Search Publications
Simultaneous observations of magnetotail reconnection and bright X-ray aurora on 2 October 2002
RèMe, H.; Lucek, E. A.; Mouikis, C. +9 more
We present simultaneous Cluster and Polar X-ray and UVI observations on 2 October 2002, when Cluster observed a magnetic reconnection diffusion region at Xgse = -16.6 Re. At the same time a bright auroral feature appeared at the footpoint of the magnetic field line connecting the ionosphere and the diffusion region. However, we found that the elec…
Solar terrestrial effects of two distinct types
Kane, R. P.
The occurrence frequencies or fluxes of most of the solar phenomena show a 11-year cycle like that of sunspots. However, the average characteristics of these phenomena may not show a 11-year cycle. Among the terrestrial parameters, some related directly to the occurrence frequencies of solar phenomena (for example, ionospheric number densities rel…
Multiple Scattered Sight Lines to the Red QSO 2MASX J10494334+5837501
Hines, Dean C.; Tremonti, Christy A.; Schmidt, Gary D. +2 more
The reddened, highly polarized QSO 2MASX J1049334+5837501 (2M 1049+5837) shows a strong IR dust signature with a spectral energy distribution peaked at ~20 µm and a luminosity of ~1011 Lsolar, but the active nucleus is outshone at optical wavelengths by the host galaxy. Remarkable variations with wavelength in the degre…
Eclipsed X-ray flares in binary stars: geometrical constraints on the flare's location and size
Sanz-Forcada, J.; Micela, G.; Favata, F.
Aims: The observation of eclipses during X-ray flares taking place in active cool stars binaries allows us to calculate the position and size of the flares. This information cannot be derived by analyzing the decay of the flares, a frequently used approach in the literature that requires the assumption of a physical model. We make use of the eclip…
Monte Carlo simulations of metal-poor star clusters
Degl'Innocenti, S.; Raimondo, G.; Fagiolini, M.
Context: Metal-poor globular clusters (GCs) can provide a probe of the earliest epoch of star formation in the Universe, being the oldest observable stellar systems. In addition, young and intermediate-age low-metallicity GCs are present in external galaxies. Nevertheless, inferring their evolutionary status by using integrated properties may suff…
The Structure and the Distance of Collinder 121 from Hipparcos and Photometry: Resolving the Discrepancy
Makarov, Valeri; Kaltcheva, Nadia
We present further arguments that the Hipparcos parallaxes for some of the clusters and associations represented in the Hipparcos catalog should be used with caution in the study of the Galactic structure. It has already been shown that the discrepancy between the Hipparcos and ground-based parallaxes for several clusters including the Pleiades, C…
Multiheight Properties of Moving Magnetic Features
Choudhary, Debi Prasad; Balasubramaniam, K. S.
We report on spectropolarimetric and dynamical properties of a moving magnetic feature (MMF) around a disk-center sunspot observed using photospheric (Fe I λλ6301.5 and 6302.5) and lower chromospheric (Mg b2 λ5172.7) lines. We find that there are 33% fewer MMFs at the lower chromosphere compared to the photosphere, implying a sophistica…
FUSE Observations of a Full Orbit of Hercules X-1: Signatures of Disk, Star, and Wind
Raymond, John C.; Vrtilek, Saeqa Dil; Still, Martin +1 more
We observed an entire 1.7 day orbit of the X-ray binary Hercules X-1 with the Far Ultraviolet Spectroscopic Explorer (FUSE). Changes in the O VI λλ1032, 1037 line profiles through eclipse ingress and egress indicate a Keplerian accretion disk spinning prograde with the orbit. These observations may show the first double-peaked accretion disk line …
Tectonic and thermal evolution of Venus and the role of volatiles: Implications for understanding the terrestrial planets
Sotin, Christophe; Stofan, Ellen R.; Smrekar, Suzanne E. +5 more
Venus is similar to Earth in size and bulk composition. The dramatic differences between the two planets indicate that planetary size alone does not control geologic evolution. Earth's geology is dominated by plate tectonics, or active lid convection. The crater retention age of Venus demonstrates that the planet has been very geologically active …
Witnessing the Formation of a Galaxy Cluster at z = 0.485: Optical and X-Ray Properties of RX J1117.4+0743 ([VMF 98] 097)
Cypriano, E. S.; Ramirez, A.; Carrasco, E. R. +4 more
We present a multiwavelength study of the poor cluster RX J1117.4+0743 ([VMF 98] 097) at z=0.485, based on GMOS/Gemini South g' and r' photometry and spectroscopy, and XMM-Newton observations. We examine its nature and surroundings by analyzing the projected galaxy distribution, the galaxy velocity distribution, the weak-lensing mass reconstructio…