The sample of sources for which variability information is provided is expanded to 0.5 million stars. For 1.3 billion of those sources, parallaxes and proper motions are in addition available.
Results: Gaia DR2 contains celestial positions and the apparent brightness in G for approximately 1.7 billion sources. Methods: The raw data collected with the Gaia instruments during the first 22 months of the mission have been processed by the Gaia Data Processing and Analysis Consortium (DPAC) and turned into this second data release, which represents a major advance with respect to Gaia DR1 in terms of completeness, performance, and richness of the data products. Recommendations are made on the responsible use of Gaia DR2 results. Aims: A summary of the contents of Gaia DR2 is presented, accompanied by a discussion on the differences with respect to Gaia DR1 and an overview of the main limitations which are still present in the survey. In addition epoch astrometry and photometry are provided for a modest sample of minor planets in the solar system. We present the second Gaia data release, Gaia DR2, consisting of astrometry, photometry, radial velocities, and information on astrophysical parameters and variability, for sources brighter than magnitude 21. The accurate measurement of the mass of π Men b contributes to make the brown dwarf desert a bit greener.read more read lessĪbstract: Context. Our determination of the 3D architecture of the π Men planetary system and the high relative misalignment of the planetary orbital planes put constraints on and challenge the theories of the formation and dynamical evolution of planetary systems. The π Men system represents a nice example of the extreme precision radial velocities that can be obtained with ESPRESSO for bright targets. This leads to the precise measurement of its absolute mass M Jup, indicating that π Men b can be classified as a brown dwarf.Conclusions. We improve the ephemeris of π Men c using 18 additional TESS transits, and, in combination with the astrometric measurements, we determine the inclination of the orbital plane of π Men b with high precision ( deg). we can exclude companions with a minimum mass less than ~2 M ⊕ within the orbit of π Men c). The residuals show a root mean square of 1.2 m s−1, which is half that of the HARPS data based on the residuals, we put limits on the presence of additional low-mass planets (e.g. The ESPRESSO radial velocities alone (37 nightly binned data with typical uncertainty of 10 cm s−1 ) allow for a precise retrieval of the Doppler signal induced by π Men c. We present a precise characterization of the planetary system around π Men. We used the high-resolution spectra of ESPRESSO for an independent determination of the stellar fundamental parameters.Results. We further characterized the system by means of absolute astrometry with HIPPARCOS and Gaia. We analysed the enlarged spectroscopic and photometric datasets and compared the results to those in the literature. We also take advantage of the new photometric transits of π Men c observed by TESS over a time span that overlaps with that of the ESPRESSO follow-up campaign.Methods.
With the new ESPRESSO observations, which cover a time span of 200 days, we aim to improve the precision and accuracy of the planet parameters and search for additional low-mass companions. The star hosts a multi-planet system (a transiting 4 M ⊕ planet at ~0.07 au and a sub-stellar companion on a ~2100-day eccentric orbit), which is particularly suitable for a precise multi-technique characterization.Aims. The bright star π Men was chosen as the first target for a radial velocity follow-up to test the performance of ESPRESSO, the new high-resolution spectrograph at the European Southern Observatory’s Very Large Telescope. Abstract: $\pi$ Men hosts a transiting super Earth ($P\appro圆27$ d, $m\approx482$ $M_$, and shows that the planetary orbital planes are highly misaligned.read more read lessĪbstract: Context.
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