a combination of deep, high angular resolution imaging data from the CDFS (HST/ACS GOODS survey) and ground-based near-IR Ks images to derive the evolution of the galaxy major merger rate in the redshift range 0.2 <= z<= 1.2. We select galaxies solely on the basis of their J-band rest-frame absolute magnitude, which is a go…
Reappraising Transition Region Line Widths in Light of Recent Alfvén Wave Discoveries
De Pontieu, Bart; McIntosh, Scott W.; Tarbell, Theodore D.
We provide a new interpretation of ultraviolet transition region emission line widths observed by the SUMER instrument on the Solar and Heliospheric Observatory (SOHO). This investigation is prompted by observations of the chromosphere at unprecedented spatial and temporal resolution from the Solar Optical Telescope (SOT) on Hinode revealing that …
The Quiet-Sun Differential Emission Measure from Radio and UV Measurements
Landi, E.; Chiuderi Drago, F.
In the present work we combine UV and radio observations of the quiet Sun to determine the differential emission measure (DEM) of the average quiet solar atmosphere from the photosphere (5600 K) to the corona. UV line intensities have been used to constrain the DEM above 30,000 K, and the radio spectrum from 1.5 to 345 GHz has been used to extend …
XMM-Newton and Chandra Observations of Abell 2626: Interacting Radio Jets and Cooling Core with Jet Precession?
Sarazin, Craig L.; Reiprich, Thomas H.; Wong, Ka-Wah +1 more
We present a detailed analysis of the XMM-Newton and Chandra observations of Abell 2626 focused on the X-ray and radio interactions. Within the region of the radio minihalo (~70 kpc), there are substructures that are probably produced by the central radio source and the cooling core. We find that there is no obvious correlation between the radio b…
Prevalence of Tidal Interactions among Local Seyfert Galaxies
Tang, Ya-Wen; Ho, Paul T. P.; Lim, Jeremy +1 more
No mechanisms have hitherto been conclusively demonstrated to be responsible for initiating optically luminous nuclear (Seyfert) activity in local disk galaxies. Only a small minority of such galaxies are visibly disturbed in optical starlight, with the observed disturbances being at best marginally stronger than those found in matched samples of …
Correlation between the Sharp Variation of the Transport Rate of Magnetic Helicity and Solar Eruptive Events
Tan, Baolin; Zhang, Yin; Yan, Yihua
In this Letter we report a close relationship between the variations of the transport rate of magnetic helicity (dH/dt) and a microwave burst. The latter may be regarded as a prompt signal of nonthermal energetic particles originating from the magnetic reconnection during solar flaring events. We analyze the observations of magnetograms of MDI/SOH…
The Thermal Structure of an Active Region Observed Outside the Solar Disk
Landi, E.; Feldman, U.
In the present work we analyze an extensive active region spectrum observed by the SUMER instrument on board SOHO with the aim of determining the thermal structure of the emitting plasma. We found that the plasma is made of three distinct, isothermal components, whose physical properties are similar to coronal hole, quiet-Sun, and active region pl…
Comparative Analysis of Nonthermal Emissions and Electron Transport in a Solar Flare
Yokoyama, T.; Minoshima, T.; Mitani, N.
We study nonthermal emission in a solar flare occurring on 2003 May 29 using RHESSI hard X-ray (HXR) and Nobeyama microwave observations. This flare shows several typical behaviors of HXR and microwave emission: time delay of microwave peaks relative to HXR peaks, loop-top microwave and footpoint HXR sources, and a harder electron energy distribut…