Start year
1986
Organizational Unit
Organizing institutions
Grants related:
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.
Members
Principal investigator
Domingo Aníbal
García Hernández
Project staff
Arturo
Manchado Torres
Thomas
Masseron
Olga María
Zamora Sánchez
LUCIO
CRIVELLARI
Collaborators
Dr.
P. García Lario
Dr.
G. García Segura
Dr.
L. Stanghellini
Dr.
E. Villaver
Carlos
Allende Prieto
Jorge
García Rojas
Dr.
B. Plez
Dr.
A. Karakas
Dr.
M. Lugaro
Dr.
D. Lambert
Dr.
P. Ventura
Dr.
F. Cataldo
Dr.
Andres Yague
Dr.
Sun Kwok
Dr.
R. Szczerba
Dr.
J.M. Trigo Rodríguez
Dr.
K. Rao
S. Sadjadi
M. Manteiga
C. Dafonte
R. Santoveña
L. Bianchi
Sz. Mészáros
S. Cristallo
L. Piersanti
Results
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.
Scientific activity
Related publications
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Hot bottom burning and s-process nucleosynthesis in massive AGB stars at the beginning of the thermally-pulsing phaseWe report the first spectroscopic identification of massive Galactic asymptotic giant branch (AGB) stars at the beginning of the thermal pulse (TP) phase. These stars are the most Li-rich massive AGBs found to date, super Li-rich AGBs with log ɛ (Li) ~ 3-4. The high Li overabundances are accompanied by weak or no s-process element (i.e. Rb and Zr)García-Hernández, D. A. et al.
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72013 -
The changing nebula around the hot R Coronae Borealis star DY CentauriAmong the distinguishing characteristics of the remarkable hot R Coronae Borealis star DY Centauri, which was recently found to be a spectroscopic binary, is the presence of nebular forbidden lines in its optical spectrum. A compilation of photometry from 1970 to the present suggests that the star has evolved to higher effective temperatures. AKameswara Rao, N. et al.
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52013 -
Photolytic Decomposition of Hydrogenated C70: C70H38 and C70D38The hydrogenated C70 fullerenes C70H38 and C70D38 have been photolyzed at 245nm under Ar or He flow. The photolysis rate constant have been measured: k = 1.54x10-3s-1 for C70H38, and the photolysis of C70D38 occurs at a rate of 1.17x10-3s-1. A remarkable isotope effect in the photolysis of the two molecules has been determined kH/kD = 1.32. TheManchado, A. et al.
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32009Citations0 -
Kinetic Isotope Effects on the Photolysis of C60H18 and C60D18Fullerane C60H18 and its deuterated analogous C60D18 were synthesized in n-hexane solution by a reduction reaction of C60 under the action of HCl or DCl on Zn dust. The resulting solutions were subjected to UV irradiation at 245nm from a low pressure mercury lamp under He. It was found that at 212nm the photolysis rate constant of C60H18 moleculeManchado, A. et al.
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32009Citations0 -
Perdeuterofulleranes: Synthesis and Properties of C70D38 and C70H38Perdeutero[70]fullerane, C70D38 and the hydrogenated analogous C70H38 have been synthesized using nascent deuterium or hydrogen generated by the action of DCl or HCl on Zn dust in toluene or benzene solvents. The FT-IR spectra of C70D38 and C70H38 have been studied. A better oxidation stability of C70D38 has been observed by FT-IR spectroscopy inManchado, A. et al.
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32009Citations0 -
Synthesis and FT-IR Spectroscopy of Perdeuterofullerane: C60D36 Evidences of Isotope Effect in the Stability of C60D36Perdeuterofullerane, C60D36 was synthesized in toluene solution from DCl and Zn. The FT-IR spectrum of C60D36 was compared with that of C60H36, and the C-H stretching and bending shift due to deuteration was measured so that H/ D = 1.36. The thermal stability of C60D36 was studied under N2 by thermogravimetric and differential thermal analysis. ItManchado, A. et al.
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32009Citations0 -
Low and High Temperature Infrared Spectroscopy of C60 and C70 FullerenesThe FT-IR spectra of the fullerenes C60 and C70 have been recorded in the temperature range between 523 K (+250 degrees C) and 93 K (-180 degrees C). As a general rule, it has been observed a shift of the infrared absorption bands toward higher frequencies at lower temperatures. As expected, at 93 K the infrared spectra appear better resolved withManchado, A. et al.
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32010Citations0 -
A Simple Synthesis of C60H18 from C60 Fullerene and Hydrogen IodideC60 fullerene can be easily hydrogenated in aromatic solvent under mild conditions with aqueous hydrogen iodide (HI). The resulting black product has the molecular formula C60H24 center dot 2I2 on the basis of the FT-IR spectroscopy and of the thermogravimetric analysis. When this compound is heated under N2 it releases I2 and HI producingIglesias-Groth, S. et al.
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32010Citations0 -
Characterization of Hydrogenated Fullerene Mixture of C60Hx and C70HxA commercially available hydrogenated mixture of fullerenes (HMF) composed of 77% C60Hx and 22% C70Hx has been analyzed by liquid chromatographic analysis (HPLC), electronic absorption, FT-IR spectroscopy, solubility and by thermal analysis (TGA). The results confirm that the HMF is composed by a mixture of C60Hx and C70Hx with a high degree ofIglesias-Groth, S. et al.
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32010Citations0 -
Determination of the Integrated Molar Absorptivity and Molar Extinction Coefficient of Hydrogenated FullerenesThe integrated molar absorptivity (Psi) and the molar extinction coefficient (epsilon) of each infrared transition of the hydrogenated fullerenes (known as fulleranes) C60H36, C70H38 and a mixture of fulleranes generally referred as 77% of C60Hx and 22% C70Hy with x approximate to y > 30 were determined. These data are useful for the searchManchado, A. et al.
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02013Citations0 -
On the Radical Anion Spectra of Fullerenes C-60 and C-70The radical anion spectra of C-60 and C-70 can be easily generated and studied in primary aliphatic amines. In these conditions the C-60-center dot and C-70-center dot species are accompanied by the dianions C-60(2-) and C-70(2-). In the near infrared region the electronic transitions at 1075, 1058 and 991 nm were assigned to C-60-center dot whileManchado, A. et al.
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02013Citations0 -
Far- and mid-infrared spectroscopy of complex organic matter of astrochemical interest: coal, heavy petroleum fractions and asphaltenesThe coexistence of a large variety of molecular species (i.e. aromatic, cycloaliphatic and aliphatic) in several astrophysical environments suggests that unidentified infrared emission (UIE) occurs from small solid particles containing a mix of aromatic and aliphatic structures (e.g. coal, petroleum, etc.), renewing the astronomical interest onManchado, A. et al.
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32013 -
Diffuse interstellar bands in fullerene planetary nebulae: the fullerenes - diffuse interstellar bands connectionWe present high-resolution (R ~ 15 000) VLT/UVES optical spectra of two planetary nebulae (PNe; Tc 1 and M 1-20) where C60 (and C70) fullerenes have already been found. These spectra are of high quality (S/N > 300) for PN Tc 1, which permits us to search for the expected electronic transitions of neutral C60 and diffuse interstellar bands (DIBs)García-Hernández, D. A. et al.
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22013 -
Synthesis of polyphenylacetylene by radiation-induced polymerization in deoxycholic acid clathratePhenylacetylene was polymerized as inclusion compound (clathrate) inside deoxycholic acid (DOCA) crystals. The polymerization was initiated by γ radiation and a total dose of 320 kGy was employed. The resulting polyphenylacetylene (PPA) was isolated by dissolution of deoxycholic acid in boiling ethanol. PPA high polymer was accompanied by a seriesIglesias-Groth, S. et al.
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42009 -
Short-lived radioactivity in the early solar system: The Super-AGB star hypothesisThe composition of the most primitive solar system condensates, such as calcium-aluminum-rich inclusions (CAIs) and micron-sized corundum grains, show that short-lived radionuclides (SLR), e.g., 26Al, were present in the early solar system. Their abundances require a local or stellar origin, which, however, is far from being understood. We presentLugaro, Maria et al.
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92012 -
High-resolution Optical Spectroscopy of DY Cen: Diffuse Interstellar Bands in a Proto-fullerene Circumstellar Environment?We search high-resolution and high-quality VLT/UVES optical spectra of the hot R Coronae Borealis star DY Cen for electronic transitions of the C60 molecule and diffuse interstellar bands (DIBs). We report the non-detection of the strongest C60 electronic transitions (e.g., those at ~3760, 3980, and 4024 Å). The absence of C60 absorption bands mayGarcía-Hernández, D. A. et al.
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112012 -
The Hot R Coronae Borealis Star DY Centauri is a BinaryThe remarkable hot R Coronae Borealis (RCB) star DY Cen is revealed to be the first and only binary system to be found among the RCB stars and their likely relatives, including the extreme helium stars and the hydrogen-deficient carbon stars. Radial velocity determinations from 1982 to 2010 have shown that DY Cen is a single-lined spectroscopicKameswara Rao, N. et al.
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112012 -
Infrared Study of Fullerene Planetary NebulaeWe present a study of 16 planetary nebulae (PNe) where fullerenes have been detected in their Spitzer Space Telescope spectra. This large sample of objects offers a unique opportunity to test conditions of fullerene formation and survival under different metallicity environments because we are analyzing five sources in our own Galaxy, four in theGarcía-Hernández, D. A. et al.
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122012 -
The mixed chemistry phenomenon in Galactic Bulge PNeAims: We investigate the dual-dust chemistry phenomenon in planetary nebulae (PNe) and discuss reasons for its occurrence, by analyzing Spitzer/IRS spectra of a sample of 40 Galactic PNe among which 26 belong to the Galactic Bulge (GB). Methods: The mixed chemistry is derived from the simultaneous detection of Polycyclic Aromatic Hydrocarbon (PAH)Perea-Calderón, J. V. et al.
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22009 -
Rubidium, zirconium, and lithium production in intermediate-mass asymptotic giant branch starsContext. A recent survey of a large sample of Galactic intermediate-mass (>3 M&sun;) asymptotic giant branch (AGB) stars shows that they exhibit large overabundances of rubidium (Rb) up to 100-1000 times solar. In contrast, zirconium (Zr) is not enriched in these stars compared to its solar abundances. These observations set constraints on ourvan Raai, M. A. et al.
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42012
