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Context. M-dwarf spectra are complex and notoriously difficult to model, posing challenges to understanding their photospheric properties and compositions in depth. Vanadium (V) is an iron-group element whose abundance supposedly closely tracks that of iron, but has origins that are not completely understood. Aims. Our aim is to characterize a series of neutral vanadium atomic absorption lines in the 800-910 nm wavelength region of high signal-to-noise, high-resolution, telluric-corrected M-dwarf spectra from the CARMENES survey. Many of these lines are prominent and exhibit a distinctive broad and flat-bottom shape, which is a result of hyperfine structure (HFS). We investigate the potential and implications of these HFS split lines for abundance analysis of cool stars. Methods. With standard spectral synthesis routines, as provided by the spectroscopy software iSpec and the latest atomic data (including HFS) available from the VALD3 database, we modeled these striking line profiles. We used them to measure V abundances of cool dwarfs. Results. We determined V abundances for 135 early M dwarfs (M0.0 V to M3.5 V) in the CARMENES guaranteed time observations sample. They exhibit a [V/Fe]-[Fe/H] trend consistent with that derived from nearby FG dwarfs. The tight (±0.1 dex) correlation between [V/H] and [Fe/H] suggests the potential application of V as an alternative metallicity indicator in M dwarfs. We also show hints that neglecting to model HFS could partially explain the temperature correlation in V abundance measurements observed in previous studies of samples involving dwarf stars with Teff 5300 K. Conclusions. Our work suggests that HFS can impact certain absorption lines in cool photospheres more severely than in Sun-like ones. Therefore, we advocate that HFS should be carefully treated in abundance studies in stars cooler than ∼5000 K. On the other hand, strong HFS split lines in high-resolution spectra present an opportunity for precision chemical analyses of large samples of cool stars. The V-to-Fe trends exhibited by the local M dwarfs continue to challenge theoretical models of V production in the Galaxy. © ESO 2021., CARMENES is an instrument at the Centro Astronomico Hispano-Aleman (CAHA) at Calar Alto (Almeria, Spain), operated jointly by the Junta de Andalucia and the Instituto de Astrofisica de Andalucia (CSIC). CARMENES was funded by the Max-Planck-Gesellschaft (MPG), the Consejo Superior de Investigaciones Cientificas (CSIC), the Ministerio de Economia y Competitividad (MINECO) and the European Regional Development Fund (ERDF) through projects FICTS-2011-02, ICTS-2017-07-CAHA-4, and CAHA16-CE-3978, and the members of the CARMENES Consortium (Max-Planck-Institut fur Astronomie, Instituto de Astrofisica de Andalucia, Landessternwarte Konigstuhl, Institut de Ciencies de l'Espai, Institut fur Astrophysik Gottingen, Universidad Complutense de Madrid, Thuringer Landessternwarte Tautenburg, Instituto de Astrofisica de Canarias, Hamburger Sternwarte, Centro de Astrobiologia and Centro Astronomico Hispano-Aleman), with additional contributions by the MINECO, the Deutsche Forschungsgemeinschaft (DFG) through the Major Research Instrumentation Programme and Research Unit FOR2544 "Blue Planets around Red Stars", the Klaus Tschira Stiftung, the states of Baden-Wurttemberg and Niedersachsen, and by the Junta de Andalucia. We acknowledge financial support from the Agencia Estatal de Investigacion of the Ministerio de Ciencia, Innovacion y Universidades and the ERDF through projects PID2019-109522GB-C5[1:4]/AEI/10.13039/501100011033 and the Centre of Excellence "Severo Ochoa" and "Maria de Maeztu" awards to the Instituto de Astrofisica de Canarias (CEX2019-000920-S), Instituto de Astrofisicade Andalucia (SEV-2017-0709), and Centro de Astrobiologia (MDM-2017-0737), the Generalitat de Catalunya/CERCA programme, the Austrian Science Fund (P 33 140-N), the Ministerio de Universidades (FPU15/01476), the DFG (SPP 1992 JE 701/5-1), and NASA (NNX17AG24G). This work has made use of the VALD database, operated at Uppsala University, the Institute of Astronomy RAS in Moscow, and the University of Vienna.

Obscuration and confusion conspire to limit our knowledge of the inner Milky Way. Even at moderate distances, the identification of stellar systems becomes compounded by the extremely high density of background sources. Here we provide a very revealing example of these complications by unveiling a large, massive, young cluster in the Sagittarius arm that has escaped detection until now despite containing more than 30 stars brighter than $G=13$. By combining Gaia DR2 astrometry, Gaia and 2MASS photometry and optical spectroscopy, we find that the new cluster, which we name Valparaiso~1, located at $\sim2.3\:$kpc, is about 75~Ma old and includes a large complement of evolved stars, among which we highlight the 4~d classical Cepheid CM~Sct and an M-type giant that probably represents the first detection of an AGB star in a Galactic young open cluster. Although strong differential reddening renders accurate parameter determination unfeasible with the current dataset, direct comparison to clusters of similar age suggests that Valparaiso~1 was born as one of the most massive clusters in the Solar Neighbourhood, with an initial mass close to $10^{4}\:$M$_{\odot}$., 12 pages, 10 figures, accepted for publication in MNRAS

The TESS mission has reported a wealth of new planetary systems around bright and nearby stars amenable for detailed characterization of the planet properties and their atmospheres. However, not all interesting TESS planets orbit around bright host stars. TOI-263b is a validated ultra-short period substellar object in a 0.56-day orbit around a faint (V=18.97) M3.5 dwarf star. The substellar nature of TOI-263b was explored using multi-color photometry, which determined a true radius of 0.87+-0.21 Rj, establishing TOI-263b's nature ranging from an inflated Neptune to a brown dwarf. The orbital period-radius parameter space occupied by TOI-263b is quite unique, which prompted a further characterization of its true nature. Here, we report radial velocity measurements of TOI-263 obtained with 3 VLT units and the ESPRESSO spectrograph to retrieve the mass of TOI-263b. We find that TOI-263b is a brown dwarf with a mass of 61.6+-4.0 Mj. Additionally, the orbital period of the brown dwarf is found to be synchronized with the rotation period of the host star, and the system is found to be relatively active, possibly revealing a star--brown dwarf interaction. All these findings suggest that the system's formation history might be explained via disc fragmentation and later migration to close-in orbits. If the system is found to be unstable, TOI-263 is an excellent target to test the migration mechanisms before the brown dwarf becomes engulfed by its parent star., Accepted for Publication in Astronomy and Astrophysics

We observed two transits of the iconic gas giant HD 209458b between 380 and 780 nm, using the high-resolution ESPRESSO spectrograph. The derived planetary transmission spectrum exhibits features at all wavelengths where the parent star shows strong absorption lines, for example, NaI, MgI, FeI, FeII, CaI, VI, H$\alpha$, and KI. We interpreted these features as the signature of the deformation of the stellar line profiles due to the Rossiter-McLaughlin effect, combined with the centre-to-limb effects on the stellar surface, which is in agreement with similar reports recently presented in the literature. We also searched for species that might be present in the planetary atmosphere but not in the stellar spectra, such as TiO and VO, and obtained a negative result. Thus, we find no evidence of any planetary absorption, including previously reported NaI, in the atmosphere of HD 209458b. The high signal-to-noise ratio in the transmission spectrum allows us to compare the modelled deformation of the stellar lines in assuming different one-dimensional stellar atmospheric models. We conclude that the differences among various models and observations remain within the precision limits of the data. However, the transmission light curves are better explained when the centre-to-limb variation is not included in the computation and only the Rossiter-McLaughlin deformation is considered. This demonstrates that ESPRESSO is currently the best facility for spatially resolving the stellar surface spectrum in the optical range using transit observations and carrying out empirical validations of stellar models., Comment: 21 pages, 19 figures. Accepted

Aims. We report on ESPRESSO high-resolution transmission spectroscopic observations of two primary transits of the highly-irradiated, ultra-hot Jupiter-size planet WASP-76b. We investigate the presence of several key atomic and molecular features of interest that may reveal the atmospheric properties of the planet. Methods. We extracted two transmission spectra of WASP-76b with R approx 140,000 using a procedure that allowed us to process the full ESPRESSO wavelength range (3800-7880 A) simultaneously. We observed that at a high signal-to-noise ratio, the continuum of ESPRESSO spectra shows wiggles that are likely caused by an interference pattern outside the spectrograph. To search for the planetary features, we visually analysed the extracted transmission spectra and cross-correlated the observations against theoretical spectra of different atomic and molecular species. Results. The following atomic features are detected: Li I, Na I, Mg I, Ca II, Mn I, K I, and Fe I. All are detected with a confidence level between 9.2 sigma (Na I) and 2.8 sigma (Mg I). We did not detect the following species: Ti I, Cr I, Ni I, TiO, VO, and ZrO. We impose the following 1 sigma upper limits on their detectability: 60, 77, 122, 6, 8, and 8 ppm, respectively. Conclusions. We report the detection of Li I on WASP-76b for the first time. In addition, we found the presence of Na I and Fe I as previously reported in the literature. We show that the procedure employed in this work can detect features down to the level of ~ 0.1 % in the transmission spectrum and ~ 10 ppm by means of a cross-correlation method. We discuss the presence of neutral and singly ionised features in the atmosphere of WASP-76b., 20 pages, 19 figures, accepted for publication in Astronomy and Astrophysics

Aims. We present a spectroscopic analysis of the extremely luminous red star VX Sgr based on high-resolution observations combined with AAVSO light curve data. Given the puzzling characteristics of VX Sgr, we explore three scenarios for its nature: a massive red supergiant (RSG) or hypergiant (RHG), a Thorne Zytkow object (TZO), and an extreme Asymptotic Giant Branch (AGB) star. Methods. Sampling more than one whole cycle of photometric variability, we derive stellar atmospheric parameters by using state-of-the-art PHOENIX atmospheric models. We compare them to optical and near infrared spectral types. We report on some key features due to neutral elemental atomic species such as Li I, Ca I, and Rb I. Results. We provide new insights into its luminosity, evolutionary stage as well as its pulsation period. Based on all the data, there are two strong reasons to believe that VX Sgr is some sort of extreme AGB star. Firstly, its Mira-like behaviour during active phases. VX Sgr shows light variations with amplitudes much larger than any known RSG and clearly larger than all RHGs. In addition, it displays Balmer line emission and, as shown here for the first time, line doubling of its metallic spectrum at maximum light, both characteristics typical of Miras. Secondly, unlike any known RSG or RHG, VX Sgr displays strong Rb I lines. In addition to the photospheric lines that are sometimes seen, it always shows circumstellar components whose expansion velocity is compatible with that of the OH masers in the envelope, demonstrating a continuous enrichment of the outer atmosphere with s-process elements, a behaviour that can only be explained by third dredge up during the thermal pulse phase., Comment: 16 pages, 10 Figures, accepted for publication in Astronomy and Astrophysics

ESPRESSO is the new high-resolution spectrograph of ESO's Very-Large Telescope (VLT). It was designed for ultra-high radial-velocity precision and extreme spectral fidelity with the aim of performing exoplanet research and fundamental astrophysical experiments with unprecedented precision and accuracy. It is able to observe with any of the four Unit Telescopes (UT) of the VLT at a spectral resolving power of 140,000 or 190,000 over the 378.2 to 788.7 nm wavelength range, or with all UTs together, turning the VLT into a 16-m diameter equivalent telescope in terms of collecting area, while still providing a resolving power of 70,000. We provide a general description of the ESPRESSO instrument, report on the actual on-sky performance, and present our Guaranteed-Time Observation (GTO) program with its first results. ESPRESSO was installed on the Paranal Observatory in fall 2017. Commissioning (on-sky testing) was conducted between December 2017 and September 2018. The instrument saw its official start of operations on October 1st, 2018, but improvements to the instrument and re-commissioning runs were conducted until July 2019. The measured overall optical throughput of ESPRESSO at 550 nm and a seeing of 0.65 arcsec exceeds the 10% mark under nominal astro-climatic conditions. We demonstrate a radial-velocity precision of better than 25 cm/s during one night and 50 cm/s over several months. These values being limited by photon noise and stellar jitter show that the performanceis compatible with an instrumental precision of 10 cm/s. No difference has been measured across the UTs neither in throughput nor RV precision. The combination of the large collecting telescope area with the efficiency and the exquisite spectral fidelity of ESPRESSO opens a new parameter space in RV measurements, the study of planetary atmospheres, fundamental constants, stellar characterisation and many other fields., 26 pages, 28 figures

Context: SteParSyn is an automatic code written in Python 3.X designed to infer the stellar atmospheric parameters Teff, log(g), and [Fe/H] of FGKM-type stars following the spectral synthesis method. Aims: We present a description of the SteParSyn code and test its performance against a sample of late-type stars that were observed with the HERMES spectrograph mounted at the 1.2-m Mercator Telescope. This sample contains 35 late-type targets with well-known stellar parameters determined independently from spectroscopy. The code is available to the astronomical community in a GitHub repository. Methods: SteParSyn uses a Markov chain Monte Carlo (MCMC) sampler to explore the parameter space by comparing synthetic model spectra generated on the fly to the observations. The synthetic spectra are generated with an spectral emulator. Results: We computed Teff, log(g), and [Fe/H] for our sample stars and discussed the performance of the code. We calculated an internal scatter for these targets of -12 +- 117 K in Teff, 0.04 +- 0.14 dex in log(g), and 0.05 +- 0.09 dex in [Fe/H]. In addition, we find that the log(g) values obtained with SteParSyn are consistent with the trigonometric surface gravities to the 0.1 dex level. Finally, SteParSyn can compute stellar parameters that are accurate down to 50 K, 0.1 dex, and 0.05 dex for Teff, log(g), and [Fe/H] for stars with vsini, 15 pages, 10 figures. Accepted for publication in A&A

Despite swift progress in the characterisation of exoplanet atmospheres in composition and structure, the study of atmospheric dynamics has not progressed at the same speed. While theoretical models have been developed to describe the lower layers of the atmosphere and, disconnected, the exosphere, little is known about the intermediate layers up to the thermosphere. We aim to provide a clearer picture of atmospheric dynamics for the class of ultra hot Jupiters, highly-irradiated gas giants, on the example of WASP-76~b. We analysed two datasets jointly, obtained with the HARPS and ESPRESSO spectrographs, to interpret the resolved planetary sodium doublet. We then applied an updated version of the MERC code, with added planetary rotation, also provides the possibility to model the latitude dependence of the wind patterns. We retrieve the highest Bayesian evidence for an isothermal atmosphere, interpreted as a mean temperature of $3389\pm227$ K, a uniform day-to-night side wind of $5.5^{+1.4}_{-2.0}\,$ km/s in the lower atmosphere with a vertical wind in the upper atmosphere of $22.7^{+4.9}_{-4.1}\,$ km/s, switching atmospheric wind patterns at $10^{-3}$ bar above the reference surface pressure ($10$ bar). Our results for WASP-76~b are compatible with previous studies of the lower atmospheric dynamics of WASP-76~b and other ultra hot Jupiters. They highlight the need for vertical winds in the intermediate atmosphere above the layers probed by global circulation model studies to explain the line broadening of the sodium doublet in this planet. This work demonstrates the capability of exploiting the resolved spectral line shapes to observationally constrain possible wind patterns in exoplanet atmospheres, an invaluable input to more sophisticated 3D atmospheric models in the future., 17 pages, 20 figures, submitted to A&A 15.Feb.2021, accepted for publication in A&A 20.Jul.2021

Due to their ubiquity and very long main-sequence lifetimes, abundance determinations in M dwarfs provide a powerful and alternative tool to GK dwarfs to study the formation and chemical enrichment history of our Galaxy. In this study, abundances of the neutron-capture elements Rb, Sr, and Zr are derived, for the first time, in a sample of nearby M dwarfs. We focus on stars in the metallicity range-0.5 ≲ [Fe/H] ≲ +0.3, an interval poorly explored for Rb abundances in previous analyses. To do this we use high-resolution, high-signal-to-noise-ratio, optical and near-infrared spectra of 57 M dwarfs observed with CARMENES. The resulting [Sr/Fe] and [Zr/Fe] ratios for most M dwarfs are almost constant at about the solar value, and are identical to those found in GK dwarfs of the same metallicity. However, for Rb we find systematic underabundances ([Rb/Fe] < 0.0) by a factor two on average. Furthermore, a tendency is found for Rb-but not for other heavy elements (Sr, Zr)-to increase with increasing metallicity such that [Rb/Fe] ≳ 0.0 is attained at metallicities higher than solar. These are surprising results, never seen for any other heavy element, and are difficult to understand within the formulation of the s-and r-processes, both contributing sources to the Galactic Rb abundance. We discuss the reliability of these findings for Rb in terms of non-LTE (local thermodynamic equilibrium) effects, stellar activity, or an anomalous Rb abundance in the Solar System, but no explanation is found. We then interpret the full observed [Rb/Fe] versus [Fe/H] trend within the framework of theoretical predictions from state-of-the-art chemical evolution models for heavy elements, but a simple interpretation is not found either. In particular, the possible secondary behaviour of the [Rb/Fe] ratio at super-solar metallicities would require a much larger production of Rb than currently predicted in AGB stars through the s-process without overproducing Sr and Zr. © 2020 ESO., CARMENES is an instrument for the Centro Astronomico Hispano-Aleman (CAHA) at Calar Alto (Almeria, Spain), operated jointly by the Junta de Andalucia and the Instituto de Astrofisica de Andalucia (CSIC). CARMENES was funded by the Max-Planck-Gesellschaft (MPG), the Consejo Superior de Investigaciones Cientificas (CSIC), the Ministerio de Economia y Competitividad (MINECO) and the European Regional Development Fund (ERDF) through projects FICTS-2011-02, ICTS-2017-07-CAHA-4, and CAHA16-CE-3978, and the members of the CARMENES Consortium (Max-Planck-Institut fur Astronomie, Instituto de Astrofisica de Andalucia, Landessternwarte Konigstuhl, Institut de Ciencies de l'Espai, Institut fur Astrophysik Gottingen, Universidad Complutense de Madrid, Thuringer Landessternwarte Tautenburg, Instituto de Astrofisica de Canarias, Hamburger Sternwarte, Centro de Astrobiologia and Centro Astronomico Hispano-Aleman), with additional contributions by the MINECO, the Deutsche Forschungsgemeinschaft through the Major Research Instrumentation Programme and Research Unit FOR2544 "Blue Planets around Red Stars", the Klaus Tschira Stiftung, the states of Baden-Wurttemberg and Niedersachsen, and by the Junta de Andalucia. We acknowledge financial support from the Agencia Estatal de Investigacion of the Ministerio de Ciencia e Innovacion, the Universidad Complutense de Madrid, the Fundacao para a Ciencia e a Tecnologia, the Generalitat de Catalunya, ERDF, and NASA through projects PGC2018-095317-B-C21, PID2019-109522GB-C51/2/3/4, PGC2018-098153-B-C33, AYA2016-79425-C3[1,2,3]-P, FPU15/01476, UID[B,P]/04434/2020, PTDC/FIS-AST/28953/2017, POCI-01-0145-FEDER-028953, SEV-2015-0548, SEV-2017-0709, MDM-20170737, NNX17AG24G, and the CERCA programme.

Classical Cepheids in open clusters play an important role in benchmarking stellar evolution models, anchoring the cosmic distance scale, and invariably securing the Hubble constant. NGC 6649, NGC 6664 and Berkeley 55 are three pertinent clusters that host classical Cepheids and red (super)giants, and an analysis was consequently initiated to assess newly acquired spectra ($\approx$50), archival photometry, and $Gaia$ DR2 data. Importantly, for the first time chemical abundances are determined for the evolved members of NGC 6649 and NGC 6664. We find that they are slightly metal-poor relative to the mean Galactic gradient, and an overabundance of Ba is observed. Those clusters likely belong to the thin disc, and the latter finding supports D'Orazi et al. (2009) "$s$-enhanced" scenario. NGC 6664 and Berkeley 55 exhibit radial velocities consistent with Galactic rotation, while NGC 6649 displays a peculiar velocity. The resulting age estimates for the clusters ($\approx$70 Ma) imply masses for the (super)giant demographic of $\approx$6 M$_{sun}$. Lastly, the observed yellow-to-red (super)giant ratio is lower than expected, and the overall differences relative to models reflect outstanding theoretical uncertainties., 24 pages, 15 tables and 13 figures. Accepted for publication in A&A

The High Optical Resolution Spectrograph (HORuS) is a new high-resolution echelle spectrograph available on the 10.4 m Gran Telescopio Canarias (GTC). We report on the first HORuS observations of a transit of the super-Earth planet 55 Cnc e. We investigate the presence of Na I and H$\alpha$ in its transmission spectrum and explore the capabilities of HORuS for planetary transmission spectroscopy. Our methodology leads to residuals in the difference spectrum between the in-transit and out-of-transit spectra for the Na I doublet lines of (3.4 $\pm$ 0.4) $\times$ 10$^{-4}$, which sets an upper limit to the detection of line absorption from the planetary atmosphere that is one order of magnitude more stringent that those reported in the literature. We demonstrate that we are able to reach the photon-noise limit in the residual spectra using HORuS to a degree that we would be able to easily detect giant planets with larger atmospheres. In addition, we modelled the structure, chemistry and transmission spectrum of 55 Cnc e using state-of-the-art open source tools., Comment: Accepted for publication in MNRAS

Toledo-Padrón, B. et al., Context. An accurate characterization of the known exoplanet population is key to understanding the origin and evolution of planetary systems. Determining true planetary masses through the radial velocity (RV) method is expected to experience a great improvement thanks to the availability of ultra-stable echelle spectrographs. Aims. We took advantage of the extreme precision of the new-generation echelle spectrograph ESPRESSO to characterize the transiting planetary system orbiting the G2V star K2-38 located at 194 pc from the Sun with V 11.4. This system is particularly interesting because it could contain the densest planet detected to date. Methods. We carried out a photometric analysis of the available K2 photometric light curve of this star to measure the radius of its two known planets, K2-38b and K2-38c, with Pb = 4.01593 ± 0.00050 d and Pc = 10.56103 ± 0.00090 d, respectively. Using 43 ESPRESSO high-precision RV measurements taken over the course of 8 months along with the 14 previously published HIRES RV measurements, we modeled the orbits of the two planets through a Markov chain Monte Carlo analysis, significantly improving their mass measurements. Results. Using ESPRESSO spectra, we derived the stellar parameters, Teff = 5731 ± 66, log g = 4.38 ± 0.11 dex, and [Fe/H] = 0.26 ± 0.05 dex, and thus the mass and radius of K2-38, Ma = 1.03-0.02+0.04 MaS and Ra = 1.06-0.06+0.09 RaS. We determine new values for the planetary properties of both planets. We characterize K2-38b as a super-Earth with RP = 1.54 ± 0.14 RaS and Mp = 7.3-1.0+1.1 MaS, and K2-38c as a sub-Neptune with RP = 2.29 ± 0.26 RaS and Mp = 8.3-1.3+1.3 MaS. Combining the radius and mass measurements, we derived a mean density of ρp = 11.0-2.8+4.1 g cm-3 for K2-38b and ρp = 3.8-1.1+1.8 g cm-3 for K2-38c, confirming K2-38b as one of the densest planets known to date. Conclusions. The best description for the composition of K2-38b comes from an iron-rich Mercury-like model, while K2-38c is better described by a rocky-model with H2 envelope. The maximum collision stripping boundary shows how giant impacts could be the cause for the high density of K2-38b. The irradiation received by each planet places them on opposite sides of the radius valley. We find evidence of a long-period signal in the RV time-series whose origin could be linked to a 0.25-3 MJ planet or stellar activity., With funding from the Spanish government through the "María de Maeztu Unit of Excellence" accreditation (MDM-2017-0737)

Existing and upcoming instrumentation is collecting large amounts of astrophysical data, which require efficient and fast analysis techniques. We present a deep neural network architecture to analyze high-resolution stellar spectra and predict stellar parameters such as effective temperature, surface gravity, metallicity, and rotational velocity. With this study, we firstly demonstrate the capability of deep neural networks to precisely recover stellar parameters from a synthetic training set. Secondly, we analyze the application of this method to observed spectra and the impact of the synthetic gap (i.e., the difference between observed and synthetic spectra) on the estimation of stellar parameters, their errors, and their precision. Our convolutional network is trained on synthetic PHOENIX-ACES spectra in different optical and near-infrared wavelength regions. For each of the four stellar parameters, Teff, log g, [M/H], and v sin i, we constructed a neural network model to estimate each parameter independently. We then applied this method to 50 M dwarfs with high-resolution spectra taken with CARMENES (Calar Alto high-Resolution search for M dwarfs with Exo-earths with Near-infrared and optical Échelle Spectrographs), which operates in the visible (520-960 nm) and near-infrared wavelength range (960-1710 nm) simultaneously. Our results are compared with literature values for these stars. They show mostly good agreement within the errors, but also exhibit large deviations in some cases, especially for [M/H], pointing out the importance of a better understanding of the synthetic gap. © 2020 ESO., CARMENES is an instrument for the Centro Astronomico Hispano-Aleman de Calar Alto (CAHA, Almeria, Spain). CARMENES is funded by the German Max-Planck-Gesellschaft (MPG), the Spanish Consejo Superior de Investigaciones Cientificas(CSIC), European Regional Development Fund (ERDF) through projects FICTS-2011-02, ICTS-2017-07-CAHA-4, and CAHA16-CE-3978, and the members of the CARMENES Consortium (Max-Planck-Institut fur Astronomie, Instituto de Astrofisicade Andalucia, Landessternwarte Konigstuhl, Institut de Ciencies de l'Espai, Insitut fur Astrophysik Gottingen, Universidad Complutense de Madrid, Thuringer Landessternwarte Tautenburg, Instituto de Astrofisica de Canarias, Hamburger Sternwarte, Centro de Astrobiologia and Centro Astronomico Hispano-Aleman), with additional contributions by the Spanish Ministry of Economy, the German Science Foundation through the Major Research Instrumentation Programme and DFG Research Unit FOR2544 "Blue Planets around Red Stars", the Klaus Tschira Stiftung, the states of Baden-Wurttemberg and Niedersachsen, and by the Junta de Andalucia. We acknowledge financial support from NASA through grant NNX17AG24G, the Agencia Estatal de Investigacion of the Ministerio de Ciencia through fellowship FPU15/01476, Innovacion y Universidades and the ERDF through projects PID2019-109522GB-C51/2/3/4, AYA2016-79425-C3-1/2/3-P and AYA2018-84089, the FundacAo para a Ciencia e a Tecnologia through and ERDF through grants UID/FIS/04434/2019, UIDB/04434/2020 and UIDP/04434/2020, PTDC/FIS-AST/28953/2017, and COMPETE2020 - Programa Operacional Competitividade e InternacionalizacAo POCI-01-0145-FEDER-028953.

Full list of authors: Gutiérrez Albarrán, M. L.; Montes, D.; Gómez Garrido, M.; Tabernero, H. M.; González Hernández, J. I.; Marfil, E.; Frasca, A.; Lanzafame, A. C.; Klutsch, A.; Franciosini, E.; Randich, S.; Smiljanic, R.; Korn, A. J.; Gilmore, G.; Alfaro, E. J.; Baratella, M.; Bayo, A.; Bensby, T.; Bonito, R.; Carraro, G. Delgado Mena, E.; Feltzing, S.; Gonneau, A.; Heiter, U.; Hourihane, A.; Jiménez Esteban, F.; Jofre, P.; Masseron, T.; Monaco, L.; Morbidelli, L.; Prisinzano, L.; Roccatagliata, V.; Sousa, S.; Van der Swaelmen, M.; Worley, C. C.; Zaggia, S., Context. Previous studies of open clusters have shown that lithium depletion is not only strongly age dependent but also shows a complex pattern with other parameters that is not yet understood. For pre- and main-sequence late-type stars, these parameters include metallicity, mixing mechanisms, convection structure, rotation, and magnetic activity. Aims. We perform a thorough membership analysis for a large number of stars observed within the Gaia-ESO survey (GES) in the field of 20 open clusters, ranging in age from young clusters and associations, to intermediate-age and old open clusters. Methods. Based on the parameters derived from the GES spectroscopic observations, we obtained lists of candidate members for each of the clusters in the sample by deriving radial velocity distributions and studying the position of the kinematic selections in the EW(Li)-versus-Teff plane to obtain lithium members. We used gravity indicators to discard field contaminants and studied [Fe/H] metallicity to further confirm the membership of the candidates. We also made use of studies using recent data from the Gaia DR1 and DR2 releases to assess our member selections. Results. We identified likely member candidates for the sample of 20 clusters observed in GES (iDR4) with UVES and GIRAFFE, and conducted a comparative study that allowed us to characterize the properties of these members as well as identify field contaminant stars, both lithium-rich giants and non-giant outliers. Conclusions. This work is the first step towards the calibration of the lithium-age relation and its dependence on other GES parameters. During this project we aim to use this relation to infer the ages of GES field stars, and identify their potential membership to young associations and stellar kinematic groups of different ages. © ESO 2020., Financial support was provided by the Universidad Complutense de Madrid and by the Spanish Ministry of Economy and Competitiveness (MINECO) from project AYA2016-79425-C3-1-P. We acknowledge the support from INAF and Ministero dell' Istruzione, dell' Universita' e della Ricerca (MIUR) in the form of the grant "Premiale VLT 2012". T.B. was funded by the project grant "The New Milky Way" from the Knut and Alice Wallenberg Foundation. J.I.G.H. acknowledges financial support from the Spanish Ministry of Science, Innovation and Universities (MICIU) under the 2003 Ramon y Cajal program RYC-2013-14875, and also from the Spanish Ministry project MICIU AYA2017-86389-P. E.M. acknowledges financial support from the Spanish Ministerio de Ciencia e Innovacion through fellowship FPU15/01476. A.G. acknowledges support from the European Union FP7 programme from the UK space agency. U.H. acknowledges support from the Swedish National Space Agency (SNSA/Rymdstyrelsen). F.J.E. acknowledges financial support from the Spanish MINECO/FEDER through the grant AyA2017-84089. S.G.S acknowledges the support of Fundacao para a Ciencia e Tecnologia (FCT) through national funds and research grant (project ref. UID/FIS/04434/2013, and PTDC/FIS-AST/7073/2014). S.G.S also acknowledges the support from FCT through Investigador FCT contract of reference IF/00028/2014 and POPH/FSE (EC) by FEDER funding through the program "Programa Operacional de Factores de Competitividad" - COMPETE MT also acknowledges support from the FCT - Fundacao para a Ciencia e a Tecnologia through national funds (PTDC/FIS-AST/28953/2017) and by FEDER -Fundo Europeu de Desenvolvimento Regional through COMPETE2020 - Programa Operacional Competitividade e Internacionalizacao (POCI-01-0145-FEDER-028953). TM acknowledges support from the State Research Agency (AEI) of the Spanish Ministry of Science, Innovation and Universities (MCIU) and the European Regional Development Fund (FEDER) under grant AYA2017-88254-P Based on data products from observations made with ESO Telescopes at the La Silla Paranal Observatory under programme focusID 188.B-3002. These data products have been processed by the Cambridge Astronomy Survey Unit (CASU) at the Institute of Astronomy, University of Cambridge, and by the FLAMES/UVES reduction team at INAF-Osservatorio Astrofisico di Arcetri. These data have been obtained from the GES Data Archive, prepared and hosted by theWide Field Astronomy Unit, Institute for Astronomy, University of Edinburgh, which is funded by the UK Science and Technology Facilities Council. This work was partly supported by the European Union FP7 programme through ERC grant number 320360 and by the Leverhulme Trust through grant RPG-2012-541. The results presented here benefit from discussions held during GES workshops and conferences supported by the ESF (European Science Foundation) through the GREAT Research Network Programme. This work was also supported by Fundacao para a Ciencia e Tecnologia (FCT) through the research grants UID/FIS/04434/2019, UIDB/04434/2020 and UIDP/04434/2020. This work has made use of data from the European Space Agency (ESA) mission Gaia (https://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, https://www.cosmos.esa.int/web/gaia/dpac/consortium).Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. This publication makes use of the VizieR database (Ochsenbein et al. 2000) and the SIMBAD database (Wenger et al. 2000), both operated at CDS, Centre de Donnees astronomiques de Strasbourg, France. This research also made use of the WEBDA database, operated at the Department of Theoretical Physics and Astrophysics of the Masaryk University, and the interactive graphical viewer and editor for tabular data TOPCAT (Taylor 2005). For the analysis of the distributions of RV and metallicity we used RStudio Team (2015). Integrated Development for R. RStudio, Inc., Boston, MA (http://www.rstudio.com/).Finally, we would like to thank the anonymous referee for helpful comments and suggestions.

Context. The detection and characterization of exoplanet atmospheres is currently one of the main drivers pushing the development of new observing facilities. In this context, high-resolution spectrographs are proving their potential and showing that high-resolution spectroscopy will be paramount in this field. Aims. We aim to make use of ESPRESSO high-resolution spectra, which cover two transits of HD 209458b, to probe the broadband transmission optical spectrum of the planet. Methods. We applied the chromatic Rossiter-McLaughin method to derive the transmission spectrum of HD 209458b. We compared the results with previous HST observations and with synthetic spectra. Results. We recover a transmission spectrum of HD 209458b similar to the one obtained with HST data. The models suggest that the observed signal can be explained by only Na, only TiO, or both Na and TiO, even though none is fully capable of explaining our observed transmission spectrum. Extra absorbers may be needed to explain the full dataset, though modeling approximations and observational errors can also be responsible for the observed mismatch. Conclusions. Using the chromatic Rossiter-McLaughlin technique, ESPRESSO is able to provide broadband transmission spectra of exoplanets from the ground, in conjunction with space-based facilities, opening good perspectives for similar studies of other planets., With funding from the Spanish government through the "María de Maeztu Unit of Excellence" accreditation (MDM-2017-0737)

With the purpose of assessing classic spectroscopic methods on high-resolution and high signal-to-noise ratio spectra in the near-infrared wavelength region, we selected a sample of 65 F-, G-, and K-type stars observed with CARMENES, the new, ultra-stable, double channel spectrograph at the 3.5 m Calar Alto telescope. We computed their stellar atmospheric parameters (Teti, log g, 4, and [Fell I]) by means of the STEPAR code, a PYTHON implementation of the equivalent width method that employs the 2017 version of the MOOG code and a grid of MARCS model atmospheres. We compiled four Fe 1 and Fe tl line lists suited to metal-rich dwarfs, metal-poor dwarfs, metal-rich giants, and metal-poor giants that cover the wavelength range from 5300 to 17 100 A, thus substantially increasing the number of identified Fe! and Felt lines up to 653 and 23, respectively, We examined the impact of the near-infrared Fe and Fen lines upon our parameter determinations after an exhaustive literature search, placing special emphasis on the 14 Gala benchmark stars contained in our sample, Even though our parameter determinations remain in good agreement with the literature values, the increase in the number of Fel and Feu lines when the near-infrared region is taken into account reveals a deeper Teff scale that might stem from a higher sensitivity of the near-infrared lines to Tff.C 2020 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society, CARMENES is an instrument for the Centro Astronomico Hispano en Andaluc ' ia at Calar Alto (CAHA). CARMENES is funded by the German Max-Plank Gesellschaft (MPG), the Spanish Consejo Superior de InvestigacionesCientificas (CSIC), the European Union through FEDER/ERF FICTS-2011-02 funds, and the members of the CARMENES Consortium (Max-Plank-Institut fur Astronomie, Instituto de Astrofisica deAndalucia, LandessternwarteKonigstuhl, Institut de Ciencies de l'Espai, Institut fur Astrophysik Gottingen, Universidad Complutense de Madrid, Thuringer Landessternwarte Tautenberg, Instituto de Astrofisica de Canarias, Hamburger Sternwarte, Centro de Astrobiologia and Centro Astronomico Hispano en Andalucia), with additional contributions by the Ministerio de Asuntos Economicos y Transformacion Digital, the German Research Foundation (DFG) through the Major Research Instrumentation Programme and DFG Research Unit FOR2544 Blue Planets around Red Stars', the Klaus Tschira Stiftung, the states of Baden-Wurttemberg and Niedersachsen, and by the Junta de Andalucia. The authors acknowledge financial support from the Fundacao para a Ciencia e a Tecnologia (FCT) through national funds (PTDC/FIS-AST/28953/2017) and by Fundo Europeu de Desenvolvimento Regional (FEDER) through COMPETE2020 -Programa Operacional Competitividade e Internacionalizacao (POCI01-0145-FEDER-028953), the Ministerio de Ciencia e Innovacion through fellowship FPU15/01476, and projects AYA2016-79425C3-1/2/3-P, and the Universidad Complutense de Madrid. JIGH acknowledges financial support from the Ministerio de Ciencia e Innovacion under the 2013 Ramon y Cajal programme RYC-201314875, and from the project AYA2017-86389-P. This work has made use of the VALD database, operated at Uppsala University, the Institute of Astronomy RAS in Moscow, and the University of Vienna. We thank Calar Alto Observatory for the allocation of director's discretionary time to this programme. EM would also like to warmly thank the staff at the Hamburger Sternwarte for their hospitality during his stay funded by project EST18/00162 from the Ministerio de Ciencia e Innovacion. Based on data from the CARMENES data archive at CAB (INTA-CSIC).

Damasso, M. et al., Context. 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. 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. 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. 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. We analysed the enlarged spectroscopic and photometric datasets and compared the results to those in the literature. We further characterized the system by means of absolute astrometry with HIPPARCOS and Gaia. We used the high-resolution spectra of ESPRESSO for an independent determination of the stellar fundamental parameters. Results. We present a precise characterization of the planetary system around π Men. 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. 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. we can exclude companions with a minimum mass less than ∼2 M· within the orbit of π Men c). 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 (ib =45.8-1.1+1.4 deg). This leads to the precise measurement of its absolute mass mb =14.1-0.4+0.5 MJup, indicating that π Men b can be classified as a brown dwarf. Conclusions. The π Men system represents a nice example of the extreme precision radial velocities that can be obtained with ESPRESSO for bright targets. 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 accurate measurement of the mass of π Men b contributes to make the brown dwarf desert a bit greener., With funding from the Spanish government through the "María de Maeztu Unit of Excellence" accreditation (MDM-2017-0737)

Context: StePar is an automatic code written in Python 3.X designed to compute the stellar atmospheric parameters Teff, log(g), [Fe/H], and of FGK-type stars by means of the EW method. This code has already been extensively tested in different spectroscopic studies of FGK-type stars with several spectrographs and against myriads of Gaia-ESO Survey UVES U580 spectra of late-type, low-mass stars as one of its thirteen pipelines. Aims: We describe the code and test it against a library of well characterised Gaia benchmark stars. We also release the code to the community and provide the link for download. Methods: We carried out the required EW determination of Fe I and Fe II spectral lines using the automatic tool TAME. StePar implements a grid of MARCS model atmospheres and the MOOG radiative transfer code to compute stellar atmospheric parameters by means of a Downhill Simplex minimisation algorithm. Results: We show the results of the benchmark star test and also discuss the limitations of the EW method, and hence the code. In addition, we found a small internal scatter for the benchmark stars of 9 +- 32 K in Teff, 0.00 +- 0.07 dex in log(g), and 0.00 +- 0.03 dex in [Fe/H]. Finally, we advise against using StePar on double-lined spectroscopic binaries or spectra with R < 30,000, SNR < 20 or vsini >15 km/s as well as stars later than K4 or earlier than F6., 18 pages, 6 figures. Accepted in Astronomy and Astrophysics. StePar webpage: https://github.com/hmtabernero/StePar

We determine the radii and masses of 293 nearby, bright M dwarfs of the CARMENES survey. This is the first time that such a large and homogeneous high-resolution (R>80 000) spectroscopic survey has been used to derive these fundamental stellar parameters. We derived the radii using Stefan-Boltzmann's law. We obtained the required effective temperatures $T_{\rm eff}$ from a spectral analysis and we obtained the required luminosities L from integrated broadband photometry together with the Gaia DR2 parallaxes. The mass was then determined using a mass-radius relation that we derived from eclipsing binaries known in the literature. We compared this method with three other methods: (1) We calculated the mass from the radius and the surface gravity log g, which was obtained from the same spectral analysis as $T_{\rm eff}$. (2) We used a widely used infrared mass-magnitude relation. (3) We used a Bayesian approach to infer stellar parameters from the comparison of the absolute magnitudes and colors of our targets with evolutionary models. Between spectral types M0V and M7V our radii cover the range $0.1\,R_{\normalsize\odot}, Comment: Accepted by A&A, 27 pages, 20 figures

Context. Teegarden's Star is the brightest and one of the nearest ultra-cool dwarfs in the solar neighbourhood. For its late spectral type (M7.0 V), the star shows relatively little activity and is a prime target for near-infrared radial velocity surveys such as CARMENES. Aims. As part of the CARMENES search for exoplanets around M dwarfs, we obtained more than 200 radial-velocity measurements of Teegarden's Star and analysed them for planetary signals. Methods. We find periodic variability in the radial velocities of Teegarden's Star. We also studied photometric measurements to rule out stellar brightness variations mimicking planetary signals. Results. We find evidence for two planet candidates, each with 1.1 M minimum mass, orbiting at periods of 4.91 and 11.4 d, respectively. No evidence for planetary transits could be found in archival and follow-up photometry. Small photometric variability is suggestive of slow rotation and old age. Conclusions. The two planets are among the lowest-mass planets discovered so far, and they are the first Earth-mass planets around an ultra-cool dwarf for which the masses have been determined using radial velocities.© ESO 2019., M.Z. acknowledges support from the Deutsche Forschungsgemeinschaft under DFG RE 1664/12-1 and Research Unit FOR2544 >Blue Planets around Red Stars>, project no. RE 1664/14-1. CARMENES is an instrument for the Centro Astronomico Hispano-Aleman de Calar Alto (CAHA, Almeria, Spain). CARMENES is funded by the German Max-Planck-Gesellschaft (MPG), the Spanish Consejo Superior de Investigaciones Cientificas (CSIC), the European Union through FEDER/ERF FICTS-2011-02 funds, and the members of the CARMENES Consortium (Max-Planck-Institut fur Astronomie, Instituto de Astrofisica de Andalucia, Landessternwarte Konigstuhl, Institut de Ciencies de l'Espai, Institut fur Astrophysik Gottingen, Universidad Complutense de Madrid, Thuringer Landessternwarte Tautenburg, Instituto de Astrofisica de Canarias, Hamburger Sternwarte, Centro de Astrobiologia and Centro Astronomico Hispano-Aleman), with additional contributions by the Spanish Ministry of Economy, the German Science Foundation through the Major Research Instrumentation Programme and DFG Research Unit FOR2544 >Blue Planets around Red Stars>, the Klaus Tschira Stiftung, the states of Baden-Wurttemberg and Niedersachsen, and by the Junta de Andalucia. Based on data from the CARMENES data archive at CAB (INTA-CSIC). This article is based on observations made with the MuSCAT2 instrument, developed by ABC, at Telescopio Carlos Sanchez operated on the island of Tenerife by the IAC in the Spanish Observatorio del Teide. Data were partly collected with the 150-cm and 90-cm telescopes at the Sierra Nevada Observatory (SNO) operated by the Instituto de Astrofisica de Andalucia (IAA-CSIC). Data were partly obtained with the MONET/South telescope of the MOnitoring NEtwork of Telescopes, funded by the Alfried Krupp von Bohlen und Halbach Foundation, Essen, and operated by the Georg-August-Universitat Gottingen, the McDonald Observatory of the University of Texas at Austin, and the South African Astronomical Observatory. We acknowledge financial support from the Spanish Agencia Estatal de Investigacion of the Ministerio de Ciencia, Innovacion y Universidades and the European FEDER/ERF funds through projects AYA2015-69350-C3-2-P, AYA2016-79425-C3-1/2/3-P, AYA2018-84089, BES-2017-080769, BES-2017-082610, ESP2015-65712-C5-5-R, ESP2016-80435-C2-1/2-R, ESP2017-87143-R, ESP2017-87676-2-2, ESP2017-87676-C5-1/2/5-R, FPU15/01476, RYC-2012-09913, the Centre of Excellence >Severo Ochoa> and >Maria de Maeztu> awards to the Instituto de Astrofisica de Canarias (SEV-2015-0548), Instituto de Astrofisica de Andalucia (SEV-2017-0709), and Centro de Astrobiologia (MDM-2017-0737), the Generalitat de Catalunya through CERCA programme>, the Deutsches Zentrum fur Luft-und Raumfahrt through grants 50OW0204 and 50OO1501, the European Research Council through grant 6 94 513, the Italian Ministero dell'instruzione, dell'universita de della ricerca and Universita degli Studi di Roma Tor Vergata through FFABR 2017 and >Mission: Sustainability 2016>, the UK Science and Technology Facilities Council through grant ST/P000592/1, the Israel Science Foundation through grant 848/16, the Chilean CONICYT-FONDECYT through grant 31 80 405, the Mexican CONACYT through grant CVU 4 48 248, the JSPS KAKENHI through grants JP18H01265 and 18H05439, and the JST PRESTO through grant JPMJPR1775.

NGC 2345 is a young open cluster hosting seven blue and red supergiants, low metallicity and a high fraction of Be stars which makes it a privileged laboratory to study stellar evolution. We aim to improve the determination of the cluster parameters and study the Be phenomenon. Our objective is also to characterise its seven evolved stars by deriving their atmospheric parameters and chemical abundances. We performed a complete analysis combining for the first time $ubvy$ photometry with spectroscopy as well as $Gaia$ Data Release 2. We obtained spectra with classification purposes for 76 stars and high-resolution spectroscopy for an in-depth analysis of the blue and red evolved stars. We identify a new red supergiant and 145 B-type likely members within a radius of 18.7$\pm$1.2 arcmin, which implies an initial mass, $M_{\textrm{cl}}\approx$5200 M$_{\odot}$. We find a distance of 2.5$\pm$0.2 kpc for NGC 2345, placing it at $R_{\textrm{GC}}$=10.2$\pm$0.2 kpc. Isochrone fitting supports an age of 56$\pm$13 Ma, implying masses around 6.5 M$_{\odot}$ for the supergiants. A high fraction of Be stars ($\approx$10$\%$) is found. From the spectral analysis we estimate for the cluster an average $v_{\textrm{rad}}$=$+58.6\pm0.5$ kms$^{-1}$ and a low metallicity, [Fe/H]=$-$0.28$\pm$0.07. We also have determined chemical abundances for Li, O, Na, Mg, Si, Ca, Ti, Ni, Rb, Y, and Ba for the evolved stars. The chemical composition of the cluster is consistent with that of the Galactic thin disc. One of the K supergiants, S50, is a Li-rich star, presenting an A(Li)$\approx$2.1. An overabundance of Ba is found, supporting the enhanced $s$-process. NGC 2345 has a low metallicity for its Galactocentric distance, comparable to typical LMC stars. It is massive enough to serve as a testbed for theoretical evolutionary models for massive intermediate-mass stars., Comment: 26 pages, 19 figures and 16 tables. Accepted for publication in A&A

Context The study of exoplanet atmospheres is essential for understanding the formation, evolution, and composition of exoplanets. The transmission spectroscopy technique is playing a significant role in this domain. In particular, the combination of state-of-The-Art spectrographs at low-And high-spectral resolution is key to our understanding of atmospheric structure and composition. Aims. We observed two transits of the close-in sub-Saturn-mass planet, WASP-127b, with ESPRESSO in the frame of the Guaranteed Time Observations Consortium. We aim to use these transit observations to study the system architecture and the exoplanet atmosphere simultaneously. Methods. We used the Reloaded Rossiter-McLaughlin technique to measure the projected obliquity λ and the projected rotational velocity veq sin(i∗). We extracted the high-resolution transmission spectrum of the planet to study atomic lines. We also proposed a new cross-correlation framework to search for molecular species and we applied it to water vapor. Results. The planet is orbiting its slowly rotating host star (veq sin(i∗) = 0.53-0.05+0.07 km s-1) on a retrograde misaligned orbit (λ =-128.41-5.46+5.60 °). We detected the sodium line core at the 9-σ confidence level with an excess absorption of 0.34 ± 0.04%, a blueshift of 2.74 ± 0.79 km s-1, and a full width at half maximum of 15.18 ± 1.75 km s-1. However, we did not detect the presence of other atomic species but set upper limits of only a few scale heights. Finally, we put a 3-σ upper limit on the average depth of the 1600 strongest water lines at equilibrium temperature in the visible band of 38 ppm. This constrains the cloud-deck pressure between 0.3 and 0.5 mbar by combining our data with low-resolution data in the near-infrared and models computed for this planet. Conclusions. WASP-127b, with an age of about 10 Gyr, is an unexpected exoplanet by its orbital architecture but also by the small extension of its sodium atmosphere (~7 scale heights). ESPRESSO allows us to take a step forward in the detection of weak signals, thus bringing strong constraints on the presence of clouds in exoplanet atmospheres. The framework proposed in this work can be applied to search for molecular species and study cloud-decks in other exoplanets., With funding from the Spanish government through the "María de Maeztu Unit of Excellence" accreditation (MDM-2017-0737)

We investigated almost 500 stars distributed among 193 binary or multiple systems made of late-F, G-, or early-K primaries and late-K or M dwarf companion candidates. For all of them, we compiled or measured coordinates, J-band magnitudes, spectral types, distances, and proper motions.With these data, we established a sample of 192 physically bound systems. In parallel, we carried out observations with HERMES/Mercator and obtained high resolution spectra for the 192 primaries and five secondaries. We used these spectra and the automatic StePar code for deriving precise stellar atmospheric parameters: Teff, log g, Vmicro, and chemical abundances for 13 atomic species, including [Fe/H]. After computing Galactocentric space velocities for all the primary stars, we performed a kinematic analysis and classified them in different Galactic populations and stellar kinematic groups of very different ages, which match our own metallicity determinations and isochronal age estimations. In particular, we identified three systems in the halo and 33 systems in the young Local Association, Ursa Major and Castor moving groups, and IC 2391 and Hyades Superclusters. We finally studied the exoplanet-metallicity relation in our 193 primaries and made a list 13 M-dwarf companions with very high metallicity that can be the targets of new dedicated exoplanet surveys. All in all, our dataset will be of great help for future works on the accurate determination of metallicity of M dwarfs., accepted for publication in MNRAS, 49 pages, 11 figures and 10 tables

NGC 3105 is a young open cluster hosting blue, yellow and red supergiants. This rare combination makes it an excellent laboratory to constrain evolutionary models of high-mass stars. It is poorly studied and fundamental parameters such as its age or distance are not well defined. We intend to characterize in an accurate way the cluster as well as its evolved stars, for which we derive for the first time atmospheric parameters and chemical abundances. We identify 126 B-type likely members within a radius of 2.7$\pm$0.6 arcmin, which implies an initial mass, $M_{cl}\approx$4100 M$_{\odot}$. We find a distance of 7.2$\pm$0.7 kpc for NGC 3105, placing it at $R_{GC}$=10.0$\pm$1.2 kpc. Isochrone fitting supports an age of 28$\pm$6 Ma, implying masses around 9.5 M$_{\odot}$ for the supergiants. A high fraction of Be stars ($\approx$25 %) is found at the top of the main sequence down to spectral type b3. From the spectral analysis we estimate for the cluster a $v_{rad}$=+46.9$\pm$0.9 km s$^{-1}$ and a low metallicity, [Fe/H]=-0.29$\pm$0.22. We also have determined, for the first time, chemical abundances for Li, O, Na, Mg, Si, Ca, Ti, Ni, Rb, Y, and Ba for the evolved stars. The chemical composition of the cluster is consistent with that of the Galactic thin disc. An overabundance of Ba is found, supporting the enhanced $s$-process. NGC 3105 has a low metallicity for its Galactocentric distance, comparable to typical LMC stars. It is a valuable spiral tracer in a very distant region of the Carina-Sagittarius spiral arm, a poorly known part of the Galaxy. As one of the few Galactic clusters containing blue, yellow and red supergiants, it is massive enough to serve as a testbed for theoretical evolutionary models close to the boundary between intermediate and high-mass stars., 18 pages, 13 figures. Accepted for publication in A&A

The CARMENES radial velocity (RV) survey is observing 324 M dwarfs to search for any orbiting planets. In this paper, we present the survey sample by publishing one CARMENES spectrum for each M dwarf. These spectra cover the wavelength range 520¿1710 nm at a resolution of at least R >80 000, and we measure its RV, H¿ emission, and projected rotation velocity. We present an atlas of high-resolution M-dwarf spectra and compare the spectra to atmospheric models. To quantify the RV precision that can be achieved in low-mass stars over the CARMENES wavelength range, we analyze our empirical information on the RV precision from more than 6500 observations. We compare our high-resolution M-dwarf spectra to atmospheric models where we determine the spectroscopic RV information content, Q, and signal-to-noise ratio. We find that for all M-type dwarfs, the highest RV precision can be reached in the wavelength range 700¿900 nm. Observations at longer wavelengths are equally precise only at the very latest spectral types (M8 and M9). We demonstrate that in this spectroscopic range, the large amount of absorption features compensates for the intrinsic faintness of an M7 star. To reach an RV precision of 1 m s¿1 in very low mass M dwarfs at longer wavelengths likely requires the use of a 10 m class telescope. For spectral types M6 and earlier, the combination of a red visual and a near-infrared spectrograph is ideal to search for low-mass planets and to distinguish between planets and stellar variability. At a 4 m class telescope, an instrument like CARMENES has the potential to push the RV precision well below the typical jitter level of 3-4 m s-1. © ESO 2018., We thank an anonymous referee for prompt attention and helpful comments that helped to improve the quality of this paper. CARMENES is an instrument for the Centro Astronomico Hispano-Aleman de Calar Alto (CAHA, Almeria, Spain). CARMENES is funded by the German Max-Planck-Gesellschaft (MPG), the Spanish Consejo Superior de Investigaciones Cientificas (CSIC), the European Union through FEDER/ERF FICTS-2011-02 funds, and the members of the CARMENES Consortium (Max-Planck-Institut fur Astronomie, Instituto de Astrofisica de Andalucia, Landessternwarte Konigstuhl, Institut de Ciencies de l'Espai, Insitut fur Astrophysik Gottingen, Universidad Complutense de Madrid, Thuringer Landessternwarte Tautenburg, Instituto de Astrofisica de Canarias, Hamburger Sternwarte, Centro de Astrobiologia and Centro Astronomico Hispano-Aleman), with additional contributions by the Spanish Ministry of Economy, the German Science Foundation through the Major Research Instrumentation Programme and DFG Research Unit FOR2544 >Blue Planets around Red Stars>, the Klaus Tschira Stiftung, the states of Baden-Wurttemberg and Niedersachsen, and by the Junta de Andalucia. This work has made use of the VALD database, operated at Uppsala University, the Institute of Astronomy RAS in Moscow, and the University of Vienna. We acknowledge the following funding programs: European Research Council (ERC-279347), Deutsche Forschungsgemeinschaft (RE 1664/12-1, RE 2694/4-1), Bundesministerium fur Bildung und Forschung (BMBF-05A14MG3, BMBF-05A17MG3), Spanish Ministry of Economy and Competitiveness (MINECO, grants AYA2015-68012-C2-2-P, AYA2016-79425-C3-1,2,3-P, AYA2015-69350-C3-2-P, AYA2014-54348-C03-01, AYA2014-56359-P, AYA2014-54348-C3-2R, AYA2016-79425-C3-3-P and 2013 Ramon y Cajal program RYC-2013-14875), Fondo Europeo de Desarrollo Regional (FEDER, grant ESP2016-80435-C2-1-R, ESP2015-65712-C5-5-R), Generalitat de Catalunya/CERCA programme, Spanish Ministerio de Educacion, Cultura y Deporte, programa de Formacion de Profesorado Universitario (grant FPU15/01476), Deutsches Zentrum fur Luft- und Raumfahrt (grants 50OW0204 and 50OO1501), Office of Naval Research Global (award no. N62909-15-1-2011), Mexican CONACyT grant CB-2012-183007.

The design and construction of CARMENES has been presented at previous SPIE conferences. It is a next-generation radial-velocity instrument at the 3.5m telescope of the Calar Alto Observatory, which was built by a consortium of eleven Spanish and German institutions. CARMENES consists of two separate échelle spectrographs covering the wavelength range from 0.52 to 1.71¿m at a spec-tral resolution of R < 80,000, fed by fibers from the Cassegrain focus of the telescope. CARMENES saw ¿First Light¿ on Nov 9, 2015. During the commissioning and initial operation phases, we established basic performance data such as throughput and spectral resolution. We found that our hollow-cathode lamps are suitable for precise wavelength calibration, but their spectra contain a number of lines of neon or argon that are so bright that the lamps cannot be used in simultaneous exposures with stars. We have therefore adopted a calibration procedure that uses simultaneous star / Fabry Pérot etalon exposures in combination with a cross-calibration between the etalons and hollow-cathode lamps during daytime. With this strategy it has been possible to achieve 1-2 m/s precision in the visible and 5-10 m/s precision in the near-IR; further improvements are expected from ongoing work on temperature control, calibration procedures and data reduction. Comparing the RV precision achieved in different wavelength bands, we find a ¿sweet spot¿ between 0.7 and 0.8¿m, where deep TiO bands provide rich RV information in mid-M dwarfs. This is in contrast to our pre-survey models, which predicted comparatively better performance in the near-IR around 1¿m, and explains in part why our near-IR RVs do not reach the same precision level as those taken with the visible spectrograph. We are now conducting a large survey of 340 nearby M dwarfs (with an average distance of only 12pc), with the goal of finding terrestrial planets in their habitable zones. We have detected the signatures of several previously known or suspected planets and also discovered several new planets. We find that the radial velocity periodograms of many M dwarfs show several significant peaks. The development of robust methods to distinguish planet signatures from activity-induced radial velocity jitter is therefore among our priorities. Due to its large wavelength coverage, the CARMENES survey is generating a unique data set for studies of M star atmospheres, rotation, and activity. The spectra cover important diagnostic lines for activity (H alpha, Na I D1 and D2, and the Ca II infrared triplet), as well as FeH lines, from which the magnetic field can be inferred. Correlating the time series of these features with each other, and with wavelength-dependent radial velocities, provides excellent handles for the discrimination between planetary companions and stellar radial velocity jitter. These data are also generating new insight into the physical properties of M dwarf atmospheres, and the impact of activity and flares on the habitability of M star planets. © 2018 SPIE., CARMENES is an instrument for the Centro Astronomico Hispano-Aleman de Calar Alto (CAHA, Almeria, Spain). CARMENES is funded by the German Max-Planck-Gesellschaft (MPG), the Spanish Consejo Superior de Investigaciones Cientificas (CSIC), the European Union through FEDER/ERF FICTS-2011-02 funds, and the members of the CARMENES Consortium (Max-Planck-Institut fur Astronomie, Instituto de Astrofisica de Andalucia, Landessternwarte Konigstuhl, Institut de Ciencies de l'Espai, Insitut fur Astrophysik Gottingen, Universidad Complutense de Madrid, Thuringer Landessternwarte Tautenburg, Instituto de Astrofisica de Canarias, Hamburger Sternwarte, Centro de Astrobiologia and Centro Astronomico Hispano-Aleman), with additional contributions by the Spanish Ministry of Science, the German Science Foundation through the Major Research Instrumentation Program and DFG Research Unit FOR2544 "Blue Planets around Red Stars", the Klaus Tschira Stiftung, the states of Baden-Wurttemberg and Niedersachsen, and by the Junta de Andalucia.

NGC 6067 is a young open cluster hosting the largest population of evolved stars among known Milky Way clusters in the 50-150 Ma age range. It thus represents the best laboratory in our Galaxy to constrain the evolutionary tracks of 5-7 M$_{\odot}$ stars. We have used high-resolution spectra of a large sample of bright cluster members (45), combined with archival photometry, to obtain accurate parameters for the cluster as well as stellar atmospheric parameters. We derive a distance of 1.78$\pm$0.12 kpc, an age of 90$\pm$20 Ma and a tidal radius of 14.8$^{6.8}_{3.2}$ arcmin. We estimate an initial mass above 5700 M$_{\odot}$, for a present-day evolved population of two Cepheids, two A supergiants and 12 red giants with masses $\approx$6 M$_{\odot}$. We also determine chemical abundances of Li, O, Na, Mg, Si, Ca, Ti, Ni, Rb, Y and Ba for the red clump stars. We find a supersolar metallicity, [Fe/H]=+0.19$\pm$0.05, and a homogeneus chemical composition, consistent with the Galactic metallicity gradient. The presence of a Li-rich red giant, star 276 with A(Li)=2.41, is also detected. An over-abundance of Ba is found, supporting the enhanced $s$-process. The ratio of yellow to red giants is much smaller than one, in agreement with models with moderate overshooting, but the properties of the cluster Cepheids do not seem consistent with current Padova models for supersolar metallicity., Comment: 27 pages, 21 figures, 17 tables, Accepted for publication in MNRAS

The CARMENES instrument is a pair of high-resolution (R greater than or similar to 80, 000) spectrographs covering the wavelength range from 0.52 to 1.71 mu m, optimized for precise radial velocity measurements. It was installed and commissioned at the 3.5 m telescope of the Calar Alto observatory in Southern Spain in 2015. The first large science program of CARMENES is a survey of similar to 300 M dwarfs, which started on Jan 1, 2016. We present an overview of all subsystems of CARMENES (front end, fiber system, visible-light spectrograph, near-infrared spectrograph, calibration units, etalons, facility control, interlock system, instrument control system, data reduction pipeline, data flow, and archive), and give an overview of the assembly, integration, verification, and commissioning phases of the project. We show initial results and discuss further plans for the scientific use of CARMENES.

The Gaia-ESO Survey is obtaining high-quality spectroscopic data for about 10^5 stars using FLAMES at the VLT. UVES high-resolution spectra are being collected for about 5000 FGK-type stars. These UVES spectra are analyzed in parallel by several state-of-the-art methodologies. Our aim is to present how these analyses were implemented, to discuss their results, and to describe how a final recommended parameter scale is defined. We also discuss the precision (method-to-method dispersion) and accuracy (biases with respect to the reference values) of the final parameters. These results are part of the Gaia-ESO 2nd internal release and will be part of its 1st public release of advanced data products. The final parameter scale is tied to the one defined by the Gaia benchmark stars, a set of stars with fundamental atmospheric parameters. A set of open and globular clusters is used to evaluate the physical soundness of the results. Each methodology is judged against the benchmark stars to define weights in three different regions of the parameter space. The final recommended results are the weighted-medians of those from the individual methods. The recommended results successfully reproduce the benchmark stars atmospheric parameters and the expected Teff-log g relation of the calibrating clusters. Atmospheric parameters and abundances have been determined for 1301 FGK-type stars observed with UVES. The median of the method-to-method dispersion of the atmospheric parameters is 55 K for Teff, 0.13 dex for log g, and 0.07 dex for [Fe/H]. Systematic biases are estimated to be between 50-100 K for Teff, 0.10-0.25 dex for log g, and 0.05-0.10 dex for [Fe/H]. Abundances for 24 elements were derived: C, N, O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Mo, Ba, Nd, and Eu. The typical method-to-method dispersion of the abundances varies between 0.10 and 0.20 dex., Comment: 39 pages, A&A accepted

In recent years, temperature scales in cool supergiants (CSGs) have been disputed, and the possibility that spectral types (SpTs) do not depend primarily on temperature has been raised. We explore the relations between different observed parameters and the capability of deriving accurate intrinsic stellar parameters from them through the analysis of the largest spectroscopic sample of CSGs to date from SMC and LMC. We explore possible correlations between different observational parameters, also making use of near- and mid-infrared colours and literature on photometric variability. Direct comparison between the behaviour of atomic lines (Fe I, Ti I, and Ca II) in the observed spectra and synthetic atmospheric models provides compelling evidence that effective temperature is the prime underlying variable driving the SpT sequence in CSGs. However, there is a clear correlation between SpT and luminosity, with later ones tending to correspond to more luminous stars with heavier mass loss. The population of CSGs in the SMC is characterised by a higher degree of spectral variability, early spectral types (centred on type K1) and low mass-loss rates (at least as measured by dust-sensitive mid-infrared colours). The population in the LMC displays less spectroscopic variability and later spectral types. The distribution of spectral types is not single-peaked. Instead, the brightest CSGs have a significantly different distribution from less luminous objects, presenting mostly M subtypes (centred on M2), and increasing mass-loss rates for later types. In conclusion, the observed properties of CSGs in the SMC and the LMC cannot be described correctly by standard evolutionary models. The very strong correlation between spectral type and bolometric luminosity, supported by all data from the Milky Way, cannot be reproduced at all by current evolutionary tracks., 25 pages, 24 figures

Type Ia supernovae are thought to occur when a white dwarf made of carbon and oxygen accretes sufficient mass to trigger a thermonuclear explosion1. The accretion could be slow, from an unevolved (main-sequence) or evolved (subgiant or giant) star2, 3 (the single-degenerate channel), or rapid, as the primary star breaks up a smaller orbiting white dwarf3, 4 (the double-degenerate channel). A companion star will survive the explosion only in the single-degenerate channel5. Both channels might contribute to the production of type Ia supernovae6, 7, but the relative proportions of their contributions remain a fundamental puzzle in astronomy. Previous searches for remnant companions have revealed one possible case for SN 1572 (refs 8, 9), although that has been questioned10. More recently, observations have restricted surviving companions to be small, main-sequence stars11, 12, 13, ruling out giant companions but still allowing the single-degenerate channel. Here we report the results of a search for surviving companions of the progenitor of SN 1006 (ref. 14). None of the stars within 4 arc minutes of the apparent site of the explosion is associated with the supernova remnant, and we can firmly exclude all giant and subgiant stars from being companions of the progenitor. In combination with previous results, our findings indicate that fewer than 20 per cent of type Ia supernovae occur through the single-degenerate channel., This work was supported by the Spanish Ministerio de Ciencia e Innovación (MICINN), the Universidad Complutense de Madrid (UCM) and the Comunidad de Madrid, and is based on observations collected with the UVES spectrograph at the VLT/UT2 8.2-m Kueyen Telescope (ESO run ID, 69.D-0397(A)) at the Paranal Observatory, Chile. We are grateful to the Cerro Paranal Observatory staff and to the User Support Department of ESO for their hel.

We have completed a survey down to R = 15 mag of the stars within a circle of 4 arcmin radius around the nominal center of the remnant of SN 1006, one of the three historical Type Ia supernovae (the other two being SN 1572 and SN 1604), in search of a possible surviving binary companion of the white dwarf whose explosion gave rise to the supernova. The stellar parameters (effective temperature, surface gravity, and metallicity), as well as the radial velocities of all the stars, have been measured from spectra obtained with the UVES spectrograph at the VLT, and from the former and the available photometry, distances have been determined. Chemical abundances of the Fe-peak elements Cr, Mn, Co, and Ni have also been measured to check for possible contamination of the stellar surface by the supernova ejecta. The limiting magnitude of the survey would allow us to find stellar companions of the red-giant type, subgiant stars, and main–sequence stars down to F5–6. Unlike in SN 1572, where a subgiant of type G0–1 has been proposed as the companion of SN 1572, for SN 1006 we can discard the possibility that SN 1006 had a red giant or subgiant companion.

This paper describes the analysis of UVES and GIRAFFE spectra acquired by the Gaia-ESO Public Spectroscopic Survey in the fields of young clusters whose population includes pre-main sequence (PMS) stars. Both methods that have been extensively used in the past and new ones developed in the contest of the Gaia-ESO survey enterprise are available and used. The internal precision of these quantities is estimated by inter-comparing the results obtained by such different methods, while the accuracy is estimated by comparison with independent external data, like effective temperature and surface gravity derived from angular diameter measurements, on a sample of benchmarks stars. Specific strategies are implemented to deal with fast rotation, accretion signatures, chromospheric activity, and veiling. The analysis carried out on spectra acquired in young clusters' fields during the first 18 months of observations, up to June 2013, is presented in preparation of the first release of advanced data products. Stellar parameters obtained with the higher resolution and larger wavelength coverage from UVES are reproduced with comparable accuracy and precision using the smaller wavelength range and lower resolution of the GIRAFFE setup adopted for young stars, which allows us to provide with confidence stellar parameters for the much larger GIRAFFE sample. Precisions are estimated to be $\approx$ 120 K r.m.s. in Teff, $\approx$0.3 dex r.m.s. in logg, and $\approx$0.15 dex r.m.s. in [Fe/H], for both the UVES and GIRAFFE setups., 22 pages, 18 figures, accepted for publication on A&A

In this contribution talk we summarize the results of our ongoing project of detailed analysis of the chemical content (chemical tagging) as a promising powerful method to provide clear constraints on the membership of FGK kinematic candidates to stellar kinematic groups of different ages that can be used as an alternative or complementary to the methods that use kinematics, photometry or age indicators. This membership information is very important to better understand the star formation history in the solar neighborhood discerning between field-like stars (associated with dynamical resonances (bar) or spiral structure) and real physical structures of coeval stars with a common origin (debris of star-forming aggregates in the disk). We have already applied the chemical tagging method to constrain the membership of FGK candidate stars to the Hyades supercluster and the Ursa Major moving group and in this contribution we present the preliminary results of our study of the Castor moving group., Comment: Proceedings of IAU Symposium 314 'Young Stars & Planets Near the Sun', held on May 11-15 2015 in Atlanta (GA), USA (J. H. Kastner, B. Stelzer, & S. A. Metchev, eds.)

In the current era of large spectroscopic surveys of the Milky Way, reference stars for calibrating astrophysical parameters and chemical abundances are of paramount importance. We determine elemental abundances of Mg, Si, Ca, Sc, Ti, V, Cr, Mn, Co and Ni for our predefined set of Gaia FGK benchmark stars. By analysing high-resolution and high-signal to noise spectra taken from several archive datasets, we combined results of eight different methods to determine abundances on a line-by-line basis. We perform a detailed homogeneous analysis of the systematic uncertainties, such as differential versus absolute abundance analysis, as well as we assess errors due to NLTE and the stellar parameters in our final abundances. Our results are provided by listing final abundances and the different sources of uncertainties, as well as line-by-line and method-by-method abundances. The Gaia FGK benchmark stars atmospheric parameters are already being widely used for calibration of several pipelines applied to different surveys. With the added reference abundances of 10 elements this set is very suitable to calibrate the chemical abundances obtained by these pipelines., Comment: Accepted for publication in A&A, Printer format: 65 pages, 18 figures, 25 tables

Context. Stars are born together from giant molecular clouds and, if we assume that the priors were chemically homogeneous and well-mixed, we expect them to share the same chemical composition. Most of the stellar aggregates are disrupted while orbiting the Galaxy and most of the dynamic information is lost, thus the only possibility of reconstructing the stellar formation history is to analyze the chemical abundances that we observe today. Aims. The chemical tagging technique aims to recover disrupted stellar clusters based merely on their chemical composition. We evaluate the viability of this technique to recover co-natal stars that are no longer gravitationally bound. Methods. Open clusters are co-natal aggregates that have managed to survive together. We compiled stellar spectra from 31 old and intermediate-age open clusters, homogeneously derived atmospheric parameters, and 17 abundance species, and applied machine learning algorithms to group the stars based on their chemical composition. This approach allows us to evaluate the viability and efficiency of the chemical tagging technique. Results. We found that stars at different evolutionary stages have distinct chemical patterns that may be due to NLTE effects, atomic diffusion, mixing, and biases. When separating stars into dwarfs and giants, we observed that a few open clusters show distinct chemical signatures while the majority show a high degree of overlap. This limits the recovery of co-natal aggregates by applying the chemical tagging technique. Nevertheless, there is room for improvement if more elements are included and models are improved., Comment: accepted for publication in Astronomy and Astrophysics. Corrected typos

Stellar kinematic groups are kinematical coherent groups of stars which might share a common origin.These groups spread through the Galaxy over time due to tidal effects caused by Galactic rotation and disc heating.However, the chemical information survives these processes. The information provided by the analysis of chemical elements can reveal the origin of these kinematic groups. Here we investigate the origin of the stars that belong to the Ursa Major Moving Group. We present high-resolution spectroscopic observations obtained from three different spectrographs of kinematically selected FGK stars of the Ursa Major moving group. Stellar atmospheric parameters (Teff, log(g), xi, and [Fe/H]) were determined using our own automatic code (StePar) which makes use of the sensitivity of iron equivalent widths measured in the spectra. We critically compare the StePar results with other methods (Teff values derived using the infrared flux method and log(g) values based on Hipparcos parallaxes). We derived the chemical abundances of 20 elements, and their [X/Fe] ratios of all stars in the sample. We perform a differential abundance analysis with respect to a reference star of the UMa MG (HD115043). We have also carried out a systematic comparison of the abundance pattern of the Ursa Major MG and the Hyades SC with the thin disc stellar abundances. Our chemical tagging analysis indicates that the Ursa Major MG is less affected by field star contamination than other moving groups (such as the Hyades SC). We find a roughly solar iron composition for the finally selected stars, whereas the [X/Fe] ratios are roughly sub-solar except for super-solar Barium abundance.We conclude that 29 out of 44 (i.e. 66 %) candidate stars share a similar chemical composition. In addition, we find that the abundance pattern of the Ursa Major MG might be marginally different from that of the Hyades SC., A&A, in press. arXiv admin note: text overlap with arXiv:1205.4879

Knowledge of the abundance distribution of star forming regions and young clusters is critical to investigate a variety of issues, from triggered star formation and chemical enrichment by nearby supernova explosions to the ability to form planetary systems.In spite of this, detailed abundance studies are currently available for relatively few regions. In this context, we present the analysis of the metallicity of the Gamma Velorum cluster, based on the products distributed in the first internal release of the Gaia-ESO Survey. The Gamma Velorum candidate members have been observed with FLAMES, using both UVES and Giraffe, depending on the target brightness and spectral type. In order to derive a solid metallicity determination for the cluster, membership of the observed stars must be first assessed. To this aim, we use several membership criteria including radial velocities, surface gravity estimates, and the detection of the photospheric lithium line. Out of the 80 targets observed with UVES, we identify 14 high-probability members. We find that the metallicity of the cluster is slightly subsolar, with a mean [Fe/H]=-0.057+/-0.018 dex. Although J08095427-4721419 is one of the high-probability members, its metallicity is significantly larger than the cluster average. We speculate about its origin as the result of recent accretion episodes of rocky bodies of ~60 M_Sun hydrogen-depleted material from the circumstellar disk., 13 pages, 10 figures, 7 tables, Accepted for publication in Astronomy & Astrophysics

Context. The homogenization of the stellar parameters is an important goal for large observational spectroscopic surveys, but it is very difficult to achieve it because of the diversity of the spectroscopic analysis methods used within a survey, such as spectrum synthesis and the equivalent width method. To solve this problem, constraints to the spectroscopic analysis can be set, such as the use of a common line-list. Aims. We present a procedure for selecting the best spectral lines from a given input line-list, which then allows us to derive accurate stellar parameters with the equivalent width method. Methods. To select the lines, we used four very well known benchmark stars, for which we have high-quality spectra. From an initial line-list, the equivalent width of each individual line was automatically measured for each benchmark star using ARES, then we performed a local thermodynamic equilibrium analysis with MOOG to compute individual abundances. The results allowed us to choose the best lines which give consistent abundance values for all the benchmark stars from which we then created a final line-list. Results. To verify its consistency, the compiled final line-list was tested for a small sample of stars. These stars were selected to cover different ranges in the parameter space for FGK stars. We show that the obtained parameters agree well with previously determined values., 9 pages. 5 figures, accepted for publication in A&A

Context. Recent metallicity determinations in young open clusters and star-forming regions suggest that the latter may be characterized by a slightly lower metallicity than the Sun and older clusters in the solar vicinity. However, these results are based on small statistics and inhomogeneous analyses. The Gaia-ESO Survey is observing and homogeneously analyzing large samples of stars in several young clusters and star-forming regions, hence allowing us to further investigate this issue. Aims. We present a new metallicity determination of the Chamaeleon I star-forming region, based on the products distributed in the first internal release of the Gaia-ESO Survey. Methods. 48 candidate members of Chamaeleon I have been observed with the high-resolution spectrograph UVES. We use the surface gravity, lithium line equivalent width and position in the Hertzsprung-Russell diagram to confirm the cluster members and we use the iron abundance to derive the mean metallicity of the region. Results. Out of the 48 targets, we confirm 15 high probability members. Considering the metallicity measurements for 9 of them, we find that the iron abundance of Chamaeleon I is slightly subsolar with a mean value [Fe/H]=-0.08+/-0.04 dex. This result is in agreement with the metallicity determination of other nearby star-forming regions and suggests that the chemical pattern of the youngest stars in the solar neighborhood is indeed more metal-poor than the Sun. We argue that this evidence may be related to the chemical distribution of the Gould Belt that contains most of the nearby star-forming regions and young clusters., Comment: 13 pages, 11 figures, 3 tables, Accepted for publication in Astronomy & Astrophysics

Stellar kinematic groups are kinematical coherent groups of stars that might have a common origin. These groups are dispersed throughout the Galaxy over time by the tidal effects of both Galactic rotation and disc heating, although their chemical content remains unchanged. The aim of chemical tagging is to establish that the abundances of every element in the analysis are homogeneus among the members. We study the case of the Hyades Supercluster to compile a reliable list of members (FGK stars) based on our chemical tagging analysis. For a total of 61 stars from the Hyades Supercluster, stellar atmospheric parameters (Teff, logg, xi, and [Fe/H]) are determined using our code called StePar, which is based on the sensitivity to the stellar atmospheric parameters of the iron EWs measured in the spectra. We derive the chemical abundances of 20 elements and find that their [X/Fe] ratios are consistent with Galactic abundance trends reported in previous studies. The chemical tagging method is applied with a carefully developed differential abundance analysis of each candidate member of the Hyades Supercluster, using a well-known member of the Hyades cluster as a reference (vB 153). We find that only 28 stars (26 dwarfs and 2 giants) are members, i.e. that 46% of our candidates are members based on the differential abundance analysis. This result confirms that the Hyades Supercluster cannot originate solely from the Hyades cluster., A&A, in press

Ehrenreich, D.et al., Ultrahot giant exoplanets receive thousands of times Earth’s insolation. Their high-temperature atmospheres (greater than 2,000 kelvin) are ideal laboratories for studying extreme planetary climates and chemistry. Daysides are predicted to be cloud-free, dominated by atomic species and much hotter than nightsides. Atoms are expected to recombine into molecules over the nightside, resulting in different day and night chemistries. Although metallic elements and a large temperature contrast have been observed, no chemical gradient has been measured across the surface of such an exoplanet. Different atmospheric chemistry between the day-to-night (‘evening’) and night-to-day (‘morning’) terminators could, however, be revealed as an asymmetric absorption signature during transit. Here we report the detection of an asymmetric atmospheric signature in the ultrahot exoplanet WASP-76b. We spectrally and temporally resolve this signature using a combination of high-dispersion spectroscopy with a large photon-collecting area. The absorption signal, attributed to neutral iron, is blueshifted by −11 ± 0.7 kilometres per second on the trailing limb, which can be explained by a combination of planetary rotation and wind blowing from the hot dayside. In contrast, no signal arises from the nightside close to the morning terminator, showing that atomic iron is not absorbing starlight there. We conclude that iron must therefore condense during its journey across the nightside., With funding from the Spanish government through the "María de Maeztu Unit of Excellence" accreditation (MDM-2017-0737)

Surveys have shown that super-Earth and Neptune-mass exoplanets are more frequent than gas giants around low-mass stars, as predicted by the core accretion theory of planet formation. We report the discovery of a giant planet around the very-low-mass star GJ 3512, as determined by optical and near-infrared radial-velocity observations. The planet has a minimum mass of 0.46 Jupiter masses, very high for such a small host star, and an eccentric 204-day orbit. Dynamical models show that the high eccentricity is most likely due to planet-planet interactions. We use simulations to demonstrate that the GJ 3512 planetary system challenges generally accepted formation theories, and that it puts constraints on the planet accretion and migration rates. Disk instabilities may be more efficient in forming planets than previously thought.Copyright © 2019 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science, This research was supported by the following programs, grants, and fellowships: Spanish Ministry for Science, Innovation and Universities (MCIU) ESP2014-54062-R, ESP2014-54362P, AYA2015-69350-C3-2-P, BES-2015-074542, AYA2016-79425-C3-1/2/3-P, ESP2016-76076-R, ESP2016-80435-C2-1-R, ESP2016-80435-C2-2-R, ESP2017-87143-R, ESP2017-87676-C05-02-R, ESP-2017-87676-2-2, RYC-2012-09913 (>Ramon y Cajal> program), and FPU15/01476; Israel Science Foundation grant 848/16, CONICYT-FONDECYT/Chile Postdoctorado 3180405; Deutsches Zentrum fur Luft-un Raumfahrt (DLR) 50OW0204 and 50OO1501; Italian Minister of Instruction, University and Research (MIUR), FFABR 2017; University of Rome Tor Vergata, >Mission: Sustainability 2016> fund; European Research Council under the European Union Horizon 2020 research and innovation program 694513; Mexican national council for science and technology CONACYT, CVU 448248; the >Center of Excellence Severo Ochoa> award for the Instituto de Astrofisica de Andalucia (SEV-2017-0709); Generalitat de Catalunya/CERCA program; Fondo Europeo de Desarollo Regional (FEDER); German Science Foundation (DFG) Research Unit FOR2544 >Blue Planets around Red Stars> and Priority Programs SPP 1833, >Building a Habitable Earth> and SPP 1992, >Exploring the Diversity of Extrasolar Planets> NSF grants PHY17-48958 and PHY-1607761; Swiss National Science Foundation under grant BSGIO_155816 >PlaneltsInTime' and within the framework of the NCCR PlanetS; Queen Mary University of London Scholarship and STFC Consolidated Grant ST/P000592/1; Spanish MCIU FPI-SO predoctoral contract BES-2017-082610 and the Knut and Alice Wallenberg Foundation.

The appendix tables are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/609/A117, Context. The main goal of the CARMENES survey is to find Earth-mass planets around nearby M-dwarf stars. Seven M dwarfs included in the CARMENES sample had been observed before with HIRES and HARPS and either were reported to have one short period planetary companion (GJ 15 A, GJ 176, GJ 436, GJ 536 and GJ 1148) or are multiple planetary systems (GJ 581 and GJ 876). Aims. We aim to report new precise optical radial velocity measurements for these planet hosts and test the overall capabilities of CARMENES. Methods. We combined our CARMENES precise Doppler measurements with those available from HIRES and HARPS and derived new orbital parameters for the systems. Bona-fide single planet systems were fitted with a Keplerian model. The multiple planet systems were analyzed using a self-consistent dynamical model and their best fit orbits were tested for long-term stability. Results. We confirm or provide supportive arguments for planets around all the investigated stars except for GJ 15 A, for which we find that the post-discovery HIRES data and our CARMENES data do not show a signal at 11.4 days. Although we cannot confirm the super-Earth planet GJ 15 Ab, we show evidence for a possible long-period (P = 7030 d) Saturn-mass (msini = 51.8M) planet around GJ 15 A. In addition, based on our CARMENES and HIRES data we discover a second planet around GJ 1148, for which we estimate a period P = 532.6 days, eccentricity e = 0.342 and minimum mass msini = 68.1M. Conclusions. The CARMENES optical radial velocities have similar precision and overall scatter when compared to the Doppler measurements conducted with HARPS and HIRES. We conclude that CARMENES is an instrument that is up to the challenge of discovering rocky planets around low-mass stars.© ESO, 2018., CARMENES is an instrument for the Centro Astronomico Hispano-Aleman de Calar Alto (CAHA, Almeria, Spain). CARMENES is funded by the German Max-Planck-Gesellschaft (MPG), the Spanish Consejo Superior de Investigaciones Cientificas (CSIC), the European Union through FEDER/ERF FICTS-2011-02 funds, and the members of the CARMENES Consortium (Max-Planck-Institut fur Astronomie, Instituto de Astrofisica de Andalucia, Landessternwarte Konigstuhl, Institut de Ciencies de l'Espai, Insitut fur Astrophysik Gottingen, Universidad Complutense de Madrid, Thuringer Landessternwarte Tautenburg, Instituto de Astrofisica de Canarias, Hamburger Sternwarte, Centro de Astrobiologia and Centro Astronomico Hispano-Aleman), with additional contributions by the Spanish Ministry of Economy, the German Science Foundation (DFG), the Klaus Tschira Stiftung, the states of Baden-Wurttemberg and Niedersachsen, the DFG Research Unit FOR2544 >Blue Planets around Red Stars>, and by the Junta de Andalucia. This work has made use of data from the European Space Agency (ESA) mission Gaia (https://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, https://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. This work used the Systemic Console package (Meschiari et al. 2009) for cross-checking our Keplerian and Dynamical fits and the python package astroML (VanderPlas et al. 2012) for the calculation of the GLS periodogram. The IEEC-CSIC team acknowledges support by the Spanish Ministry of Economy and Competitiveness (MINECO) and the Fondo Europeo de Desarrollo Regional (FEDER) through grant ESP2016-80435-C2-1-R, as well as the support of the Generalitat de Catalunya/CERCA programme. The IAA-CSIC team acknowledges support by the Spanish Ministry of Economy and Competitiveness (MINECO) through grants AYA2014-54348-C03-01 and AYA2016-79425-C3-3-P as well as FEDER funds. The UCM team acknowledges support by the Spanish Ministry of Economy and Competitiveness (MINECO) from projects AYA2015-68012-C2-2-P and AYA2016-79425- C3-1,2,3-P and the Spanish Ministerio de Educacion, Cultura y Deporte, programa de Formacion de Profesorado Universitario, under grant FPU15/01476. T. T. and M.K. thank to Jan Rybizki for the very helpful discussion in the early phases of this work. V.J.S.B. is supported by grant AYA2015-69350-C3-2-P from the Spanish Ministry of Economy and Competiveness (MINECO). J.C.S. acknowledges funding support from Spanish public funds for research under project ESP2015-65712-C5-5-R (MINECO/FEDER), and under Research Fellowship program >Ramon y Cajal> with reference RYC2012-09913 (MINECO/FEDER). The contributions of M.A. were supported by DLR (Deutsches Zentrum fur Luft- und Raumfahrt) through the grants 50OW0204 and 50OO1501. J.L.-S. acknowledges the Office of Naval Research Global (award No. N62909-15- 1-2011) for support. C.d.B. acknowledges that this work has been supported by Mexican CONACyT research grant CB-2012-183007 and the Spanish Ministry of Economy and Competitivity through projects AYA2014-54348-C3-2-R. J.I.G.H., and R.R. acknowledge financial support from the Spanish Ministry project MINECO AYA2014-56359-P. J.I.G.H. also acknowledges financial support from the Spanish MINECO under the 2013 Ramon y Cajal program MINECO RYC-2013-14875. V. Wolthoff acknowledges funding from the DFG Research Unit FOR2544 >Blue Planets around Red Stars>, project No. RE 2694/4-1.We thank the anonymous referee for the excellent comments that helped to improve the quality of this paper.

Gaia and its complementary spectroscopic surveys combined will yield the most comprehensive database of kinematic and chemical information of stars in the Milky Way. The Gaia FGK benchmark stars play a central role in this matter as they are calibration pillars for the atmospheric parameters and chemical abundances for various surveys. The spectroscopic analyses of the benchmark stars are done by combining different methods, and the results will be affected by the systematic uncertainties inherent in each method. In this paper we explore some of these systematic uncertainties. We determined line abundances of Ca, Cr, Mn and Co for four benchmark stars using six different methods. We changed the default input parameters of the different codes in a systematic way and found in some cases significant differences between the results. Since there is no consensus on the correct values for many of these default parameters, we urge the community to raise discussions towards standard input parameters that could alleviate the difference in abundances obtained by different methods. In this work we provide quantitative estimates of uncertainties in elemental abundances due to the effect of differing technical assumptions in spectrum modelling., A&A accepted

We report on the first star discovered to host a planet detected by radial velocity (RV) observations obtained within the CARMENES survey for exoplanets around M dwarfs. HD 147379 (V = 8.9 mag, M = 0.58 ± 0.08 M⊙), a bright M0.0 V star at a distance of 10.7 pc, is found to undergo periodic RV variations with a semi-amplitude of K = 5.1 ± 0.4 m s−1 and a period of P = 86.54 ± 0.06 d. The RV signal is found in our CARMENES data, which were taken between 2016 and 2017, and is supported by HIRES/Keck observations that were obtained since 2000. The RV variations are interpreted as resulting from a planet of minimum mass mP sin i = 25 ± 2 M⊕, 1.5 times the mass of Neptune, with an orbital semi-major axis a = 0.32 au and low eccentricity (e < 0.13). HD 147379 b is orbiting inside the temperate zone around the star, where water could exist in liquid form. The RV time-series and various spectroscopic indicators show additional hints of variations at an approximate period of 21.1 d (and its first harmonic), which we attribute to the rotation period of the star., FEDER/ERF FICTS-2011-02 funds, Major Research Instrumentation Programme and DFG Research Unit FOR2544 “Blue Planets around Red Stars, European Research Council (ERC-279347), Deutsche Forschungsgemeinschaft (RE 1664/12-1, RE 2694/4-1), Bundesministerium für Bildung und Forschung (BMBF-05A14MG3, BMBF-05A17MG3), Spanish Ministry of Economy and Competitiveness (MINECO, grants AYA2015-68012-C2-2-P, AYA2016-79425-C3-1,2,3-P, AYA2015-69350-C3-2-P, AYA2014-54348-C03- 01, AYA2014-56359-P, AYA2014-54348-C3-2-R, AYA2016-79425-C3-3-P and 2013 Ramòn y Cajal program RYC-2013-14875), Fondo Europeo de Desarrollo Regional (FEDER, grant ESP2016-80435-C2-1-R, ESP2015-65712-C5- 5-R), Generalitat de Catalunya/CERCA programme, Spanish Ministerio de Educación, Cultura y Deporte, programa de Formación de Profesorado Universitario (grant FPU15/01476), Deutsches Zentrum für Luft- und Raumfahrt (grants 50OW0204 and 50OO1501), Office of Naval Research Global (award no. N62909-15-1-2011), Mexican CONACyT grant CB-2012-183007.

The ESPRESSO spectrograph is a new powerful tool to detect and characterize extrasolar planets. Its design allows unprecedented radial velocity precision (down to a few tens of cm/s) and long-term thermo-mechanical stability. We present the first standalone detection of an extrasolar planet by blind radial velocity search using ESPRESSO and aim at showing the power of the instrument in characterizing planetary signals at different periodicities in long time spans. We use 41 ESPRESSO measurements of HD\,22496 within a time span of 895 days with a median photon noise of 18 cm/s. A radial velocity analysis is performed to test the presence of planets in the system and to account for the stellar activity of this K5-K7 main sequence star. For benchmarking and comparison, we attempt the detection with 43 archive HARPS measurements and compare the results yielded by the two datasets. We also use four TESS sectors to search for transits. We find radial velocity variations compatible with a close-in planet with an orbital period of $P=5.09071\pm0.00026$ days when simultaneously accounting for the effects of stellar activity at longer time scales ($P_{\rm rot}=34.99^{+0.58}_{-0.53}$ days). We characterize the physical and orbital properties of the planet and find a minimum mass of $5.57^{+0.73}_{-0.68}$ $\mathrm{M}_{\oplus}$, right in the dichotomic regime between rocky and gaseous planets. Although not transiting according to TESS data, if aligned with the stellar spin axis, the absolute mass of the planet must be below 16 $\mathrm{M}_{\oplus}$. We find no significant evidence for additional signals with semi-amplitudes above 56 cm/s at 95% confidence. With a modest set of radial velocity measurements, ESPRESSO is capable of detecting and characterizing low-mass planets and constrain the presence of planets in the habitable zone of K-dwarfs down to the rocky-mass regime., Comment: Accepted for publication in A&A. 12 pages, 8 figures, 3 tables