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Context. The inner regions of the discs of high-mass young stellar objects (HMYSOs) are still poorly known due to the small angular scales and the high visual extinction involved.Aims. We deploy near-infrared spectro-interferometry to probe the inner gaseous disc in HMYSOs and investigate the origin and physical characteristics of the CO bandhead emission (2.3-2.4 mu m).Methods. We present the first GRAVITY/VLTI observations at high spectral (R=4000) and spatial (mas) resolution of the CO overtone transitions in NGC 2024 IRS 2.Results. The continuum emission is resolved in all baselines and is slightly asymmetric, displaying small closure phases (<= 8 degrees). Our best ellipsoid model provides a disc inclination of 34 degrees +/- 1 degrees, a disc major axis position angle (PA) of 166 degrees +/- 1 degrees, and a disc diameter of 3.99 +/- 0.09 mas (or 1.69 +/- 0.04 au, at a distance of 423 pc). The small closure phase signals in the continuum are modelled with a skewed rim, originating from a pure inclination effect. For the first time, our observations spatially and spectrally resolve the first four CO bandheads. Changes in visibility, as well as differential and closure phases across the bandheads are detected. Both the size and geometry of the CO-emitting region are determined by fitting a bidimensional Gaussian to the continuum-compensated CO bandhead visibilities. The CO-emitting region has a diameter of 2.74 +/-(0.08)(0.07) +/- 0.07 0.08 mas (1.16 +/- 0.03 au), and is located in the inner gaseous disc, well within the dusty rim, with inclination and PA matching the dusty disc geometry, which indicates that both dusty and gaseous discs are coplanar. Physical and dynamical gas conditions are inferred by modelling the CO spectrum. Finally, we derive a direct measurement of the stellar mass of M-* similar to 14.7(-3.6)(+2)M(circle dot) M * similar to 14 . 7 - 3.6 + 2 M circle dot by combining our interferometric and spectral modelling results.

Context. Studies of the dust distribution, composition, and evolution of protoplanetary disks provide clues for understanding planet formation. However, little is known about the innermost regions of disks where telluric planets are expected to form.Aims. We aim constrain the geometry of the inner disk of the T Tauri star RY Lup by combining spectro-photometric data and interferometric observations in the near-infrared (NIR) collected at the Very Large Telescope Interferometer. We use PIONIER data from the ESO archive and GRAVITY data that were obtained in June 2017 with the four 8m telescopes.Methods. We use a parametric disk model and the 3D radiative transfer code MCFOST to reproduce the spectral energy distribution (SED) and match the interferometric observations. MCFOST produces synthetic SEDs and intensity maps at different wavelengths from which we compute the modeled interferometric visibilities and closure phases through Fourier transform.Results. To match the SED from the blue to the millimetric range, our model requires a stellar luminosity of 2.5 L-circle dot, higher than any previously determined values. Such a high value is needed to accommodate the circumstellar extinction caused by the highly inclined disk, which has been neglected in previous studies. While using an effective temperature of 4800 K determined through high-resolution spectroscopy, we derive a stellar radius of 2.29 R-circle dot. These revised fundamental parameters, when combined with the mass estimates available (in the range 1.3-1.5 M-circle dot), lead to an age of 0.5-2.0 Ma for RY Lup, in better agreement with the age of the Lupus association than previous determinations. Our disk model (that has a transition disk geometry) nicely reproduces the interferometric GRAVITY data and is in good agreement with the PIONIER ones. We derive an inner rim location at 0.12 au from the central star. This model corresponds to an inclination of the inner disk of 50 degrees, which is in mild tensi

Context. The inner regions of the discs of high-mass young stellar objects (HMYSOs) are still poorly known due to the small angular scales and the high visual extinction involved.Aims. We deploy near-infrared spectro-interferometry to probe the inner gaseous disc in HMYSOs and investigate the origin and physical characteristics of the CO bandhead emission (2.3-2.4 mu m).Methods. We present the first GRAVITY/VLTI observations at high spectral (R=4000) and spatial (mas) resolution of the CO overtone transitions in NGC 2024 IRS 2.Results. The continuum emission is resolved in all baselines and is slightly asymmetric, displaying small closure phases (<= 8 degrees). Our best ellipsoid model provides a disc inclination of 34 degrees +/- 1 degrees, a disc major axis position angle (PA) of 166 degrees +/- 1 degrees, and a disc diameter of 3.99 +/- 0.09 mas (or 1.69 +/- 0.04 au, at a distance of 423 pc). The small closure phase signals in the continuum are modelled with a skewed rim, originating from a pure inclination effect. For the first time, our observations spatially and spectrally resolve the first four CO bandheads. Changes in visibility, as well as differential and closure phases across the bandheads are detected. Both the size and geometry of the CO-emitting region are determined by fitting a bidimensional Gaussian to the continuum-compensated CO bandhead visibilities. The CO-emitting region has a diameter of 2.74 +/-(0.08)(0.07) +/- 0.07 0.08 mas (1.16 +/- 0.03 au), and is located in the inner gaseous disc, well within the dusty rim, with inclination and PA matching the dusty disc geometry, which indicates that both dusty and gaseous discs are coplanar. Physical and dynamical gas conditions are inferred by modelling the CO spectrum. Finally, we derive a direct measurement of the stellar mass of M-* similar to 14.7(-3.6)(+2)M(circle dot) M * similar to 14 . 7 - 3.6 + 2 M circle dot by combining our interferometric and spectral modelling results.

Context. Studies of the dust distribution, composition, and evolution of protoplanetary disks provide clues for understanding planet formation. However, little is known about the innermost regions of disks where telluric planets are expected to form.Aims. We aim constrain the geometry of the inner disk of the T Tauri star RY Lup by combining spectro-photometric data and interferometric observations in the near-infrared (NIR) collected at the Very Large Telescope Interferometer. We use PIONIER data from the ESO archive and GRAVITY data that were obtained in June 2017 with the four 8m telescopes.Methods. We use a parametric disk model and the 3D radiative transfer code MCFOST to reproduce the spectral energy distribution (SED) and match the interferometric observations. MCFOST produces synthetic SEDs and intensity maps at different wavelengths from which we compute the modeled interferometric visibilities and closure phases through Fourier transform.Results. To match the SED from the blue to the millimetric range, our model requires a stellar luminosity of 2.5 L-circle dot, higher than any previously determined values. Such a high value is needed to accommodate the circumstellar extinction caused by the highly inclined disk, which has been neglected in previous studies. While using an effective temperature of 4800 K determined through high-resolution spectroscopy, we derive a stellar radius of 2.29 R-circle dot. These revised fundamental parameters, when combined with the mass estimates available (in the range 1.3-1.5 M-circle dot), lead to an age of 0.5-2.0 Ma for RY Lup, in better agreement with the age of the Lupus association than previous determinations. Our disk model (that has a transition disk geometry) nicely reproduces the interferometric GRAVITY data and is in good agreement with the PIONIER ones. We derive an inner rim location at 0.12 au from the central star. This model corresponds to an inclination of the inner disk of 50 degrees, which is in mild tensi

Aims. To investigate the inner regions of protoplanetary discs, we performed near-infrared interferometric observations of the classical T Tauri binary system S CrA. Methods. We present the first VLTI-GRAVITY high spectral resolution (R similar to 4000) observations of a classical T Tauri binary, S CrA (composed of S CrAN and S CrA S and separated by similar to 1.4), combining the four 8m telescopes in dual-field mode. Results. Our observations in the near-infrared K-band continuum reveal a disc around each binary component, with similar halfflux radii of about 0.1 au at d similar to 130 pc, inclinations (i = 28 +/- 3 degrees and i = 22 +/- 6 degrees), and position angles (PA = 0 degrees +/- 6 degrees and PA = -2 degrees +/- 12 degrees), suggesting that they formed from the fragmentation of a common disc. The S CrAN spectrum shows bright He i and Br gamma line emission exhibiting inverse PCygni profiles, typically associated with infalling gas. The continuum-compensated Br gamma line visibilities of S CrAN show the presence of a compact Br gamma emitting region whose radius is about similar to 0.06 au, which is twice as big as the truncation radius. This component is mostly tracing a wind. Moreover, a slight radius change between the blue-and red-shifted Br gamma line components is marginally detected. Conclusions. The presence of an inverse PCygni profile in the He i and Br gamma lines, along with the tentative detection of a slightly larger size of the blue-shifted Br gamma line component, hint at the simultaneous presence of a wind and magnetospheric accretion in S CrA N.

Aims. To investigate the inner regions of protoplanetary discs, we performed near-infrared interferometric observations of the classical T Tauri binary system S CrA. Methods. We present the first VLTI-GRAVITY high spectral resolution (R similar to 4000) observations of a classical T Tauri binary, S CrA (composed of S CrAN and S CrA S and separated by similar to 1.4), combining the four 8m telescopes in dual-field mode. Results. Our observations in the near-infrared K-band continuum reveal a disc around each binary component, with similar halfflux radii of about 0.1 au at d similar to 130 pc, inclinations (i = 28 +/- 3 degrees and i = 22 +/- 6 degrees), and position angles (PA = 0 degrees +/- 6 degrees and PA = -2 degrees +/- 12 degrees), suggesting that they formed from the fragmentation of a common disc. The S CrAN spectrum shows bright He i and Br gamma line emission exhibiting inverse PCygni profiles, typically associated with infalling gas. The continuum-compensated Br gamma line visibilities of S CrAN show the presence of a compact Br gamma emitting region whose radius is about similar to 0.06 au, which is twice as big as the truncation radius. This component is mostly tracing a wind. Moreover, a slight radius change between the blue-and red-shifted Br gamma line components is marginally detected. Conclusions. The presence of an inverse PCygni profile in the He i and Br gamma lines, along with the tentative detection of a slightly larger size of the blue-shifted Br gamma line component, hint at the simultaneous presence of a wind and magnetospheric accretion in S CrA N.

Spatially resolving the inner dust cavity (or gap) of the so-called (pre-) transitional disks is a key to understanding the connection between the processes of planetary formation and disk dispersal. The disk around the Herbig star HD139614 is of particular interest since it presents a pretransitional nature with an au-sized gap structure that is spatially resolved by mid-infrared interferometry in the dust distribution. With the aid of new near-infrared interferometric observations, we aim to characterize the 0.1-10 au region of the HD 139614 disk further and then identify viable mechanisms for the inner disk clearing. We report the first multiwavelength modeling of the interferometric data acquired on HD 139614 with the VLTI instruments PIONIER, AMBER, and MIDI, complemented by Herschel/PACS photometric measurements. We first performed a geometrical modeling of the new near-infrared interferometric data, followed by radiative transfer modeling of the complete dataset using the code RADMC3D. We confirm the presence of a gap structure in the warm mu m-sized dust distribution, extending from about 2.5 au to 6 au, and constrained the properties of the inner dust component: e.g., a radially increasing dust surface density profile, and a depletion in dust of similar to 10(3) relative to the outer disk. Since self-shadowing and photoevaporation appears unlikely to be responsible for the au-sized gap of HD 139614, we thus tested if dynamical clearing could be a viable mechanism using hydrodynamical simulations to predict the structure of the gaseous disk. Indeed, a narrow au-sized gap is consistent with the expected effect of the interaction between a single giant planet and the disk. Assuming that small dust grains are well coupled to the gas, we found that an approximately 3 M-jup planet located at similar to 4.5 au from the star could, in less than 1 Myr, reproduce most of the aspects of the dust surface density profile, while no significant depletion (in gas) occurred

Spatially resolving the inner dust cavity (or gap) of the so-called (pre-) transitional disks is a key to understanding the connection between the processes of planetary formation and disk dispersal. The disk around the Herbig star HD139614 is of particular interest since it presents a pretransitional nature with an au-sized gap structure that is spatially resolved by mid-infrared interferometry in the dust distribution. With the aid of new near-infrared interferometric observations, we aim to characterize the 0.1-10 au region of the HD 139614 disk further and then identify viable mechanisms for the inner disk clearing. We report the first multiwavelength modeling of the interferometric data acquired on HD 139614 with the VLTI instruments PIONIER, AMBER, and MIDI, complemented by Herschel/PACS photometric measurements. We first performed a geometrical modeling of the new near-infrared interferometric data, followed by radiative transfer modeling of the complete dataset using the code RADMC3D. We confirm the presence of a gap structure in the warm mu m-sized dust distribution, extending from about 2.5 au to 6 au, and constrained the properties of the inner dust component: e.g., a radially increasing dust surface density profile, and a depletion in dust of similar to 10(3) relative to the outer disk. Since self-shadowing and photoevaporation appears unlikely to be responsible for the au-sized gap of HD 139614, we thus tested if dynamical clearing could be a viable mechanism using hydrodynamical simulations to predict the structure of the gaseous disk. Indeed, a narrow au-sized gap is consistent with the expected effect of the interaction between a single giant planet and the disk. Assuming that small dust grains are well coupled to the gas, we found that an approximately 3 M-jup planet located at similar to 4.5 au from the star could, in less than 1 Myr, reproduce most of the aspects of the dust surface density profile, while no significant depletion (in gas) occurred