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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…
Statistical properties of tail plasma sheet electrons above 40 keV
Lavraud, B.; Daly, P.; Taylor, M. G. G. T. +3 more
We use data from four tail seasons (2001-2004) of the Cluster spacecraft to study statistical features of energetic electrons (40-400 keV) in the magnetotail plasma sheet in combination with plasma parameters and indices of geomagnetic activity. We find that the horizontal magnetic field magnitude best orders the energetic electron observations. U…
Jupiter's polar clouds and waves from Cassini and HST images: 1993 2006
Hueso, R.; Sánchez-Lavega, A.; Pérez-Hoyos, S. +1 more
For a variety of reasons, Jupiter's polar areas are probably the less observed regions of the planet. To study the dynamics and cloud vertical structure in the polar regions of the planet (latitudes 50° to 80° in both hemispheres) we have used images of Jupiter obtained from the ultraviolet to near infrared (258 to 939 nm) by the Cassini Imagining…
Confirmation and utilization of the ``production function'' size-frequency distributions of Martian impact craters
Neukum, Gerhard; Werner, Stephanie; Hartmann, William K.
On any planetary surface, impacts of interplanetary bodies create an initial (or ``production function'') size-frequency distribution (SFD) of impact craters. Recent questions have been raised about whether this size distribution can be reliably detected, especially at small sizes. In a test area, we confirm an excellent fit to the distribution we…
Monitoring Venus’ mesospheric winds in support of Venus Express: IRAM 30-m and APEX observations
Lellouch, E.; Moreno, R.; Moullet, A. +1 more
We report on direct wind measurements in Venus' mesosphere (90-115 km), performed in support of Venus Express, and based on CO millimeter observations. Most observations, sampling the CO(2-1) and CO(1-0) lines, were acquired with the IRAM 30-m telescope, over four distinct periods: (i) Summer 2006; (ii) May-June 2007, in association with the coord…
Origin of chromatic features in multiple quasars. Variability, dust, or microlensing
Yonehara, A.; Richter, P.; Hirashita, H.
Aims:In some of lensed quasars, color differences between multiple images are observed at optical/near-infrared wavelengths. There are three possible origins for the color differences: intrinsic variabilities of quasars, differential dust extinction, and quasar microlensing. We examine how these possible scenarios can reproduce the observed chroma…
Sizes of transition-region structures in coronal holes and in the quiet Sun
Tu, C. -Y.; Marsch, E.; Tian, H. +2 more
Aims: We study the height variations of the sizes of chromospheric and transition-region features in a small coronal hole and the adjacent quiet Sun, considering images of the intensity, Doppler shift, and non-thermal motion of ultraviolet emission lines as measured by SUMER (Solar Ultraviolet Measurements by Emitted Radiation), together with the …
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…