References of "Surdej, Jean"
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See detailHE 0435-1223 lensed QSO VRi light curves (Ricci+, 2011)
Ricci, Davide ULg; Poels, Joël ULg; Elyiv, Andrii ULg et al

Textual, factual or bibliographical database (2011)

We present VRi photometric observations of the quadruply imaged quasar HE0435-1223, carried out with the Danish 1.54m telescope at the La Silla Observatory. Our aim was to monitor and study the magnitudes ... [more ▼]

We present VRi photometric observations of the quadruply imaged quasar HE0435-1223, carried out with the Danish 1.54m telescope at the La Silla Observatory. Our aim was to monitor and study the magnitudes and colors of each lensed component as a function of time. [less ▲]

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See detailA sub-Saturn Mass Planet, MOA-2009-BLG-319Lb
Miyake, N.; Sumi, T.; Dong, Subo et al

in Astrophysical Journal (2011), 1010

We report the gravitational microlensing discovery of a sub-Saturn mass planet, MOA-2009-BLG-319Lb, orbiting a K or M-dwarf star in the inner Galactic disk or Galactic bulge. The high cadence observations ... [more ▼]

We report the gravitational microlensing discovery of a sub-Saturn mass planet, MOA-2009-BLG-319Lb, orbiting a K or M-dwarf star in the inner Galactic disk or Galactic bulge. The high cadence observations of the MOA-II survey discovered this microlensing event and enabled its identification as a high magnification event approximately 24 hours prior to peak magnification. As a result, the planetary signal at the peak of this light curve was observed by 20 different telescopes, which is the largest number of telescopes to contribute to a planetary discovery to date. The microlensing model for this event indicates a planet-star mass ratio of q = (3.95 +/- 0.02) x 10^{-4} and a separation of d = 0.97537 +/- 0.00007 in units of the Einstein radius. A Bayesian analysis based on the measured Einstein radius crossing time, t_E, and angular Einstein radius, \theta_E, along with a standard Galactic model indicates a host star mass of M_L = 0.38^{+0.34}_{-0.18} M_{Sun} and a planet mass of M_p = 50^{+44}_{-24} M_{Earth}, which is half the mass of Saturn. This analysis also yields a planet-star three-dimensional separation of a = 2.4^{+1.2}_{-0.6} AU and a distance to the planetary system of D_L = 6.1^{+1.1}_{-1.2} kpc. This separation is ~ 2 times the distance of the snow line, a separation similar to most of the other planets discovered by microlensing. [less ▲]

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See detailA much lower density for the transiting extrasolar planet WASP-7.
Southworth, J.; Dominik, M.; Jorgensen, U~G et al

Textual, factual or bibliographical database (2011)

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See detailA much lower density for the transiting extrasolar planet WASP-7 (Research Note)
Southworth, J.; Dominik, M.; Jorgensen, U~G et al

in Astronomy and Astrophysics (2011), 527

We present the first high-precision photometry of the transiting extrasolar planetary system WASP-7, obtained using telescope defocussing techniques and reaching a scatter of 0.68 mmag per point. We find ... [more ▼]

We present the first high-precision photometry of the transiting extrasolar planetary system WASP-7, obtained using telescope defocussing techniques and reaching a scatter of 0.68 mmag per point. We find that the transit depth is greater and that the host star is more evolved than previously thought. The planet has a significantly larger radius (1.330 +/- 0.093 Rjup versus 0.915 +0.046 -0.040 Rjup) and much lower density (0.41 +/- 0.10 rhojup versus 1.26 +0.25 -0.21 rhojup) and surface gravity (13.4 +/- 2.6 m/s2 versus 26.4 +4.4 -4.0 m/s2) than previous measurements showed. Based on the revised properties it is no longer an outlier in planetary mass--radius and period--gravity diagrams. We also obtain a more precise transit ephemeris for the WASP-7 system. [less ▲]

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See detailERRATUM: "Physical Properties of the 0.94 Day Period Transiting Planetary System WASP-18" (2009, ApJ, 707, 167)
Southworth, John; Hinse, T. C.; Dominik, M. et al

in Astrophysical Journal (2010), 723(2), 1829

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See detailHigh-precision photometry by telescope defocusing - III. The transiting planetary system WASP-2 star
Southworth, John; Mancini, L.; Novati, S Calchi et al

in Monthly Notices of the Royal Astronomical Society (2010), 408

ABSTRACT We present high-precision photometry of three transits of the extrasolar planetary system WASP-2, obtained by defocusing the telescopes, and achieving scatters of between 0.42 and 0.73 mmag ... [more ▼]

ABSTRACT We present high-precision photometry of three transits of the extrasolar planetary system WASP-2, obtained by defocusing the telescopes, and achieving scatters of between 0.42 and 0.73 mmag versus the best-fitting model. These data are modelled using the JKTEBOP code, and taking into account the light from the recently discovered faint star close to the system. The physical properties of the WASP-2 system are derived using tabulated predictions from five different sets of stellar evolutionary models, allowing both statistical and systematic error bars to be specified. We find the mass and radius of the planet to be M[SUB]b[/SUB] = 0.846 +/- 0.055 +/- 0.023M[SUB]Jup[/SUB] and R[SUB]b[/SUB] = 1.043 +/- 0.029 +/- 0.015R[SUB]Jup[/SUB]. It has a low equilibrium temperature of 1281 +/- 21K, in agreement with a recent finding that it does not have an atmospheric temperature inversion. The first of our transit data sets has a scatter of only 0.42mmag with respect to the best-fitting light-curve model, which to our knowledge is a record for ground-based observations of a transiting extrasolar planetary system. Based on data collected by MiNDSTEp with the Danish 1.54-m telescope at the ESO La Silla Observatory. E-mail: jkt@astro.keele.ac.uk ‡ Royal Society University Research Fellow. [less ▲]

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See detailOGLE-2009-BLG-092/MOA-2009-BLG-137: A Dramatic Repeating Event with the Second Perturbation Predicted by Real-time Analysis
Ryu, Y*-H; Han, C.; Hwang, K*-H et al

in Astrophysical Journal (2010), 723(1), 81-88

We report the result of the analysis of a dramatic repeating gravitational microlensing event OGLE-2009-BLG-092/MOA-2009-BLG-137, for which the light curve is characterized by two distinct peaks with ... [more ▼]

We report the result of the analysis of a dramatic repeating gravitational microlensing event OGLE-2009-BLG-092/MOA-2009-BLG-137, for which the light curve is characterized by two distinct peaks with perturbations near both peaks. We find that the event is produced by the passage of the source trajectory over the central perturbation regions associated with the individual components of a wide-separation binary. The event is special in the sense that the second perturbation, occurring ~100 days after the first, was predicted by the real-time analysis conducted after the first peak, demonstrating that real-time modeling can be routinely done for binary and planetary events. With the data obtained from follow-up observations covering the second peak, we are able to uniquely determine the physical parameters of the lens system. We find that the event occurred on a bulge clump giant and it was produced by a binary lens composed of a K- and M-type main-sequence stars. The estimated masses of the binary components are M [SUB]1[/SUB] = 0.69 ± 0.11 M [SUB]sun[/SUB] and M [SUB]2[/SUB] = 0.36 ± 0.06 M [SUB]sun[/SUB], respectively, and they are separated in projection by r [SUB]bottom[/SUB] = 10.9 ± 1.3 AU. The measured distance to the lens is D [SUB]L[/SUB] = 5.6 ± 0.7 kpc. We also detect the orbital motion of the lens system. [less ▲]

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See detailFirst manufactured diamond AGPM vector vortex for the L- and N-bands: metrology and expected performances
Delacroix, Christian ULg; Forsberg, Pontus; Karlsson, Mikael et al

Conference (2010, October 28)

The AGPM (Annular Groove Phase Mask, Mawet et al. 2005) is an optical vectorial vortex coronagraph (or vector vortex) synthesized by a circular subwavelength grating, that is a grating with a period ... [more ▼]

The AGPM (Annular Groove Phase Mask, Mawet et al. 2005) is an optical vectorial vortex coronagraph (or vector vortex) synthesized by a circular subwavelength grating, that is a grating with a period smaller than λ/n (λ being the observed wavelength and n the refractive index of the grating substrate). Since it is a phase mask, it allows to reach a high contrast with a small working angle. Moreover, its subwavelength structure provides a good achromatization over wide spectral bands. Recently, we have manufactured and measured our first N-band prototypes that allowed us to validate the reproducibility of the microfabrication process. Here, we present newly produced mid-IR diamond AGPMs in the N-band (~10 µm), and in the most wanted L-band (~3.5 µm). We first give an extrapolation of the expected coronagraph performances. We then present the manufacturing and measurement results, using diamond-optimized microfabrication techniques such as nano-imprint lithography (NIL) and reactive ion etching (RIE). Finally, the subwavelength grating profile metrology combines surface metrology (scanning electron microscopy, atomic force microscopy, white light interferometry) with diffractometry on an optical polarimetric bench and cross correlation with theoretical simulations using rigorous coupled wave analysis (RCWA). [less ▲]

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See detailExtra-solar planet imaging: ground vs space based coronagraphs
Hanot, Charles ULg; Absil, Olivier ULg; Boccaletti, A. et al

Conference (2010, October 28)

In the context of exoplanet detection, a large majority of the 400 detected exoplanets have been found by indirect methods. Today, progress in the field of high contrast and angular resolution imaging has ... [more ▼]

In the context of exoplanet detection, a large majority of the 400 detected exoplanets have been found by indirect methods. Today, progress in the field of high contrast and angular resolution imaging has allowed direct images of several exoplanetary systems to be taken (cf. HR 8799, Fomalhaut and β Pic). In the near future, several new instruments are going to dramatically improve our sensitivity to exoplanet detection. Among these, SPHERE (Spectro Polarimetric High contrast Exoplanet REsearch) at the VLT, MIRI (Mid Infra-Red Instrument) onboard JWST and EPICS at the ELT will be equipped with coronagraphs to reveal faint objects in the vicinity of nearby stars. We made use of the Lyon group (COND) evolutionary models of young (sub-)stellar objects and exoplanets to compare the sensitivities of these different instruments using their estimated coronagraphic profiles. From this comparison, we present a catalogue of targets which are particularly well suited for the different instruments. [less ▲]

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See detailFrequency of Solar-like Systems and of Ice and Gas Giants Beyond the Snow Line from High-magnification Microlensing Events in 2005-2008
Gould, A.; Dong, Subo; Gaudi, B. S. et al

in Astrophysical Journal (2010), 720

We present the first measurement of the planet frequency beyond the "snow line," for the planet-to-star mass-ratio interval –4.5 < log q < –2, corresponding to the range of ice giants to gas giants. We ... [more ▼]

We present the first measurement of the planet frequency beyond the "snow line," for the planet-to-star mass-ratio interval –4.5 < log q < –2, corresponding to the range of ice giants to gas giants. We find \endgraf\vbox{\begin{center}$\displaystyle{d^2 N{_{\rm pl}}\over d\log q\, d\log s} = (0.36\pm 0.15)\;{\rm dex}^{-2}$\end{center}}\noindentat the mean mass ratio q = 5 × 10 –4 with no discernible deviation from a flat (Öpik's law) distribution in log-projected separation s. The determination is based on a sample of six planets detected from intensive follow-up observations of high-magnification ( A>200) microlensing events during 2005-2008. The sampled host stars have a typical mass M host ~ 0.5 M sun [less ▲]

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See detailRound table discussion
Coude Du Foresto, V.; Hummel, C. A.; Perrin, G. et al

in Proceedings of the JENAM 2010 Symposium (2010, September 01)

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See detailFirst steps in the development of a piston sensor for large aperture space telescopes
Guerri, Géraldine ULg; Roose, Stéphane ULg; Stockman, Yvan ULg et al

in Oschmann, J.; Clampin, M.; MacEwen, H. (Eds.) Space Telescopes and Instrumentation 2010: Optical, Infrared, and Millimeter Wave (2010, July 01)

Nowadays spaceborne missions for astronomy or Earth imaging need high resolution observation which implies the development of large aperture telescopes. This can be achieved by multi-aperture telescopes ... [more ▼]

Nowadays spaceborne missions for astronomy or Earth imaging need high resolution observation which implies the development of large aperture telescopes. This can be achieved by multi-aperture telescopes or large segmented telescopes. One of the major issues is the phasing of the sub-apertures or the segments of such telescopes. A cophasing sensor is therefore mandatory to achieve the ultimate resolution of these telescopes. In this framework, Liège Space Center (CSL) concern is the development of a compact cophasing sensor to phase new large lightweight segmented mirrors for future space telescopes. The sensor concept has its origins in new phase retrieval algorithms which have been recently developed. In this paper, we outline the concept and the experimental validation results of our piston sensor breadboard which is currently under development in our laboratory. Finally, future prospects and further developments of our experiment are presented. [less ▲]

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See detailOGLE 2008-BLG-290: an accurate measurement of the limb darkening of a galactic bulge K Giant spatially resolved by microlensing
Fouqué, P.; Heyrovský, D.; Dong, S. et al

in Astronomy and Astrophysics (2010), 518

Context. Not only is gravitational microlensing a successful tool for discovering distant exoplanets, but it also enables characterization of the lens and source stars involved in the lensing event. <BR ... [more ▼]

Context. Not only is gravitational microlensing a successful tool for discovering distant exoplanets, but it also enables characterization of the lens and source stars involved in the lensing event. <BR /> Aims: In high-magnification events, the lens caustic may cross over the source disk, which allows determination of the angular size of the source and measurement of its limb darkening. <BR /> Methods: When such extended-source effects appear close to maximum magnification, the resulting light curve differs from the characteristic Paczyński point-source curve. The exact shape of the light curve close to the peak depends on the limb darkening of the source. Dense photometric coverage permits measurement of the respective limb-darkening coefficients. <BR /> Results: In the case of the microlensing event OGLE 2008-BLG-290, the K giant source star reached a peak magnification at about 100. Thirteen different telescopes have covered this event in eight different photometric bands. Subsequent light-curve analysis yielded measurements of linear limb-darkening coefficients of the source in six photometric bands. The best-measured coefficients lead to an estimate of the source effective temperature of about 4700[SUP]+100[/SUP][SUB]-200[/SUB] K. However, the photometric estimate from colour-magnitude diagrams favours a cooler temperature of 4200 ± 100 K. <BR /> Conclusions: Because the limb-darkening measurements, at least in the CTIO/SMARTS2 V_s- and I_s-bands, are among the most accurate obtained, the above disagreement needs to be understood. A solution is proposed, which may apply to previous events where such a discrepancy also appeared. [less ▲]

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See detailAnnular groove phase mask coronagraph in diamond for mid-IR wavelengths: manufacturing assessment and performance analysis
Delacroix, Christian ULg; Forsberg, P.; Karlsson, M. et al

in Oschmann, J.; Clampin, M.; MacEwen, H. (Eds.) Space Telescopes and Instrumentation 2010: Optical, Infrared, and Millimeter Wave (2010, July 01)

Phase-mask coronagraphs are known to provide high contrast imaging capabilities while preserving a small inner working angle, which allows searching for exoplanets or circumstellar disks with smaller ... [more ▼]

Phase-mask coronagraphs are known to provide high contrast imaging capabilities while preserving a small inner working angle, which allows searching for exoplanets or circumstellar disks with smaller telescopes or at longer wavelengths. The AGPM (Annular Groove Phase Mask, Mawet et al. 2005[SUP]1[/SUP]) is an optical vectorial vortex coronagraph (or vector vortex) induced by a rotationally symmetric subwavelength grating (i.e. with a period smaller than λ/n, λ being the observed wavelength and n the refractive index of the grating substrate). In this paper, we present our first midinfrared AGPM prototypes imprinted on a diamond substrate. We firstly give an extrapolation of the expected coronagraph performances in the N-band (~10 μm), and prospects for down-scaling the technology to the most wanted L-band (~3.5 μm). We then present the manufacturing and measurement results, using diamond-optimized microfabrication techniques such as nano-imprint lithography (NIL) and reactive ion etching (RIE). Finally, the subwavelength grating profile metrology combines surface metrology (scanning electron microscopy, atomic force microscopy, white light interferometry) with diffractometry on an optical polarimetric bench and cross correlation with theoretical simulations using rigorous coupled wave analysis (RCWA). [less ▲]

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