Search Publications
An XMM-Newton view of the X-ray flat radio-quiet quasar PG 1416-129
Nandra, K.; Turner, T. J.; Porquet, D. +3 more
Aims:The radio-quiet quasar PG 1416-129 (z=0.129) exhibits atypical optical and X-ray properties. Between 1990 and 2000, in response to its optical continuum decrease, the “classical” broad component of Hβ almost completely disappeared, with a factor of 10 decrease in the line flux. In addition, the width of the broad component of the Hβ line decr…
Ultraviolet spectroscopy of Comet 9P/Tempel 1 with Alice/Rosetta during the Deep Impact encounter
Parker, Joel Wm.; Bertaux, Jean-Loup; Stern, S. Alan +5 more
We report on spectroscopic observations of periodic Comet 9P/Tempel 1 by the Alice ultraviolet spectrograph on the Rosetta spacecraft in conjunction with NASA's Deep Impact mission. Our objectives were to measure an increase in atomic and molecular emissions produced by the excavation of volatile sub-surface material. We unambiguously detected ato…
Secular light curve of Comet 28P/Neujmin 1 and of spacecraft target Comets 1P/Halley, 9P/Tempel 1, 19P/Borrelly, 21P/Giacobinni Zinner, 26P/Grigg Skjellerup, 67P/Churyumov Gerasimenko, and 81P/Wild 2
Ferrín, Ignacio
We present the secular light curves of eight comets listed in the title. Two plots per comet are needed to study these objects: a reduced magnitude (to Δ=1 AU = geocentric distance) vs time, and a reduced magnitude vs LogR (R=heliocentric distance). A total of over 16 new parameters, are measured from both plots, and give an unprecedented amount o…
Response of the magnetosheath-cusp region to a coronal mass ejection
Lucek, E.; Fazakerley, A. N.; Reme, H. +6 more
Cluster made an unusual magnetosheath-exterior cusp crossing during the first 2.5 hours of a coronal mass ejection (CME) that flowed past Earth for about 7 hours on 24 October 2003. During the first 2.5 hours (1525-1802 UT) the solar wind dynamic pressure remained high and stable though the CME had a discontinuity after 40 min (1605 UT), when the …
The Huygens Probe Descent Trajectory Working Group: Organizational framework, goals, and implementation
Lebreton, Jean-Pierre; Witasse, Olivier; Matson, Dennis L. +3 more
Cassini/Huygens, a flagship mission to explore the rings, atmosphere, magnetic field, and moons that make up the Saturn system, is a joint endeavor of the National Aeronautics and Space Administration, the European Space Agency, and Agenzia Spaziale Italiana. Comprising two spacecraft - a Saturn orbiter built by NASA and a Titan entry/descent prob…
X-ray detection of the substellar twin 2MASS J11011926-7732383 AB
Micela, G.; Stelzer, B.
Context: 2MASS J11011926-7732383 AB (hereafter 2M 1101 AB), located in the Cha I star forming region, is a rare wide-separation brown dwarf binary. Being spatially resolvable in many wavebands, it is a unique target for studying the properties of substellar twins.
Aims: Here, we exploit the coeval pair 2M 1101 AB to examine the influence of ph…
Statistical properties of small-amplitude Langmuir waves in the Earth's electron foreshock
Soucek, J.; Décréau, P.; Krasnoselskikh, V. V. +2 more
We present the results of a statistical study of Langmuir waves observed by the Cluster spacecraft in the Earth's electron foreshock. To classify the probability density distributions of the logarithms of the wave energies, a Pearson technique is used. We show that experimental distributions can be better approximated, in a statistical sense, by B…
Possible eigenmode trapping in density enhancements in Saturn's inner magnetosphere
Gurnett, D. A.; Menietti, J. D.; Yoon, P. H.
We report a re-examination of observations of radio waves and banded fine structure observed by Cassini in the Saturn inner magnetosphere. These emissions have been identified in the past as Z-mode emission from possible density cavities along the inner edge of the Saturn plasma torus. A careful examination of the emission fine structure in a regi…
The correlations of ions density with geomagnetic activity and solar dynamic pressure in cusp region
Dandouras, I.; Lucek, E.; Reme, H. +5 more
A statistical study of the properties of ions (O+, He+ and H+) measured by the Cluster-II in cusp region as a function of the solar wind dynamic pressure and geomagnetic index Kp respectively was made during the summer and fall of 2001-2003. The main results are that: (1) O+ ion density responds in a significant way to geomagnetic index Kp, and He…
Modeling time delays in the X-ray spectrum of the Seyfert galaxy MCG-6-30-15
Ponti, G.; Karas, V.; Czerny, B. +1 more
Aims:We propose a reflection model of the time delays detected during an exceptionally bright, single flare in MCG-6-30-15. We consider a scenario in which the delays of the hard X-rays with respect to the soft X-rays are caused by the presence of the delayed reflection component.
Methods: We employ a model of the flare, which is accompanied b…