Publication archive

Publication archive

Thanks to the recent generation of high energy observatories, astrophysics is witnessing a golden age of discovery in the X-ray domain. Current technical evaluation demonstrates that the XMM-Newton spacecraft and its scientific instruments can continue to provide first class X-ray observations far into the next decade. Other missions to be launched soon, like Herschel, Planck, GLAST, as well as new ground-based developments, will open up new challenging opportunities for multi-wavelength and follow-up observations to which XMM-Newton is ideally placed to make a major contribution. This publication is the proceedings of a workshop held to summarise our current knowledge of X-ray astrophysics, discuss some of the major achievements of the past years and identify the fundamental questions still to be addressed. The main focus of the workshop was to identify the scientific topics with the highest scientific importance and impact and the observing programs of maximum long-term value to the entire astronomical community.
Published: 10 December 2009
Commentary on: Jansen F., Lumb D., Altieri B., et al., 2001, A&A, 365, L1; Strüder L., Briel U., Dennerl K., et al., 2001, A&A, 365, L18; Turner M. J. L., Abbey A., Arnaud M., et al., 2001, A&A, 365, L27 The XMM-Newton X-ray observatory (previously known as the X-Ray Multi-Mirror Mission, XMM) was launched on 10 December 1999 by the first commercial Ariane 5 launch into a highly eccentric, 48 h orbit. XMM-Newton has been a key project of the European Space Agency (ESA), defined as a cornerstone mission in ESA's Horizon 2000 program. Nearly ten years after its launch, XMM-Newton operates flawlessly and has become a workhorse at the forefront of X-ray astronomy. The paper by Jansen et al. (2001), written by some of the key people in the project, is the defining post-launch paper for the XMM-Newton observatory, summarizing the key features of the satellite, various parts of the ground segment, software, and calibration. It is the opening article in a series of papers in the same A&A special issue (Vol. 365) that present more details on the instruments, software, and calibration, together with an impressive suite of ``first results' papers from across all fields of X-ray astronomy. The papers by Strüder et al. (2001) and Turner et al. (2001) describe the X-ray imaging cameras onboard (XMM-Newton) in detail.
Published: 10 December 2009
The downstream region of a collisionless quasiparallel shock is structured containing bulk flows with high kinetic energy density from a previously unidentified source. We present Cluster multispacecraft measurements of this type of supermagnetosonic jet as well as of a weak secondary shock front within the sheath, that allow us to propose the following generation mechanism for the jets: The local curvature variations inherent to quasiparallel shocks can create fast, deflected jets accompanied by density variations in the downstream region. If the speed of the jet is super(magneto)sonic in the reference frame of the obstacle, a second shock front forms in the sheath closer to the obstacle. Our results can be applied to collisionless quasiparallel shocks in many plasma environments.
Published: 09 December 2009
Reference: SRE-PA/2009/071/GC

This technical review report for the SPICA candidate mission presents the outcome of ESA's internal review of this M-class candidate mission in the Cosmic Vision 2015-2025 plan. The review was concluded at the end of the mission assessment phase and carried out in frame of the down-selection to 3 or 4 M-class missions, which will proceed to the definition phase. The main goal of this internal review was to identify the mission's critical issues and associated risks at technical, programmatic and financial level.

Published: 08 December 2009
In the book "The Cluster Active Archive - Studying the Earth's Space Plasma Environment", Astrophysics and Space Science Proceedings, H. Laakso et al. (eds.), ISBN 978-90-481-3498-4 (Print) 978-90-481-3499-1 (Online), Springer, 2010

The Chinese National Space Agency (CNSA) Double Star (DSP) spacecraft, TC-1 and TC-2 were launched in December 2003 and July 2004 into near equatorial and polar orbits respectively. During more than 3 years of operations they have maintained a close phasing with the ESA four-spacecraft mission to produce the first, well coordinated multi-scale measurements, sampling phenomena with five and six spacecraft. In this short paper we give a brief review of the DSP mission and show its joint capability with Cluster by showing examples of use of some early and more recent analysis techniques and their application to (more than) four spacecraft. We highlight a selection of some co-ordinated events, focussing on dayside phenomena, but also with a brief discussion of a tail event. Other reviews in this special issue will deal more completely with coverage of the other regions of the magnetosphere.

Published: 04 December 2009
In the book "The Cluster Active Archive - Studying the Earth's Space Plasma Environment", Astrophysics and Space Science Proceedings, H. Laakso et al. (eds.), ISBN 978-90-481-3498-4 (Print) 978-90-481-3499-1 (Online), Springer, 2010

Part of original abstract follows:
At the time of writing, Cluster is approaching 8 years of successful operation and continues to fulfill, if not exceed its scientific objectives. After a nominal mission lifetime of 2 years Cluster currently in its extended mission phase, up to June 2009, with a further extension request submitted for a further 3.5 years. The primary goals of the Cluster mission include three-dimensional studies of small-scale plasma structures and turbulence in the key plasma regions in the Earth's environment: solar wind and bow shock, magnetopause, polar cusps, magnetotail, and auroral zone. During the course of the mission, the relative distance between the four spacecraft is being varied to form a nearly perfect tetrahedral configuration at 100, 250, 600, 2,000, 5,000 and 10,000 km inter-spacecraft separation targeted to study scientifically interesting regions at different scales. In the last few years, the constellation strategy has moved towards a multi-scale concept, enabling two scale sizes to be investigated at the same time. In these cases, three spacecraft are separated by 10,000 km with the last spacecraft separated from this plane by varying distances from 16 km up to several 1,000 km. In this paper, we provide a brief overview of the mission concept and implementation and highlight a number of Cluster's latest science results, which include: the first observation of three dimensional (3-D) surface waves on the bow shock, the first 3-D analysis of turbulence in the magnetosheath, the discovery of magnetosonic waves accelerating electrons to MeV energies in the radiation belts, along with a number of discoveries involving magnetic reconnection.

Published: 04 December 2009
In the book "The Cluster Active Archive - Studying the Earth's Space Plasma Environment", Astrophysics and Space Science Proceedings, H. Laakso et al. (eds.), ISBN 978-90-481-3498-4 (Print) 978-90-481-3499-1 (Online), Springer, 2010

The four-satellite Cluster mission investigates the small-scale structures and physical processes related to interaction between the solar wind and the magnetospheric plasma. The Cluster Active Archive (CAA) (URL: http://caa.estec.esa.int) will contain the entire set of Cluster high-resolution data and other allied products in a standard format and with a complete set of metadata in machine readable format. The total amount of the data files in compressed format is expected to exceed 50 TB. The data archive is publicly accessible and suitable for science use and publication by the world-wide scientific community. The CAA aims to provide user-friendly services for searching and accessing these data and ancillary products. The CAA became operational in February 2006 and as of Summer 2008 has data from most of the Cluster instruments for at least the first 5 years of operations (2001-2005). The coverage and range of products are being continually improved with more than 200 datasets available from each spacecraft, including high-resolution magnetic and electric DC fields and wave spectra; full three-dimensional electron and ion distribution functions from a few eV to hundreds of keV; and various ancillary and browse products to help with spacecraft and event location. The CAA is continuing to extend and improve the online capabilities of the system and the quality of the existing data. It will add new data files for years 2006-2009 and is preparing for the long-term archive with complete coverage after the completion of the Cluster mission.

Published: 04 December 2009
We examine traversals on 20 November 2001 of the equatorial magnetopause boundary layer simultaneously at ~1500 magnetic local time (MLT) by the Geotail spacecraft and at ~1900 MLT by the Cluster spacecraft, which detected rolled-up MHD-scale vortices generated by the Kelvin-Helmholtz instability (KHI) under prolonged northward interplanetary magnetic field conditions. Our purpose is to address the excitation process of the KHI, MHD-scale and ion-scale structures of the vortices, and the formation mechanism of the low-latitude boundary layer (LLBL). The observed KH wavelength (>4 x 104 km) is considerably longer than predicted by the linear theory from the thickness (~1000 km) of the dayside velocity shear layer. Our analyses suggest that the KHI excitation is facilitated by combined effects of the formation of the LLBL presumably through high-latitude magnetopause reconnection and compressional magnetosheath fluctuations on the dayside, and that breakup and/or coalescence of the vortices are beginning around 1900 MLT. Current layers of thickness a few times ion inertia length ~100 km and of magnetic shear ~60° existed at the trailing edges of the vortices. Identified in one such current sheet were signatures of local reconnection: Alfvénic outflow jet within a bifurcated current sheet, nonzero magnetic field component normal to the sheet, and field-aligned beam of accelerated electrons. Because of its incipient nature, however, this reconnection process is unlikely to lead to the observed dusk-flank LLBL. It is thus inferred that the flank LLBL resulted from other mechanisms, namely, diffusion and/or remote reconnection unidentified by Cluster.
Published: 04 December 2009
This report presents an overview of the assessment study phase of the SPICA candidate M-class Cosmic Vision mission.
Published: 02 December 2009
This report presents an overview of the assessment study phase of the Solar Orbiter candidate M-class Cosmic Vision mission. Note: This report has been superseded by the Solar Orbiter definition study report (Red Book), released in July 2011, which is linked from the right-hand menu.
Published: 01 December 2009
This report presents an overview of the assessment study phase of the Marco Polo candidate M-class Cosmic Vision mission.
Published: 02 December 2009
This report presents an overview of the assessment study phase of the Euclid candidate M-class Cosmic Vision mission.
Published: 01 December 2009
This report presents an overview of the assessment study phase of the Cross-Scale candidate M-class Cosmic Vision mission.
Published: 01 December 2009

Executive Summary of the mission study by Thales Alenia Space (Reference: SD-RP-AI-0673).

The scope of this study was to provide technical definition and programmatic assessments of the whole space segment (Spacecraft + Earth Re-entry Capsule + Guidance Navigation & Control and of Touch & Go System + Sampling Acquisition & Transfer System), including development schedule and industrial costs evaluation. This information will support the selection process of the M mission to enter the definition Phase in the first half of 2010.

Published: 01 December 2009
On 16 March 2005, the Cluster spacecraft crossed a shock almost at the transition between the quasi-perpendicular and quasi-parallel regimes (ThetaBn = 46°) preceded by an upstream low-frequency (~0.02 Hz in the spacecraft frame) wave train observed for more than 10 mn. The wave semicycle nearest to the shock was found to grow in time, steepen and reflect an increasing fraction of the incoming ions. This gives strong indication that this pulsation is becoming a new shock front, standing ~5lambdap upstream of the main front and growing to shock-like amplitude on a timescale of ~35 Omegap. Downstream of the main shock transition, remnants of an older front are found indicating that the reformation is cyclic. This provides a unique example where the dynamics of shock reformation can be sequentially followed. The process shares many characteristics with simulations of reforming quasi-parallel shocks.
Published: 25 November 2009
The variability of energetic electron fluxes (>40 keV) within the plasma sheet is explored using measurements from the Cluster spacecraft from 2001 through 2005. Only cases where the spacecraft remains inside the plasma sheet throughout the event are considered. Interesting cases were found using a combination of automated methods and visual inspection. Events are classified into 4 main types: (1) plasma sheet empty of energetic electrons; (2) decreasing plasma sheet energetic electron fluxes; (3) increasing plasma sheet energetic electron fluxes; and (4) sharp (rising and falling) variations in plasma sheet energetic electron fluxes during a single plasma sheet crossing. Case studies are presented for each type of event. The time it takes to fill/empty the plasma sheet of energetic electrons is quantified based on these events. Extreme events, most of which are associated with enhanced geomagnetic activity, showed that energetic electrons in the plasma sheet can vary up to several orders of magnitude. Interestingly, the energetic electron fluxes inside the plasma sheet can still undergo rapid variations when the solar wind is calm and geomagnetic activity is low.
Published: 18 November 2009
We report an all-sky image of energetic neutral atoms (ENAs) >6 kilo-electron volts produced by energetic protons occupying the region (heliosheath) between the boundary of the extended solar atmosphere and the local interstellar medium (LISM). The map obtained by the Ion and Neutral Camera (INCA) onboard Cassini reveals a broad belt of energetic protons whose nonthermal pressure is comparable to that of the local interstellar magnetic field. The belt, centered at ~260° ecliptic longitude extending from north to south and looping back through ~80°, appears to be ordered by the local interstellar magnetic field. The shape revealed by the ENA image does not conform to current models, wherein the heliosphere resembles a cometlike figure aligned in the direction of Sun's travel through the LISM.
Published: 13 November 2009
Aims. In order to discover new X-ray transients, the data taken by XMM-Newton as it slews between targets are being processed and cross-correlated with other X-ray observations.
Methods. A bright source, XMMSL1 J060636.2-694933, was detected on 18 July 2006 at a position where no previous X-ray source had been seen. The XMM-Newton slew data, plus follow-up dedicated XMM-Newton and Swift observations, plus optical data acquired with the Magellan Clay telescope, and archival All-Sky Automated Survey (ASAS) data were used to classify the new object, and to investigate its properties.
Results. No XMM-Newton slew X-ray counts are detected above 1 keV and the source is seen to be over five hundred times brighter than the ROSAT All-Sky Survey upper limit at that position. The line-rich optical spectrum acquired with the Magellan telescope allows the object to be classified as an A0 auroral phase nova, and the soft X-ray spectrum indicates that the nova was in a super-soft source state in the X-ray decline seen in the follow-up X-ray observations. The archival ASAS data suggests that the nova at onset (Oct 2005) was a "very fast" nova, and an estimate of its distance is consistent with the nova being situated within the LMC.
Conclusions. With the discovery presented here of a new classical nova in the LMC, it is clear that XMM-Newton slew data are continuing to offer a powerful opportunity to find new X-ray transient objects.
Published: 08 November 2009
Abstract: We develop a model for estimating solar total irradiance since 1600 AD using the sunspot number record as input, since this is the only intrinsic record of solar activity extending back far enough in time. Sunspot number is strongly correlated, albeit nonlinearly with the 10.7-cm radio flux (F 10.7), which forms a continuous record back to 1947. This enables the nonlinear relationship to be estimated with usable accuracy and shows that relationship to be consistent over multiple solar activity cycles. From the sunspot number record we estimate 10.7 values back to 1600 AD. 10.7 is linearly correlated with the total amount of magnetic flux in active regions, and we use it as input to a simple cascade model for the other magnetic flux components. The irradiance record is estimated by using these magnetic flux components plus a very rudimentary model for the modulation of energy flow to the photosphere by the subphotospheric magnetic flux reservoir feeding the photospheric magnetic structures. Including a Monte Carlo analysis of the consequences of measurement and fitting errors, the model indicates the mean irradiance during the Maunder Minimum was about 1 ± 0.4 W /m2 lower than the mean irradiance over the last solar activity cycle.
Published: 20 November 2007
During the solar minimum of 2008, the value of total solar irradiance at 1 AU (TSI) was more than 0.2 Wm/2 lower than during the last minimum in 1996, indicating for the first time a directly observed long-term change. In contrast, chromospheric indices and hence solar UV irradiance do not exhibit a similar change. Comparison of TSI with other activity parameters indicates that only the open solar magnetic field, BR, observed from satellites at 1 AU show a similar long-term behaviour. The values at the minima correlate well and the linear fit provides a direct physical relationship between TSI and BR during the minimum times. This correlation allows an unambiguous reconstruction of TSI back in time, provided the open solar magnetic field can be determined from e.g. geomagnetic indices or cosmogenic radionucleides. Since the solar UV irradiance has no long-term trend, the mechanism for the secular change of TSI must differ from the effect of surface magnetism, as manifested by sunspots, faculae, and network which indeed explain well the intra-cycle variability of both total and spectral irradiance. The long-term trend of TSI is most probably caused by a global temperature change of the Sun that does not influence the UV irradiance in the same way as the surface magnetic fields.
Published: 05 November 2009
14-Jul-2020 14:01 UT

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