Search Publications
Meridional Circulation Variability from Large-Aperture Ring-Diagram Analysis of Global Oscillation Network Group and Michelson Doppler Imager Data
Howe, R.; Komm, R.; Hill, F. +3 more
Ring-diagram analysis, a local helioseismology technique, has proven to be very useful for studying solar subsurface velocity flows down to a depth of about 0.97 Rsolar. The depth range is determined by the modes used in this type of analysis, and thus depends on the size of the area analyzed. Extending the area allows us to detect lowe…
Nucleonic gamma-ray production in Vela X
Santangelo, A.; Aharonian, F.; Horns, D. +2 more
Context. The recently discovered extended very high energy gamma-ray (E>0.1~TeV=1011 eV) emission from at least three pulsar wind nebula systems (MSH 15-52, G18.0-07, and Vela X) could be hinting at a possibly new class of objects which is called in the following "TeV plerions". In some of these systems, particle acceleration could b…
On the propagation of brightening after filament/prominence eruptions, as seen by SoHO-EIT
Mason, H. E.; Isobe, H.; Tripathi, D.
Aims.To study the relationship between the propagation of brightening and erupting filaments/prominences in order to get some insight into the three-dimensional picture of magnetic reconnection.
Methods: .Analysis of the observations taken with the EIT (Extreme-ultraviolet Imaging Telescope) aboard SoHO (Solar and Heliospheric Observatory).
Modeling of PMS Ae/Fe stars using UV spectra
Blondel, P. F. C.; Djie, H. R. E. Tjin A.
Context: .Spectral classification of AeFe stars, based on visual observations, may lead to ambiguous conclusions.
Aims: . We aim to reduce these ambiguities by using UV spectra for the classification of these stars, because the rise of the continuum in the UV is highly sensitive to the stellar spectral type of A/F-type stars.
Methods: . …
A large cloud outburst at Titan's south pole
Brown, Michael E.; Bouchez, Antonin H.; Roe, Henry G. +1 more
Images of Titan acquired over five nights in October 2004 using the adaptive optics system at the Keck Observatory show dramatic increases in tropospheric cloud activity at the south pole compared with all other images of Titan clouds to date. During this time, Titan's south polar clouds brightened to more than 18 times their typical values. The C…
Neon and Oxygen Abundances in M33
Massey, Philip; Garnett, Donald R.; Jacoby, George +1 more
We present new spectroscopic observations of 13 H II regions in the Local Group spiral galaxy M33. The regions observed range from 1 to 7 kpc in distance from the nucleus. Of the 13 H II regions observed, the [O III] λ4363 line was detected in six regions. Electron temperatures were thus able to be determined directly from the spectra using the [O…
XMM-Newton spectroscopy of the cluster of galaxies 2A 0335+096
Kaastra, J. S.; de Plaa, J.; Verbunt, F. +5 more
We present here the results of a deep (130 ks) XMM-Newton observation of the cluster of galaxies 2A 0335+096. The deep exposure allows us to study in detail its temperature structure and its elemental abundances. We fit three different thermal models and find that the multi-temperature wdem model fits our data best. We find that the abundance stru…
Radio science investigations by VeRa onboard the Venus Express spacecraft
Pätzold, M.; Bird, M. K.; Imamura, T. +10 more
The Venus Express Radio Science Experiment (VeRa) uses radio signals at wavelengths of 3.6 and 13 cm ("X"- and "S"-band, respectively) to investigate the Venus surface, neutral atmosphere, ionosphere, and gravity field, as well as the interplanetary medium. An ultrastable oscillator (USO) provides a high quality onboard reference frequency source;…
Continuum γ-ray emission from light dark matter positrons and electrons
Schanne, S.; Sizun, P.; Cassé, M.
The annihilation of light dark matter was recently advocated as a possible explanation of the large positron injection rate at the Galactic center deduced from observations by the SPI spectrometer aboard INTEGRAL. The modelling of internal Bremsstrahlung and in-flight annihilation radiations associated to this process drastically reduced the mass …
Coronal Observations of CMEs. Report of Working Group A
Schwenn, R.; Pick, M.; Reiner, M. +15 more
CMEs have been observed for over 30 years with a wide variety of instruments. It is now possible to derive detailed and quantitative information on CME morphology, velocity, acceleration and mass. Flares associated with CMEs are observed in X-rays, and several different radio signatures are also seen. Optical and UV spectra of CMEs both on the dis…