Search Publications
Ground calibration of the Chandrayaan-1 X-ray Solar Monitor (XSM)
Andersson, H.; Grande, M.; Alha, L. +9 more
The Chandrayaan-1 XSM ground calibrations are introduced. The aim of these calibrations was to characterize the performance of XSM, which enables a reliable spectral analysis with the solar X-ray data. The calibrations followed an improved procedure based on our experience from the SMART-1 XSM. The most important tasks in the calibrations were det…
In situ radiometric dating on Mars: Investigation of the feasibility of K-Ar dating using flight-type mass and X-ray spectrometers
Barber, S.; Talboys, D. L.; Bridges, J. C. +9 more
The absolute chronology of Mars is poorly known and, as a consequence, a key science aim is to perform accurate radiometric dating of martian geological materials. The scientific benefits of in situ radiometric dating are significant and arguably of most importance is the calibration of the martian cratering rate, similar to what has been achieved…
CME-flare association during the 23rd solar cycle
Beheary, M. M.; Youssef, M.; Mawad, R. +2 more
The relation between coronal mass ejections (CMEs) and solar flares are statistically studied. More than 10,000 CME events observed by SOHO/LASCO during the period 1996-2005 have been analyzed. The soft X-ray flux measurements provided by the Geostationary Operational Environmental Satellite (GOES), recorded more than 20,000 flares in the same tim…
The spectroscopically confirmed huge cosmic structure at z = 0.55
Finoguenov, A.; Tanaka, M.; Koyama, Y. +3 more
We report on the spectroscopic confirmation of a huge cosmic structure around the CL0016 cluster at z=0.55. We made wide-field imaging observations of the surrounding regions of the cluster and identified more than 30 concentrations of red galaxies near the cluster redshift. The follow-up spectroscopic observations of the most prominent part of th…
Sounding the subsurface of Athabasca Valles using MARSIS radar data: Exploring the volcanic and fluvial hypotheses for the origin of the rafted plate terrain
Gurnett, Donald A.; Frigeri, Alessandro; Heggy, Essam +8 more
To test the volcanic and fluvial hypotheses for the origin of the rafted plate terrain observed in the vicinity of Athabasca Valles (5°N, 150°E, Central Elysium Planitia), we investigated the subsurface radar echo from the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) 5-MHz band data over this area. The backscattered signal l…
New absolute magnitude calibrations for W Ursa Majoris type binaries
Demircan, O.; Eker, Z.; Bilir, S. +2 more
Parallaxes of W UMa stars in the Hipparcos catalogue have been analyzed. 31 W UMa stars, which have the most accurate parallaxes (σπ/π<0.15) which are neither associated with a photometric tertiary nor with evidence of a visual companion, were selected for re-calibrating the Period-Luminosity-Color (PLC) relation of W UMa stars. Usin…
Suzaku Observation Adjacent to the South End of the Radio Arc
Koyama, Katsuji; Tsuru, Takeshi Go; Fukuoka, Ryosuke +1 more
Suzaku observed the Galactic center region near the Radio Arc at ∼20' southeast of Sagittarius A*. In an 18' × 18' field of view, we found four distinct X-ray sources: a bright star and a diffuse source associated with star clusters in the soft band (0.5-2.0keV), a small clump in a higher energy band (4-6keV), and a peculiar clump in th…
A dam around the Water Fountain Nebula?. The dust shell of IRAS16342-3814 spatially resolved with VISIR/VLT
Waters, L. B. F. M.; Peletier, R. F.; Verhoelst, T. +4 more
Context: Bipolar morphologies in planetary nebulae (PNe) are believed to be closely linked to binary central stars. Either by collimating a fast stellar wind or by driving a jet via accretion in the central system, dusty torii or stable disks may be crucial ingredients for the shaping of PNe.
Aims: We study the dust distribution in the very yo…
Impact of a Radius and Composition Variation on Stratification of the Solar Subsurface Layers
Lefebvre, S.; Turck-Chièze, S.; Nghiem, P. A. P.
Several works have reported changes of the Sun's subsurface stratification inferred from f-mode or p-mode observations. Recently, a nonhomologous variation of the subsurface layers with depth and time has been deduced from f-modes. Progress on this important transition zone between the solar interior and the external part supposes a good understan…
Different Types of Ultraluminous X-Ray Sources in NGC 4631
Soria, Roberto; Ghosh, Kajal K.
We have re-examined the most luminous X-ray sources in the starburst galaxy NGC 4631, using XMM-Newton, Chandra, and ROSAT data. The most interesting source is a highly variable supersoft ultraluminous X-ray source (ULX). We suggest that its bolometric luminosity ~ a few 1039 erg s-1 in the high/supersoft state: this is an or…