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The HIA instrument on board the Tan Ce 1 Double Star near-equatorial spacecraft and its first results
Lundin, R.; Dandouras, I.; Klecker, B. +16 more
On 29 December 2003, the Chinese spacecraft Tan Ce 1 (TC-1), the first component of the Double Star mission, was successfully launched within a low-latitude eccentric orbit. In the framework of the scientific cooperation between the Academy of Sciences of China and ESA, several European instruments, identical to those developed for the Cluster spa…
Ultraviolet, X-Ray, and Optical Radiation from the Geminga Pulsar
Romani, R. W.; Pavlov, G. G.; Zavlin, V. E. +1 more
We observed the γ-ray pulsar Geminga with the FUV-MAMA and NUV-MAMA detectors of the Space Telescope Imaging Spectrometer to measure Geminga's spectrum and pulsations in the ultraviolet. The slope of the far-ultraviolet (FUV) spectrum is close to that of a Rayleigh-Jeans spectrum, suggesting that the FUV radiation is dominated by thermal emission …
High-velocity streams of dust originating from Saturn
Grün, Eberhard; Kempf, Sascha; Srama, Ralf +5 more
High-velocity submicrometre-sized dust particles expelled from the jovian system have been identified by dust detectors on board several spacecraft. On the basis of periodicities in the dust impact rate, Jupiter's moon Io was found to be the dominant source of the streams. The grains become positively charged within the plasma environment of Jupit…
Evidence for radio-source heating of groups
Hardcastle, M. J.; Croston, J. H.; Birkinshaw, M.
We report evidence that the gas properties of X-ray groups containing radio galaxies differ from those of radio-quiet groups. For a well-studied sample of ROSAT-observed groups, we found that more than half of the elliptical-dominated groups can be considered `radio-loud', and that radio-loud groups are likely to be hotter at a given X-ray luminos…
The Local Helioseismology of Inclined Magnetic Fields and the Showerglass Effect
Braun, D. C.; Cally, P. S.; Lindsey, C. +1 more
We present evidence for the dependence of helioseismic Doppler signatures in active regions on the line-of-sight angle in inclined magnetic fields. Using data from the Michelson Doppler Imager (MDI) on board the Solar and Heliospheric Observatory, we performed phase-sensitive holography in the penumbrae of sunspots over the course of several days …
On the Nature of Coronal EIT Waves
Erdélyi, R.; Ballai, I.; Pintér, B.
Large-scale eruption events in the solar atmosphere can generate global waves, i.e., waves that propagate over distances comparable to the solar radius. In the low solar corona, global waves observed by SOHO EIT, generated by coronal mass ejections or flares, are usually referred to as ``EIT waves.'' The nature of these global waves is the subject…
M31's Heavy-Element Distribution and Outer Disk
MacArthur, Lauren A.; Courteau, Stéphane; Worthey, Guy +1 more
Hubble Space Telescope imaging of 11 fields in M31 were reduced to color-magnitude diagrams. The fields were chosen to sample all galactocentric radii to 50 kpc (~9 disk scale lengths, or >99.9% of the total light enclosed). The colors of the red giants at each pointing map to an abundance distribution with errors of order 0.1 dex in [M/H]. The…
First Soft X-Ray Observations of Global Coronal Waves with the GOES Solar X-Ray Imager
Mann, G.; Aurass, H.; Warmuth, A.
We present the first observations of global coronal waves obtained with the Solar X-Ray Imager (SXI) aboard the GOES-12 satellite. Focusing on six events, the basic morphological and kinematic characteristics of the waves observed in soft X-rays are derived. Taking advantage of SXI's high temporal cadence and comparing the wave signatures with ext…
Footpoint excitation of standing acoustic waves in coronal loops
Doyle, J. G.; Erdélyi, R.; Bradshaw, S. J. +1 more
A new theoretical model for the study of slow standing sausage mode oscillations in hot (T > 6 MK) active region coronal loops is presented. These oscillations are observed by the SUMER spectrometer on board the SoHO satellite. The model contains the transition region and the upper chromosphere which enables us to study the entire process of ho…
The X-Ray Spectral Properties and Variability of Luminous High-Redshift Active Galactic Nuclei
Brandt, W. N.; Strauss, Michael A.; Vignali, C. +4 more
We perform a detailed investigation of moderate- to high-quality X-ray spectra of 10 of the most luminous active galactic nuclei (AGNs) known at z>4 (up to z~6.28). This study includes five new XMM-Newton observations and five archived X-ray observations (four by XMM-Newton and one by Chandra). We find that the X-ray power-law photon indices of…