Search Publications
Statistical Properties of Solar Active Regions Obtained from an Automatic Detection System and the Computational Biases
Liu, Yang; Wang, Yuming; Zhang, Jie
We have developed a computational software system to automate the process of identifying solar active regions (ARs) and quantifying their physical properties based on high-resolution synoptic magnetograms constructed from Michelson Doppler Imager (MDI; on board the SOHO spacecraft) images from 1996 to 2008. The system, based on morphological analy…
Limitations of multispacecraft data techniques in measuring wave number spectra of space plasma turbulence
Belmont, G.; Sahraoui, F.; Rezeau, L. +1 more
Unambiguous determination of spatial properties of space plasma turbulence from temporal measurements has been one of the major goals of the Cluster mission. For that purpose, techniques, such as the k filtering, have been developed. Such multipoint measurement techniques combine several time series recorded simultaneously at different points in s…
High-resolution HST/ACS images of detached shells around carbon stars
Eriksson, K.; Gustafsson, B.; Olofsson, H. +2 more
Context. Overall spherically symmetric, geometrically thin gas and dust shells have been found around a handful of asymptotic giant branch (AGB) carbon stars. Their dynamical ages lie in the range of 103 to 104 years. A tentative explanation for their existence is that they have formed as a consequence of mass-loss-rate modul…
SDSS J094533.99+100950.1 - the remarkable weak emission line quasar
Hryniewicz, K.; Czerny, B.; Nikołajuk, M. +1 more
Weak emission line quasars are a rare and puzzling group of objects. In this paper, we present one more object of this class found in the Sloan Digital Sky Survey (SDSS). The quasar SDSS J094533.99+100950.1, lying at z = 1.66, has practically no CIV emission line, a red continuum very similar to the second steepest of the quasar composite spectra …
On the Stellar Content of the Carina Dwarf Spheroidal Galaxy
Walker, A. R.; Prada Moroni, P. G.; Degl'Innocenti, S. +20 more
We present deep, accurate, and homogeneous multiband optical (U, B, V, I) photometry of the Carina dwarf spheroidal galaxy, based on more than 4000 individual CCD images from three different ground-based telescopes. Special attention was given to the photometric calibration, and the precision for the B, V, and I bands is generally better than 0.01…
Periodic mass-loss episodes due to an oscillation mode with variable amplitude in the hot supergiant HD 50064
Auvergne, M.; Dupret, M. -A.; Baudin, F. +15 more
Aims: We aim to interpret the photometric and spectroscopic variability of the luminous blue variable supergiant HD 50064 (V = 8.21).
Methods: CoRoT space photometry and follow-up high-resolution spectroscopy with a time base of 137 d and 169 d, respectively, was gathered, analysed, and interpreted using standard time series analysis and…
A Variable Black Hole X-ray Source in an NGC 1399 Globular Cluster
Kundu, Arunav; Zepf, Stephen E.; Maccarone, Thomas J. +2 more
We have discovered an accreting black hole (BH) in a spectroscopically confirmed globular cluster (GC) in NGC 1399 through the monitoring of its X-ray activity. The source, with a peak luminosity of L X ~= 2 × 1039 erg s-1, reveals an order of magnitude change in the count rate within sime10 ks in a Chandra obser…
Negative ions at Titan and Enceladus: recent results
Johnson, Robert E.; Coates, Andrew J.; Waite, J. Hunter +7 more
CoRoT light curves of RR Lyrae stars. CoRoT 101128793: long-term changes in the Blazhko effect and excitation of additional modes
Auvergne, M.; Deleuil, M.; Poretti, E. +13 more
Context. The CoRoT (Convection, Rotation and planetary Transits) space mission provides a valuable opportunity to monitor stars with uninterrupted time sampling for up to 150 days at a time. The study of RR Lyrae stars, performed in the framework of the Additional Programmes belonging to the exoplanetary field, will particularly benefit from such …
The Mawrth Vallis Region of Mars: A Potential Landing Site for the Mars Science Laboratory (MSL) Mission
Mangold, Nicolas; Bibring, Jean-Pierre; Poulet, François +11 more
The primary objective of NASA's Mars Science Laboratory (MSL) mission, which will launch in 2011, is to characterize the habitability of a site on Mars through detailed analyses of the composition and geological context of surface materials. Within the framework of established mission goals, we have evaluated the value of a possible landing site i…