Showing papers by "Roberto Ragazzoni published in 2013"

The PLATO 2.0 Mission

Abstract: PLATO 2.0 has recently been selected for ESA's M3 launch opportunity (2022/24). Providing accurate key planet parameters (radius, mass, density and age) in statistical numbers, it addresses fundamental questions such as: How do planetary systems form and evolve? Are there other systems with planets like ours, including potentially habitable planets? The PLATO 2.0 instrument consists of 34 small aperture telescopes (32 with 25 sec readout cadence and 2 with 2.5 sec candence) providing a wide field-of-view (2232 deg2) and a large photometric magnitude range (4-16 mag). It focusses on bright (4-11 mag) stars in wide fields to detect and characterize planets down to Earth-size by photometric transits, whose masses can then be determined by ground-based radial-velocity follow-up measurements. Asteroseismology will be performed for these bright stars to obtain highly accurate stellar parameters, including masses and ages. The combination of bright targets and asteroseismology results in high accuracy for the bulk planet parameters: 2%, 4-10% and 10% for planet radii, masses and ages, respectively. The planned baseline observing strategy includes two long pointings (2-3 years) to detect and bulk characterize planets reaching into the habitable zone (HZ) of solar-like stars and an additional step-and-stare phase to cover in total about 50% of the sky. PLATO 2.0 will observe up to 1,000,000 stars and detect and characterize hundreds of small planets, and thousands of planets in the Neptune to gas giant regime out to the HZ. It will therefore provide the first large-scale catalogue of bulk characterized planets with accurate radii, masses, mean densities and ages. This catalogue will include terrestrial planets at intermediate orbital distances, where surface temperatures are moderate. Coverage of this parameter range with statistical numbers of bulk characterized planets is unique to PLATO 2.0.

CHEOPS: A transit photometry mission for ESA's small mission programme

Abstract: Ground based radial velocity (RV) searches continue to discover exoplanets below Neptune mass down to Earth mass. Furthermore, ground based transit searches now reach milli-mag photometric precision and can discover Neptune size planets around bright stars. These searches will find exoplanets around bright stars anywhere on the sky, their discoveries representing prime science targets for further study due to the proximity and brightness of their host stars. A mission for transit follow-up measurements of these prime targets is currently lacking. The first ESA S-class mission CHEOPS (CHaracterizing ExoPlanet Satellite) will fill this gap. It will perform ultra-high precision photometric monitoring of selected bright target stars almost anywhere on the sky with sufficient precision to detect Earth sized transits. It will be able to detect transits of RV-planets by photometric monitoring if the geometric configuration results in a transit. For Hot Neptunes discovered from the ground, CHEOPS will be able to improve the transit light curve so that the radius can be determined precisely. Because of the host stars' brightness, high precision RV measurements will be possible for all targets. All planets observed in transit by CHEOPS will be validated and their masses will be known. This will provide valuable data for constraining the mass-radius relation of exoplanets, especially in the Neptune-mass regime. During the planned 3.5 year mission, about 500 targets will be observed. There will be 20% of open time available for the community to develop new science programmes.

CHEOPS: A Transit Photometry Mission for ESA's Small Mission Programme

Abstract: Ground based radial velocity (RV) searches continue to discover exoplanets below Neptune mass down to Earth mass. Furthermore, ground based transit searches now reach milli-mag photometric precision and can discover Neptune size planets around bright stars. These searches will find exoplanets around bright stars anywhere on the sky, their discoveries representing prime science targets for further study due to the proximity and brightness of their host stars. A mission for transit follow-up measurements of these prime targets is currently lacking. The first ESA S-class mission CHEOPS (CHaracterizing ExoPlanet Satellite) will fill this gap. It will perform ultra-high precision photometric monitoring of selected bright target stars almost anywhere on the sky with sufficient precision to detect Earth sized transits. It will be able to detect transits of RV-planets by photometric monitoring if the geometric configuration results in a transit. For Hot Neptunes discovered from the ground, CHEOPS will be able to improve the transit light curve so that the radius can be determined precisely. Because of the host stars' brightness, high precision RV measurements will be possible for all targets. All planets observed in transit by CHEOPS will be validated and their masses will be known. This will provide valuable data for constraining the mass-radius relation of exoplanets, especially in the Neptune-mass regime. During the planned 3.5 year mission, about 500 targets will be observed. There will be 20% of open time available for the community to develop new science programmes.

On the radio and near-infrared jet of pks 2155-304 and its close environment

Abstract: PKS 2155–304 is one of the brightest BL Lac objects in the sky and a very well-studied target from radio to TeV bands We report on high-resolution (~0''12) direct imaging of the field of PKS 2155–304 using adaptive optics near-IR (NIR) observations in the J and Ks bands obtained with the ESO Multi-Conjugate Adaptive Optics Demonstrator on the Very Large Telescope These data are complemented with archival Very Large Array images at various frequencies to investigate the properties of the close environment of the source We characterize the faint galaxies that form the poor group associated with the target No radio emission is present for these galaxies, while an old radio jet at ~20 kpc from the nucleus of PKS 2155–304 and a jet-like structure of ~2 kpc (~1'') in the eastern direction are revealed No counterparts of these radio jets are found in the NIR or in archival Chandra observations

On the radio and NIR jet of PKS 2155-304 and its close environment

Abstract: PKS 2155-304 is one of the brightest BL Lac object in the sky and a very well studied target from radio to TeV bands. We report on high-resolution (~ 0.12 arcsec) direct imaging of the field of PKS 2155-304 using adaptive optics near-IR observations in J and Ks bands obtained with the ESO multi-conjugate adaptive optic demonstrator (MAD) at the Very Large Telescope. These data are complemented with archival VLA images at various frequencies to investigate the properties of the close environment of the source. We characterized the faint galaxies that form the poor group associated to the target. No radio emission is present for these galaxies, while an old radio jet at ~ 20 kpc from the nucleus of PKS 2155-304 and a jet-like structure of ~ 2 kpc (~ 1 arcsec) in the eastern direction are revealed. No counterparts of these radio jets are found in the NIR or in archival Chandra observations.

JANUS on the JUICE Mission: the Camera to Investigate Ganymede, Europa, Callisto and the Jovian System

Abstract: The detailed investigation of three of Jupiter‘s Galilean satellites (Ganymede, Europa, and Callisto), which are believed to harbour subsurface water oceans, is central to elucidating the conditions for habitability of icy worlds in planetary systems. The study of the Jupiter system and the possible existence of habitable environments offer the best opportunity for understanding the origins and formation of the gas giants and their satellite systems. The JUpiter ICy moons Explorer (JUICE) camera system JANUS (Jovis, Amorum ac Natorum Undique Scrutator) will determine the formation and characteristics of magmatic, tectonic, and impact features, relate them to surface forming processes, constrain global and regional surface ages, and investigate the processes of erosion and deposition. Global medium resolution imaging of Ganymede and important parts of the surface of Callisto better than 400 m/pixel (resolution limited by mission data volume) will provide context information. Selected targets will be investigated with high-resolution imaging with spatial resolution from 25 m/pixel down to 3 m/pixel. The camera system has 13 panchromatic, broadand narrow-band filters in the 0.36 μm to 1.1 μm range, and provides stereo imaging capabilities. JANUS will also allow relating spectral, laser and radar measurements to geomorphology and thus will provide the overall geological context. Introduction: The Galilean satellites Io, Europa, Ganymede and Callisto show an increase in geologic activity with decreasing distance to Jupiter [e.g. 1]. Io, nearest to Jupiter, is volcanically active. Europa could still be tectonically and volcanically active today, while Callisto, the outermost Galilean satellite, is geologically inactive. Ganymede holds a key position in the Jovian satellite system in terms of geologic evolution because it features old, densely-cratered terrain, like most of Callisto, but also widespread tectonically resurfaced regions, similar to most of the surface of Europa. Investigating Ganymede, the largest satellite in the solar system, from an orbiter is essential because of (1) its wide range of surface ages which reveals a geologic record of several billions of years, (2) its great variety in geologic and geomorphic units, (3) its active magnetic dynamo, and (4) the possible presence of a subsurface ocean. The three icy Galilean satellites Callisto, Ganymede and Europa show a tremendous diversity of surface features and differ significantly in their specific evolutionary paths. Each of these moons exhibits its own fascinating geologic history – formed by competition and also combination of external and internal processes. Their origins and evolutions are influenced by factors such as density, temperature, composition (volatile compounds), stage of differentiation, volcanism, tectonism, the rheological reaction of ice and salts to stress, tidal effects, and interactions with the Jovian magnetosphere and space. These interactions are still recorded in the present surface geology. The record of geological processes spans from possible cryovolcanism through widespread tectonism to surface degradation and impact cratering. The huge scientific return of JANUS is not only based on the geology of the Galilean satellites, that in any case represent the driving case for the design, but also on the observation of the Jupiter atmosphere and the satellite exospheres, using specific filters, the Jupiter rings and the minor satellites for astrometric purposes and on the contribution in the determination of the rotational status of Ganymede, to constrain its internal structure. The JANUS Experiment Outstanding questions that will be addressed by JUICE Imaging [2]: What are the relative roles of EPSC Abstracts Vol. 8, EPSC2013-506, 2013 European Planetary Science Congress 2013 c © Author(s) 2013 EPSC European Planetary Science Congress tectonism and cryovolcanism in shaping the dark and bright terrains on Ganymede? What does the distribution of craters on the Galilean satellites tells us about the evolution of the impactor population in the Jovian system through time? How is the geological evolution of Ganymede and Europa related to the impact, tectonic and cryovolcanic history and how is the geological evolution correlated with differentiation processes and stages? What are the ages of specific geological units on Ganymede and Europa, and how will these findings contribute to our understanding of the origin and evolution of the Jupiter system? What is the rheological response of ices and ice/salt/clathrate mixtures w.r.t. tectonic stress? To what extent are surfaces altered by cosmic weathering and what are the major exogenic surface alteration processes (micrometeorites, radiation, charged particles)? What are the fine-scale characteristics of non-ice materials on Callisto? By which intriguing mechanisms is CO2-replenishment taking place on Callisto? Performance of the Instrument Required to Fulfil the Anticipated Goals: JANUS is the next logical step after the impressive successes of the imaging studies by Voyager, Galileo and Cassini of the Jovian system. JANUS will allow orders-ofmagnitude steps ahead in terms of coverage and/or resolution and/or time evolution on many targets in Jupiter system. JANUS spatial resolution ranges from 400 m/pixel to 100 can be maintained in almost all observational scenarios. Figure 1: Ground Resolution and surface coverage for Ganymede by JANUS compared to Galileo. Instrument Design: The JANUS camera consists of three units with physical I/F with JUICE: a) the optical head including the telescope and mounting structure, the filter wheels and the focal plane; b) the proximity electronics; c) the main electronics including camera control, data handling, compression and power supply. The following architectural design was developed: a catadioptric telescope with excellent optical quality is coupled with a framing detector, avoiding any scanning mechanism and, above all, any operational requirement on the S/C. The JANUS design is tuned to have the highest probability to guarantee a great scientific success to the mission by the best usage of the resources allocated on imaging by JUICE through the implementation of a single NAC channel, with WAC capabilities, with high reliability due to the redundancy philosophy. Our proposal has also the advantage to obtain the low to medium resolution Ganymede global coverage earlier during the mission, allowing better choice of observation targets for the high-resolution phase. References: [1] Stephan, K., R. Jaumann, and R. Wagner. 2013. Geology of Icy Bodies. In: The Science of Solar System Ices, edited by M. S. Gutipati and J. Castillo-Rogez. Astrophys. and Space Sci. Libr. 356, p. 279 – 367, Springer Science+Business Media, New York, USA. [2] Grasset, O., et al., 2013. JUpiter ICy moons Explorer (JUICE): an ESA mission to orbit Ganymede and to characterise the Jupiter system, Planet. and Space Sci 78, 121, doi.org/10.1016/j.pss.2012.12.002.

LINC-NIRVANA for the large binocular telescope: setting up the world’s largest near infrared binoculars for astronomy

Abstract: LINC-NIRVANA (LN) is the near-infrared, Fizeau-type imaging interferometer for the large binocular telescope (LBT) on Mt. Graham, Arizona (elevation of 3267 m). The instrument is currently being built by a consortium of German and Italian institutes under the leadership of the Max Planck Institute for Astronomy in Heidelberg, Germany. It will combine the radiation from both 8.4 m primary mirrors of LBT in such a way that the sensitivity of a 11.9 m telescope and the spatial resolution of a 22.8 m telescope will be obtained within a 10.5×10.5 arcsec 2 scientific field of view. Interferometric fringes of the combined beams are tracked in an oval field with diameters of 1 and 1.5 arcmin. In addition, both incoming beams are individually corrected by LN’s multiconjugate adaptive optics system to reduce atmospheric image distortion over a circular field of up to 6 arcmin in diameter. A comprehensive technical overview of the instrument is presented, comprising the detailed design of LN’s four major systems for interferometric imaging and fringe tracking, both in the near infrared range of 1 to 2.4 μm, as well as atmospheric turbulence correction at two altitudes, both in the visible range of 0.6 to 0.9 μm. The resulting performance capabilities and a short outlook of some of the major science goals will be presented. In addition, the roadmap for the related assembly, integration, and verification process are discussed. To avoid late interface-related risks, strategies for early hardware as well as software interactions with the telescope have been elaborated. The goal is to ship LN to the LBT in 2014.

Software and control system for the VLT Survey Telescope

Abstract: The VLT Survey Telescope (VST) has started the regular operations in 2011 after a successful commissioning at Cerro Paranal (Chile), the site which hosts the best facilities for optical astronomy operated by the European Southern Observatory (ESO). After a short description of the instrument, this paper mainly focuses on the telescope control software, which is in charge of the real-time control of the hardware and of the overall coordination of the operations, including pointing and tracking, active optics and presets. We describe the main features of the software implementation in the context of the ESO observatory standards, and the goals reached during the commissioning phase and in the first year of operations.

Multiple FoV MCAO on its way to the sky

Abstract: LINC-NIRVANA, an infrared camera working in a Fizeau interferometric layout, takes advantage of the Layer Oriented MCAO MFoV technique to correct a 2 arcmin FoV using only Natural Guide Stars (NGSs), exploiting the central 10 arcsec with a resolving power of a 23 meter telescope. For each arm of the LBT telescope 2 WaveFront Sensors (WFSs) optically conjugated, respectively at ground and high (7 km) layers, are used to search for NGSs. To avoid unnecessary waste of photons the two sensors look at different FoVs. The groundlayer one, essentially limited by practical conditions, searches for up to 12 NGSs in an annular 2-6 arcmin FoV, while the high-layer one, limited by the pupils superposition, looks for up to 8 NGSs in the central 2 arcmin FoV. The concept has left paper's realm to become glass and metal a few years ago. With the completion of the 2 highlayer WFSs by INAF-Bologna and, recently with the successful tests performed on the first ground-layer WFSs by INAF-Padova, further followed by the GWS Pathfinder experiment to test the ground layer correction at LBT, in collaboration with MPIA-Heidelberg, the concept is finally getting closer to its on-sky commissioning, foreseen in the next very few years. In this paper the basic concepts of MFoV MCAO will be revised, the current status of the system described and the near future toward final completion of the instrument depicted. Moreover a possible path for this concept toward an ELT will be traced.

Telescope, comprising a spherical primary mirror, with wide field of view and high optical resolution

Abstract: Telescope with wide Field of View, high optical resolution and continuity of the field of view comprising a spherical primary mirror, wherein a) said telescope is equipped with a system of repartitioning of the Field of View, b) that said system of repartitioning of the Field of View is placed in proximity of the focus of the primary mirror, and is constituted by a secondary mirror composed by n planar reflective surfaces, c) said n planar reflective surfaces are contiguous one to the other and form a continuous multifaceted prismatic reflector, in such a way as to obtain the continuity of the field of view over the whole field, d) said n planar reflective surfaces are followed by a corresponding number of optical cameras that form n portions of immage in n distinct focal planes, e) a collecting and recording element is positioned on each n-th focal plane