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Densities and Velocities in Fast Coronal Mass Ejections: Radiative Pumping of the O VI Doublet
Raymond, J. C.; Ciaravella, A.
In very fast coronal mass ejections (CMEs), it is possible for O VI ions to scatter Lyβ photons that originate in the solar chromosphere and for the λ1037 transition of O VI to scatter λ1032 photons from the solar transition region. This scattering process can be identified by departures of the O VI I1032/I1037 intensity rati…
Very High Iron Abundance of the Hot Gas around the cD Galaxy of the MKW 4 Cluster
Fukazawa, Yasushi; Kawano, Naomi; Kawashima, Kengo
We observed a nearby X-ray-bright poor cluster MKW 4 with Chandra. The iron abundance is found to increase dramatically from 0.3 to 1.3 solar within 150" of the cD galaxy NGC 4073. Then MKW 4 is the second cluster to exhibit a significantly high metallicity of greater than 1 solar, after the Centaurus Cluster. Weakness of the central cool componen…
A View of PKS 2155-304 with XMM-Newton Reflection Grating Spectrometers
Maraschi, L.; Tavecchio, F.; Treves, A. +2 more
We present the high-resolution X-ray spectrum of the BL Lac object PKS 2155-304 taken with the RGS units on board XMM-Newton in 2000 November. We detect an O VII Kα resonant absorption line from warm/hot local gas at 21.59 Å (~4.5 σ detection). The line profile is possibly double peaked. We do not confirm the strong 20.02 Å absorption line seen wi…
Pickup ions at Dione and Enceladus: Cassini Plasma Spectrometer simulations
Crary, F.; Johnson, R. E.; Young, D. T. +5 more
Voyager images of the icy satellites of Saturn, Dione and Enceladus, suggest that they may have been geologically active and are not only composed of ice. Recent observations by the Hubble Space Telescope have shown the presence of ozone at both Dione and Rhea, which also implies the presence of molecular oxygen at these bodies. Observations of Ar…
Flow burst-induced large-scale plasma sheet oscillation
Balogh, A.; Glassmeier, K. -H.; RèMe, H. +7 more
On 12 August 2001 the Cluster spacecraft measured a rapid flux transport event, consisting of a strong perpendicular earthward flow burst combined with a dipolarization of the magnetic field after a strong compression of the magnetotail. Combining the Cluster data with those from ground-based magnetometers, we find that this event is related to pa…
Looking Closely at Medusa: Star-forming Knots at the Center of NGC 4194
Kaiser, M. E.; Weistrop, D.; Eggers, D. +3 more
We report high-resolution ultraviolet and visible-wavelength imaging of the blue compact galaxy NGC 4194 (the Medusa) using the Hubble Space Telescope. A complete sample of 38 UV-bright knots is identified. These knots produce 20% of the ultraviolet emission from the area of the galaxy observed. The bright end of the knot flux distribution can be …
Boron Benchmarks for the Galactic Disk
Cunha, Katia; McGrath, Elizabeth J.; Lambert, David L. +1 more
Sixteen Population I solar-type dwarfs have been selected to ascertain the baseline B abundance in the Galactic disk for a range of a factor of 4 in metallicity: from [Fe/H] of -0.5 to +0.1. All the stars selected are undepleted in Be, which ensures that they have also retained their full initial abundance of B. Evaluation of the trend of B with F…
XMM-Newton observations of the young open cluster Blanco 1. I. X-ray spectroscopy and photometry
Harnden, F. R., Jr.; Micela, G.; Sciortino, S. +2 more
We present an X-ray study of the high metallicity young open cluster Blanco 1 based on XMM-Newton data. X-ray spectroscopy of cluster members is presented for the first time as well as new X-ray distribution functions of late-type stars. We detected all known dF and dG stars in the EPIC field and 80% and 90% of dK and dM stars, respectively. The X…
On the propagation of low-frequency fluctuations in the plasma sheet: 1. Cluster observations and magnetohydrodynamic analysis
Budnik, E.; Balogh, A.; Lucek, E. +6 more
Low-frequency pressure and magnetic oscillations observed by Cluster in the plasma sheet are investigated with the aim of determining if they are magnetohydrodynamic (MHD) eigenmodes. We analyze the plasma sheet crossing occurring on 22 August 2001, as the magnetosphere was first quiet and then active, and compare the observations with theoretical…
On the propagation of low-frequency fluctuations in the plasma sheet: 2. Characterization of the MHD eigenmodes and physical implications
Budnik, E.; Balogh, A.; Lucek, E. +7 more
In a first analysis of the low-frequency fluctuations observed by Cluster during a crossing of the plasma sheet [, 2004], we identify oscillations that likely correspond to MHD eigenmodes. They are intense (10 nT), have a rather short period (20-25 s), have a wavelength of ∼5 Re, and are observed during an active period that follows a s…