Related papers: The most massive stars in the Arches cluster
Young massive (M >10^4 Msun) stellar clusters are a good laboratory to study the evolution of massive stars. Only a dozen of such clusters are known in the Galaxy. Here we report about a new young massive stellar cluster in the Milky Way.…
We have obtained HST and ground-based observations of a sample of 20 O-type stars in the LMC and SMC, including six of the hottest massive stars known (subtypes O2-3) in the R136 cluster. In general, these data include (a) the HST UV…
Young massive stars and stellar clusters continuously form in the Galactic disk, generating new HII regions within their natal giant molecular clouds and subsequently enriching the interstellar medium via their winds and supernovae. Massive…
The three young clusters in the Galactic Center represent the closest examples of massive starbursts and they define the upper mass limit of the Galactic cluster mass functions. In this review, I describe the characteristics and content of…
We review the properties of massive star evolution in different environments, where the major environmental factor is metallicity. Comparisons between evolutionary models and observations of massive OB, WR stars and related objects are…
We present a detailed study of two luminous super star clusters in the starburst galaxy M82. Spectra, covering 3250-8790 A at a resolution of 1.6 A, were obtained at the 4.2 m William Herschel Telescope (WHT) for cluster F and the highly…
We derive age constraints for 1639 red giants in the APOKASC sample for which seismic parameters from Kepler, as well as effective temperatures, metallicities and [alpha/Fe] values from APOGEE DR12 are available. We investigate the relation…
In the search of a sample of metal-poor bright giants using Str{\"o}mgren photometry, we serendipitously found a sample of 26 young (ages younger than 1 Gyr) metal-rich giants, some of which have high rotational velocities.We determined the…
We examine star clusters in the irregular, starburst galaxy NGC 1569 from HST images. In addition to the two known super star clusters, we identify 45 other clusters that are compact but resolved. Integrated UVI colors of the clusters span…
The distribution of OB stars along with that of H$\alpha$, $^{12}$CO, dust infrared emission, and neutral hydrogen is carried out in order to provide a more complete picture of interactions of the young massive stars and the observed…
We report metallicities for three $\sim$Gyr-old stars in the Milky Way nuclear star cluster (NSC) using high-resolution near-infrared spectroscopy. We derive effective temperatures from a calibration with Sc line strength, which yields…
We present our recent efforts to unveil and understand the origin of massive stars outside the three massive star clusters in the Galactic Center. From our HST/NICMOS survey of the Galactic Center, we have identified 180 Paschen-alpha…
We present near-infrared photometry and K-band spectra of newly-identified massive stars in the Quintuplet Cluster, one of the three massive clusters projected within 50 pc of the Galactic Center. We find that the cluster contains a variety…
We present the results of an investigation of post-Main Sequence mass loss from stars in clusters in the Magellanic Clouds, based around an imaging survey in the L'-band (3.8 micron) performed with the VLT at ESO. The data are complemented…
The properties of the brightest resolved stars in an arc that was originally identified by Sun et al. (2005) and is located in the extraplanar regions of M82 are discussed. The stars form an elongated structure that is traced over a…
We present ultra-deep ($\simeq 20-30$ hours), rest-frame UV spectroscopy with NIRSpec/JWST of two UV-bright galaxies at $z\sim 8.7$, CEERS-1019 and CEERS-1025 ($Z_{\rm neb} \simeq 0.1 Z_{\odot}$). The spectra reveal exceptionally strong…
The most massive stars provide an essential source of recycled material for young clusters and galaxies. While very massive stars (VMS, M>100M) are relatively rare compared to O stars, they lose disproportionately large amounts of mass…
We report the discovery of a previously unknown massive Galactic star cluster at l=29.22, b=-0.20. Identified visually in mid-IR images from the Spitzer GLIMPSE survey, the cluster contains at least 8 late-type supergiants, based on…
We present H- and K-band NIRSPEC spectroscopy of super star clusters (SSCs) in the irregular starburst galaxy NGC 1569, obtained at the Keck Observatory. We fit these photospheric spectra to NextGen model atmospheres to obtain effective…
Using our deep optical and near-infrared photometry along with multiwavelength archival data, we here present a detailed study of the Galactic H II region Sh 2-305, to understand the star/star-cluster formation. On the basis of excess…