Several spectroscopic analyses of stars with planets have recently been carried out. One of the most remarkable results is that planet-harbouring stars are on average more metal-rich than solar-type disc stars. Two main explanations have been suggested to link this metallicity excess with the presence of planets. The first of these, the “self-enrichement” hypothesis, attributes the origin of the observed overabundance of metals to the accretion of large amounts of metal-rich H- and He-depleted rocky planetesimal materials on to the star. The opposite view, the “primordial” hypothesis, considers the metallicity enhancement to be caused by the high metal content of the protoplanetary cloud from which the planetary system formed. Light elements may give fundamental information about the mixing, diffusion and angular momentum history of exoplanets hosts, as well as stellar activity caused by interaction with. Studies of Be, Li and the isotopic could give evidences to distinguish between different planet formation theories. Evidences of pollution have been found in HD82943 by Israelian et al.(2001, Nature, 411, 163; 2003, A&A, 405, 753).
The “self-enrichement” scenario should lead to a relative overabundance of refractories, such as Si, Mg, Ca, Ti and the iron-group elements, compared to volatiles, such as CNO, S and Zn. Differents spectroscopic studies of Fe (Santos et al. 2001, A&A, 373, 1019; 2003, A&A, 398, 363; 2004, A&A, 415, 1153) and other elements (Bodaghee et al 2003, A&A, 404, 715; Ecuvillon, Israelian, Santos et al. 2004, A&A, 418, 703; 2004, A&A, 426, 619) have been completed.
The spectroscopic analisis of metal rich stars can also give us a valuable information about yields of chemical elements produced by supernovae during the last 10 Gyr. An alternative method to investigate products of supernova explosions is by studying secondary stars in Low Mass X-ray binary systems (LMXB). The secondary stars in LMXBs have survived the supernova explosions and could have captured a part of the matter ejected during the explosion. This material can be mixed in the convection zone in a way that the final surface abundanced will be altered. Thus, a study of abundance anomalies in the atmospheres of these stars can provide us an information about nucleosynthesis and evolution of massive stars and also about supernova explosions. This new idea was applied for the first time by Israelian et al. (1999, Nature 401, 142) in the spectroscopic study of GRO J1655-40 (Nova Scorpii 1994), a LMXB with a black hole which has the most reliable mass determination. The analysis has shown that the abundances of O, Mg, Si and S are from 6 to 10 times larger compared with the Sun. These results were considered as the evidence that a supernova explosion took place and created the black hole in the system where the low mass secondary star could not produce these elements
- The planet-metallicity correlation is reviewed showing that the metallicity distribution of stars hosting low-mass planets (below 30 M⊕) is indistinguishable from that from the solar neighborhood sample in terms of metallicity distribution.
- We found that 3D 6Li/7Li corrections are always negative, showing that 1D LTE analysis can significantly overestimate the presence of 6Li (up to 4.9% points) in the atmospheres of solar-like dwarf stars. Although 3D NLTE spectral synthesis implies an extensive computational effort, the results can be made accessible with parametric tools like the ones presented by us
- We have analyzed the behaviour of chemical abundances of Cu, Zn, Sr, Y, Zr, Ba, Ce, Nd, and Eu in the large and homogeneous HARPS-GTO planet search sample.We compared the [X/Fe] ratios of such elements in different metallicity bins and we find that planet hosts present higher abundances of Zn for [Fe/H] < -0.1 dex.
- We found that 100% of planetary sample in HARPS-GTO present C/O < 0.8. 86% of stars with high-mass companions present 0.8 > C/O > 0.4, while 14% present C/O values lower than 0.4. Regarding Mg/Si, all stars with low-mass planetary companion showed values between one and two, while 85% of the high-mass companion sample does.
A compositional link between rocky exoplanets and their host stars
Stars and planets both form by accreting material from a surrounding disk. Because they grow from the same material, theory predicts that there should be a relationship between their compositions. In this study, we search for a compositional link between rocky exoplanets and their host stars. We estimate the iron-mass fraction of rocky exoplanetsAdibekyan, Vardan et al.
The CARMENES search for exoplanets around M dwarfs. Stellar atmospheric parameters of target stars with SteParSyn
We determined effective temperatures, surface gravities, and metallicities for a sample of 343 M dwarfs observed with CARMENES, the double-channel, high-resolution spectrograph installed at the 3.5 m telescope at Calar Alto Observatory. We employed SteParSyn, a Bayesian spectral synthesis implementation particularly designed to infer the stellarMarfil, E. et al.
Chemical abundances of 1111 FGK stars from the HARPS GTO planet search program. IV. Carbon and C/O ratios for Galactic stellar populations and planet hosts
Context. To understand the formation and composition of planetary systems, it is essential to have insights into the chemical composition of their host stars. In particular, C/O elemental ratios are useful for constraining the density and bulk composition of terrestrial planets. Aims: We study the carbon abundances with a twofold objective. On theDelgado Mena, E. et al.
SWEET-Cat 2.0: The Cat just got SWEETer. Higher quality spectra and precise parallaxes from Gaia eDR3
Aims: The catalog of Stars With ExoplanETs (SWEET-Cat) was originally introduced in 2013. Since then many more exoplanets have been confirmed, increasing significantly the number of host stars listed there. A crucial step toward a comprehensive understanding of these new worlds is the precise and homogeneous characterization of their host starsSousa, S. G. et al.
Hubble spectroscopy of LB-1: Comparison with B+black-hole and Be+stripped-star models
Context. LB-1 (alias ALS 8775) has been proposed as either an X-ray dim B-type star plus black hole (B+BH) binary or a Be star plus an inflated stripped star (Be+Bstr) binary. The latter hypothesis contingent upon the detection and characterization of the hidden broad-lined star in a composite optical spectrum. Aims: Our study is aimed at testingLennon, D. J. et al.
Stellar clustering and orbital architecture of planetary systems
Context. Revealing the mechanisms shaping the architecture of planetary systems is crucial for our understanding of their formation and evolution. In this context, it has been recently proposed that stellar clustering might be the key in shaping the orbital architecture of exoplanets. Aims: The main goal of this work is to explore the factors thatAdibekyan, V. et al.
The Gaia-ESO Survey: Calibrating the lithium-age relation with open clusters and associations. I. Cluster age range and initial membership selections
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 activityGutiérrez Albarrán, M. L. et al.
Benchmark stars, benchmark spectrographs. Detailed spectroscopic comparison of ESPRESSO, PEPSI, and HARPS data for Gaia benchmark stars
Context. Gaia benchmark stars are selected to be calibration stars for different spectroscopic surveys. Very high-quality and homogeneous spectroscopic data for these stars are therefore required. We collected ultrahigh-resolution ESPRESSO spectra for 30 of the 34 Gaia benchmark stars and made them public. Aims: We quantify the consistency of theAdibekyan, V. et al.
Phase-dependent Study of Near-infrared Disk Emission Lines in LB-1
The mass, origin, and evolutionary stage of the binary system LB-1 have been intensely debated, following the claim that it hosts an ∼70M☉ black hole, in stark contrast with the expectations for Galactic remnants. We conducted a high-resolution, phase-resolved spectroscopic study of its Paschen lines, using the Calar Alto 3.5 m telescope. We findLiu, Jifeng et al.
Stellar atmospheric parameters of FGK-type stars from high-resolution optical and near-infrared CARMENES spectra
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 stellarMarfil, E. et al.
A detailed non-LTE analysis of LB-1: Revised parameters and surface abundances
Context. It has recently been proposed that LB-1 is a binary system at 4 kpc consisting of a B-type star of 8 M☉ and a massive stellar black hole (BH) of 70 M☉. This finding challenges our current theories of massive star evolution and formation of BHs at solar metallicity. Aims: Our objective is to derive the effective temperature, surface gravitySimón-Díaz, S. et al.
STEPAR: an automatic code to infer stellar atmospheric parameters
Context. STEPAR is an automatic code written in Python 3.X designed to compute the stellar atmospheric parameters Teff, log g, [Fe/H], and ξ of FGK-type stars by means of the equivalent width (EW) method. This code has already been extensively tested in different spectroscopic studies of FGK-type stars with several spectrographs and againstTabernero, H. M. et al.
Abundance to age ratios in the HARPS-GTO sample with Gaia DR2. Chemical clocks for a range of [Fe/H]
Aims: The purpose of this work is to evaluate how several elements produced by different nucleosynthesis processes behave with stellar age and provide empirical relations to derive stellar ages from chemical abundances. Methods: We derived different sets of ages using Padova and Yonsei-Yale isochrones and HIPPARCOS and Gaia parallaxes for a sampleDelgado Mena, E. et al.
The metallicity-period-mass diagram of low-mass exoplanets
The number of exoplanet detections continues to grow following the development of better instruments and missions. Key steps for the understanding of these worlds comes from their characterization and statistical studies. We explore the metallicity-period-mass diagram for known exoplanets by using an updated version of The Stellar parameters forSousa, S. G. et al.
SWEET-Cat updated. New homogenous spectroscopic parameters
Context. Exoplanets have now been proven to be very common. The number of its detections continues to grow following the development of better instruments and missions. One key step for the understanding of these worlds is their characterization, which mostly depend on their host stars. Aims: We perform a significant update of the Stars WithSousa, S. G. et al.
3D non-LTE corrections for Li abundance and 6Li/7Li isotopic ratio in solar-type stars. I. Application to HD 207129 and HD 95456
Context. Convective motions in solar-type stellar atmospheres induce Doppler shifts that affect the strengths and shapes of spectral absorption lines and create slightly asymmetric line profiles. One-dimensional (1D) local thermodynamic equilibrium (LTE) studies of elemental abundances are not able to reproduce this phenomenon, which becomesHarutyunyan, G. et al.
Chemical Abundances of Neutron-capture Elements in Exoplanet-hosting Stars
To understand the formation and composition of planetary systems it is important to study their host stars composition since both are formed in the same stellar nebula. In this work, we analyze the behaviour of chemical abundances of Cu, Zn, Sr, Y, Zr, Ba, Ce, Nd, and Eu in the large and homogeneous HARPS-GTO planet search sample (R ˜ 115000). ThisDelgado Mena, E. et al.
C/O vs. Mg/Si ratios in solar type stars: The HARPS sample
Context. Aims: We aim to present a detailed study of the magnesium-to-silicon and carbon-to-oxygen ratios (Mg/Si and C/O) and their importance in determining the mineralogy of planetary companions. Methods: Using 499 solar-like stars from the HARPS sample, we determined C/O and Mg/Si elemental abundance ratios to study the nature of the possibleSuárez-Andrés, L. et al.
Constraining planet structure and composition from stellar chemistry: trends in different stellar populations
Context. The chemical composition of stars that have orbiting planets provides important clues about the frequency, architecture, and composition of exoplanet systems. Aims: We explore the possibility that stars from different galactic populations that have different intrinsic abundance ratios may produce planets with a different overallSantos, N. C. et al.
MASTER Optical Detection of the First LIGO/Virgo Neutron Star Binary Merger GW170817
Following the discovery of the gravitational-wave source GW170817 by three Laser Interferometer Gravitational-wave Observatory (LIGO)/Virgo antennae (Abbott et al., 2017a), the MASTER Global Robotic Net telescopes obtained the first image of the NGC 4993 host galaxy. An optical transient, MASTER OTJ130948.10-232253.3/SSS17a was later found, whichLipunov, V. M. et al.