In the framework of the AGB model for the formation in Globular Clusters of a "second generation" of stars showing the sign of p-processing in the abundances of light elements, we present new ideas and model results aimed at solving the discrepancies between observed and computed abundances. We focus on the problem of preserving a large Sodium abundance, while at the same time allowing anyway...
Fluorine, an elusive yet crucial element in the field of galactic archaeology, has its significance masked by its rarity, complicating our understanding of chemical and stellar evolution. The debate over its origins is ongoing, with candidates ranging from massive stars and AGB stars to Wolf-Rayet stars and novae. In response, we've launched an ambitious project using the GIANO-B instrument on...
Recently, Mira variables have gained renewed attention as a viable alternative to Cepheids for the initial step in the cosmological distance scale. Their advantages include being inherently brighter in the infrared spectrum, more prevalent, and found in diverse environments. Moreover, their evolutionary endpoint as white dwarfs links them to the progenitors of Type Ia supernovae, and as such...
To investigate possible ways to resolve the Hubble tension other
distance indicators than cepheids, TRGB and SNIa and have seen a renewed
interest in the past years.
The Mira PL-relation is one of them, but in this contribution I want to
discuss the so-called JAGB stars that were introduced by Madore and Freedman in 2020. The name refers to the fact that the sample of interest are (carbon)...
I will present the J-region asymptotic giant branch (JAGB) method, a new standard candle that leverages the constant luminosities of color-selected, carbon-rich AGB stars. Using NIR imaging of 11 galaxies collected from the Magellan Telescope, we find the mode of the carbon star luminosity function in the J band is an accurate and precise method for measuring distances that are independent of...
The Gaia DR3 has parametrised 5.6 million stars based on their Radial Velocity Spectrometer (RVS) spectra (DPAC/GSP-spec module, Recio-Blanco et al., 2023). We have selected a sample of 153,544 GSP-spec stars with known spectroscopic atmospheric parameters, chemical abundances, and with asteroseismic TESS data. The asteroseismic and spectroscopic surface gravities are found to be in very...
We have recently investigated the origin of chemical signatures
observed in the oldest star of our Galaxy using a
stochastic chemical evolution model. The elements we have studied are
carbon, nitrogen, and oxygen, but also the neutron capture elements. We
have found that rotating massive stars are a promising way to explain
several signatures observed in these fossil stars. Analyzing...
