Publication archive

Publication archive

The first open Workshop on the Marco Polo mission, jointly organized by the Côte d'Azur Observatory and ESA, was held on 5 and 6 June 2008. More than 80 participants attended the two-day workshop in Cannes, France, which included the following sessions:
I.Missions: general studies and programmatics
II.Physical properties of NEOs from laboratory experiments, simulations and observations
III.Instrumentation for global and local characterization
IV.Sampling mechanisms and analysis
V.Japanese-European Collaboration

The 25+ presentations given at the workshop are available in PDF format via the following link:


Published: 07 June 2008
Is it possible for life to exist on Enceladus, the tiny (500 km diameter) icy satellite of Saturn? The Cassini mission found giant gaseous plumes erupting from a tectonically active and warm south polar region. One highly publicized interpretation is that liquid water is present, possibly within tens of meters of the surface, or possibly only at depths of tens of kilometers. An antithetical interpretation is that Enceladus is frigid, stiff, thoroughly solid and composed of ice with interstitial gases to great depths. However, liquid water is just one of the three environmental conditions that are generally thought to be prerequisites for life. There must also be access to the elements out of which complex molecular structures can be constructed--mainly C, H, O, N, S, and--as well as an energy source that can drive metabolism. We examine the range of possible environments on Enceladus that are consistent with the observations in terms of their implications for harboring life.
Published: 14 June 2008
We report Double Star spacecraft observations of the dusk-flank magnetopause and its boundary layer under predominantly northward interplanetary magnetic field (IMF). Under such conditions the flank low-latitude boundary layers (LLBL) of the magnetosphere are known to broaden. The primary candidate processes associated with the transport of solar wind plasma into the LLBL are: (1) local diffusive plasma transport associated with the Kelvin-Helmholtz instability (KHI), (2) local plasma penetration owing to magnetic reconnection in the vicinity of the KHI-driven vortices, and (3) via a pre-existing boundary layer formed through double high-latitude reconnection on the dayside. Previous studies have shown that a cold population of solar wind origin is typically mixed with a hot population of magnetospheric origin in the LLBL. The present observations show the coexistence of three distinct ion populations in the dusk LLBL, during an interval when the magnetopause is unstable to the KHI: (1) a typical hot magnetospheric population, (2) a cold population that shows parallel temperature anisotropy, and (3) a distinct third cold population that shows perpendicular temperature anisotropy. Although no unambiguous conclusion may be drawn from this single event, we discuss the possible mechanisms at work and the origin of each population by envisaging three likely sources: hot magnetospheric plasma sheet, cold magnetosheath of solar wind origin, and cold plasma of ionospheric origin.
Published: 12 June 2008
A method has been developed for extracting magnetospheric ion distributions from Energetic Neutral Atom (ENA) measurements made by the NUADU instrument on the TC-2 spacecraft. Based on a constrained linear inversion, this iterative technique is suitable for use in the case of an ENA image measurement, featuring a sharply peaked spatial distribution. The method allows for magnetospheric ion distributions to be extracted from a low-count ENA image recorded over a short integration time (5 min). The technique is demonstrated through its application to a set of representative ENA images recorded in energy Channel~2 (hydrogen: 50-81 keV, oxygen: 138-185 keV) of the NUADU instrument during a geomagnetic storm. It is demonstrated that this inversion method provides a useful tool for extracting ion distribution information from ENA data that are characterized by high temporal and spatial resolution. The recovered ENA images obtained from inverted ion fluxes match most effectively the measurements made at maximum ENA intensity.
Published: 12 June 2008
We present an XMM-Newton observation of the long-overlooked radio source G350.1-0.3. The X-ray spectrum of G350.1-0.3 can be fit by a shocked plasma with two components: a high-temperature (1.5 keV) region with a low ionization timescale and enhanced abundances, plus a cooler (0.36 keV) component in ionization equilibrium and with solar abundances. The X-ray spectrum and the presence of nonthermal, polarized, radio emission together demonstrate that G350.1-0.3 is a young, luminous supernova remnant (SNR), for which archival H I and 12CO data indicate a distance of 4.5 kpc. The diameter of the source then implies an age of only ~900 years. The SNR's distorted appearance and small size and the presence of 12CO emission along the SNR's eastern edge all indicate that the source is interacting with a complicated distribution of dense ambient material. An unresolved X-ray source, XMMU J172054.5-372652, is detected a few arcminutes west of the brightest SNR emission. The thermal X-ray spectrum and lack of any multiwavelength counterpart suggest that this source is a neutron star associated with G350.1-0.3, most likely a 'central compact object', as seen coincident with other young SNRs such as Cassiopeia A.
Published: 10 June 2008
XMM-Newton is one of ESA's most successful science missions. Launched in December 1999, the spacecraft is technically able to continue this scientific success story and now, encouraged by its impressive scientific output, ESA has already extended XMM-Newton's operations well beyond its original 10-year design lifetime. This article looks at the impact of XMM-Newton since its launch in December 1999.
Published: 07 June 2008
The magnetic field that surrounds the Earth is rarely quiet. An explanation for the explosive nature of magnetic storms is gathering support from satellite data.
Published: 30 March 2001
Observations made by a unique constellation of Cluster (at 14-16 RE), TC2, Goes10, and LANL spacecraft (near 6.6 RE) have allowed us to study the details of three reconnection events in the middle of a thick plasma sheet with the reconnection X-line located unusually close to Earth (10-12 RE). We use mapping along field lines with magnetospheric models adapted to magnetic field observations to confirm that the reconnection region mapped onto localized auroral brightenings. Using simultaneous observations in the inflow and outflow regions, we describe an encounter with a localized tailward Alfvénic jet produced by a short isolated reconnection pulse. A good correlation between intense E and ion [BV] indicates that the concurrent strong turbulence could not destroy the frozen-in ion behavior in the reconnection outflow. We find that a steady quadrupole-like distribution of the magnetic By component in the turbulent reconnection outflow extended far beyond the ion diffusion region and existed for several minutes. We demonstrate an apparent Vx flow reversal, formed owing to the reappearance (switch-on) of reconnection at another location, rather than to a continuous motion of the active X-line. Using the Liouville mapping technique, we show that the acceleration of outflow electrons, after the particles passed a potential drop of 180 V, is consistent with Fermi/betatron acceleration. We also suggest another interpretation of the energetic particle bursts at the onsets, to emphasize the role of seed population and explain the sudden burst as a consequence of changing magnetic topology.
Published: 06 June 2008
Context. The INTEGRAL mission has led to the discovery of a new type of supergiant X-ray binaries (SGXBs), whose physical properties differ from those of previously known SGXBs. Those sources are in the course of being unveiled by means of multi-wavelength X-rays, optical, near- and mid-infrared observations, and two classes are appearing. The first class consists of obscured persistent SGXBs and the second is populated by the so-called supergiant fast X-ray transients (SFXTs).
Aims. We report here mid-infrared (MIR) observations of the companion stars of twelve SGXBs from these two classes in order to assess the contribution of the star and the material enshrouding the system to the total emission. Methods. We used data from observations we carried out at ESO/VLT with VISIR, as well as archival and published data, to perform broad-band spectral energy distributions of the companion stars and fitted them with a combination of two black bodies representing the star and a MIR excess due to the absorbing material enshrouding the star, if there was any.
Results. We detect a MIR excess in the emission of IGR J16318-4848, IGR J16358-4726, and perhaps IGR J16195-4945. The other sources do not exhibit any MIR excess even when the intrinsic absorption is very high. Indeed, the stellar winds of supergiant stars are not suitable for dust production, and we show that this behaviour is not changed by the presence of the compact object. Concerning IGR J16318-4848 and probably IGR J16358-4726, the MIR excess can be explained by their sgB[e] nature and the presence of an equatorial disk around the supergiant companion in which dust can be produced. -- Remainder of abstract is truncated --
Published: 06 June 2008
Context. The INTEGRAL hard X-ray observatory has revealed an emerging population of highly obscured X-ray binary systems through multi-wavelength observations. Previous studies have shown that many of these sources are high-mass X-ray binaries hosting neutron stars orbiting around luminous and evolved companion stars. Aims. To better understand this newly-discovered population, we have selected a sample of sources for which an accurate localisation is available to identify the stellar counterpart and reveal the nature of the companion star and of the binary system.
Methods. We performed an intensive study of a sample of thirteen INTEGRAL sources, through multi-wavelength optical to NIR photometric and spectroscopic observations, using EMMI and SofI instruments at the ESO NTT telescope. We performed accurate astrometry and identified candidate counterparts for which we give the optical and NIR magnitudes. We detected many spectral lines allowing us to determine the spectral type of the companion star. We fitted with stellar black bodies the mid-infrared to optical spectral energy distributions of these sources. From the spectral analysis and SED fitting we identified the nature of the companion stars and of the binary systems.
Results. Through spectroscopic analysis of the most likely candidates we found the spectral types of IGR J16320-4751, IGR J16358-4726, IGR J16479-4514, IGR J17252-3616, IGR J18027-2016: They all host OB type supergiant companion stars, with IGR J16358-4726 likely hosting an sgB[e]. Our spectra also confirm the supergiant O and B nature of IGR J17391-3021 and IGR J19140+0951. From SED fitting we found that IGR J16418-4532 is a (likely OB supergiant) HMXB, IGR J16393-4643 a (likely BIV-V star) HMXB, and IGR J18483-0311 a likely HMXB system. -- Remainder of abstract is truncated --
Published: 06 June 2008
The report for the 36th COSPAR Meeting covers the missions of the Scientific Programme of ESA in the areas of astronomy, Solar System science and fundamental physics.
Published: 02 May 2006
We report observations from a conjunction of FAST and Cluster during an interval of downward current at an MLT of 3-4 h on field lines mapping to the PSBL. Both spacecraft see upgoing electrons with an energy of a few hundred eV, suggesting substantial acceleration has occurred below FAST's altitude of 3200 km. At Cluster, isolated bursts of electrons are seen, and modeling indicates that the current mapped from the ionosphere exists as a collection of current filaments at Cluster (4-5 RE). The current filaments are aligned with the background magnetic field and have a perpendicular scale at Cluster of about 100 km (which maps to 10-20 km in the ionosphere), and is similar to the mapped width observed by FAST. The electron beams are quasi-steady during a Cluster spacecraft transit time of 1 min. The field aligned current densities at FAST and Cluster are of the order of a few microAms-2 and 0.05 microAm-2, respectively, and j/B is conserved along a current filament.
Published: 04 June 2008
This extract of ESA's Report to the 36th COSPAR Meeting held in Beijing, China in July 2006, covers the Ulysses mission.
Published: 02 May 2006
We present energetic neutral atom (ENA) images in the energy range 45 to 50 keV for H and 92 to 138 keV for O measured by the Neutral Atom Detector Unit (NUADU) onboard Double Star TC-2 during a geomagnetic storm on 8 May 2005. We compare the ion fluxes deduced from inversion of the NUADU image with those calculated using the Comprehensive Ring Current Model (CRCM). This comparison shows that the two approaches are consistent when used to derive the configuration of the corresponding global ion distribution and the peak ion fluxes. The deduced peak ion flux is located in the premidnight sector at 1540 UT, while the deduced ion peak flux is located in the midnight sector at 1610 UT. There are strong ion fluxes in the region between L = 2 and L = 4 which form a closed loop configuration. The ion peak flux is about 2.2×106/cm²/sr/keV/s. The deduced ion distribution agrees well with the NUADU measurement. The agreement between the inverted ion distributions and the CRCM results give us confidence in applying our ENA imaging and modeling techniques to the study of the evolution of the inner magnetosphere plasma distribution and the global dynamics of the ring current during magnetic storms.
Published: 31 May 2008
This document provides the top level science requirements and the implied top level payload and mission requirements for Euclid, ESA's mission to map the dark Universe. Euclid will tightly constrain the dark energy equation of state and address key cosmological questions. This Issue 4 of the Science Requirements Document (SciRD) will be the basis for the Euclid mission and payload design during the Definition Phase.

[This is an abbreviated version of the original document abstract.]

Published: 05 March 2010
We study the plasma turbulence, at scales larger than the ion inertial length scale, downstream of a quasiparallel bow shock using Cluster multispacecraft measurements. We show that turbulence is intermittent and well described by the extended structure function model, which takes into account the spatial inhomogeneity of the cascade rate. For the first time we use multispacecraft observations to characterize the evolution of magnetosheath turbulence, particularly its intermittency, as a function of the distance from the bow shock. The intermittency significantly changes over the distance of the order of 100 ion inertial lengths, being increasingly stronger and anisotropic away from the bow shock.
Published: 22 May 2008
This document describes the detailed scientific requirements for the Marco Polo mission. These requirements are derived from discussions by the Science Study Team (SST) of the Marco Polo study and is based on the scientific objectives as described in the Marco Polo Proposal to ESA's Cosmic Vision programme (RD 01). [This is an abbreviated version of the original document abstract.]
Published: 21 May 2009
This Payload Definition Document (PDD) is a compilation of the Cross-Scale strawman payload requirements and of their related reference design. The PDD plays a key role in defining the resources required by the Cross-Scale instruments and in providing the information necessary to conduct the mission assessment study and the preliminary spacecraft design. [This is an abbreviated version of the original document abstract.]
Published: 05 April 2008
We report measurements of night-side airglow emission in the atmosphere of Venus in the OH (2-0), OH (1-0), O2(a-X) (0-1), and O2(a-X) (0-0) bands. This is the first detection of the first three of these airglow emissions on another planet. These observations provide the most direct observational constraints to date on H, OH, and O3, key species in the chemistry of Venus' upper atmosphere. (This is an abbreviated abstract from the paper "First detection of hydroxyl in the atmosphere of Venus", by Piccioni et al, published in Astronomy & Astrophysics, A&A 483, L29-L33 (2008))
Published: 20 May 2008
25-Oct-2020 19:19 UT

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