Search Publications

Energy-dependent Time Lags in the Seyfert 1 Galaxy NGC 4593

Rao, A. R.; Sriram, K.; Agrawal, V. K.

We investigate the energy-time lag dependence of the source NGC 4593 using XMM-Newton/EPIC pn data. We found that the time lag dependency is linear in nature with respect to the logarithm of different energy bands. We also investigate the frequency-dependent time lags and identify that at some frequency range (5 × 10^-5 Hz to 2 × 10^…

On the statistical detection of propagating waves in polar coronal holes

Doyle, J. G.; Gupta, G. R.; Banerjee, D. +2 more

Context: Waves are important to the study of dynamical processes in coronal holes and the acceleration of the fast solar wind. A spectral time series was taken with the SUMER spectrometer on-board SoHO on 20 October 1996. The observations were obtained in the N iv 765 Å transition region line and the Ne viii 770 Å line of the low corona.
Aims:…

On some properties of coronal mass ejections in solar cycle 23

Mittal, Nishant; Narain, Udit

We have investigated some properties such as speed, apparent width, acceleration, latitude, mass and kinetic energy, etc. of all types of coronal mass ejections (CMEs) observed during the period 1996-2007 by SOHO/LASCO covering the solar cycle 23. The results are in satisfactory agreement with previous investigations.

Supersonic Continuation of the Evershed Flow Outside a Sunspot as Observed with Hinode

Martínez Pillet, V.; Katsukawa, Y.; Ruiz Cobo, B. +1 more

We report on the discovery of mostly horizontal field channels just outside sunspot penumbrae (in the so-called "moat" region) that are seen to sustain supersonic flows (line-of-sight component of 6 km s^-1). The spectral signature of these supersonic flows corresponds to circular polarization profiles with an additional, satellite, thir…

The Cartwheel galaxy with XMM-Newton

Wolter, A.; Trinchieri, G.; Crivellari, E.

Aims: The extreme environment provided by the Cartwheel ring is analyzed to study its X-ray and optical-UV properties. We compare the Cartwheel with the other members of its group and study the system as a whole in the X-ray band.
Methods: We analyze the data of the Cartwheel galaxy obtained with XMM-Newton in two different periods (December 2…

A search for massive ultra-compact dwarf galaxies in the Centaurus galaxy cluster

Infante, L.; Hilker, M.; Kissler-Patig, M. +3 more

Context: In a previous paper, we initiated a search for ultra-compact dwarf galaxies (UCDs) in the Centaurus galaxy cluster, resulting in the discovery of 27 compact objects with -12.2<M_V<-10.9 mag. Our overall survey completeness was 15-20% within 120 kpc projected clustercentric distance.
Aims: To constrain the luminosity distribution…

The role of small versus large scale magnetic topologies in global waves

Delannée, C.

Context: Coronal waves are large-scale structures that propagate through the lower corona over distances of hundreds of megameters. They are believed to be related to coronal mass ejections (CMEs). Attrill and collaborators suggested that the propagation of the wave front is due to consecutive reconnections in the quiet Sun of favourably orientate…

Multiwavelength Observation of Electron Acceleration in the 2006 December 13 Flare

Krucker, S.; Kubo, M.; Isobe, H. +8 more

We present a multiwavelength observation of a solar flare occurring on 2006 December 13 with Hinode, RHESSI, and the Nobeyama Radio Observatory to study the electron acceleration site and mechanism. The Solar Optical Telescope (SOT) on board Hinode observed elongated flare ribbons, and RHESSI observed double-footpoint hard X-ray (HXR) sources appe…

A New Supernova Remnant Candidate and an Associated Outflow in the Sagittarius C Region

Koyama, K.; Nobukawa, M.; Tsuru, T. G. +3 more

Spectral Analyses of the Nearest Persistent Ultraluminous X-Ray Source M 33 X-8

Weng, Shan-Shan; Wang, Jun-Xian; Gu, Wei-Min +1 more

We provide a detailed analysis of 12 XMM observations of the nearest persistent extragalactic ultraluminous X-ray source (ULX), M 33 X-8. No significant spectral evolution has been detected for the period of the observations, and therefore we combine the individual observations to increase the signal-to-noise ratio for a spectral fitting. The comb…