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A young exoplanet at last The number of known extrasolar planets is well into three figures, but until now, none has been what you might call 'young'. Now a massive young planet, six times the mass of Jupiter, has been detected in the dust disk around the nearby star TW Hydrae (TW Hya). At just 8–10 million years old, TW Hya had already been identified as a likely location for developing planets, and the building blocks for a planetary system are present in its circumstellar disk. The new observation is significant as it puts a direct constraint on the timescale of extrasolar planet formation. There is a general consensus that planets form within disks of dust and gas around newly born stars. However, the timescale of planet formation remains unclear. The detection of a planet of mass 9.8 ± 3.3 M Jupiter around TW Hydrae, a nearby young star with an age of only 8–10 Myr, orbiting with a period of 3.56 days is reported. This demonstrates that planets can form within 10Myr, before the disk has been dissipated by stellar winds and radiation. There is a general consensus that planets form within disks of dust and gas around newly born stars 1 , 2 . Details of their formation process, however, are still a matter of ongoing debate. The timescale of planet formation remains unclear, so the detection of planets around young stars with protoplanetary disks is potentially of great interest. Hitherto, no such planet has been found. Here we report the detection of a planet of mass (9.8±3.3) M Jupiter around TW Hydrae (TW Hya), a nearby young star with an age of only 8–10 Myr that is surrounded by a well-studied circumstellar disk. It orbits the star with a period of 3.56 days at 0.04  au , inside the inner rim of the disk. This demonstrates that planets can form within 10 Myr, before the disk has been dissipated by stellar winds and radiation.

Observations of the circumstellar disk in the Bok globule CB 26 at 110, 230, and 270 GHz are presented together with the results of the simulations and estimates of the disk parameters. These observations were obtained using the SMA, IRAM Plateau de Bure, and OVRO interferometers. The maps have relatively high angular resolutions (0.4″-1″), making it possible to study the spatial structure of the gas-dust disk. The disk parameters are reconstructed via a quantitative comparison of observational and theoretical intensity maps. The disk model used to construct the theoretical maps is based on the assumption of hydrostatic and radiative equilibrium in the vertical direction, while the radial surface-density profile is described phenomenologically. The system of equations for the transfer of the infrared and ultraviolet radiation is solved in the vertical direction, in order to compute the thermal structure of the disk. The disk best-fit parameters are derived for the each map and all the maps simultaneously, using a conjugate gradient method. The degrees of degeneracy of the parameters describing the thermal structure and density distribution of the disk are analyzed in detail. All three maps indicate the presence of an inner dust-free region with a diameter of approximately 35 AU, in agreement with the conclusions of other studies. The inclination of the disk is 78°, which is smaller than the value adopted in our earlier study of rotating molecular outflows from CB 26. The model does not provide any evidence for the growth of dust particles above a max ≈ 0.02 cm.

The PRIMA (Phase-Referenced Imaging and Micro-arcsecond Astrometry) facility at ESO VLTI (Paranal observatory) is expected to be commissioned in mid 2008. The ESPRI (Exoplanet Search with PRIMA) consortium is currently preparing an astrometric survey to search for extrasolar planets. To achieve the scientific goal of this survey, a careful selection of target and reference stars is necessary. Apart from catalog search and modelling, extensive and dedicated preparatory observations are indispensable. Here we present two aspects of the preparatory observation programs: A high dynamic range near infrared (NIR) imaging survey to search for astrometric reference stars around the preselected target stars and characterization of the target stars by using high-resolution spectroscopy.

The Exoplanet Search with PRIma (ESPRI) will use the PRIMA dual-feed astrometric capability on the Very Large Telescope Interferometer (VLTI) to perform astrometric detections of extra-solar planets. We present an overview of our data-reduction strategy for achieving 10-μarcsecond accuracy narrow-angle astrometry using the PRIMA instrument. We discuss the error budget for astrometric measurements, and those aspects of our strategy which are designed to minimise the astrometric measurement errors.

We describe the ongoing hardware and software developments that shall enable the ESO VLTI to perform narrow-angle differential delay astrometry in K-band with an accuracy of up to 10 μarcsec. The ultimate goal of these efforts is to perform an astrometric search for extrasolar planets around nearby stars.

The Astrometric Data-Reduction Software (ADRS) processes fringe, delay, environmental, and calibration data for PRIMA narrow-angle astrometry. It is automated software designed to provide fully-calibrated differential delays and separation angles. The ADRS is divided into on-line and off-line processing. The former deals with calibration and data compression, while the latter applies corrections and calculates science quantities. PRIMA is the first VLTI instrument that may require removal of long-term environmental trends. The trend identification and fitting routines are not part of the distributed on-line and off-line processing software. Instead, files containing fit parameters will be updated regularly. Coding is presently underway. The PRIMA error budget summarizes the principal sources of error in PRIMA astrometric observations.

Issue Title: Magnetic Fields and Star Foramtion: Theory Versus Observations (Guest Editor: A.I. Gómez de Castro, M. Heyer, E. Vázquez-Semadeni, R. Rrebolo, M. Tagger and R.E. Pudritz) We study the influence and structure of the magnetic field in the early phases of low-mass star formation using polarization maps of Bok globules at a wavelength of 850 μm, obtained with the Submillimeter Common-User Bolometer Array (SCUBA) at the James Clerk Maxwell Telescope (JCMT). We discuss observations of the following sources: CB 26--a small globule with a nearly dispersed dense core and a young and large circumstellar disk, CB 54--a large globule with a massive dense core and a deeply embedded young stellar cluster, and B 335, CB 230, and CB 244--three nearby, relatively isolated small globules with low-mass protostellar cores. We find strongly aligned polarization vectors in the case of CB 26, B 335, and CB 230, whereas the vector orientations in the case of CB 54 and CB 244 are more or less randomly distributed. The degree of polarization, amounting to several percent, was found to decrease toward the center in each source. Assuming dichroic emission by aligned non-spherical grains as the polarization mechanism, where the magnetic field plays a role in the alignment process, we derive magnetic field strengths and structures from the observed polarization patterns. We compare the magnetic field topology with the morphology and outflow directions of the globules. In the Class 0 sources B 335, CB 230, and CB 244, the magnetic field is oriented almost perpendicular to the ouflow direction. In contrast, the inclination between outflow axis and magnetic field direction is much more moderate (36°) in the more evolved Class I source CB26.[PUBLICATION ABSTRACT]

Aiming to detect planetary companions to young stars with debris disks via the radial velocity method, we observed HD114082 during April 2018 - August 2022 as one of the targets of our RVSPY program (Radial Velocity Survey for Planets around Young stars). We used the FEROS spectrograph, mounted to the MPG/ESO 2.2 m telescope in Chile, to obtain high signal-to-noise spectra and time series of precise radial velocities (RVs). Additionally, we analyzed archival HARPS spectra and TESS photometric data. We used the CERES, CERES++ and SERVAL pipelines to derive RVs and activity indicators and ExoStriker for the independent and combined analysis of the RVs and TESS photometry. We report the discovery of a warm super-Jovian companion around HD114082 based on a 109.8\\(\\pm\\)0.4 day signal in the combined RV data from FEROS and HARPS, and on one transit event in the TESS photometry. The best-fit model indicates a 8.0\\(\\pm\\)1.0 Mjup companion with a radius of 1.00\\(\\pm\\)0.03 Rjup in an orbit with a semi-major axis of 0.51\\(\\pm\\)0.01 au and an eccentricity of 0.4\\(\\pm\\)0.04. The companions orbit is in agreement with the known near edge-on debris disk located at about 28 au. HD114082b is possibly the youngest (15\\(\\pm\\)6 Myr), and one of only three younger than 100 Myr giant planetary companions for which both their mass and radius have been determined observationally. It is probably the first properly model-constraining giant planet that allows distinguishing between hot and cold-start models. It is significantly more compatible with the cold-start model.

The disk-outflow connection plays a key role in extracting excess angular momentum from a forming protostar. We have previously reported the discovery of a small molecular outflow from the edge-on T Tauri star in the Bok globule CB26 that shows a peculiar velocity pattern, reminiscent of an outflow that corotates with the disk. We report new, high-resolution mm-interferometric observations of CB26 with the aim of revealing the morphology and kinematics of the outflow at the disk-outflow interface. The IRAM PdBI was used to observe CO(2-1) at 1.3mm with a resolution of 0.5\". Using a physical model of the disk, which was derived from the dust emission, we employed chemo-dynamical modeling combined with line radiative transfer to constrain kinematic parameters and to construct a model of the CO emission from the disk that allowed us to separate the emission of the disk from that of the outflow. Our observations confirm the disk-wind nature of the rotating molecular outflow from CB26. The new high-resolution data reveal an X-shaped morphology of the CO emission close to the disk, and vertical streaks extending from the disk surface with a small half-opening angle of ~7deg, which can be traced out to vertical heights of ~500au. We interpret this emission as the combination of the disk atmosphere and a well-collimated disk wind, which we trace down to vertical heights of 40au, where it is launched from the surface of the flared disk at radii of 20-45au. The observed CO outflow has a total momentum flux of 1e-5 Msun km/s/yr, which is nearly three orders of magnitude larger than the maximum thrust that can be provided by the luminosity of the central star. We conclude that photoevaporation cannot be the main driving mechanism for this outflow, but it must be predominantly an MHD disk wind. It is thus far the best-resolved rotating disk wind observed to be launched from a circumstellar disk.