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See detailSPHERE+: Imaging young Jupiters down to the snowline
Boccaletti, A.; Chauvin, G.; Mouillet, D. et al

E-print/Working paper (2020)

SPHERE (Beuzit et al,. 2019) has now been in operation at the VLT for more than 5 years, demonstrating a high level of performance. SPHERE has produced outstanding results using a variety of operating ... [more ▼]

SPHERE (Beuzit et al,. 2019) has now been in operation at the VLT for more than 5 years, demonstrating a high level of performance. SPHERE has produced outstanding results using a variety of operating modes, primarily in the field of direct imaging of exoplanetary systems, focusing on exoplanets as point sources and circumstellar disks as extended objects. The achievements obtained thus far with SPHERE (~200 refereed publications) in different areas (exoplanets, disks, solar system, stellar physics...) have motivated a large consortium to propose an even more ambitious set of science cases, and its corresponding technical implementation in the form of an upgrade. The SPHERE+ project capitalizes on the expertise and lessons learned from SPHERE to push high contrast imaging performance to its limits on the VLT 8m-telescope. The scientific program of SPHERE+ described in this document will open a new and compelling scientific window for the upcoming decade in strong synergy with ground-based facilities (VLT/I, ELT, ALMA, and SKA) and space missions (Gaia, JWST, PLATO and WFIRST). While SPHERE has sampled the outer parts of planetary systems beyond a few tens of AU, SPHERE+ will dig into the inner regions around stars to reveal and characterize by mean of spectroscopy the giant planet population down to the snow line. Building on SPHERE's scientific heritage and resounding success, SPHERE+ will be a dedicated survey instrument which will strengthen the leadership of ESO and the European community in the very competitive field of direct imaging of exoplanetary systems. With enhanced capabilities, it will enable an even broader diversity of science cases including the study of the solar system, the birth and death of stars and the exploration of the inner regions of active galactic nuclei. [less ▲]

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See detailExploring the R CrA environment with SPHERE. Discovery of a new stellar companion
Mesa, D.; Bonnefoy, M.; Gratton, R. et al

in Astronomy and Astrophysics (2019), 624

<BR /> Aims: R Coronae Australis (R CrA) is the brightest star of the Coronet nebula of the Corona Australis (CrA) star forming region. This star is very red in color, probably due to dust absorption, and ... [more ▼]

<BR /> Aims: R Coronae Australis (R CrA) is the brightest star of the Coronet nebula of the Corona Australis (CrA) star forming region. This star is very red in color, probably due to dust absorption, and is strongly variable. High-contrast instruments allow for an unprecedented direct exploration of the immediate circumstellar environment of this star. <BR /> Methods: We observed R CrA with the near-infrared (NIR) channels (IFS and IRDIS) of SPHERE at the Very Large Telescope (VLT). In this paper, we used four different epochs, three of which are from open time observations while one is from SPHERE guaranteed time. The data were reduced using the data reduction and handling pipeline and the SPHERE Data Center. We implemented custom IDL routines on the reduced data with the aim to subtract the speckle halo. We have also obtained pupil-tracking H-band (1.45-1.85 μm) observations with the VLT/SINFONI NIR medium-resolution (R ̃ 3000) spectrograph. <BR /> Results: A companion was found at a separation of 0.156″ from the star in the first epoch and increasing to 0.184″ in the final epoch. Furthermore, several extended structures were found around the star, the most noteworthy of which is a very bright jet-like structure northeast from the star. The astrometric measurements of the companion in the four epochs confirm that it is gravitationally bound to the star. The SPHERE photometry and SINFONI spectrum, once corrected for extinction, point toward a spectral type object that is early M with a mass between 0.3 and 0.55 M[SUB]☉[/SUB]. The astrometric analyis provides constraints on the orbit paramenters: e ̃ 0.4, semimajor axis at 27-28 au, inclination of ̃70°, and a period larger than 30 yr. We were also able to put constraints of few M[SUB]Jup[/SUB] on the mass of possible other companions down to separations of few tens of au. <P />Based on observations made with European Southern Observatory (ESO) telescopes at Paranal Observatory in Chile, under programs ID 095.C-0787(A), 097.C-0591(A), 1100.C-0481(H), 0101.C-0350(A) and 2101.C-5048(A).The SPHERE and SINFONI images are only available at the CDS via anonymous ftp to <A href="http://cdsarc.u-strasbg.fr/">http://cdsarc.u-strasbg.fr</A> (ftp://130.79.128.5) or via <A href="http://cdsarc.u-strasbg.fr/viz- bin/qcat?J/A+A/624/A4">http://cdsarc.u-strasbg.fr/viz- bin/qcat?J/A+A/624/A4</A> [less ▲]

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See detailThe Circumstellar Disk HD 169142: Gas, Dust, and Planets Acting in Concert?
Pohl, A.; Benisty, M.; Pinilla, P. et al

in Astrophysical Journal (2017), 850

HD 169142 is an excellent target for investigating signs of planet-disk interaction due to previous evidence of gap structures. We perform J-band (̃1.2 μm) polarized intensity imaging of HD 169142 with ... [more ▼]

HD 169142 is an excellent target for investigating signs of planet-disk interaction due to previous evidence of gap structures. We perform J-band (̃1.2 μm) polarized intensity imaging of HD 169142 with VLT/SPHERE. We observe polarized scattered light down to 0.″16 (̃19 au) and find an inner gap with a significantly reduced scattered-light flux. We confirm the previously detected double-ring structure peaking at 0.″18 (̃21 au) and 0.″56 (̃66 au) and marginally detect a faint third gap at 0.″70-0.″73 (̃82-85 au). We explore dust evolution models in a disk perturbed by two giant planets, as well as models with a parameterized dust size distribution. The dust evolution model is able to reproduce the ring locations and gap widths in polarized intensity but fails to reproduce their depths. However, it gives a good match with the ALMA dust continuum image at 1.3 mm. Models with a parameterized dust size distribution better reproduce the gap depth in scattered light, suggesting that dust filtration at the outer edges of the gaps is less effective. The pileup of millimeter grains in a dust trap and the continuous distribution of small grains throughout the gap likely require more efficient dust fragmentation and dust diffusion in the dust trap. Alternatively, turbulence or charging effects might lead to a reservoir of small grains at the surface layer that is not affected by the dust growth and fragmentation cycle dominating the dense disk midplane. The exploration of models shows that extracting planet properties such as mass from observed gap profiles is highly degenerate. <P />Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO program 095.C-0273. [less ▲]

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See detailA Herschel resolved far-infrared dust ring around HD 207129
Marshall, J. P.; Löhne, T.; Montesinos, B. et al

in Astronomy and Astrophysics (2011), 529

Context. Dusty debris discs around main sequence stars are thought to be the result of continuous collisional grinding of planetesimals in the system. The majority of these systems are unresolved and ... [more ▼]

Context. Dusty debris discs around main sequence stars are thought to be the result of continuous collisional grinding of planetesimals in the system. The majority of these systems are unresolved and analysis of the dust properties is limited by the lack of information regarding the dust location. <BR /> Aims: The Herschel DUNES key program is observing 133 nearby, Sun-like stars (<20 pc, FGK spectral type) in a volume limited survey to constrain the absolute incidence of cold dust around these stars by detection of far infrared excess emission at flux levels comparable to the Edgeworth-Kuiper belt (EKB). <BR /> Methods: We have observed the Sun-like star HD 207129 with Herschel PACS and SPIRE. In all three PACS bands we resolve a ring-like structure consistent with scattered light observations. Using α Boötis as a reference point spread function (PSF), we deconvolved the images, clearly resolving the inner gap in the disc at both 70 and 100 μm. <BR /> Results: We have resolved the dust-producing planetesimal belt of a debris disc at 100 μm for the first time. We measure the radial profile and fractional luminosity of the disc, and compare the values to those of discs around stars of similar age and/or spectral type, placing this disc in context of other resolved discs observed by Herschel/DUNES. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA. [less ▲]

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See detailResolving the cold debris disc around a planet-hosting star. PACS photometric imaging observations of q1 Eridani (HD 10647, HR 506)
Liseau, R.; Eiroa, C.; Fedele, D. et al

in Astronomy and Astrophysics (2010), 518

Context. About two dozen exo-solar debris systems have been spatially resolved. These debris discs commonly display a variety of structural features such as clumps, rings, belts, excentric distributions ... [more ▼]

Context. About two dozen exo-solar debris systems have been spatially resolved. These debris discs commonly display a variety of structural features such as clumps, rings, belts, excentric distributions and spiral patterns. In most cases, these features are believed to be formed, shaped and maintained by the dynamical influence of planets orbiting the host stars. In very few cases has the presence of the dynamically important planet(s) been inferred from direct observation. Aims. The solar-type star q1 Eri is known to be surrounded by debris, extended on scales of 30”. The star is also known to host at least one planet, albeit on an orbit far too small to make it responsible for structures at distances of tens to hundreds of AU. The aim of the present investigation is twofold: to determine the optical and material properties of the debris and to infer the spatial distribution of the dust, which may hint at the presence of additional planets. Methods. The Photodetector Array Camera and Spectrometer (PACS) aboard the Herschel Space Observatory allows imaging observations in the far infrared at unprecedented resolution, i.e. at better than 6” to 12” over the wavelength range of 60 μm to 210 μm. Together with the results from ground-based observations, these spatially resolved data can be modelled to determine the nature of the debris and its evolution more reliably than what would be possible from unresolved data alone. Results. For the first time has the q1 Eri disc been resolved at far infrared wavelengths. The PACS observations at 70 μm, 100 μm and 160 μm reveal an oval image showing a disc-like structure in all bands, the size of which increases with wavelength. Assuming a circular shape yields the inclination of its equatorial plane with respect to that of the sky, i > 53°. The results of image de-convolution indicate that i likely is larger than 63°, where 90° corresponds to an edge-on disc. Conclusions. The observed emission is thermal and optically thin. The resolved data are consistent with debris at temperatures below 30 K at radii larger than 120 AU. From image de-convolution, we find that q1 Eri is surrounded by an about 40 AU wide ring at the radial distance of ~85 AU. This is the first real Edgeworth-Kuiper Belt analogue ever observed. [less ▲]

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See detailCold DUst around NEarby Stars (DUNES). First results. A resolved exo-Kuiper belt around the solar-like star ζ2 Ret
Eiroa, C.; Fedele, D.; Maldonado, J. et al

in Astronomy and Astrophysics (2010), 518

We present the first far-IR observations of the solar-type stars δ Pav, HR 8501, 51 Peg and ζ2 Ret, taken within the context of the DUNES Herschel open time key programme (OTKP). This project uses the ... [more ▼]

We present the first far-IR observations of the solar-type stars δ Pav, HR 8501, 51 Peg and ζ2 Ret, taken within the context of the DUNES Herschel open time key programme (OTKP). This project uses the PACS and SPIRE instruments with the objective of studying infrared excesses due to exo-Kuiper belts around nearby solar-type stars. The observed 100 μm fluxes from δ Pav, HR 8501, and 51 Peg agree with the predicted photospheric fluxes, excluding debris disks brighter than Ldust/ ~ 5 × 10-7 (1σ level) around those stars. A flattened, disk-like structure with a semi-major axis of ~100 AU in size is detected around ζ2 Ret. The resolved structure suggests the presence of an eccentric dust ring, which we interpret as an exo-Kuiper belt with Ldust/ ≈ 10-5. [less ▲]

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