相关论文: Modelling chromospheric line profiles as diagnosti…

In this study we test the possibility that the asymmetry in the profiles of the H-alpha and Ca II K lines in red giant stars is due to the presence of an active chromosphere rather than to mass loss. To this end, we compare line profiles…

Chromospheric model calculations of the Halpha line for selected red giant branch (RGB) and asymptotic giant branch (AGB) stars in the globular clusters M13, M15, and M92 are constructed to derive mass loss rates. The model spectra are…

The surface [C/N] of red giants is correlated with birth mass, but not directly impacted by mass loss. Exploiting this, we compare asteroseismic masses of red giants with the same [C/N] and but different evolutionary states. We find bulk…

We herein determine the average integrated mass loss from stars stars belonging to the dominant metal-poor population ([Fe/H] ~ --1.7) of the Galactic globular cluster omega Centauri (NGC 5139) during their red giant and horizontal branch…

Spectra of the He I 10830 Angstrom line were obtained with NIRSPEC on the Keck 2 telescope for metal-deficient field giant stars. This line is ubiquitous in stars with T_eff greater than 4500K and M_V fainter than -1.5. Fast outflows are…

High resolution spectra of 110 selected red giant stars in the globular cluster M15 (NGC 7078) were obtained with Hectochelle at the MMT telescope in 2005 May, 2006 May, and 2006 October. Echelle orders containing Halpha and Ca H & K are…

The amount of mass lost by stars during the red-giant branch (RGB) phase is one of the main parameters to understand and correctly model the late stages of stellar evolution. Nevertheless, a fully-comprehensive knowledge of the RGB mass…

Mass loss on the red giant branch (RGB) influences stellar evolution, properties of stellar populations, and Galactic chemical enrichment, yet remains poorly constrained observationally. Current models provide limited insight into how…

Red giant stars play a key role in advancing our understanding of stellar mass loss. However, its initial mass and the amount of mass lost during this phase remain uncertain. In this study, we investigate the asteroseismic signatures of…

As part of the search for planets around evolved stars, we can understand planet populations around significantly higher-mass stars than the Sun on the main sequence. This population is difficult to study any other way, particularly with…

Asteroseismic masses of globular cluster (GC) stars are invaluable to investigate stellar evolution. Previously, only two GCs have been seismically studied. We present new detections of solar-like oscillations in the clusters M9 and M19,…

We present the results of a survey of radial velocities over a wide region extending from r~10 arcmin out to r~80 arcmin (~1.5 tidal radii) within the massive star cluster omega Centauri. The survey was performed with FLAMES@VLT, to study…

Near-infrared spectra of 21 giants in omega Centauri, spanning the whole range of metallicities observed in this cluster, are presented. This work is part of a coordinated photometric and spectroscopic campaign in the optical and in the…

We present [Fe/H] and [Ca/Fe] of $\sim600$ red giant branch (RGB) members of the globular cluster $\omega$ Centauri. We collect medium-resolution ($R\sim2000$) spectra using the Blanco 4 m telescope at the Cerro Tololo Inter-American…

Mass loss remains a major uncertainty in stellar modelling. In low-mass stars, mass loss is most significant on the red giant branch (RGB), and will impact the star's evolutionary path and final stellar remnant. Directly measuring the mass…

High resolution spectra of 123 red giant stars in the globular cluster M13 and 64 red giant stars in M92 were obtained with Hectochelle at the MMT telescope. Emission and line asymmetries in Halpha, and Ca K are identified, characterizing…

Context: Mass loss from red giants in old globular clusters affects the horizontal branch (HB) morphology and post-HB stellar evolution including the production of ultraviolet-bright stars, dredge up of nucleosynthesis products and…

The main aim of the present work is to derive an empirical mass-loss (ML) law for Population II stars in first and second ascent red giant branches. We used the Spitzer InfraRed Array Camera (IRAC) photometry obtained in the 3.6-8 micron…

Using the Spitzer IRAC camera we have obtained mid-IR photometry of the red giant branch stars in the Galactic globular cluster 47 Tuc. About 100 stars show an excess of mid-infrared light above that expected from their photospheric…

We recently identified a substantial population of galaxies at z>2 with red rest-frame optical colors. These distant red galaxies (DRGs) are efficiently selected by the simple observed color criterion J-K>2.3. In this paper we present NIR…