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See detailUnveiling the β Pictoris system, coupling high contrast imaging, interferometric, and radial velocity data
Lagrange, A. M.; Rubini, P.; Nowak, M. et al

in Astronomy and Astrophysics (2020), 642

Context. The nearby and young β Pictoris system hosts a well resolved disk, a directly imaged massive giant planet orbiting at ≃9 au, as well as an inner planet orbiting at ≃2.7 au, which was recently ... [more ▼]

Context. The nearby and young β Pictoris system hosts a well resolved disk, a directly imaged massive giant planet orbiting at ≃9 au, as well as an inner planet orbiting at ≃2.7 au, which was recently detected through radial velocity (RV). As such, it offers several unique opportunities for detailed studies of planetary system formation and early evolution. <BR /> Aims: We aim to further constrain the orbital and physical properties of β Pictoris b and c using a combination of high contrast imaging, long base-line interferometry, and RV data. We also predict the closest approaches or the transit times of both planets, and we constrain the presence of additional planets in the system. <BR /> Methods: We obtained six additional epochs of SPHERE data, six additional epochs of GRAVITY data, and five additional epochs of RV data. We combined these various types of data in a single Markov-chain Monte Carlo analysis to constrain the orbital parameters and masses of the two planets simultaneously. The analysis takes into account the gravitational influence of both planets on the star and hence their relative astrometry. Secondly, we used the RV and high contrast imaging data to derive the probabilities of presence of additional planets throughout the disk, and we tested the impact of absolute astrometry. <BR /> Results: The orbital properties of both planets are constrained with a semi-major axis of 9.8 ± 0.4 au and 2.7 ± 0.02 au for b and c, respectively, and eccentricities of 0.09 ± 0.1 and 0.27 ± 0.07, assuming the HIPPARCOS distance. We note that despite these low fitting error bars, the eccentricity of β Pictoris c might still be over-estimated. If no prior is provided on the mass of β Pictoris b, we obtain a very low value that is inconsistent with what is derived from brightness-mass models. When we set an evolutionary model motivated prior to the mass of β Pictoris b, we find a solution in the 10-11 M[SUB]Jup[/SUB] range. Conversely, β Pictoris c's mass is well constrained, at 7.8 ± 0.4 M[SUB]Jup[/SUB], assuming both planets are on coplanar orbits. These values depend on the assumptions on the distance of the β Pictoris system. The absolute astrometry HIPPARCOS-Gaia data are consistent with the solutions presented here at the 2σ level, but these solutions are fully driven by the relative astrometry plus RV data. Finally, we derive unprecedented limits on the presence of additional planets in the disk. We can now exclude the presence of planets that are more massive than about 2.5 M[SUB]Jup[/SUB] closer than 3 au, and more massive than 3.5 M[SUB]Jup[/SUB] between 3 and 7.5 au. Beyond 7.5 au, we exclude the presence of planets that are more massive than 1-2 M[SUB]Jup[/SUB]. <BR /> Conclusions: Combining relative astrometry and RVs allows one to precisely constrain the orbital parameters of both planets and to give lower limits to potential additional planets throughout the disk. The mass of β Pictoris c is also well constrained, while additional RV data with appropriate observing strategies are required to properly constrain the mass of β Pictoris b. [less ▲]

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See detailDirect confirmation of the radial-velocity planet β Pictoris c
Nowak, M.; Lacour, S.; Lagrange, A.-M. et al

in Astronomy and Astrophysics (2020), 642

Context. Methods used to detect giant exoplanets can be broadly divided into two categories: indirect and direct. Indirect methods are more sensitive to planets with a small orbital period, whereas direct ... [more ▼]

Context. Methods used to detect giant exoplanets can be broadly divided into two categories: indirect and direct. Indirect methods are more sensitive to planets with a small orbital period, whereas direct detection is more sensitive to planets orbiting at a large distance from their host star. This dichotomy makes it difficult to combine the two techniques on a single target at once. <BR /> Aims: Simultaneous measurements made by direct and indirect techniques offer the possibility of determining the mass and luminosity of planets and a method of testing formation models. Here, we aim to show how long-baseline interferometric observations guided by radial-velocity can be used in such a way. <BR /> Methods: We observed the recently-discovered giant planet β Pictoris c with GRAVITY, mounted on the Very Large Telescope Interferometer. <BR /> Results: This study constitutes the first direct confirmation of a planet discovered through radial velocity. We find that the planet has a temperature of T = 1250 ± 50 K and a dynamical mass of M = 8.2 ± 0.8 M[SUB]Jup[/SUB]. At 18.5 ± 2.5 Myr, this puts β Pic c close to a `hot start' track, which is usually associated with formation via disk instability. Conversely, the planet orbits at a distance of 2.7 au, which is too close for disk instability to occur. The low apparent magnitude (M[SUB]K[/SUB] = 14.3 ± 0.1) favours a core accretion scenario. <BR /> Conclusions: We suggest that this apparent contradiction is a sign of hot core accretion, for example, due to the mass of the planetary core or the existence of a high-temperature accretion shock during formation. [less ▲]

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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 detailSpatially Resolving the Quasar Broad Emission Line Region
Gravity Collaboration; Abuter, R.; Accardo, M. et al

in Messenger (2019), 178

The angular resolution of the Very Large Telescope Interferometer (VLTI) and the excellent sensitivity of GRAVITY have led to the first detection of spatially resolved kinematics of high velocity atomic ... [more ▼]

The angular resolution of the Very Large Telescope Interferometer (VLTI) and the excellent sensitivity of GRAVITY have led to the first detection of spatially resolved kinematics of high velocity atomic gas near an accreting super- massive black hole, revealing rotation on sub-parsec scales in the quasar 3C 273 at a distance of 550 Mpc. The observations can be explained as the result of circular orbits in a thick disc configuration around a 300 million solar mass black hole. Within an ongoing Large Programme, this capability will be used to study the kinematics of atomic gas and its relation to hot dust in a sample of quasars and Seyfert galaxies. We will measure a new radius-luminosity relation from spatially resolved data and test the current methods used to measure black hole mass in large surveys. [less ▲]

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See detailHigh-contrast imaging of HD 163296 with the Keck/NIRC2 L'-band vortex coronograph
Guidi, G.; Ruane, G.; Williams, J. P. et al

in Monthly Notices of the Royal Astronomical Society (2018), 479

We present observations of the nearby (D~100 pc) Herbig star HD 163296 taken with the vortex coronograph at Keck/NIRC2 in the L' band (3.7 μm) to search for planetary mass companions in the ringed disc ... [more ▼]

We present observations of the nearby (D~100 pc) Herbig star HD 163296 taken with the vortex coronograph at Keck/NIRC2 in the L' band (3.7 μm) to search for planetary mass companions in the ringed disc surrounding this pre-main-sequence star. The images reveal an arc-like region of scattered light from the disc surface layers that is likely associated with the first bright ring detected with ALMA in the λ = 1.3mm dust continuum at ~65 au. We also detect a point-like source at ~0.5 arcsec projected separation in the north-east direction, close to the inner edge of the second gap in the millimetre images. Comparing the point source photometry with the atmospheric emission models of non-accreting giant planets, we obtain a mass of 6-7 MJ for a putative protoplanet, assuming a system age of 5 Myr. Based on the contrast at a 95 per cent level of completeness calculated on the emission-free regions of our images, we set upper limits for the masses of giant planets of 8-15 MJ, 4.5-6.5 MJ, and 2.5-4.0MJ at the locations of the first, second, and third gap in the millimetre dust continuum, respectively. Further deep, high-resolution thermal IR imaging of the HD 163296 system are warranted to confirm the presence and nature of the point source and to better understand the structure of the dust disc. © 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. [less ▲]

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See detailDiscovery of a point-like source and a third spiral arm in the transition disk around the Herbig Ae star MWC 758
Reggiani, Maddalena ULiege; Christiaens, Valentin ULiege; Absil, Olivier ULiege et al

in Astronomy and Astrophysics (2018), 611

Transition disks offer the extraordinary opportunity to look for newly born planets and investigate the early stages of planet formation. In this context we observed the Herbig A5 star MWC 758 with the L ... [more ▼]

Transition disks offer the extraordinary opportunity to look for newly born planets and investigate the early stages of planet formation. In this context we observed the Herbig A5 star MWC 758 with the L band vector vortex coronagraph installed in the near-infrared camera and spectrograph NIRC2 at the Keck II telescope, with the aim of unveiling the nature of the spiral structure by constraining the presence of planetary companions in the system. Our high-contrast imaging observations show a bright (delta L=7.0+/-0.3 mag) point-like emission, south of MWC 758 at a deprojected separation of about 20 au (r=0.111+/- 0. 004 arcsec) from the central star. We also recover the two spiral arms (south-east and north-west), already imaged by previous studies in polarized light, and discover a third one to the south-west of the star. No additional companions were detected in the system down to 5 Jupiter masses beyond 0.6 arcsec from the star. We propose that the bright L band emission could be caused by the presence of an embedded and accreting protoplanet, although the possibility of it being an asymmetric disk feature cannot be excluded. The spiral structure is probably not related to the protoplanet candidate, unless on an inclined and eccentric orbit, and it could be due to one (or more) yet undetected planetary companions at the edge of or outside the spiral pattern. Future observations and additional simulations will be needed to shed light on the true nature of the point-like source and its link with the spiral arms. [less ▲]

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See detailDeep imaging search for planets forming in the TW Hya protoplanetary disk with the Keck/NIRC2 vortex coronagraph
Ruane, G.; Mawet, D.; Kastner, J. et al

in Astronomical Journal (2017), 154

Distinct gap features in the nearest protoplanetary disk, TW Hya (distance of 59.5$\pm$0.9 pc), may be signposts of ongoing planet formation. We performed long-exposure thermal infrared coronagraphic ... [more ▼]

Distinct gap features in the nearest protoplanetary disk, TW Hya (distance of 59.5$\pm$0.9 pc), may be signposts of ongoing planet formation. We performed long-exposure thermal infrared coronagraphic imaging observations to search for accreting planets especially within dust gaps previously detected in scattered light and submm-wave thermal emission. Three nights of observations with the Keck/NIRC2 vortex coronagraph in $L^\prime$ (3.4-4.1$\mu$m) did not reveal any statistically significant point sources. We thereby set strict upper limits on the masses of non-accreting planets. In the four most prominent disk gaps at 24, 41, 47, and 88 au, we obtain upper mass limits of 1.6-2.3, 1.1-1.6, 1.1-1.5, and 1.0-1.2 Jupiter masses ($M_J$) assuming an age range of 7-10 Myr for TW Hya. These limits correspond to the contrast at 95\% completeness (true positive fraction of 0.95) with a 1\% chance of a false positive within $1^{\prime\prime}$ of the star. We also approximate an upper limit on the product of planet mass and planetary accretion rate of $M_p\dot{M}\lesssim10^{-8} M_J^2/yr$ implying that any putative $\sim0.1 M_J$ planet, which could be responsible for opening the 24 au gap, is presently accreting at rates insufficient to build up a Jupiter mass within TW Hya's pre-main sequence lifetime. [less ▲]

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See detailFirst scattered-light images of the gas-rich debris disk around 49 Ceti
Choquet, É.; Milli, J.; Wahhaj, Z. et al

in Astrophysical Journal. Letters (2017), 834(2), 12

We present the first scattered-light images of the debris disk around 49 ceti, a ~40 Myr A1 main sequence star at 59 pc, famous for hosting two massive dust belts as well as large quantities of atomic and ... [more ▼]

We present the first scattered-light images of the debris disk around 49 ceti, a ~40 Myr A1 main sequence star at 59 pc, famous for hosting two massive dust belts as well as large quantities of atomic and molecular gas. The outer disk is revealed in reprocessed archival Hubble Space Telescope NICMOS F110W images, as well as new coronagraphic H band images from the Very Large Telescope SPHERE instrument. The disk extends from 1.1" (65 AU) to 4.6" (250 AU), and is seen at an inclination of 73degr, which refines previous measurements at lower angular resolution. We also report no companion detection larger than 3 M_Jup at projected separations beyond 20 AU from the star (0.34"). Comparison between the F110W and H-band images is consistent with a grey color of 49 ceti's dust, indicating grains larger than >2microns. Our photometric measurements indicate a scattering efficiency / infrared excess ratio of 0.2-0.4, relatively low compared to other characterized debris disks. We find that 49 ceti presents morphological and scattering properties very similar to the gas-rich HD 131835 system. From our constraint on the disk inclination we find that the atomic gas previously detected in absorption must extend to the inner disk, and that the latter must be depleted of CO gas. Building on previous studies, we propose a schematic view of the system describing the dust and gas structure around 49 ceti and hypothetic scenarios for the gas nature and origin. [less ▲]

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See detailDiscovery of a low-mass companion inside the debris ring surrounding the F5V star HD 206893
Milli, J.; Hibon, P.; Christiaens, Valentin ULiege et al

in Astronomy and Astrophysics (2017), 597

<BR /> Aims: Uncovering the ingredients and the architecture of planetary systems is a very active field of research that has fuelled many new theories on giant planet formation, migration, composition ... [more ▼]

<BR /> Aims: Uncovering the ingredients and the architecture of planetary systems is a very active field of research that has fuelled many new theories on giant planet formation, migration, composition, and interaction with the circumstellar environment. We aim at discovering and studying new such systems, to further expand our knowledge of how low-mass companions form and evolve. <BR /> Methods: We obtained high-contrast H-band images of the circumstellar environment of the F5V star HD 206893, known to host a debris disc never detected in scattered light. These observations are part of the SPHERE High Angular Resolution Debris Disc Survey (SHARDDS) using the InfraRed Dual-band Imager and Spectrograph (IRDIS) installed on VLT/SPHERE. <BR /> Results: We report the detection of a source with a contrast of 3.6 × 10[SUP]-5[/SUP] in the H-band, orbiting at a projected separation of 270 milliarcsec or 10 au, corresponding to a mass in the range 24 to 73 M[SUB]Jup[/SUB] for an age of the system in the range 0.2 to 2 Gyr. The detection was confirmed ten months later with VLT/NaCo, ruling out a background object with no proper motion. A faint extended emission compatible with the disc scattered light signal is also observed. <BR /> Conclusions: The detection of a low-mass companion inside a massive debris disc makes this system an analog of other young planetary systems such as β Pictoris, HR 8799 or HD 95086 and requires now further characterisation of both components to understand their interactions. [less ▲]

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See detailFIRST, a fibered aperture masking instrument. II. Spectroscopy of the Capella binary system at the diffraction limit
Huby, Elsa ULiege; Duchêne, G.; Marchis, F. et al

in Astronomy and Astrophysics (2013), 560

Aims: FIRST is a prototype instrument built to demonstrate the capabilities of the pupil remapping technique, using single-mode fibers and working at visible wavelengths. Our immediate objective is to ... [more ▼]

Aims: FIRST is a prototype instrument built to demonstrate the capabilities of the pupil remapping technique, using single-mode fibers and working at visible wavelengths. Our immediate objective is to demonstrate the high angular resolution capability of the instrument and to show that the spectral resolution of the instrument enables characterization of stellar companions. Methods: The FIRST-18 instrument is an improved version of FIRST-9 that simultaneously recombines two sets of nine fibers instead of one, thus greatly enhancing the (u, v) plane coverage. We report on observations of the binary system Capella at three epochs over a period of 14 months (≳4 orbital periods) with FIRST-18 mounted on the 3 m Shane telescope at Lick Observatory. The binary separation during our observations ranges from 0.8 to 1.2 times the diffraction limit of the telescope at the central wavelength of the spectral band. Results: We successfully resolved the Capella binary system at all epochs, with an astrometric precision as good as 1 mas under the best observing conditions. FIRST also gives access to the spectral flux ratio between the two components directly measured with an unprecedented spectral resolution of R ~ 300 over the 600-850 nm range. In particular, our data allow detection of the well-known overall slope of the flux ratio spectrum, leading to an estimation of the "pivot" wavelength of 0.64 ± 0.01 μm, at which the cooler component becomes the brightest. Spectral features arising from the difference in effective temperature of the two components (specifically the Hα line, TiO, and CN bands) have been used to constrain the stellar parameters. The effective temperatures we derive for both components are slightly lower (5-7%) than the well-established properties for this system. This difference mainly comes from deeper molecular features than those predicted by state-of-the-art stellar atmospheric models, suggesting that molecular line lists used in the photospheric models are incomplete and/or oscillator strengths are underestimated, most likely concerning the CN molecule. Conclusions: These results demonstrate the power of FIRST, which is a fibered pupil remapping-based instrument, in terms of high angular resolution and show that the direct measurement of the spectral flux ratio provides valuable information to characterize little known companions. [less ▲]

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See detailFIRST, a fibered aperture masking instrument. I. First on-sky test results
Huby, Elsa ULiege; Perrin, G.; Marchis, F. et al

in Astronomy and Astrophysics (2012), 541

Aims: In this paper we present the first on-sky results with the fibered aperture masking instrument FIRST. Its principle relies on the combination of spatial filtering and aperture masking using single ... [more ▼]

Aims: In this paper we present the first on-sky results with the fibered aperture masking instrument FIRST. Its principle relies on the combination of spatial filtering and aperture masking using single-mode fibers, a novel technique that is aimed at high dynamic range imaging with high angular resolution. Methods: The prototype has been tested with the Shane 3-m telescope at Lick Observatory. The entrance pupil is divided into sub-pupils feeding single-mode fibers. The flux injection into the fibers is optimized by a segmented mirror. The beams are spectrally dispersed and recombined in a non-redundant exit configuration in order to retrieve all contrasts and phases independently. Results: The instrument works at visible wavelengths between 600 nm and 760 nm and currently uses nine of the 30 43 cm sub-apertures constituting the full pupil. First fringes were obtained on Vega and Deneb. Stable closure phases were measured with standard deviations on the order of 1 degree. Closure phase precision can be further improved by addressing some of the remaining sources of systematic errors. While the number of fibers used in the experiment was too small to reliably estimate visibility amplitudes, we have measured closure amplitudes with a precision of 10% in the best case. Conclusions: These first promising results obtained under real observing conditions validate the concept of the fibered aperture masking instrument and open the way for a new type of ground-based instrument working in the visible. The next steps of the development will be to improve the stability and the sensitivity of the instrument in order to achieve more accurate closure phase and visibility measurements, and to increase the number of sub-pupils to reach full pupil coverage. [less ▲]

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See detailHigh Dynamic Range Imaging with the FIRST instrument
Perrin, G.; Lacour, S.; Huby, Elsa ULiege et al

Conference (2010, October 01)

A concept to achieve high dynamic range images from the ground is presented. The main idea is to calibrate turbulent fluctuations of wavefronts in a telescope pupil with a fibered fully redundant aperture ... [more ▼]

A concept to achieve high dynamic range images from the ground is presented. The main idea is to calibrate turbulent fluctuations of wavefronts in a telescope pupil with a fibered fully redundant aperture mask. This is the principle of the FIRST instrument whose first prototype version is to see stellar photons in July 2010 at Lick Observatory. Lab results and hopefully first sky results will be presented. [less ▲]

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