References of "Surdej, Jean"
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See detailGaia Data Release 1: Testing parallaxes with local Cepheids and RR Lyrae stars
Clementini, G.; Eyer, L.; Ripepi, V. et al

in Astronomy and Astrophysics (2017), 605

Context. Parallaxes for 331 classical Cepheids, 31 Type II Cepheids, and 364 RR Lyrae stars in common between Gaia and the Hipparcos and Tycho-2 catalogues are published in Gaia Data Release 1 (DR1) as ... [more ▼]

Context. Parallaxes for 331 classical Cepheids, 31 Type II Cepheids, and 364 RR Lyrae stars in common between Gaia and the Hipparcos and Tycho-2 catalogues are published in Gaia Data Release 1 (DR1) as part of the Tycho-Gaia Astrometric Solution (TGAS). Aims. In order to test these first parallax measurements of the primary standard candles of the cosmological distance ladder, which involve astrometry collected by Gaia during the initial 14 months of science operation, we compared them with literature estimates and derived new period-luminosity (PL), period-Wesenheit (PW) relations for classical and Type II Cepheids and infrared PL, PL-metallicity (PLZ), and optical luminosity-metallicity (MV-[Fe/H]) relations for the RR Lyrae stars, with zero points based on TGAS. Methods. Classical Cepheids were carefully selected in order to discard known or suspected binary systems. The final sample comprises 102 fundamental mode pulsators with periods ranging from 1.68 to 51.66 days (of which 33 with σΩ/Ω< 0.5). The Type II Cepheids include a total of 26 W Virginis and BL Herculis stars spanning the period range from 1.16 to 30.00 days (of which only 7 with σΩ/Ω< 0.5). The RR Lyrae stars include 200 sources with pulsation period ranging from 0.27 to 0.80 days (of which 112 with σΩ/Ω< 0.5). The new relations were computed using multi-band (V,I,J,Ks) photometry and spectroscopic metal abundances available in the literature, and by applying three alternative approaches: (i) linear least-squares fitting of the absolute magnitudes inferred from direct transformation of the TGAS parallaxes; (ii) adopting astrometry-based luminosities; and (iii) using a Bayesian fitting approach. The last two methods work in parallax space where parallaxes are used directly, thus maintaining symmetrical errors and allowing negative parallaxes to be used. The TGAS-based PL,PW,PLZ, and MV- [Fe/H] relations are discussed by comparing the distance to the Large Magellanic Cloud provided by different types of pulsating stars and alternative fitting methods. Results. Good agreement is found from direct comparison of the parallaxes of RR Lyrae stars for which both TGAS and HST measurements are available. Similarly, very good agreement is found between the TGAS values and the parallaxes inferred from the absolute magnitudes of Cepheids and RR Lyrae stars analysed with the Baade-Wesselink method. TGAS values also compare favourably with the parallaxes inferred by theoretical model fitting of the multi-band light curves for two of the three classical Cepheids and one RR Lyrae star, which were analysed with this technique in our samples. The K-band PL relations show the significant improvement of the TGAS parallaxes for Cepheids and RR Lyrae stars with respect to the Hipparcos measurements. This is particularly true for the RR Lyrae stars for which improvement in quality and statistics is impressive. Conclusions. TGAS parallaxes bring a significant added value to the previous Hipparcos estimates. The relations presented in this paper represent the first Gaia-calibrated relations and form a work-in-progress milestone report in the wait for Gaia-only parallaxes of which a first solution will become available with Gaia Data Release 2 (DR2) in 2018. © ESO, 2017. [less ▲]

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See detailHigh dynamic range thermal infrared imager for the VLTI
Defrere, Denis ULiege; Absil, Olivier ULiege; Ertel, Steve et al

in Pott, Jörg-Uwe; Surdej, Jean (Eds.) Future of otpical-infrared interferometry in Europe (2017)

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See detail9ème (bis) Cours de Mécanique Analytique II (2016-17), Bac3 phys, Master 1 Sc. Sp.
Surdej, Jean ULiege

Learning material (2016)

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See detailOptimizing the subwavelength grating of L-band annular groove phase masks for high coronagraphic performance
Vargas Catalán, E.; Huby, Elsa ULiege; Forsberg, P. et al

in Astronomy and Astrophysics (2016), 595

Context. The annular groove phase mask (AGPM) is one possible implementation of the vector vortex coronagraph, where the helical phase ramp is produced by a concentric subwavelength grating. For several ... [more ▼]

Context. The annular groove phase mask (AGPM) is one possible implementation of the vector vortex coronagraph, where the helical phase ramp is produced by a concentric subwavelength grating. For several years, we have been manufacturing AGPMs by etching gratings into synthetic diamond substrates using inductively coupled plasma etching. <BR /> Aims: We aim to design, fabricate, optimize, and evaluate new L-band AGPMs that reach the highest possible coronagraphic performance, for applications in current and forthcoming infrared high-contrast imagers. <BR /> Methods: Rigorous coupled wave analysis (RCWA) is used for designing the subwavelength grating of the phase mask. Coronagraphic performance evaluation is performed on a dedicated optical test bench. The experimental results of the performance evaluation are then used to accurately determine the actual profile of the fabricated gratings, based on RCWA modeling. <BR /> Results: The AGPM coronagraphic performance is very sensitive to small errors in etch depth and grating profile. Most of the fabricated components therefore show moderate performance in terms of starlight rejection (a few 100:1 in the best cases). Here we present new processes for re-etching the fabricated components in order to optimize the parameters of the grating and hence significantly increase their coronagraphic performance. Starlight rejection up to 1000:1 is demonstrated in a broadband L filter on the coronagraphic test bench, which corresponds to a raw contrast of about 10[SUP]-5[/SUP] at two resolution elements from the star for a perfect input wave front on a circular, unobstructed aperture. <BR /> Conclusions: Thanks to their exquisite performance, our latest L-band AGPMs are good candidates for installation in state of the art and future high-contrast thermal infrared imagers, such as METIS for the E-ELT. [less ▲]

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See detail8ème Cours de Mécanique Analytique II (2016-17), Bac3 phys, Master 1 Sc. Sp.
Surdej, Jean ULiege

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See detail7ème Cours de Mécanique Analytique II (2016-17), Bac3 phys, Master 1 Sc. Sp.
Surdej, Jean ULiege

Learning material (2016)

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See detailGaia Data Release 1. Summary of the astrometric, photometric, and survey properties
Gaia Collaboration; Brown, A. G. A.; Vallenari, A. et al

in Astronomy and Astrophysics (2016), 595

Context. At about 1000 days after the launch of Gaia we present the first Gaia data release, Gaia DR1, consisting of astrometry and photometry for over 1 billion sources brighter than magnitude 20.7. <BR ... [more ▼]

Context. At about 1000 days after the launch of Gaia we present the first Gaia data release, Gaia DR1, consisting of astrometry and photometry for over 1 billion sources brighter than magnitude 20.7. <BR /> Aims: A summary of Gaia DR1 is presented along with illustrations of the scientific quality of the data, followed by a discussion of the limitations due to the preliminary nature of this release. <BR /> Methods: The raw data collected by Gaia during the first 14 months of the mission have been processed by the Gaia Data Processing and Analysis Consortium (DPAC) and turned into an astrometric and photometric catalogue. <BR /> Results: Gaia DR1 consists of three components: a primary astrometric data set which contains the positions, parallaxes, and mean proper motions for about 2 million of the brightest stars in common with the Hipparcos and Tycho-2 catalogues - a realisation of the Tycho-Gaia Astrometric Solution (TGAS) - and a secondary astrometric data set containing the positions for an additional 1.1 billion sources. The second component is the photometric data set, consisting of mean G-band magnitudes for all sources. The G-band light curves and the characteristics of 3000 Cepheid and RR Lyrae stars, observed at high cadence around the south ecliptic pole, form the third component. For the primary astrometric data set the typical uncertainty is about 0.3 mas for the positions and parallaxes, and about 1 mas yr[SUP]-1[/SUP] for the proper motions. A systematic component of 0.3 mas should be added to the parallax uncertainties. For the subset of 94 000 Hipparcos stars in the primary data set, the proper motions are much more precise at about 0.06 mas yr[SUP]-1[/SUP]. For the secondary astrometric data set, the typical uncertainty of the positions is 10 mas. The median uncertainties on the mean G-band magnitudes range from the mmag level to 0.03 mag over the magnitude range 5 to 20.7. <BR /> Conclusions: Gaia DR1 is an important milestone ahead of the next Gaia data release, which will feature five-parameter astrometry for all sources. Extensive validation shows that Gaia DR1 represents a major advance in the mapping of the heavens and the availability of basic stellar data that underpin observational astrophysics. Nevertheless, the very preliminary nature of this first Gaia data release does lead to a number of important limitations to the data quality which should be carefully considered before drawing conclusions from the data. [less ▲]

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See detailThe Gaia mission
Gaia Collaboration; Prusti, T.; de Bruijne, J. H. J. et al

in Astronomy and Astrophysics (2016), 595

Gaia is a cornerstone mission in the science programme of the EuropeanSpace Agency (ESA). The spacecraft construction was approved in 2006, following a study in which the original interferometric concept ... [more ▼]

Gaia is a cornerstone mission in the science programme of the EuropeanSpace Agency (ESA). The spacecraft construction was approved in 2006, following a study in which the original interferometric concept was changed to a direct-imaging approach. Both the spacecraft and the payload were built by European industry. The involvement of the scientific community focusses on data processing for which the international Gaia Data Processing and Analysis Consortium (DPAC) was selected in 2007. Gaia was launched on 19 December 2013 and arrived at its operating point, the second Lagrange point of the Sun-Earth-Moon system, a few weeks later. The commissioning of the spacecraft and payload was completed on 19 July 2014. The nominal five-year mission started with four weeks of special, ecliptic-pole scanning and subsequently transferred into full-sky scanning mode. We recall the scientific goals of Gaia and give a description of the as-built spacecraft that is currently (mid-2016) being operated to achieve these goals. We pay special attention to the payload module, the performance of which is closely related to the scientific performance of the mission. We provide a summary of the commissioning activities and findings, followed by a description of the routine operational mode. We summarise scientific performance estimates on the basis of in-orbit operations. Several intermediate Gaia data releases are planned and the data can be retrieved from the Gaia Archive, which is available through the Gaia home page. <A href="http://www.cosmos.esa.int/gaia">http://www.cosmos.esa.int/gaia</A> [less ▲]

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See detail6ème Cours de Mécanique Analytique II (2016-17), Bac3 phys, Master 1 Sc. Sp.
Surdej, Jean ULiege

Learning material (2016)

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See detailLinking CAI abundance to polarimetric response in a population of ancient asteroids
Devogele, Maxime ULiege; Tanga, Paolo; Bendjoya, Philippe et al

Conference (2016, October 18)

Polarimetry constitutes one of the fundamental tools for characterizing the surface texture and composition of airless Solar System bodies. In 2006, polarimetric observations led to the discovery of a new ... [more ▼]

Polarimetry constitutes one of the fundamental tools for characterizing the surface texture and composition of airless Solar System bodies. In 2006, polarimetric observations led to the discovery of a new type of asteroids, which displays a peculiar polarimetric response. These asteroids are collectively known as "Barbarians", from (234) Barbara the first discovered one.The most commonly accepted explanation for this perculiar polarization response seems to be the presence of a high percentage of fluffy-type Calcium Aluminium-rich Inclusions (CAIs), whose optical properties could produce the observed polarization. Their reflectance spectra also exibit an absorption feature in the near-infrared around 2.1-2.2 microns, that is characteristic of this peculiar group.Based on these results, we organized a systematic polarimetric and near-infrared observational campaign of known Barbarians or candidate asteroids. These campaigns include members of the family of 1040 Klumpkea, 2085 Henan and 729 Watsonia, which are known to contain Barbarian and/or L-type asteroids also suspected to have such a polarimetric behaviour. We have made use of the ToPo polarimeter at the 1m telescope of the Centre pédagogique Planète et Univers (C2PU, Observatoire de la Côte d'Azur, France). The spectroscopic observations in the near-infrared were obtained with the SpeX instrument at the NASA's InfraRed Telescope Facility (IRTF).By combining polarimetry and spectroscopy we find a correlation between the abundance of CAIs and the inversion angle of the phase-polarization curve of Barbarian asteroids. This is the first time that a direct link has been established between a specific polarimetric response and the surface composition of asteroids. In addition, we find a considerable variety of CAI abundance from one object to the other, consistent with a wide range of possible albedos. Since these asteroids constitute a reservoir of primitive Solar System material, understanding their origin can shed light on the processes driving the formation and transport of the refractory minerals that first condensed in the protoplanetary disk. [less ▲]

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See detailCours No 3: Astrophysique et Techniques Spatiales: Ingés aéro/ Ingés Phys 2016-2017 (Fichier PDF + vidéos: mov)
Surdej, Jean ULiege

Learning material (2016)

In this course of Astronomy and space techniques, we introduce all the necessary concepts that enable us to understand basic observational data as well as modern ground-based and space telescopes and ... [more ▼]

In this course of Astronomy and space techniques, we introduce all the necessary concepts that enable us to understand basic observational data as well as modern ground-based and space telescopes and their instrumentation. This course has been designed for future engineers willing to understand and communicate with other people basic concepts of astronomy as well as to those wishing to pursue more specialized studies in astrophysics (cf. end-of-year thesis oriented towards astrophysics, master in space sciences, PhD in astrophysics, ...) or a future career in this field. In the first part of this course, we present the main discoveries in astrophysics already known by the antique greek astronomers, including an introduction to the different spherical coordinate systems and to photometry. [less ▲]

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See detailCours No 2: Astrophysique et Techniques Spatiales: Ingés aéro/ Ingés Phys 2016-2017 (Fichier PDF + vidéos: mov)
Surdej, Jean ULiege

Learning material (2016)

In this course of Astronomy and space techniques, we introduce all the necessary concepts that enable us to understand basic observational data as well as modern ground-based and space telescopes and ... [more ▼]

In this course of Astronomy and space techniques, we introduce all the necessary concepts that enable us to understand basic observational data as well as modern ground-based and space telescopes and their instrumentation. This course has been designed for future engineers willing to understand and communicate with other people basic concepts of astronomy as well as to those wishing to pursue more specialized studies in astrophysics (cf. end-of-year thesis oriented towards astrophysics, master in space sciences, PhD in astrophysics, ...) or a future career in this field. In the first part of this course, we present the main discoveries in astrophysics already known by the antique greek astronomers, including an introduction to the different spherical coordinate systems and to photometry. [less ▲]

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See detailCours No 1: Astrophysique et Techniques Spatiales: Ingés aéro/ Ingés Phys 2016-2017 (Fichier PDF + vidéos: mov)
Surdej, Jean ULiege

Learning material (2016)

In this course of Astronomy and space techniques, we introduce all the necessary concepts that enable us to understand basic observational data as well as modern ground-based and space telescopes and ... [more ▼]

In this course of Astronomy and space techniques, we introduce all the necessary concepts that enable us to understand basic observational data as well as modern ground-based and space telescopes and their instrumentation. This course has been designed for future engineers willing to understand and communicate with other people basic concepts of astronomy as well as to those wishing to pursue more specialized studies in astrophysics (cf. end-of-year thesis oriented towards astrophysics, master in space sciences, PhD in astrophysics, ...) or a future career in this field. In the first part of this course, we present the main discoveries in astrophysics already known by the antique greek astronomers, including an introduction to the different spherical coordinate systems and to photometry. [less ▲]

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See detailEnd-to-end simulations of the E-ELT/METIS coronagraphs
Carlomagno, Brunella ULiege; Absil, Olivier ULiege; Kenworthy, Matthew et al

in Marchetti, E.; Close, L.; Véran, J.-P. (Eds.) Adaptive Optics Systems V (2016, July 27)

The direct detection of low-mass planets in the habitable zone of nearby stars is an important science case for future E-ELT instruments such as the mid-infrared imager and spectrograph METIS, which ... [more ▼]

The direct detection of low-mass planets in the habitable zone of nearby stars is an important science case for future E-ELT instruments such as the mid-infrared imager and spectrograph METIS, which features vortex phase masks and apodizing phase plates (APP) in its baseline design. In this work, we present end-to-end performance simulations, using Fourier propagation, of several METIS coronagraphic modes, including focal-plane vortex phase masks and pupil-plane apodizing phase plates, for the centrally obscured, segmented E-ELT pupil. The atmosphere and the AO contributions are taken into account. Hybrid coronagraphs combining the advantages of vortex phase masks and APPs are considered to improve the METIS coronagraphic performance. [less ▲]

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See detailSmart co-phasing system for segmented mirror telescopes
Simar, Juan Felipe ULiege; Stockman, Yvan ULiege; Surdej, Jean ULiege

in SPIE 9906, Ground-based and Airborne Telescopes VI (2016, July 27)

Space observations of fainter and more distant astronomical objects constantly require telescope primary mirrors with a larger size. The diameter of monolithic primary mirrors is limited to 10 m because ... [more ▼]

Space observations of fainter and more distant astronomical objects constantly require telescope primary mirrors with a larger size. The diameter of monolithic primary mirrors is limited to 10 m because of manufacturing and logistics limitations. For space telescopes, monolithic primary mirrors are limited to less than 5 m due to fairing capacity. Segmented primary mirrors thus constitute an alternative solution to deal with the steadily increase of the primary mirror size. The optical path difference between the individual segments must be close to zero (few nm) in order to be diffraction limited over the full telescope aperture. In this paper a new system that may co-phase 7 segments at once with the light of a star and without artificial one is proposed. First the measuring methods and feedback system is explained, then the breadboard setup is presented and the results are analyzed and discussed, finally a comparison with Keck telescope is performed. This system can be adapted in order to be used in the co-phasing system of future segmented mirrors, its dynamic range starts from several hundred of microns till some tenths of nanometers [less ▲]

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See detailSmart co-phasing system for segmented mirror telescopes
Simar, Juan Felipe ULiege; Stockman, Yvan ULiege; Surdej, Jean ULiege

Poster (2016, June 30)

One of the main challenges in space observations is to observe always fainter and more compact objects. This can be achieved by increasing the telescope diameters. So, increasing the primary mirror ... [more ▼]

One of the main challenges in space observations is to observe always fainter and more compact objects. This can be achieved by increasing the telescope diameters. So, increasing the primary mirror diameters of the telescopes is the challenge solution but it is technically impossible to manufacture monolithic mirrors larger than 10m in diameter. The use of segmented mirrors thus becomes mandatory. This paper describes the results of a light co-phasing setup mounted in laboratory. This setup is able to correct a piston from 200μm to 15 nm based on coarse (200μm to 300nm) and fine (300nm to 15nm) measurement methods. Both measurements are then chained in a feedback system in order to completely co-phase and keep the segments aligned. [less ▲]

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See detailThree years of harvest with the vector vortex coronagraph in the thermal infrared
Absil, Olivier ULiege; Mawet, D.; Karlsson, M. et al

in Evans, C.; Simard, L.; Takami, H. (Eds.) Ground-based and Airborne Instrumentation for Astronomy VI (2016, June 26)

For several years, we have been developing vortex phase masks based on sub-wavelength gratings, known as Annular Groove Phase Masks. Etched onto diamond substrates, these AGPMs are currently designed to ... [more ▼]

For several years, we have been developing vortex phase masks based on sub-wavelength gratings, known as Annular Groove Phase Masks. Etched onto diamond substrates, these AGPMs are currently designed to be used in the thermal infrared (ranging from 3 to 13 μm). Our AGPMs were first installed on VLT/NACO and VLT/VISIR in 2012, followed by LBT/LMIRCam in 2013 and Keck/NIRC2 in 2015. In this paper, we review the development, commissioning, on-sky performance, and early scientific results of these new coronagraphic modes and report on the lessons learned. We conclude with perspectives for future developments and applications. [less ▲]

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