Nucleosynthesis and molecular processes in the late stages of Stellar Evolution

    General
    Description

    Low- to intermediate-mass (M < 8 solar masses, Ms) stars represent the majority of stars in the Cosmos. They finish their lives on the Asymptotic Giant Branch (AGB) - just before they form planetary nebulae (PNe) - where they experience complex nucleosynthetic and molecular processes. AGB stars are important contributors to the enrichment of the interstellar medium where new stars/planets are born (including our own Early Solar System, ESS), and to the chemical evolution of stellar systems like globular clusters (GCs) and galaxies. In particular, the more massive (M > 4-5 Ms) AGB stars synthesize very different (radio)isotopes from those formed by lower mass AGB stars and Supernova detonations, as a consequence of different nucleosynthesis mechanisms. Evolved stars in the transition phase between AGB stars and PNe also form diverse organic compounds like PAHs, and fullerene and graphene molecular nanostructures, being a wonderful laboratory for Astrochemistry. On-going massive surveys like SDSS-IV/APOGEE-2 and the upcoming James Webb Space Telescope (JWST) represent a fundamental step forward to understand the nucleosynthesis and molecular processes in evolved stars. We aim to explore the nucleosynthesis of light and heavy (radio)isotopes in AGB stars and how they contribute to the ESS radioactive inventory as well as to the formation and evolution of GCs and galaxies. We also aim at understanding the top-down formation process of fullerene and graphene molecular nanostructures in evolved stars. Finally, it is intended to perform data mining with the Gaia satellite, in order to study the AGB- PNe evolutionary phase. In addition we aim to use the GALEX database to discover binary central stars in Galactic PNe.

    Principal investigator

    1. During 2020, we have published 37 papers in high-impact international refereed astronomical journals (including one invited review) and 2 papers in the Chemistry -Physics journal FNCN.

    2. Phosphorus-rich stars with an extremely peculiar chemical abundance pattern have been discovered for the first time, challenging the theoretical nucleosynthesis predictions.

    3. It was demonstrated that the P-rich star progenitors represent a new site for s-process nucleosynthesis, with important implications for the chemical evolution of our Galaxy.

    Related publications

    • Infrared Spectral Fingerprint of Neutral and Charged Endo- and Exohedral Metallofullerenes

      Small metal-containing molecules have been detected and recognized as one of the hybrid species that are efficiently formed in space, especially in the circumstellar envelopes of evolved stars. It has also been predicted that more complex hybrid species such as those formed by metals and fullerenes (metallofullerenes) could be present in these

      Barzaga, R. et al.

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      11
      2023
      Citations
      0
    • Dust from evolved stars: a pilot analysis of the AGB to PN transition

      We present a novel approach to address dust production by low- and intermediate-mass stars. We study the asymptotic giant branch (AGB) phase, during which the formation of dust takes place, from the perspective of post-AGB and planetary nebula (PN) evolutionary stage. Using results from stellar evolution and dust formation modelling, we interpret

      Dell'Agli, F. et al.

      Advertised on:

      12
      2023
      Citations
      1
    • Measuring small-scale magnetic fields of 44 M dwarfs from SPIRou spectra with ZeeTurbo

      We present the results of an analysis aimed at probing the small-scale magnetic fields of M dwarfs observed with SPIRou, the nIR high-resolution spectro-polarimeter installed at the Canada-France-Hawaii Telescope, in the context of the SPIRou Legacy Survey. Our analysis relies on high-resolution median spectra built from several tens of spectra

      Cristofari, P. I. et al.

      Advertised on:

      12
      2023
      Citations
      0
    • GJ 806 (TOI-4481): A bright nearby multi-planetary system with a transiting hot low-density super-Earth

      One of the main scientific goals of the TESS mission is the discovery of transiting small planets around the closest and brightest stars in the sky. Here, using data from the CARMENES, MAROON-X, and HIRES spectrographs together with TESS, we report the discovery and mass determination of aplanetary system around the M1.5 V star GJ 806 (TOI-4481)

      Palle, E. et al.

      Advertised on:

      10
      2023
      Citations
      3
    • Light elements Na and Al in 58 bulge spheroid stars from APOGEE

      We identified a sample of 58 candidate stars with metallicity [Fe/H] ≲ -0.8 that likely belong to the old bulge spheroid stellar population, and analyse their Na and Al abundances from Apache Point Observatory Galactic Evolution Experiment (APOGEE) spectra. In a previous work, we inspected APOGEE-Stellar Parameter and Chemical Abundance Pipeline

      Barbuy, B. et al.

      Advertised on:

      12
      2023
      Citations
      1
    • Fullerene-indene adducts (ICMA &amp; ICBA) in an astrochemical perspective part 1: chemical thermodynamics, stability and electronic absorption spectroscopy
      García-Hernández, D. Aníbal et al.

      Advertised on:

      9
      2023
      Citations
      1
    • Fullerene-indene adducts (ICMA &amp; ICBA) in an astrochemical perspective. Part 2: FT-IR spectroscopy from −180 °C to +250 °C
      García-Hernández, D. Aníbal et al.

      Advertised on:

      10
      2023
      Citations
      0
    • TESS discovery of a super-Earth orbiting the M-dwarf star TOI-1680

      We report the discovery by the TESS mission of a super-Earth on a 4.8-days orbit around an inactive M4.5 dwarf (TOI-1680), validated by ground-based facilities. The host star is located 37.14 pc away, with a radius of 0.2100 ± 0.0064 R⊙, mass of 0.1800 ± 0.0044 M⊙, and an effective temperature of 3211 ±100 K. We validated and characterized the

      Ghachoui, M. et al.

      Advertised on:

      9
      2023
      Citations
      1
    • The origin of the planetary nebula M 1-16. A morpho-kinematic and chemical analysis

      We investigated the origin of the Planetary Nebula (PN) M 1-16 using narrow-band optical imaging, and high- and low-resolution optical spectra to perform a detailed morpho-kinematic and chemical studies. M 1-16 is revealed to be a multipolar PN that predominantly emits in [O III] in the inner part of the nebula and [N II] in the lobes. A novel

      Gómez-Muñoz, M. A. et al.

      Advertised on:

      8
      2023
      Citations
      1
    • The Eighteenth Data Release of the Sloan Digital Sky Surveys: Targeting and First Spectra from SDSS-V

      The eighteenth data release (DR18) of the Sloan Digital Sky Survey (SDSS) is the first one for SDSS-V, the fifth generation of the survey. SDSS-V comprises three primary scientific programs or "Mappers": the Milky Way Mapper (MWM), the Black Hole Mapper (BHM), and the Local Volume Mapper. This data release contains extensive targeting information

      Almeida, Andrés et al.

      Advertised on:

      8
      2023
      Citations
      30
    • An investigation of non-canonical mixing in red giant stars using APOGEE <SUP>12</SUP>C/<SUP>13</SUP>C ratios observed in open cluster stars

      Standard stellar evolution theory poorly predicts the surface abundances of chemical species in low-mass, red giant branch (RGB) stars. Observations show an enhancement of p-p chain and CNO cycle products in red giant envelopes, which suggests the existence of non-canonical mixing that brings interior burning products to the surface of these stars

      McCormick, Caroline et al.

      Advertised on:

      9
      2023
      Citations
      4
    • A Blueprint for the Milky Way's Stellar Populations. IV. A String of Pearls-the Galactic Starburst Sequence

      We continue our series of papers on phase-space distributions of stars in the Milky Way based on photometrically derived metallicities and Gaia astrometry, with a focus on the halo-disk interface in the local volume. To exploit various photometric databases, we develop a method of empirically calibrating synthetic stellar spectra based on a

      An, Deokkeun et al.

      Advertised on:

      7
      2023
      Citations
      6
    • Stellar Characterization and Radius Inflation of Hyades M-dwarf Stars from the APOGEE Survey

      We present a spectroscopic analysis of a sample of 48 M-dwarf stars (0.2 M ⊙ < M < 0.6 M ⊙) from the Hyades open cluster using high-resolution H-band spectra from the Sloan Digital Sky Survey/Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey. Our methodology adopts spectrum synthesis with LTE MARCS model atmospheres, along with

      Wanderley, Fábio et al.

      Advertised on:

      7
      2023
      Citations
      0
    • Catalog of Planetary Nebulae Detected by GALEX and Corollary Optical Surveys

      Planetary nebulae (PNs) consist of an ionized envelope surrounding a hot central star (CSPN) that emits mostly at ultraviolet (UV) wavelengths. UV observations, therefore, provide important information on both the CSPN and the nebula. We have matched the PNs in the Hong Kong/Australian Astronomical Observatory/Strasbourg Hα catalog with the Galaxy

      Gómez-Muñoz, M. A. et al.

      Advertised on:

      6
      2023
      Citations
      1
    • Two warm Neptunes transiting HIP 9618 revealed by TESS and Cheops

      HIP 9618 (HD 12572, TOI-1471, TIC 306263608) is a bright (G = 9.0 mag) solar analogue. TESS photometry revealed the star to have two candidate planets with radii of 3.9 ± 0.044 R⊕ (HIP 9618 b) and 3.343 ± 0.039 R⊕ (HIP 9618 c). While the 20.77291 d period of HIP 9618 b was measured unambiguously, HIP 9618 c showed only two transits separated by a

      Osborn, H. P. et al.

      Advertised on:

      8
      2023
      Citations
      6
    • StarHorse results for spectroscopic surveys and Gaia DR3: Chrono-chemical populations in the solar vicinity, the genuine thick disk, and young alpha-rich stars

      The Gaia mission has provided an invaluable wealth of astrometric data for more than a billion stars in our Galaxy. The synergy between Gaia astrometry, photometry, and spectroscopic surveys gives us comprehensive information about the Milky Way. Using the Bayesian isochrone-fitting code StarHorse, we derive distances and extinctions for more than

      Queiroz, A. B. A. et al.

      Advertised on:

      5
      2023
      Citations
      28
    • Unveiling the chemical fingerprint of phosphorus-rich stars. I. In the infrared region of APOGEE-2

      Context The origin of phosphorus, one of the essential elements for life on Earth, is currently unknown. Prevalent models of Galactic chemical evolution (GCE) systematically underestimate the amount of P compared to observations, especially at low metallicities. The recently discovered P-rich ([P/Fe] ≳ 1.2 dex) and metal-poor ([Fe/H] ≃ −1.0 dex)

      Brauner, Maren et al.

      Advertised on:

      5
      2023
      Citations
      0
    • The Carbon Star DY Persei May Be a Cool R Coronae Borealis Variable

      Optical and near-IR photometry suggests that the carbon star DY Persei exhibits fadings similar to those of R Coronae Borealis (RCB) variables. Photometric surveys of the Galaxy and Magellanic Clouds uncovered new DY Per variables with infrared photometry identifying them with cool carbon stars, perhaps, with an unusual tendency to shed mass. In an

      García-Hernández, D. A. et al.

      Advertised on:

      5
      2023
      Citations
      3

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