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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 detailThe search for disks or planetary objects around directly imaged companions: a candidate around DH Tauri B
Lazzoni, C.; Zurlo, A.; Desidera, S. et al

in Astronomy and Astrophysics (2020), 641

Context. In recent decades, thousands of substellar companions have been discovered with both indirect and direct methods of detection. While the majority of the sample is populated by objects discovered ... [more ▼]

Context. In recent decades, thousands of substellar companions have been discovered with both indirect and direct methods of detection. While the majority of the sample is populated by objects discovered using radial velocity and transit techniques, an increasing number have been directly imaged. These planets and brown dwarfs are extraordinary sources of information that help in rounding out our understanding of planetary systems. <BR /> Aims: In this paper, we focus our attention on substellar companions detected with the latter technique, with the primary goal of investigating their close surroundings and looking for additional companions and satellites, as well as disks and rings. Any such discovery would shed light on many unresolved questions, particularly with regard to their possible formation mechanisms. <BR /> Methods: To reveal bound features of directly imaged companions, whether for point-like or extended sources, we need to suppress the contribution from the source itself. Therefore, we developed a method based on the negative fake companion technique that first estimates the position in the field of view (FoV) and the flux of the imaged companion with high precision, then subtracts a rescaled model point spread function (PSF) from the imaged companion, using either an image of the central star or another PSF in the FoV. Next it performs techniques, such as angular differential imaging, to further remove quasi-static patterns of the star (i.e., speckle contaminants) that affect the residuals of close-in companions. <BR /> Results: After testing our tools on simulated companions and disks and on systems that were chosen ad hoc, we applied the method to the sample of substellar objects observed with SPHERE during the SHINE GTO survey. Among the 27 planets and brown dwarfs we analyzed, most objects did not show remarkable features, which was as expected, with the possible exception of a point source close to DH Tau B. This candidate companion was detected in four different SPHERE observations, with an estimated mass of ~1M[SUB]Jup[/SUB], and a mass ratio with respect to the brown dwarf of 1/10. This binary system, if confirmed, would be the first of its kind, opening up interesting questions for the formation mechanism, evolution, and frequency of such pairs. In order to address the latter, the residuals and contrasts reached for 25 companions in the sample of substellar objects observed with SPHERE were derived. If the DH Tau Bb companion is real, the binary fraction obtained is ~7%, which is in good agreement with the results obtained for field brown dwarfs. <BR /> Conclusions: While there may currently be many limitations affecting the exploration of bound features to directly imaged exoplanets and brown dwarfs, next-generation instruments from the ground and space (i.e., JWST, ELT, and LUVOIR) will be able to image fainter objects and, thus, drive the application of this technique in upcoming searches for exo-moons and circumplanetary disks. <P />Based on observations collected at Paranal Observatory, ESO (Chile) Program ID: 095.C-0298, 096.C-0241, 097.C-0865, 198.C-0209, and 0104.C-0327(A) and on observations collected at LBT Observatory. [less ▲]

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See detailOrbital and spectral characterization of the benchmark T-type brown dwarf HD 19467B
Maire, Anne-Lise ULiege; Molaverdikhani, K.; Desidera, S. et al

in Astronomy and Astrophysics (2020), 639

Context. Detecting and characterizing substellar companions for which the luminosity, mass, and age can be determined independently is of utter importance to test and calibrate the evolutionary models due ... [more ▼]

Context. Detecting and characterizing substellar companions for which the luminosity, mass, and age can be determined independently is of utter importance to test and calibrate the evolutionary models due to uncertainties in their formation mechanisms. HD 19467 is a bright and nearby star hosting a cool brown dwarf companion detected with radial velocities and imaging, making it a valuable object for such studies. <BR /> Aims: We aim to further characterize the orbital, spectral, and physical properties of the HD 19467 system. <BR /> Methods: We present new high-contrast imaging data with the SPHERE and NaCo instruments. We also analyze archival data from the instruments HARPS, NaCo, HIRES, UVES, and ASAS. Furthermore, we use proper motion data of the star from HIPPARCOS and Gaia. <BR /> Results: We refined the properties of the host star and derived an age of 8.0[SUP]+2.0[/SUP][SUB]-1.0[/SUB] Gyr based on isochrones, gyrochronology, and chemical and kinematic arguments. This age estimate is slightly younger than previous age estimates of ~9-11 Gyr based on isochrones. No orbital curvature is seen in the current imaging, radial velocity, and astrometric data. From a joint fit of the data, we refined the orbital parameters for HD 19467B, including: a period of 398[SUP]+95[/SUP][SUB]-93[/SUB] yr, an inclination of 129.8[SUP]+8.1[/SUP][SUB]-5.1[/SUB] deg, an eccentricity of 0.56 ± 0.09, a longitude of the ascending node of 134.8 ± 4.5 deg, and an argument of the periastron of 64.2[SUP]+5.5[/SUP][SUB]-6.3[/SUB] deg. We assess a dynamical mass of 74[SUP]+12[/SUP][SUB]-9[/SUB] M[SUB]J[/SUB]. The fit with atmospheric models of the spectrophotometric data of the companion indicates an atmosphere without clouds or with very thin clouds, an effective temperature of 1042[SUP]+77[/SUP][SUB]-71[/SUB] K, and a high surface gravity of 5.34[SUP]+0.8[/SUP][SUB]-0.9[/SUB] dex. The comparison to model predictions of the bolometric luminosity and dynamical mass of HD 19467B, assuming our system age estimate, indicates a better agreement with the Burrows et al. (1997, ApJ, 491, 856) models; whereas, the other evolutionary models used tend to underestimate its cooling rate. <P />The reduced images shown in Fig. 3 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/cat/J/A+A/639/A47">http://cdsarc.u-strasbg.fr/viz- bin/cat/J/A+A/639/A47</A> <P />Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programmes 1100.C-0481, 0100.C-0234, 096.C-0602, 072.C-0488, 183.C-0972, 084.D-0965, 188.C-0265, 192.C-0852, and 0100.D-0444. [less ▲]

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See detailSearching for the near-infrared counterpart of Proxima c using multi-epoch high-contrast SPHERE data at VLT★
Gratton, R.; Zurlo, A.; Le Coroller, H. et al

in Astronomy and Astrophysics (2020), 638

Context. Proxima Centauri is the closest star to the Sun and it is known to host an Earth-like planet in its habitable zone; very recently a second candidate planet was proposed based on radial velocities ... [more ▼]

Context. Proxima Centauri is the closest star to the Sun and it is known to host an Earth-like planet in its habitable zone; very recently a second candidate planet was proposed based on radial velocities. At quadrature, the expected projected separation of this new candidate is larger than 1 arcsec, making it a potentially interesting target for direct imaging. <BR /> Aims: While identification of the optical counterpart of this planet is expected to be very difficult, successful identification would allow for a detailed characterization of the closest planetary system. <BR /> Methods: We searched for a counterpart in SPHERE images acquired over four years through the SHINE survey. In order to account for the expected large orbital motion of the planet, we used a method that assumes the circular orbit obtained from radial velocities and exploits the sequence of observations acquired close to quadrature in the orbit. We checked this with a more general approach that considers Keplerian motion, called K-stacker. <BR /> Results: We did not obtain a clear detection. The best candidate has signal-to-noise ratio (S/N) = 6.1 in the combined image. A statistical test suggests that the probability that this detection is due to random fluctuation of noise is <1%, but this result depends on the assumption that the distribution of noise is uniform over the image, a fact that is likely not true. The position of this candidate and the orientation of its orbital plane fit well with observations in the ALMA 12 m array image. However, the astrometric signal expected from the orbit of the candidate we detected is 3σ away from the astrometric motion of Proxima as measured from early Gaia data. This, together with the unexpectedly high flux associated with our direct imaging detection, means we cannot confirm that our candidate is indeed Proxima c. <BR /> Conclusions: On the other hand, if confirmed, this would be the first observation in imaging of a planet discovered from radial velocities and the second planet (after Fomalhaut b) of reflecting circumplanetary material. Further confirmation observations should be done as soon as possible. <P />The reduced 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/cat/J/A+A/638/A120">http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/638/A120</A> <P />Based on data collected at the European Southern Observatory, Chile (ESO Programs 095.D-0309, 096.C-0241, 096.D-0252, 097.C-0865, 198.C-D0209, 099.D-0098, 099.C-0127. [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 detailA dusty benchmark brown dwarf near the ice line of HD 72946
Maire, Anne-Lise ULiege; Baudino, J.-L.; Desidera, S. et al

in Astronomy and Astrophysics (2020), 633

Context. HD 72946 is a bright and nearby solar-type star hosting a low- mass companion at long period (P ̃ 16 yr) detected with the radial velocity (RV) method. The companion has a minimum mass of 60.4 ± ... [more ▼]

Context. HD 72946 is a bright and nearby solar-type star hosting a low- mass companion at long period (P ̃ 16 yr) detected with the radial velocity (RV) method. The companion has a minimum mass of 60.4 ± 2.2 M[SUB]J[/SUB] and might be a brown dwarf. Its expected semi-major axis of ̃243 mas makes it a suitable target for further characterization with high-contrast imaging, in particular to measure its inclination, mass, and spectrum and thus definitely establish its substellar nature. <BR /> Aims: We aim to further characterize the orbit, atmosphere, and physical nature of HD 72946B. <BR /> Methods: We present high-contrast imaging data in the near-infrared with the Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) instrument. We also use proper motion measurements of the star from HIPPARCOS and Gaia. <BR /> Results: The SPHERE data reveal a point source with a contrast of ̃9 mag at a projected separation of ̃235 mas. No other point sources are detected in the field of view. By jointly fitting the RV, imaging, and proper motion data, we constrain all the orbital parameters of HD 72946B and assess a dynamical mass of 72.4 ± 1.6 M[SUB]J[/SUB] and a semi-major axis of 6.456.45[SUP]+0.08[/SUP][SUB]-0.07[/SUB] au. Empirical comparison of its SPHERE spectrum to template dwarfs indicates a spectral type of L5.0 ± 1.5. The J-H3 color is close to the expectations of the DUSTY models and suggests a cloudy atmosphere. Comparison with atmospheric models of the spectrophotometry suggests an effective temperature of ̃1700 K. The bolometric luminosity (log(L/L[SUB]☉[/SUB]) = -4.11 ± 0.10 dex) and dynamical mass of HD 72946B are more compatible with evolutionary models for an age range of ̃0.9-3 Gyr. The formation mechanism of the companion is currently unclear as the object appears slightly away from the bulk of model predictions. HD 72946B is currently the closest benchmark brown dwarf companion to a solar-type star with imaging, RV, and proper motion measurements. <P />Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programme 0102.C-0781. [less ▲]

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See detailPeering into the formation history of beta Pictoris b with VLTI/GRAVITY long baseline interferometry
Nowak, M.; Lacour, S.; Mollière, P. et al

in Astronomy and Astrophysics (2019), 633

Our objective is to estimate the C/O ratio in the atmosphere of beta Pictoris b and obtain an estimate of the dynamical mass of the planet, as well as to refine its orbital parameters using high-precision ... [more ▼]

Our objective is to estimate the C/O ratio in the atmosphere of beta Pictoris b and obtain an estimate of the dynamical mass of the planet, as well as to refine its orbital parameters using high-precision astrometry. We used the GRAVITY instrument with the four 8.2 m telescopes of the Very Large Telescope Interferometer to obtain K-band spectro-interferometric data on $\beta$ Pic b. We extracted a medium resolution (R=500) K-band spectrum of the planet and a high-precision astrometric position. We estimated the planetary C/O ratio using two different approaches (forward modeling and free retrieval) from two different codes (ExoREM and petitRADTRANS, respectively). Finally, we used a simplified model of two formation scenarios (gravitational collapse and core-accretion) to determine which can best explain the measured C/O ratio. Our new astrometry disfavors a circular orbit for $\beta$ Pic b ($e=0.15^{+0.05}_{-0.04}$). Combined with previous results and with Hipparcos/GAIA measurements, this astrometry points to a planet mass of $M = 12.7\pm{}2.2\,M_\mathrm{Jup}$. This value is compatible with the mass derived with the free-retrieval code petitRADTRANS using spectral data only. The forward modeling and free-retrieval approches yield very similar results regarding the atmosphere of beta Pic b. In particular, the C/O ratios derived with the two codes are identical ($0.43\pm{}0.05$ vs $0.43^{+0.04}_{-0.03}$). We argue that if the stellar C/O in $\beta$ Pic is Solar, then this combination of a very high mass and a low C/O ratio for the planet suggests a formation through core-accretion, with strong planetesimal enrichment. [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 detailVLT/SPHERE exploration of the young multiplanetary system PDS70
Mesa, D.; Keppler, M.; Cantalloube, F. et al

in Astronomy and Astrophysics (2019), 632

Context. PDS 70 is a young (5.4 Myr), nearby ( 113 pc) star hosting a known transition disk with a large gap. Recent observations with SPHERE and NACO in the near-infrared (NIR) allowed us to detect a ... [more ▼]

Context. PDS 70 is a young (5.4 Myr), nearby ( 113 pc) star hosting a known transition disk with a large gap. Recent observations with SPHERE and NACO in the near-infrared (NIR) allowed us to detect a planetary mass companion, PDS 70 b, within the disk cavity. Moreover, observations in H[SUB]α[/SUB] with MagAO and MUSE revealed emission associated to PDS 70 b and to another new companion candidate, PDS 70 c, at a larger separation from the star. PDS 70 is the only multiple planetary system at its formation stage detected so far through direct imaging. <BR /> Aims: Our aim is to confirm the discovery of the second planet PDS 70 c using SPHERE at VLT, to further characterize its physical properties, and search for additional point sources in this young planetary system. <BR /> Methods: We re-analyzed archival SPHERE NIR observations and obtained new data in Y, J, H and K spectral bands for a total of four different epochs. The data were reduced using the data reduction and handling pipeline and the SPHERE data center. We then applied custom routines (e.g., ANDROMEDA and PACO) to subtract the starlight. <BR /> Results: We re-detect both PDS 70 b and c and confirm that PDS 70 c is gravitationally bound to the star. We estimate this second planet to be less massive than 5 M[SUB]Jup[/SUB] and with a T[SUB]eff[/SUB] around 900 K. Also, it has a low gravity with logg between 3.0 and 3.5 dex. In addition, a third object has been identified at short separation ( 0.12'') from the star and gravitationally bound to the star. Its spectrum is however very blue, meaning that we are probably seeing stellar light reflected by dust and our analysis seems to demonstrate that it is a feature of the inner disk. We cannot however completely exclude the possibility that it is a planetary mass object enshrouded by a dust envelope. In this latter case, its mass should be of the order of a few tens of M[SUB]⊕[/SUB]. Moreover, we propose a possible structure for the planetary system based on our data, and find that this structure cannot be stable on a long timescale. <P />The reduced images are also 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/cat/J/A+A/632/A25">http://cdsarc.u-strasbg.fr/viz- bin/cat/J/A+A/632/A25</A> <P />Based on observation made with European Southern Observatory (ESO) telescopes at Paranal Observatory in Chile, under programs ID 095.C-0298(B), 1100.C-0481(D), 1100.C-0481(L) and 1100.C-0481(M). [less ▲]

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See detailDetermining mass limits around HD 163296 through SPHERE direct imaging data
Mesa, D.; Langlois, M.; Garufi, Antonio et al

in Monthly Notices of the Royal Astronomical Society (2019), 488

HD 163296 is a Herbig Ae/Be star known to host a protoplanetary disc with a ringed structure. To explain the disc features, previous works proposed the presence of planets embedded into the disc. We have ... [more ▼]

HD 163296 is a Herbig Ae/Be star known to host a protoplanetary disc with a ringed structure. To explain the disc features, previous works proposed the presence of planets embedded into the disc. We have observed HD 163296 with the near-infrared (NIR) branch of SPHERE composed by IRDIS (InfraRed Dual-band Imager and Spectrograph) and IFS (integral field spectrograph) with the aim to put tight constraints on the presence of substellar companions around this star. Despite the low rotation of the field of view during our observation we were able to put upper mass limits of few M[SUB]Jup[/SUB] around this object. These limits do not allow to give any definitive conclusion about the planets proposed through the disc characteristics. On the other hand, our results seem to exclude the presence of the only candidate proposed until now using direct imaging in the NIR even if some caution has to be taken considered the different wavelength bands of the two observations. [less ▲]

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See detailSPHERE view of the jet and the envelope of RY Tauri
Garufi, Antonio; Podio, L.; Bacciotti, F. et al

in Astronomy and Astrophysics (2019), 628

Context. Jets are rarely associated with pre-main sequence intermediate- mass stars. This contrasts with the frequent detection of jets in lower mass or younger stars. Optical and near-IR observations of ... [more ▼]

Context. Jets are rarely associated with pre-main sequence intermediate- mass stars. This contrasts with the frequent detection of jets in lower mass or younger stars. Optical and near-IR observations of jet-driving sources are often hindered by the presence of a natal envelope. <BR /> Aims: Jets around partly embedded sources are a useful diagnostic to constrain the geometry of the concealed protoplanetary disk. We intend to clarify how the jet-driving mechanisms are affected by both spatial anisotropies and episodic variations at the (sub-)au scale from the star. <BR /> Methods: We obtained a rich set of high-contrast VLT/SPHERE observations from 0.6 to 2.2 μm of the young intermediate-mass star RY Tau. Given the proximity to the Sun of this source, our images have the highest spatial resolution ever obtained for an atomic jet (down to 4 au). <BR /> Results: Optical observations in polarized light show no sign of the protoplanetary disk detected by ALMA. Instead, we observed a diffuse signal resembling a remnant envelope with an outflow cavity. The jet is detected in the Hα, [S II] at 1.03 μm, He I at 1.08 μm, and [Fe II] lines in the 1.25 μm and 1.64 μm. The jet appears to be wiggling and its radial width increasing with the distance is complementary to the shape of the outflow cavity suggesting a strong interaction with jet and envelope. Through the estimated tangential velocity ( 100 km s[SUP]-1[/SUP]), we revealed a possible connection between the launching time of the jet substructures and the stellar activity of RY Tau. <BR /> Conclusions: RY Tau is at an intermediate stage toward the dispersal of the natal envelope. This source shows episodic increases of mass accretion and ejection similarly to other known intermediate-mass stars. The amount of observed jet wiggle is consistent with the presence of a precessing disk warp or misaligned inner disk that would be induced by an unseen planetary or sub-stellar companion at sub- or few-au scales respectively. The high disk mass of RY Tau and of two other jet-driving intermediate-mass stars, HD 163296 and MWC480, suggests that massive, full disks are more efficient at launching prominent jets. <P />Based on observations performed with VLT/SPHERE under program ID 096.C-0241(C), 096.C-0241(F), 096.C-0248(A), 096.C-0454(A), and 1100.C-0481(A). [less ▲]

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See detailSeparating extended disc features from the protoplanet in PDS 70 using VLT/SINFONI
Christiaens, V.; Casassus, S.; Absil, Olivier ULiege et al

in Monthly Notices of the Royal Astronomical Society (2019), 486

Transition discs are prime targets to look for protoplanets and study planet-disc interactions. We present VLT/SINFONI observations of PDS 70, a transition disc with a recently claimed embedded ... [more ▼]

Transition discs are prime targets to look for protoplanets and study planet-disc interactions. We present VLT/SINFONI observations of PDS 70, a transition disc with a recently claimed embedded protoplanet. We take advantage of the angular and spectral diversity present in our data for an optimal PSF modelling and subtraction using principal component analysis (PCA). We report the redetection of PDS 70 b, both the front and far side of the outer disc edge, and the detection of several extended features in the annular gap. We compare spectral differential imaging applied before (PCA-SADI), and after (PCA-ASDI) angular differential imaging. Our tests suggest that PCA-SADI better recovers extended features, while PCA-ASDI is more sensitive to point sources. We adapted the negative fake companion (NEGFC) technique to infer the astrometry of the companion, and derived r = 193.5 ± 4.9 mas and PA =158.7[SUP]°[/SUP] ± 3.0[SUP]°[/SUP]. We used both NEGFC and ANDROMEDA to infer the K-band spectro-photometry of the protoplanet, and found results consistent with recent VLT/SPHERE observations, except for their 2018/02 epoch measurement in the K2 filter. Finally, we derived an upper limit of \dot{M_b} < 1.26 × 10^{-7} \big [ 5 M_Jup/M_b \big ] \big [ R_b/R_Jup\big ] M_Jup yr[SUP]-1[/SUP] for the accretion rate of the companion based on an adaptation of PCA-SADI/PCA-ASDI around the Brγ line (assuming no extinction). [less ▲]

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See detailEvidence for a circumplanetary disc around protoplanet PDS 70 b
Christiaens, V.; Cantalloube, F.; Casassus, S. et al

in Astrophysical Journal. Letters (2019), 877

We present the first observational evidence for a circumplanetary disc around the protoplanet PDS 70b, based on a new spectrum in the $K$ band acquired with VLT/SINFONI. We tested three hypotheses to ... [more ▼]

We present the first observational evidence for a circumplanetary disc around the protoplanet PDS 70b, based on a new spectrum in the $K$ band acquired with VLT/SINFONI. We tested three hypotheses to explain the spectrum: Atmospheric emission from the planet with either (1) a single value of extinction or (2) variable extinction, and (3) a combined atmospheric and circumplanetary disc model. Goodness-of-fit indicators favour the third option suggesting circumplanetary material contributing excess thermal emission --- most prominent at $2.3 \mu$m. Inferred accretion rates ($ 10^-7.8$--$10^-7.3 M_J$ yr$^-1$) are compatible with observational constraints based on the H$\alpha$ and Br$\gamma$ lines. For the planet, we derive an effective temperature of 1500--1600 K, surface gravity $\log(g) 4.0$, radius $ 1.6 R_J$, mass $ 10 M_J$ and possible thick clouds. Models with variable extinction lead to slightly worse fits. However, the amplitude ($\Delta A_V 3$mag) and timescale of variation ($\lesssim$ years) required for the extinction would also suggest circumplanetary material. [less ▲]

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See detailHint of curvature in the orbital motion of the exoplanet 51 Eridani b using 3 yr of VLT/SPHERE monitoring
Maire, Anne-Lise ULiege; Rodet, L.; Cantalloube, F. et al

in Astronomy and Astrophysics (2019), 624

Context. The 51 Eridani system harbors a complex architecture with its primary star forming a hierarchical system with the binary GJ 3305AB at a projected separation of 2000 au, a giant planet orbiting ... [more ▼]

Context. The 51 Eridani system harbors a complex architecture with its primary star forming a hierarchical system with the binary GJ 3305AB at a projected separation of 2000 au, a giant planet orbiting the primary star at 13 au, and a low-mass debris disk around the primary star with possible cold and warm components inferred from the spectral energy distribution. <BR /> Aims: We aim to better constrain the orbital parameters of the known giant planet. <BR /> Methods: We monitored the system over three years from 2015 to 2018 with the Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) instrument at the Very Large Telescope (VLT). <BR /> Results: We measure an orbital motion for the planet of 130 mas with a slightly decreasing separation ( 10 mas) and find a hint of curvature. This potential curvature is further supported at 3σ significance when including literature Gemini Planet Imager (GPI) astrometry corrected for calibration systematics. Fits of the SPHERE and GPI data using three complementary approaches provide broadly similar results. The data suggest an orbital period of 32[SUB]-9[/SUB][SUP]+17[/SUP] yr (i.e., 12[SUB]-2[/SUB][SUP]+4[/SUP] au in semi-major axis), an inclination of 133[SUB]-7[/SUB][SUP]+14[/SUP] deg, an eccentricity of 0.45[SUB]-0.15[/SUB][SUP]+0.10[/SUP], and an argument of periastron passage of 87[SUB]-30[/SUB][SUP]+34[/SUP] deg [mod 180°]. The time at periastron passage and the longitude of node exhibit bimodal distributions because we do not yet detect whether the planet is accelerating or decelerating along its orbit. Given the inclinations of the orbit and of the stellar rotation axis (134-144°), we infer alignment or misalignment within 18° for the star-planet spin- orbit. Further astrometric monitoring in the next 3-4 yr is required to confirm at a higher significance the curvature in the motion of the planet, determine if the planet is accelerating or decelerating on its orbit, and further constrain its orbital parameters and the star-planet spin-orbit. <P />The fitted orbits and the histogram distributions of the orbital parameters 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/A118">http://cdsarc.u-strasbg.fr/viz- bin/qcat?J/A+A/624/A118</A>Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programmes 095.C-0298, 096.C-0241, 198.C-0209, and 1100.C-0481. [less ▲]

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See detailSpectral and orbital characterisation of the directly imaged giant planet HIP 65426 b
Cheetham, A. C.; Samland, M.; Brems, S. S. et al

in Astronomy and Astrophysics (2019), 622

HIP 65426 b is a recently discovered exoplanet imaged during the course of the SPHERE-SHINE survey. Here we present new L' and M' observations of the planet from the NACO instrument at the VLT from the ... [more ▼]

HIP 65426 b is a recently discovered exoplanet imaged during the course of the SPHERE-SHINE survey. Here we present new L' and M' observations of the planet from the NACO instrument at the VLT from the NACO-ISPY survey, as well as a new Y -H spectrum and K-band photometry from SPHERE-SHINE. Using these data, we confirm the nature of the companion as a warm, dusty planet with a mid-L spectral type. From comparison of its SED with the BT-Settl atmospheric models, we derive a best-fit effective temperature of T[SUB]eff[/SUB] = 1618 ± 7 K, surface gravity log g = 3.78[SUB]-0.03[/SUB][SUP]+0.04[/SUP] and radius R = 1.17 ± 0.04R[SUB]J[/SUB] (statistical uncertainties only). Using the DUSTY and COND isochrones we estimate a mass of 8 ± 1M[SUB]J[/SUB]. Combining the astrometric measurements from our new datasets and from the literature, we show the first indications of orbital motion of the companion (2.6σ significance)and derive preliminary orbital constraints. We find a highly inclined orbit (i = 1.07[SUB]-10[/SUB][SUP]+13[/SUP] deg) with an orbital period of 800[SUB]-400[/SUB][SUP]+1200[/SUP] yr. We also report SPHERE sparse aperture masking observations that investigate the possibility that HIP 65426 b was scattered onto its current orbit by an additional companion at a smaller orbital separation. From this data we rule out the presence of brown dwarf companions with masses greater than 16 M[SUB]J[/SUB] at separations larger than 3 AU, significantly narrowing the parameter space for such a companion. <P />Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programmes 199.C-0065 (PI: Launhardt), 198.C-0209 (PI: Beuzit) and 1100.C-0481 (PI: Beuzit). [less ▲]

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See detailPost-conjunction detection of β Pictoris b with VLT/SPHERE
Lagrange, A.-M.; Boccaletti, A.; Langlois, M. et al

in Astronomy and Astrophysics (2019), 621

Context. With an orbital distance comparable to that of Saturn in the solar system, β Pictoris b is the closest (semi-major axis ≃9 au) exoplanet that has been imaged to orbit a star. Thus it offers ... [more ▼]

Context. With an orbital distance comparable to that of Saturn in the solar system, β Pictoris b is the closest (semi-major axis ≃9 au) exoplanet that has been imaged to orbit a star. Thus it offers unique opportunities for detailed studies of its orbital, physical, and atmospheric properties, and of disk-planet interactions. With the exception of the discovery observations in 2003 with NaCo at the Very Large Telescope (VLT), all following astrometric measurements relative to β Pictoris have been obtained in the southwestern part of the orbit, which severely limits the determination of the planet's orbital parameters. <BR /> Aims: We aimed at further constraining β Pictoris b orbital properties using more data, and, in particular, data taken in the northeastern part of the orbit. <BR /> Methods: We used SPHERE at the VLT to precisely monitor the orbital motion of beta β Pictoris b since first light of the instrument in 2014. <BR /> Results: We were able to monitor the planet until November 2016, when its angular separation became too small (125 mas, i.e., 1.6 au) and prevented further detection. We redetected β Pictoris b on the northeast side of the disk at a separation of 139 mas and a PA of 30° in September 2018. The planetary orbit is now well constrained. With a semi-major axis (sma) of a = 9.0 ± 0.5 au (1σ), it definitely excludes previously reported possible long orbital periods, and excludes β Pictoris b as the origin of photometric variations that took place in 1981. We also refine the eccentricity and inclination of the planet. From an instrumental point of view, these data demonstrate that it is possible to detect, if they exist, young massive Jupiters that orbit at less than 2 au from a star that is 20 pc away. <P />Based on observations collected at the European Southern Observatory under programmes 198.C-0209, 1100.C-0481. [less ▲]

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See detailThe GJ 504 system revisited. Combining interferometric, radial velocity, and high contrast imaging data
Bonnefoy, M.; Perraut, K.; Lagrange, A.-M. et al

in Astronomy and Astrophysics (2018), 618

Context. The G-type star GJ504A is known to host a 3-35 M[SUB]Jup[/SUB] companion whose temperature, mass, and projected separation all contribute to making it a test case for planet formation theories ... [more ▼]

Context. The G-type star GJ504A is known to host a 3-35 M[SUB]Jup[/SUB] companion whose temperature, mass, and projected separation all contribute to making it a test case for planet formation theories and atmospheric models of giant planets and light brown dwarfs. <BR /> Aims: We aim at revisiting the system age, architecture, and companion physical and chemical properties using new complementary interferometric, radial-velocity, and high-contrast imaging data. <BR /> Methods: We used the CHARA interferometer to measure GJ504A's angular diameter and obtained an estimation of its radius in combinationwith the HIPPARCOS parallax. The radius was compared to evolutionary tracks to infer a new independent age range for the system. We collected dual imaging data with IRDIS on VLT/SPHERE to sample the near-infrared (1.02-2.25 μm) spectral energy distribution (SED) of the companion. The SED was compared to five independent grids of atmospheric models (petitCODE,Exo-REM, BT-SETTL, Morley et al., and ATMO) to infer the atmospheric parameters of GJ 504b and evaluate model-to-model systematic errors. In addition, we used a specific model grid exploring the effect of different C/O ratios. Contrast limits from 2011 to 2017 were combined with radial velocity data of the host star through the MESS2 tool to define upper limits on the mass of additional companions in the system from 0.01 to 100 au. We used an MCMC fitting tool to constrain the companion'sorbital parameters based on the measured astrometry, and dedicated formation models to investigate its origin. <BR /> Results: We report a radius of 1.35 ± 0.04 R[SUB]☉[/SUB] for GJ504A. The radius yields isochronal ages of 21 ± 2 Myr or 4.0 ± 1.8 Gyr for the system and line-of-sight stellar rotation axis inclination of 162.4[SUB]-4.3[/SUB][SUP]+3.8[/SUP] degrees or 186.6[SUB]-3.8[/SUB][SUP]+4.3[/SUP] degrees. We re-detect the companion in the Y2, Y3, J3, H2, and K1 dual-band images. The complete 1-4 μm SED shape of GJ504b is best reproduced by T8-T9.5 objects with intermediate ages (≤ 1.5Gyr), and/or unusual dusty atmospheres and/or super-solar metallicities. All atmospheric models yield T[SUB]eff[/SUB] = 550 ± 50 K for GJ504b and point toward a low surface gravity (3.5-4.0 dex). The accuracy on the metallicity value is limited by model-to-model systematics; it is not degenerate with the C/O ratio. We derive log L/L[SUB]☉[/SUB] = -6.15 ± 0.15 dex for the companion from the empirical analysis and spectral synthesis. The luminosity and T[SUB]eff[/SUB] yield masses of M = 1.3[SUB]-0.3[/SUB][SUP]+0.6[/SUP] M[SUB]Jup[/SUB] and M = 23[SUB]-9[/SUB][SUP]+10[/SUP] M[SUB]Jup[/SUB] for the young and old age ranges, respectively. The semi-major axis (sma) is above 27.8 au and the eccentricity is lower than 0.55. The posterior on GJ 504b's orbital inclination suggests a misalignment with the rotation axis of GJ 504A. We exclude additional objects (90% prob.) more massive than 2.5 and 30 M[SUB]Jup[/SUB] with semi-major axes in the range 0.01-80 au for the young and old isochronal ages, respectively. <BR /> Conclusions: The mass and semi-major axis of GJ 504b are marginally compatible with a formation by disk-instability if the system is 4 Gyr old. The companion is in the envelope of the population of planets synthesized with our core-accretion model. Additional deep imaging and spectroscopic data with SPHERE and JWST should help to confirm the possible spin-orbit misalignment and refine the estimates on the companion temperature, luminosity, and atmospheric composition. <P />Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programs 093.C-0500, 095.C-0298, 096.C-0241, and 198.C-0209, and on interferometric observations obtained with the VEGA instrument on the CHARA Array. [less ▲]

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See detailDiscovery of a planetary-mass companion within the gap of the transition disk around PDS 70
Keppler, M.; Benisty, M.; Müller, A. et al

in Astronomy and Astrophysics (2018), 617

Context. Young circumstellar disks are the birthplaces of planets. Their study is of prime interest to understand the physical and chemical conditions under which planet formation takes place. Only very ... [more ▼]

Context. Young circumstellar disks are the birthplaces of planets. Their study is of prime interest to understand the physical and chemical conditions under which planet formation takes place. Only very few detections of planet candidates within these disks exist, and most of them are currently suspected to be disk features. <BR /> Aims: In this context, the transition disk around the young star PDS 70 is of particular interest, due to its large gap identified in previous observations, indicative of ongoing planet formation. We aim to search for the presence of an embedded young planet and search for disk structures that may be the result of disk-planet interactions and other evolutionary processes. <BR /> Methods: We analyse new and archival near-infrared images of the transition disk PDS 70 obtained with the VLT/SPHERE, VLT/NaCo, and Gemini/NICI instruments in polarimetric differential imaging and angular differential imaging modes. <BR /> Results: We detect a point source within the gap of the disk at about 195 mas ( 22 au) projected separation. The detection is confirmed at five different epochs, in three filter bands and using different instruments. The astrometry results in an object of bound nature, with high significance. The comparison of the measured magnitudes and colours to evolutionary tracks suggests that the detection is a companion of planetary mass. The luminosity of the detected object is consistent with that of an L-type dwarf, but its IR colours are redder, possibly indicating the presence of warm surrounding material. Further, we confirm the detection of a large gap of 54 au in size within the disk in our scattered light images, and detect a signal from an inner disk component. We find that its spatial extent is very likely smaller than 17 au in radius, and its position angle is consistent with that of the outer disk. The images of the outer disk show evidence of a complex azimuthal brightness distribution which is different at different wavelengths and may in part be explained by Rayleigh scattering from very small grains. <BR /> Conclusions: The detection of a young protoplanet within the gap of the transition disk around PDS 70 opens the door to a so far observationally unexplored parameter space of planetary formation and evolution. Future observations of this system at different wavelengths and continuing astrometry will allow us to test theoretical predictions regarding planet-disk interactions, planetary atmospheres, and evolutionary models. <P />Based on observations performed with ESO Telescopes at the Paranal Observatory under programmes 095.C-0298, 095.C-0404, 096.C-0333, 097.C-0206, 097.C-1001, and 099.C-0891.The reduced images and datacubes 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/617/A44">http://cdsarc.u-strasbg.fr/viz- bin/qcat?J/A+A/617/A44</A> [less ▲]

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See detailOrbital and atmospheric characterization of the planet within the gap of the PDS 70 transition disk
Müller, A.; Keppler, M.; Henning, Th et al

in Astronomy and Astrophysics (2018), 617

Context. The observation of planets in their formation stage is a crucial but very challenging step in understanding when, how, and where planets form. PDS 70 is a young pre-main sequence star surrounded ... [more ▼]

Context. The observation of planets in their formation stage is a crucial but very challenging step in understanding when, how, and where planets form. PDS 70 is a young pre-main sequence star surrounded by a transition disk, in the gap of which a planetary-mass companion has recently been discovered. This discovery represents the first robust direct detection of such a young planet, possibly still at the stage of formation. <BR /> Aims: We aim to characterize the orbital and atmospheric properties of PDS 70 b, which was first identified on May 2015 in the course of the SHINE survey with SPHERE, the extreme adaptive-optics instrument at the VLT. <BR /> Methods: We obtained new deep SPHERE/IRDIS imaging and SPHERE/IFS spectroscopic observations of PDS 70 b. The astrometric baseline now covers 6 yr, which allowed us to perform an orbital analysis. For the first time, we present spectrophotometry of the young planet which covers almost the entire near-infrared range (0.96-3.8 μm). We use different atmospheric models covering a large parameter space in temperature, log g, chemical composition, and cloud properties to characterize the properties of the atmosphere of PDS 70 b. <BR /> Results: PDS 70 b is most likely orbiting the star on a circular and disk coplanar orbit at 22 au inside the gap of the disk. We find a range of models that can describe the spectrophotometric data reasonably well in the temperature range 1000-1600 K and log g no larger than 3.5 dex. The planet radius covers a relatively large range between 1.4 and 3.7 R[SUB]J[/SUB] with the larger radii being higher than expected from planet evolution models for the age of the planet of 5.4 Myr. <BR /> Conclusions: This study provides a comprehensive data set on the orbital motion of PDS 70 b, indicating a circular orbit and a motion coplanar with the disk. The first detailed spectral energy distribution of PDS 70 b indicates a temperature typical of young giant planets. The detailed atmospheric analysis indicates that a circumplanetary disk may contribute to the total planetflux. <P />Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programmes 095.C-0298, 097.C-0206, 097.C-1001, 1100.C-0481. [less ▲]

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