Recent work measuring the binary fraction of evolved red supergiants (RSGs) in the Magellanic Clouds points to a value between 15-30%, with the majority of the companions being un-evolved B-type stars as dictated by stellar evolution. Here I extend this research to the Local Group galaxies M31 and M33, and investigate the RSG binary fraction as a function of metallicity. Recent near-IR photometric surveys of M31 and M33 have lead to the identification of a complete sample of RSGs down to a limiting $\log L/L_{\odot} \geq 4.2$. To determine the binary fraction of these M31 and M33 RSGs, I used a combination of newly obtained spectroscopy to identify single RSGs and RSG+OB binaries as well as archival UV, visible and near-IR photometry to probabilistically classify RSGs as either single or binary based on their colors. I then adjusted the observed RSG+OB binary fraction to account for observational biases. The resulting RSG binary fraction in M33 shows a strong dependence on galactocentric distance with the inner regions having a much higher binary fraction ($41.2^{+12.0}_{-7.3}$%) than the outer regions ($15.9^{+12.4}_{-1.9}$%). Such a trend is not seen in M31; instead, the binary fraction in lightly reddened regions remains constant at $33.5^{+8.6}_{-5.0}$%. I conclude the changing RSG binary fraction in M33 is due to a metallicity dependence with higher metallicity environments having higher RSG binary fractions. This dependence most likely stems not from changes in the physical properties of RSGs due to metallicity, but changes in the parent distribution of OB binaries.
Critical Metallicity of Cool Supergiant Formation. II. Physical Origin
Institute of Astronomy and Astrophysics, Academia Sinica（中央研究院天文及天文物理研究所）；Department of Physics, National Taiwan University（國立臺灣大學物理學系）；Heidelberg Institute for Theoretical Studies（海德堡理論研究所）
This paper systematically studies the relation between metallicity and mass loss of massive stars. We perform one-dimensional stellar evolution simulations and build a grid of $\sim$2000 models with initial masses ranging between 11 and 60 $M_{\odot}$ and absolute metallicities $Z$ between 0.00001 and 0.02. Steady-state winds, comprising hot main-sequence winds and cool supergiant winds, are the main drivers of the mass loss of massive stars in our models. We calculate the total mass loss over the stellar lifetime for each model. Our results reveal the existence of a critical metallicity $Z_{\…
The temperatures of red supergiants (RSGs) are expected to depend on metallicity (Z) in such a way that lower-Z RSGs are warmer. In this work, we investigate the Z-dependence of the Hayashi limit by analysing RSGs in the low-Z galaxy Wolf-Lundmark-Mellote (WLM), and compare with the RSGs in the higher-Z environments of the Small Magellanic Cloud (SMC) and Large Magellanic Cloud (LMC). We determine the effective temperature ($T_{\textrm{eff}}$) of each star by fitting their spectral energy distributions, as observed by VLT+SHOOTER, with MARCS model atmospheres. We find average temperatures of $…
We present the spectral analysis of 21 blue supergiant stars of spectral type late B to early A within the Local Group dwarf galaxy IC 1613 based on VLT-FORS2 low resolution spectra. Combining our results with studies of early B type blue supergiants we report a wide bi-modal distribution of metallicities with two peaks around [Z] $\sim -0.50$ dex and [Z] $\sim -0.85$ dex. The bi-modal distribution correlates with spatial location, when compared with column densities of neutral hydrogen in IC 1613. While the low [Z] objects appear in regions of relatively high ISM HI column densities or close …
Recent studies on the temperatures of red supergiants (RSGs) in the local universe provide us with an excellent observational constraint on RSG models. We calibrate the mixing length parameter by comparing model predictions with the empirical RSG temperatures in Small and Large Magellanic Clouds, Milky Way, and M31, which are inferred from the TiO band and the spectral energy distribution (SED). Although our RSG models are computed with the MESA code, our result may be applied to other stellar evolution codes, including the BEC and TWIN codes. We find evidence that the mixing length increases …
The distribution of stars in the Hertzsprung Russell diagram (HRD) for a stellar conglomeration represents a snapshot of its evolving stellar population. Some of the supergiant stars may transit the HRD from blue to red and then again to blue during their late evolutionary stages, as exemplified by the progenitor of SN 1987A. Others may transit a given part of the HRD more than twice in a "blue loop" and end up as red supergiants before they explode. Since stars in blue loops spend a considerable part of their lives there, these stages may change the relative number of modeled supergiants in t…
We present a direct determination of the stellar metallicity in the close pair galaxy NGC~4038 (D = 20 Mpc) based on the quantitative analysis of moderate resolution KMOS/VLT spectra of three super star clusters (SSCs). The method adopted in our analysis has been developed and optimised to measure accurate metallicities from atomic lines in the $J$-band of single red supergiant (RSG) or RSG-dominated star clusters. Hence, our metallicity measurements are not affected by the biases and poorly understood systematics inherent to strong line HII methods which are routinely applied to massive data …
X-Shooting ULLYSES: Massive stars at low metallicity XIV. Properties of SMC late-O and B supergiants reveal the metallicity dependence of winds in the Magellanic Clouds
University of Sheffield（谢菲尔德大学）；KU Leuven（荷语鲁汶大学）；Armagh Observatory and Planetarium（阿马赫天文台和天文馆）；Zentrum für Astronomie der Universität Heidelberg, Astronomisches Rechen-Institut（海德堡大学天文学中心，天文计算研究所）
We present the first quantitative spectral analysis of blue supergiant stars in the nearby galaxy NGC 2403. Out of a sample of 47 targets observed with the LRIS spectrograph at the Keck I telescope we have extracted 16 B- and A-type supergiants for which we have data of sufficient quality to carry out a comparison with model spectra of evolved massive stars and infer the stellar parameters. The radial metallicity gradient of NGC 2403 that we derive has a slope of -0.14 (+/- 0.05) dex/r_e, and is in accordance with the analysis of H II region oxygen abundances. We present evidence that the stel…
We investigate the occurrence of crystalline silicates in oxygen-rich evolved stars across a range of metallicities and mass-loss rates. It has been suggested that the crystalline silicate feature strength increases with increasing mass-loss rate, implying a correlation between lattice structure and wind density. To test this, we analyse Spitzer IRS and Infrared Space Observatory SWS spectra of 217 oxygen-rich asymptotic giant branch stars and 98 red supergiants in the Milky Way, the Large and Small Magellanic Clouds and Galactic globular clusters. These encompass a range of spectral morpholog…
We present a quantitative analysis of the low-resolution (4.5 A) spectra of 12 late-B and early-A blue supergiants (BSGs) in the metal-poor dwarf galaxy NGC 3109. A modified method of analysis is presented which does not require use of the Balmer jump as an independent temperature indicator, as used in previous studies. We determine stellar effective temperatures, gravities, metallicities, reddening, and luminosities, and combine our sample with the early-B type BSGs analyzed by Evans et al. (2007) to derive the distance to NGC 3109 using the Flux-weighted Gravity-Luminosity Relation (FGLR). U…
Constraints on the Metallicity-dependent Explodability of Massive Stars from Galactic Chemical Evolution: Toward Alleviating the Red Supergiant Problem
Kyoto University（京都大学）；The University of Tokyo（东京大学）
We present an abundance analysis of seven super-star clusters in the disk of M83. The near-infrared spectra of these clusters are dominated by Red Supergiants, and the spectral similarity in the J-band of such stars at uniform metallicity means that the integrated light from the clusters may be analysed using the same tools as those applied to single stars. Using data from VLT/KMOS we estimate metallicities for each cluster in the sample. We find that the abundance gradient in the inner regions of M83 is flat, with a central metallicity of [Z] = 0.21$\pm$0.11 relative to a Solar value of $Z_\o…
We present K-band Multi-Object Spectrograph (KMOS) observations of 18 Red Supergiant (RSG) stars in the Sculptor Group galaxy NGC 55. Radial velocities are calculated and are shown to be in good agreement with previous estimates, confirming the supergiant nature of the targets and providing the first spectroscopically confirmed RSGs in NGC 55. Stellar parameters are estimated for 14 targets using the $J$-band analysis technique, making use of state-of-the-art stellar model atmospheres. The metallicities estimated confirm the low-metallicity nature of NGC 55, in good agreement with previous stu…
We present near-IR spectroscopy of red supergiant (RSG) stars in NGC 6822, obtained with the new VLT-KMOS instrument. From comparisons with model spectra in the J-band we determine the metallicity of 11 RSGs, finding a mean value of [Z] = -0.52 $\pm$ 0.21 which agrees well with previous abundance studies of young stars and HII regions. We also find an indication for a low-significance abundance gradient within the central 1 kpc. We compare our results with those derived from older stellar populations and investigate the difference using a simple chemical evolution model. By comparing the physi…
We report a spectroscopic study on red supergiant stars (RSGs) in the irregular dwarf galaxy IC 1613 in the Local Group. We derive the effective temperatures ($T_\mathrm{eff}$) and metallicities of 14 RSGs by synthetic spectral fitting to the spectra observed with the MMIRS instrument on the MMT telescope for a wavelength range from 1.16 $μ$m to 1.23 $μ$m. A weak bimodal distribution of the RSG metallicity centered on the [Fe/H]=$-0.65$ is found, which is slightly lower than or comparable to that of the Small Magellanic Cloud (SMC). There is no evidence for spatial segregation between the meta…
Low resolution (4.5 to 5 Angstroem) spectra of 58 blue supergiant stars distributed over the disk of the Magellanic spiral galaxy NGC 55 in the Sculptor group are analyzed by means of non-LTE techniques to determine stellar temperatures, gravities and metallicities (from iron peak and alpha-elements). A metallicity gradient of -0.22 +/- 0.06$ dex/R_25 is detected. The central metallicity on a logarithmic scale relative to the Sun is [Z] = -0.37 +\- 0.03. A chemical evolution model using the observed distribution of stellar and interstellar medium gas mass column densities reproduces the observ…
We present results obtained from Stromgren photometry of 13 young (~30-220 Myr) Magellanic Cloud (MC) clusters, most of them lacking in the literature from direct metallicity measurements. We derived for them [Fe/H] values from a high-dispersion spectroscopy-based empirical calibration of the Stromgren metallicity sensitive index m1 for yellow and red supergiants (SGs). Particular care was given while estimating their respective uncertainties. In order to obtain the mean cluster metallicities, we used [Fe/H] values of selected SGs for which we required to be located within the cluster radii, p…
We present the first quantitative UV spectroscopic analysis of resolved OB stars in IC1613. Because of its alleged very low metallicity (<~1/10 Zo, from HII regions), studies in this Local Group dwarf galaxy could become a significant step forward from the SMC towards the extremely metal-poor massive stars of the early Universe. We present HST-COS data covering the ~1150-1800Å wavelength range with resolution R~2500. We find that the targets do exhibit wind features, and these are similar in strength to SMC stars. Wind terminal velocities were derived from the observed PCygni profiles with the…
We have obtained K-band Multi-Object Spectrograph (KMOS) near-IR spectroscopy for 14 red supergiant stars (RSGs) in the young massive star cluster NGC 2100 in the Large Magellanic Cloud (LMC). Stellar parameters including metallicity are estimated using the J-band analysis technique, which has been rigorously tested in the Local Universe. We find an average metallicity for NGC 2100 of [Z]=$-$0.43$\pm$0.10 dex, in good agreement with estimates from the literature for the LMC. Comparing our results in NGC 2100 with those for a Galactic cluster (at Solar-like metallicity) with a similar mass and …
We investigate the red supergiant (RSG) population of M31, obtaining radial velocities of 255 stars. These data substantiate membership of our photometrically-selected sample, demonstrating that Galactic foreground stars and extragalactic RSGs can be distinguished on the basis of B-V, V-R two-color diagrams. In addition, we use these spectra to measure effective temperatures and assign spectral types, deriving physical properties for 192 RSGs. Comparison with the solar-metallicity Geneva evolutionary tracks indicates astonishingly good agreement. The most luminous RSGs in M31 are likely evolve…
Studies on the massive star population in galaxies beyond the Local Group are the key to understand the link between their numbers and modes of star formation in different environments. We present the analysis of the massive star population of the galaxies NGC 1326A, NGC 1425 and NGC 4548 using archival Hubble Space Telescope Wide Field Planetary Camera 2 images in the F555W and F814W filters. Through high precision point spread function fitting photometry for all sources in the three fields we identified 7640 candidate blue supergiants, 2314 candidate yellow supergiants, and 4270 candidate re…
We analyzed the massive star population of the Virgo Cluster galaxy NGC 4535 using archival Hubble Space Telescope Wide Field Planetary Camera 2 images in filters F555W and F814W, equivalent to Johnson V and Kron-Cousins I. We performed high precision point spread function fitting photometry of 24353 sources including 3762 candidate blue supergiants, 841 candidate yellow supergiants and 370 candidate red supergiants. We estimated the ratio of blue to red supergiants as a decreasing function of galactocentric radius. Using Modules for Experiments in Stellar Astrophysics isochrones at solar meta…
We present a case study of using a novel method to identify red supergiant (RSG) candidates in NGC 6822, based on their 1.6 $μ$m "H-bump". We collected 32 bands of photometric data for NGC 6822 ranging from optical to MIR. By using the theoretical spectra from MARCS, we demonstrate that there is a prominent difference around 1.6 $μ$m ("H-bump") between low-surface-gravity (LSG) and high-surface-gravity (HSG) targets. Taking advantage of this feature, we identify efficient color-color diagrams (CCDs) of rzH and rzK to separate HSG and LSG targets from crossmatching of optical and NIR data. More…
X-Shooting ULLYSES: Massive Stars at low metallicity IX: Empirical constraints on mass-loss rates and clumping parameters for OB supergiants in the Large Magellanic Cloud
Red supergiants with their enormous brightness at J-band are ideal probes of cosmic chemical composition. It is therefore crucial to have realistic models of radiative transfer in their atmospheres, which will permit determination of abundances accurate to 0.15 dex, the precision attainable with future telescope facilities in galaxies as distant as tens of Mpc. Here, we study the effects of non-local thermodynamic equilibrium (NLTE) on the formation of iron, titanium, and silicon lines, which dominate J-band spectra of red supergiants. It is shown that the NLTE radiative transfer models enable…
A constant upper luminosity limit of cool supergiant stars down to the extremely low metallicity of I Zw 18
Argelander-Institut für Astronomie, Universität Bonn（波恩大学阿根兰德天文学研究所）；Institute of Science and Technology Austria (ISTA)（奥地利科学和技术研究所）；Max-Planck-Institut für Radioastronomie（马克斯·普朗克射电天文研究所）；Department of Astronomy, The Oskar Klein Centre, Stockholm University（斯德哥尔摩大学奥斯卡·克莱因中心天文学系）；Department of Physics & Engineering Physics, Morgan State University（摩根州立大学物理与工程物理系）；Centro de Astrobiología (CSIC-INTA)（天体生物学中心（西班牙国家科学技术研究委员会-国家航空航天技术研究所））
We present the most comprehensive RSG sample for the SMC up to now, including 1,239 RSG candidates. The initial sample is derived based on a source catalog for the SMC with conservative ranking. Additional spectroscopic RSGs are retrieved from the literature, as well as RSG candidates selected from the inspection of CMDs. We estimate that there are in total $\sim$ 1,800 or more RSGs in the SMC. We purify the sample by studying the infrared CMDs and the variability of the objects, though there is still an ambiguity between AGBs and RSGs. There are much less RSGs candidates ($\sim$4\%) showing P…
We present the first direct determination of a stellar metallicity in the spiral galaxy NGC4258 (D=7.6 Mpc) based on the quantitative analysis of a low-resolution (~5 AE) Keck LRIS spectrum of a blue supergiant star located in its disk. A determination of stellar metallicity in this galaxy is important for the absolute calibration of the Cepheid Period-Luminosity relation as an anchor for the extragalactic distance scale and for a better characterization of its dependence as a function of abundance. We find a value 0.2 dex lower than solar metallicity at a galactocentric distance of 8.7 kpc, i…
We present a quantitative spectroscopic study of twenty-seven red supergiants in the Sculptor Galaxy NGC 300. J-band spectra were obtained using KMOS on the VLT and studied with state of the art synthetic spectra including NLTE corrections for the strongest diagnostic lines. We report a central metallicity of [Z]= -0.03 +/- 0.05 with a gradient of -0.083 +/- 0.014 [dex/kpc], in agreement with previous studies of blue supergiants and H II-region auroral line measurements. This result marks the first application of the J-band spectroscopic method to a population of individual red supergiant star…
We use the Binary Population and Spectral Synthesis (BPASS) models to test the recent suggestion that red supergiants can provide an accurate age estimate of a co-eval stellar population that is unaffected by interacting binary stars. Ages are estimated by using both the minimum luminosity red supergiant and the mean luminosity of red supergiants in a cluster. We test these methods on a number of observed star clusters and find our results in agreement with previous estimates. Importantly we find the difference between the ages derived from stellar population models with and without a realisti…
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…
Recent supernova and transient surveys have revealed an increasing number of non-terminal stellar eruptions. Though the progenitor class of these eruptions includes the most luminous stars, little is known of the pre-supernova mechanics of massive stars in their most evolved state, thus motivating a census of possible progenitors. From surveys of evolved and unstable luminous star populations in nearby galaxies, we select a sample of yellow and red supergiant candidates in M31 and M33 for review of their spectral characteristics and spectral energy distributions. Since the position of intermed…
The mass loss rates of red supergiants (RSGs) govern their evolution towards supernova and dictate the appearance of the resulting explosion. To study how mass-loss rates change with evolution we measure the mass-loss rates (\mdot) and extinctions of 19 red supergiants in the young massive cluster NGC2100 in the Large Magellanic Cloud. By targeting stars in a coeval cluster we can study the mass-loss rate evolution whilst keeping the variables of mass and metallicity fixed. Mass-loss rates were determined by fitting DUSTY models to mid-IR photometry from WISE and Spitzer/IRAC. We find that the…
Massive stars becoming red supergiants lose a significant amount of their mass during that brief evolutionary phase. They then either explode as a hydrogen-rich supernova (SN Type II), or continue to evolve as a hotter supergiant (before exploding). The slow, dusty ejecta of the red supergiant will be over-run by the hot star wind and/or SN ejecta. I will present estimates of the conditions for this interaction and discuss some of the implications.
Blue supergiants in the Pinwheel Galaxy M101: comparison with H II region chemical abundances, spectroscopic distance and an independent determination of the Hubble constant
We present a new catalogue of cool supergiants in a section of the Perseus arm, most of which had not been previously identified. To generate it, we have used a set of well-defined photometric criteria to select a large number of candidates (637) that were later observed at intermediate resolution in the the Infrared Calcium Triplet spectral range, using a long-slit spectrograph. To separate red supergiants from luminous red giants, we used a statistical method, developed in previous works and improved in the present paper. We present a method to assign probabilities of being a red supergiant …
Increasing the statistics of evolved massive stars in the Local Group enables investigating their evolution at different metallicities. During the late stages of stellar evolution, the physics of some phenomena, such as episodic and systematic mass loss, are not well constrained. For example, the physical properties of red supergiants (RSGs) in different metallicity regimes remain poorly understood. Thus, we initiated a systematic study of RSGs in dwarf irregular galaxies (dIrrs) in the Local Group. The target selection is based on 3.6 $μ$m and 4.5 $μ$m photometry from archival Spitzer Space T…
Red supergiants (RSGs) are evolved massive stars that represent extremes, in both their physical sizes and their cool temperatures, of the massive star population. Effective temperature ($T_{\rm eff}$) is the most critical physical property needed to place a RSG on the Hertzsprung-Russell Diagram, due to the stars' cool temperatures and resulting large bolometric corrections. Several recent papers have examined the potential utility of atomic line equivalent widths in cool supergiant spectra for determining $T_{\rm eff}$ and other physical properties (dorda2016b, dorda2016a) and found strong c…
Recent studies have shown that the area around the massive, obscured cluster RSGC3 may harbour several clusters of red supergiants. In this paper, we analyse a clump of photometrically selected red supergiant candidates 20' south of RSGC3 in order to confirm the existence of another of these clusters. Using medium-resolution infrared spectroscopy around 2.27 microns, we derived spectral types and velocities along the line of sight for the selected candidates, confirming their nature and possible association. We find a compact clump of eight red supergiants and four other candidates at some dis…
This work establishes the most complete sample of red supergiants (RSGs) in twelve low-mass galaxies (WLM, IC 10, NGC 147, NGC 185, IC 1613, Leo A, Sextans B, Sextans A, NGC 6822, Pegasus Dwarf, SMC and LMC) of the Local Group, which forms the solid basis to study the properties of RSGs as well as the star formation rate (SFR) and initial mass function (IMF) of the galaxies. After removing the foreground dwarf stars by their obvious branch in the near-infrared color-color diagram ($(J-H)_0/(H-K)_0$) with the UKIRT/WFCAM and 2MASS photometry as well as the Gaia/EDR3 measurements of proper motio…
Recent studies have revealed massive star clusters in a region of the Milky Way close to the tip of the Long Bar. These clusters are heavily obscured and are characterised by a population of red supergiants. We analyse a previously unreported concentration of bright red stars ~16' away from the cluster RSGC1. We utilised near IR photometry to identify candidate red supergiants and then K-band spectroscopy of a sample to characterise their properties. We find a compact clump of eight red supergiants and five other candidates at some distance, one of which is spectroscopically confirmed as a red…
In the past few years, several clusters containing large numbers of red supergiants have been discovered. These clusters are amongst the most massive young clusters known in the Milky Way, with stellar masses reaching a few $10^4\:$M$_\odot$. They have provided us, for the first time, with large homogeneous samples of red supergiants of a given age. These large populations make them, despite heavy extinction along their sightlines, powerful laboratories to understand the evolutionary status of red supergiants. While some of the clusters, such as the eponymous RSGC1, are so obscured that their …
Red supergiants are a short-lived stage in the evolution of moderately massive stars (10-25Mo), and as such their location in the H-R diagram provides an exacting test of stellar evolutionary models. Since massive star evolution is strongly affected by the amount of mass-loss a star suffers, and since the mass-loss rates depend upon metallicity, it is highly desirable to study the physical properties of these stars in galaxies of various metallicities. Here we identify a sample of red supergiants in M31 (the most metal-rich of the Local Group galaxies) and derive their physical properties by f…
The Stellar Winds Atlas II: Black Hole Formation at Solar Metallicity
Universität Heidelberg, Zentrum für Astronomie (ZAH), Institut für Theoretische Astrophysik（海德堡大学天文学中心理论天体物理研究所）；Dipartimento di Fisica e Astronomia Galileo Galilei, Università di Padova（帕多瓦大学伽利略·伽利莱物理与天文系）；Department of Astronomy and Astrophysics, University of California, San Diego（加州大学圣地亚哥分校天文与天体物理系）；Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences（波兰科学院尼古拉·哥白尼天文中心）；Astronomický ústav, Akademie věd Ceské republiky（捷克科学院天文研究所）；Institute of Astronomy, KU Leuven（鲁汶大学天体物理研究所）；Institute of Astronomy, University of Cambridge（剑桥大学天体物理研究所）；Universität Heidelberg, Interdiszipliäres Zentrum für Wissenschaftliches Rechnen（海德堡大学跨学科科学计算中心）；INFN, Sezione di Padova（意大利国家核物理研究所帕多瓦分部）；International Hellenic University（国际希腊大学）；IAASARS, National Observatory of Athens（雅典国立天文台应用天体物理系统分析与服务研究所）；National and Kapodistrian University of Athens（雅典国立卡波季斯特里安大学）
A New Catalogue of Galactic Red Supergiants for direct detection of episodic mass-loss events
INAF-Osservatorio Astronomico di Palermo（意大利国家天体物理研究所巴勒莫天文台）；Dipartimento di Fisica e Astronomia, Università degli Studi di Padova（帕多瓦大学物理与天文学系）；Dipartimento di Fisica e Chimica, Università degli Studi di Palermo（巴勒莫大学物理与化学系）；INAF-Osservatorio Astronomico di Padova（意大利国家天体物理研究所帕多瓦天文台）；INAF-Osservatorio Astronomico di Roma（意大利国家天体物理研究所罗马天文台）
We present the first systematic study of lithium abundance in a chemically homogeneous sample of 27 red supergiants (RSGs) in the young Perseus complex. For these stars, accurate stellar parameters and detailed chemical abundances of iron and iron peak, CNO, alpha, light and neutron-capture elements have been already obtained by means of high resolution optical and near-infrared spectroscopy. The observed RSGs have half-solar metallicity, 10-30 Myr age, bolometric luminosities in the 10$^4$-10$^5$ L$_{\odot}$ range and likely mass progenitors in the 9-14 M$_{\odot}$ range. We detected the opti…
