Article
Astronomy & Astrophysics
Pavel A. Denissenkov, Chris Ruiz, Sriteja Upadhyayula, Falk Herwig
Summary: Recent spectroscopic measurements reveal high abundances of Be-7 in nova ejecta, deviating from theoretical predictions, but the assumption of enhanced He-4 abundances helps reduce this discrepancy.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Pavel A. Denissenkov, Falk Herwig, Georgios Perdikakis, Hendrik Schatz
Summary: This study investigates the impact of (n,gamma) reaction rate uncertainties on the predicted abundances of neutron-capture elements in carbon-enhanced metal-poor stars, finding that certain reactions have significant effects on the predicted abundances of barium and praseodymium.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
P. Molaro, L. Izzo, V D'Odorico, E. Aydi, P. Bonifacio, G. Cescutti, E. J. Harvey, M. Hernanz, P. Selvelli, M. della Valle
Summary: We report on the search for the Be-7 ii isotope in the outbursts of the classical nova V6595 Sgr. The observations reveal the presence of Be-7 ii and other elements in the absorption lines of the outburst spectra. The abundance of Be-7 is about half of the value commonly measured in novae. The observations also classify the nova as ONe type.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
D. Kamath, F. Dell'Agli, P. Ventura, H. Van Winckel, S. Tosi, A. Karakas
Summary: We study a sample of single Galactic post-AGB stars to determine their initial masses, chemical compositions, and progenitor ages. The luminosity and surface carbon abundance prove to be the most valuable indicators of the star's previous evolution and nucleosynthetic history. This allows us to classify the post-AGB sample into different classes based on their evolutionary history on the AGB. The analysis sheds new light on debated issues related to AGB evolution and nucleosynthesis.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Giulia C. Cinquegrana, Amanda Karakas
Summary: As metallicity increases, the mixing efficiency on the TP-AGB decreases significantly, leading to much of the nucleosynthesis being locked inside white dwarf remnants for very metal-rich stars. Additionally, temperatures at the base of the convective envelope decrease with increasing metallicity, resulting in only partial hydrogen burning for intermediate-mass models. Minor production of heavy elements via the s-process peak at strontium is found in the study, which decreases sharply with increasing metallicity. The dominance of proton capture nucleosynthesis in the models is reflected in the yields, weighted towards the lower mass regime to match the mass distribution within a galaxy.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Amanda Karakas, Giulia Cinquegrana, Meridith Joyce
Summary: New stellar evolutionary sequences of very metal-rich stars are presented using the Monash Stellar Structure code and mesa. The study reveals that metallicity has a weaker influence on hot bottom burning, while it significantly affects core mass instabilities and minimum mass for carbon ignition.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
A. Choplin, L. Siess, S. Goriely
Summary: This study investigates the possibility of i-process nucleosynthesis in low-metallicity low-mass stars during the early stages of the asymptotic giant branch (AGB) phase, in order to explain the abundance patterns of r/s-stars. Results show that the i-process elemental distribution is not strongly affected by the temporal and spatial resolution used to compute the stellar models, but there are typical uncertainties in individual abundances of approximately +/- 0.3 dex. Specific isotopic ratios of certain elements can serve as good tracers of i-process nucleosynthesis.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
S. Goriely, L. Siess, A. Choplin
Summary: This study explores the impact of nuclear uncertainties on the i-process of nucleosynthesis in low-metallicity low-mass stars during the asymptotic giant branch phase. It finds that systematic uncertainties in radiative neutron capture rates can significantly affect surface elemental abundances, with some elements being less affected than others. Improvements in direct neutron capture descriptions and constraints on photon strength functions and nuclear level densities could enhance the predictive power of simulations in this area.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
A. Choplin, S. Goriely, L. Siess
Summary: This study explores the possibility of low-mass low-metallicity AGB stars synthesizing actinides through the intermediate neutron capture process (i-process). A 1 M-circle dot model is used to compute the surface abundance, and it is found that the model can reproduce the Th abundance of star RAVE J094921.8-161722. This finding has implications for dating CEMP-r/s stars.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
A. Yague Lopez, D. A. Garcia-Hernandez, P. Ventura, C. L. Doherty, J. W. den Hartogh, S. W. Jones, M. Lugaro
Summary: This study describes the first s-process post-processing models for asymptotic giant branch (AGB) stars of masses 3, 4, and 5 solar masses at solar metallicity. The results show that the high abundance of C-12 in the He-rich intershell in ATON results in an s-process abundance pattern that favors the second peak over the first peak.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
A. Kawash, L. Chomiuk, J. Strader, E. Aydi, K. V. Sokolovsky, T. Jayasinghe, C. S. Kochanek, P. Schmeer, K. Z. Stanek, K. Mukai, B. Shappee, Z. Way, C. Basinger, T. W. -S. Holoien, J. L. Prieto
Summary: The ASAS-SN has provided unprecedented sky coverage and observing cadence for detecting Galactic transients, with the majority being accretion-powered dwarf nova outbursts. Comparison of properties between 1617 dwarf nova outbursts and classical novae show distinct differences in brightness increase during outburst, with a positive correlation between outburst amplitude and decline time for dwarf novae, in contrast to the weak negative correlation found for classical novae.
ASTROPHYSICAL JOURNAL
(2021)
Article
Astronomy & Astrophysics
Albert Bruch
Summary: Superhumps are variable phenomena observed in cataclysmic variables, coming in positive and negative flavors. Positive superhumps are common in short-period dwarf novae while negative superhumps are not preference for a particular type. This study utilizes TESS's long high-cadence light curves to analyze superhump behavior in old novae and novalike variables, resulting in the most comprehensive census of superhumps in these stars. Furthermore, eclipse epochs derived from the TESS light curves are used to update orbital ephemeris and discuss period changes.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
M. P. Roriz, C. B. Pereira, S. Junqueira, M. Lugaro, N. A. Drake, C. Sneden
Summary: We present detailed chemical compositions of four chemically peculiar stars on the first-ascent red giant branch, which lack high spectral resolution comprehensive analyses. These stars, BD+03 degrees 2688, HE 0457-1805, HE 1255-2324, and HE 2207-1746, exhibit a range in Galactic population membership with metallicities of [Fe/H] = -1.21, -0.19, -0.31, and -0.55, respectively. We obtained elemental abundances for 28 elements, including CNO group and C-12/C-13 ratios, as well as novel results for the heavy elements tungsten and thallium. All four stars show significant enhancements of neutron-capture elements, indicating enrichments from the slow neutron capture (s-process).
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Wei-Min Liu, Long Jiang, Wen-Cong Chen, Xiang-Dong Li
Summary: The disc instability mechanism (DIM) is responsible for the transient behavior of dwarf novae (DNe), with duty cycles playing a crucial role in the long-term binary evolution. Through systematic investigation, it is found that a specific range of duty cycles is required for efficient white dwarf (WD) mass growth. While the DIM significantly influences the accretion process, none of the carbon-oxygen (CO) WDs in the simulations can reach the explosion mass of Type Ia supernovae. The DIM in DNe could partially alleviate the WD mass problem.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
B. Cseh, B. Vilagos, M. P. Roriz, C. B. Pereira, V D'Orazi, A. Karakas, B. Soos, N. A. Drake, S. Junqueira, M. Lugaro
Summary: This study compares the abundance patterns of Ba stars to AGB nucleosynthesis models and verifies the compatibility between AGB model mass and independently derived AGB mass. The results indicate that most Ba stars are contaminated by low-mass, non-rotating AGB stellar models, and some observed elemental abundances are higher than the predicted values. Some stars may have lower masses than independently determined.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Chemistry, Multidisciplinary
Kassa Belay Ibrahim, Tofik Ahmed Shifa, Paolo Moras, Elisa Moretti, Alberto Vomiero
Summary: A heterointerface catalyst with strong metal support interaction (SMSI) between WMn2O4 and TiO2 is designed for efficient and stable oxygen evolution reaction (OER). The engineered heterointerface exhibits a low onset overpotential and long-term durability.
Article
Green & Sustainable Science & Technology
Getachew Solomon, Mojtaba Gilzad Kohan, Raffaello Mazzaro, Matteo Jugovac, Paolo Moras, Vittorio Morandi, Isabella Concina, Alberto Vomiero
Summary: Hierarchical nanostructures composed of NiMoO4 nanorods surrounded by active MoS2 nanosheets on a nickel foam substrate were designed and showed excellent oxygen evolution reaction performance and charge storage capacity, suggesting promising applications in the catalysis field.
ADVANCED SUSTAINABLE SYSTEMS
(2023)
Article
Chemistry, Physical
Getachew Solomon, Marco Lecca, Matteo Bisetto, Mojtaba Gilzad Kohan, Isabella Concina, Marta Maria Natile, Alberto Vomiero
Summary: Researchers have successfully reduced the photo-oxidation of Cu2O nanowires by growing a thin layer of TiO2 protective layer and an amorphous layer of VOx cocatalyst on them. The optimized photoelectrode exhibits excellent stability and high photocurrent density under simulated sunlight, demonstrating the potential of using earth-abundant materials for solar hydrogen production.
ACS APPLIED ENERGY MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Daria Pankratova, Silvia Maria Giacomelli, Khabib Yusupov, Farid Akhtar, Alberto Vomiero
Summary: This study aims to produce high-entropy oxides composed of Co-Cr-Fe-Mn-Ni-O through spark plasma sintering (SPS), testing their thermoelectric (TE) properties. The researchers successfully obtained the material using a faster and scalable process compared to the previous technique.
Article
Chemistry, Physical
Kassa Belay Ibrahim, Tofik Ahmed Shifa, Matteo Bordin, Elisa Moretti, Heng-Liang Wu, Alberto Vomiero
Summary: Confining Ni(OH)(2) nanoparticles in the vdW gaps of 2D exfoliated SnS2 (Ex-SnS2) accelerates water oxidation and ensures long-term stability in alkaline solutions. The oxidation states of Ni are found to be correlated with the rate of oxygen gas evolution, with the confined system exhibiting a higher rate compared to the unconfined system. The confinement effect contributes to the outstanding OER activity and stability of the catalyst.
Article
Physics, Multidisciplinary
M. Agostini, A. Alexander, G. R. Araujo, A. M. Bakalyarov, M. Balata, I. Barabanov, L. Baudis, C. Bauer, S. Belogurov, A. Bettini, L. Bezrukov, V. Biancacci, E. Bossio, V. Bothe, R. Brugnera, A. Caldwell, S. Calgaro, C. Cattadori, A. Chernogorov, P. -J. Chiu, T. Comellato, V. D'Andrea, E. V. Demidova, A. Di Giacinto, N. Di Marco, E. Doroshkevich, F. Fischer, M. Fomina, A. Gangapshev, A. Garfagnini, C. Gooch, P. Grabmayr, V. Gurentsov, K. Gusev, S. Hackenmueller, S. Hemmer, W. Hofmann, J. Huang, M. Hult, L. V. Inzhechik, J. Janicsko Csathy, J. Jochum, M. Junker, V. Kazalov, Y. Kermaidic, H. Khushbakht, T. Kihm, K. Kilgus, I. V. Kirpichnikov, A. Klimenko, K. T. Knoepfle, O. Kochetov, V. N. Kornoukhov, P. Krause, V. V. Kuzminov, M. Laubenstein, B. Lehnert, M. Lindner, I. Lippi, A. Lubashevskiy, B. Lubsandorzhiev, G. Lutter, C. Macolino, B. Majorovits, W. Maneschg, L. Manzanillas, G. Marshall, M. Miloradovic, R. Mingazheva, M. Misiaszek, M. Morella, Y. Meuller, I. Nemchenok, M. Neuberger, L. Pandola, K. Pelczar, L. Pertoldi, P. Piseri, A. Pullia, C. Ransom, L. Rauscher, M. Redchuk, S. Riboldi, N. Rumyantseva, C. Sada, S. Sailer, F. Salamida, S. Schoenert, J. Schreiner, M. Schuett, A. -K. Schuetz, O. Schulz, M. Schwarz, B. Schwingenheuer, O. Selivanenko, E. Shevchik, M. Shirchenko, L. Shtembari, H. Simgen, A. Smolnikov, D. Stukov, S. Sullivan, A. A. Vasenko, A. Veresnikova, C. Vignoli, K. von Sturm, T. Wester, C. Wiesinger, M. Wojcik, E. Yanovich, B. Zatschler, I. Zhitnikov, S. V. Zhukov, D. Zinatulina, A. Zschocke, A. J. Zsigmond, K. Zuber, G. Zuzel
Summary: We present the measurement of the two-neutrino double-beta decay rate of 76Ge obtained with the GERDA Phase II experiment. The half-life of the process has been determined using a subset of the GERDA exposure, 11.8 kg yr, and is reported as T2 nu 1/2=2.022+/-0.018(stat)+/-0.038(syst) x 10^21 yr. This measurement represents the most precise determination of the 76Ge two-neutrino double-beta decay half-life and is one of the most accurate measurements of a double-beta decay process. The relevant nuclear matrix element has also been extracted and reported as M2 nu eff=(0.101+/-0.001).
PHYSICAL REVIEW LETTERS
(2023)
Article
Chemistry, Physical
Jiurong Li, Jiancang Chen, Xiujian Zhao, Alberto Vomiero, Xiao Gong
Summary: Organosilane-grafted carbon dots (Si-CDs) were synthesized by hydrothermal method and can be uniformly dispersed in polyvinyl alcohol (PVA) matrix. Si-CDs/PVA thin-film LSCs exhibit excellent absorption in the UV spectral region and about 90% transmission in the visible range, with high stability and power conversion efficiency (PCE).
Proceedings Paper
Astronomy & Astrophysics
Lorenzo Roberti, Marco Pignatari, Maria Lugaro, Zsolt Fulop, Gyorgy Gyurky
Summary: Neutron-capture processes produce most heavy elements in the Solar System, but cannot create rare proton-rich stable isotopes. The gamma-process, a chain of photodisintegrations, is recognized as a feasible way to synthesize these isotopes in core collapse supernovae. However, there are discrepancies between theory and observations in this scenario. In this study, we aim to explore the gamma-process in more detail using different CCSNe models and up-to-date nuclear reaction rates. Our preliminary analysis focuses on identifying the gamma-process sites and studying progenitors of CCSNe that undergo a carbon-oxygen shell merger before the collapse of the iron core.
NUCLEAR PHYSICS IN ASTROPHYSICS - X, NPA-X 2022
(2023)
Proceedings Paper
Astronomy & Astrophysics
Jakub Skowronski, Axel Boeltzig
Summary: The C-12(p, gamma)N-13 reaction cross section is being investigated at the Laboratory for Underground Nuclear Astrophysics (LUNA) in a low-background environment. Different types of solid targets are being used in combination with two complementary detection techniques, HPGe spectroscopy and activation counting. The experimental techniques and corresponding analyses used to extract the reaction cross section are presented in order to reduce systematic uncertainties.
NUCLEAR PHYSICS IN ASTROPHYSICS - X, NPA-X 2022
(2023)
Proceedings Paper
Astronomy & Astrophysics
Sandra Zavatarelli, Eliana Masha
Summary: The NeNa and MgAl cycles have attracted much experimental activity in the past decade due to their role in synthesizing Ne, Na, and Mg isotopes during H burning in various astrophysical scenarios. These cycles are also believed to be responsible for the observed anti-correlations in O-Na and Al-Mg abundances in Galactic globular cluster stars. The first reaction in the NeNa cycle, Ne-20(p,gamma)Na-21, is the bottleneck and controls the speed of the entire cycle due to its slow reaction rate. The LUNA collaboration has initiated a new experimental effort to study the 366 keV resonance and improve the understanding of the cross section at proton energies below 400 keV.
NUCLEAR PHYSICS IN ASTROPHYSICS - X, NPA-X 2022
(2023)
Proceedings Paper
Astronomy & Astrophysics
M. La Cognata, G. G. Kiss, R. Yarmukhamedov, K. I. Tursunmakhatov, I. Wiedenhover, L. T. Baby, S. Cherubini, A. Cvetinovic, G. D'Agata, P. Figuera, G. L. Guardo, M. Gulino, S. Hayakawa, I. Indelicato, L. Lamia, M. Lattuada, F. Mudo, S. Palmerini, R. G. Pizzone, G. G. Rapisarda, S. Romano, M. L. Sergi, R. Sparta, C. Spitaleri, O. Trippella, A. Tumino, M. Anastasiou, S. A. Kuvin, N. Rijal, B. Schmidt, S. B. Igamov, S. B. Sakuta, Zs. Fulop, Gy. Gyurky, T. Szucs, Z. Halasz, E. Somorjai, Z. Hons, J. Mrazek, R. E. Tribble, A. M. Mukhamedzhanov
Summary: In this study, the external capture contribution of the He-3(alpha, gamma)Be-7 reaction was measured indirectly using the asymptotic normalization coefficient (ANC) technique. The angular distributions of deuterons emitted in the Li-6(He-3,d)Be-7 alpha-transfer reactions were measured and the ANCs were extracted from the scaling of distorted-wave Born approximation (DWBA) and coupled-channel (CC) calculations. The astrophysical S-factor for the He-3(alpha, gamma)Be-7 reaction was calculated assuming E1 direct capture and the zero energy value was found to be 0.534 +/- 0.025 keVb. The experimental and theoretical approaches were validated through the analysis of the Li-6(p,gamma)Be-7 astrophysical factor, and have important astrophysical applications in understanding the primordial lithium problem.
NUCLEAR PHYSICS IN ASTROPHYSICS - X, NPA-X 2022
(2023)
Proceedings Paper
Astronomy & Astrophysics
D. Piatti
Summary: The Li-6(p,gamma)Be-7 reaction plays important roles in three nucleosynthesis scenarios. However, the trend of Li-6(p,gamma)Be-7 S-factor at astrophysical energies was poorly constrained due to conflicting experimental results. A recent direct measurement found a resonance-like structure, but it has not been confirmed by other measurements or theoretical calculations. A new experiment at LUNA was conducted to clarify the existence of this resonance, and the results showed no evidence for it. These findings were supported by an indirect determination and a theoretical study.
NUCLEAR PHYSICS IN ASTROPHYSICS - X, NPA-X 2022
(2023)
Proceedings Paper
Astronomy & Astrophysics
D. Piatti, G. F. Ciani
Summary: The O-17(p,gamma)F-18 reaction is important for hydrogen burning in various stellar scenarios. The 65 keV resonance, which contributes significantly to the astrophysical reaction rate, is poorly constrained and only determined through indirect measurements. The LUNA collaboration has developed a high sensitivity setup at the underground location of the LUNA facility to overcome the challenges of directly measuring this resonance.
NUCLEAR PHYSICS IN ASTROPHYSICS - X, NPA-X 2022
(2023)
Article
Physics, Nuclear
E. Clement, A. Lemasson, M. Rejmund, B. Jacquot, D. Ralet, C. Michelagnoli, D. Barrientos, P. Bednarczyk, G. Benzoni, A. J. Boston, A. Bracco, B. Cederwall, M. Ciemala, J. Collado, F. Crespi, C. Domingo-Pardo, J. Dudouet, H. J. Eberth, G. de France, A. Gadea, V. Gonzalez, A. Gottardo, L. Harkness, H. Hess, A. Jungclaus, A. Kaskas, W. Korten, S. M. Lenzi, S. Leoni, J. Ljungvall, R. Menegazzo, D. Mengoni, B. Million, D. R. Napoli, J. Nyberg, Zs. Podolyak, A. Pullia, B. Quintana Arnes, F. Recchia, N. Redon, P. Reiter, M. D. Salsac, E. Sanchis, M. Senyigit, M. Siciliano, D. Sohler, O. Stezowski, C. Theisen, J. J. Valiente Dobon
Summary: This study investigates the evolution of nuclear deformation in the Xe isotopic chain and explores the relevance of O(6) symmetry. Experimental measurements reveal that the ground state band of 124Xe is prolate axially deformed, confirming the breaking of O(6) symmetry in this isotope.
Article
Physics, Particles & Fields
M. GERDA Collaboration, M. Agostini, A. Alexander, G. Araujo, A. M. Bakalyarov, M. Balata, I. Barabanov, L. Baudis, C. Bauer, S. Belogurov, A. Bettini, L. Bezrukov, V. Biancacci, E. Bossio, V. Bothe, R. Brugnera, A. Caldwell, S. Calgaro, C. Cattadori, A. Chernogorov, P. -j. Chiu, T. Comellato, V. D'Andrea, E. V. Demidova, A. Di Giacinto, N. Di Marco, E. Doroshkevich, F. Fischer, M. Fomina, A. Gangapshev, A. Garfagnini, C. Gooch, P. Grabmayr, V. Gurentsov, K. Gusev, J. Hakenmueller, S. Hemmer, W. Hofmann, M. Hult, L. V. Inzhechik, J. Janicsko Csathy, J. Jochum, M. Junker, V. Kazalov, Y. Kermaidic, H. Khushbakht, T. Kihm, K. Kilgus, I. V. Kirpichnikov, A. Klimenko, K. T. Knoepfle, O. Kochetov, V. N. Kornoukhov, P. Krause, V. V. Kuzminov, M. Laubenstein, M. Lindner, I. Lippi, A. Lubashevskiy, B. Lubsandorzhiev, G. Lutter, C. Macolino, B. Majorovits, W. Maneschg, L. Manzanillas, G. Marshall, M. Misiaszek, M. Morella, Y. Mueller, I. Nemchenok, M. Neuberger, L. Pandola, K. Pelczar, L. Pertoldi, P. Piseri, A. Pullia, L. Rauscher, M. Redchuk, S. Riboldi, N. Rumyantseva, C. Sada, S. Sailer, F. Salamida, S. Schoenert, J. Schreiner, M. Schuett, A. -k. Schuetz, O. Schulz, M. Schwarz, B. Schwingenheuer, O. Selivanenko, E. Shevchik, M. Shirchenko, L. Shtembari, H. Simgen, A. Smolnikov, D. Stukov, S. Sullivan, A. A. Vasenko, A. Veresnikova, C. Vignoli, K. von Sturm, T. Wester, C. Wiesinger, M. Wojcik, E. Yanovich, B. Zatschler, I. Zhitnikov, S. V. Zhukov, D. Zinatulina, A. Zschocke, A. J. Zsigmond, K. Zuber, G. Zuzel
Summary: We searched for tri-nucleon decays of Ge-76 in the GERDA experiment dataset, and placed a lower limit on the lifetime of these decays by analyzing the sum of the decay widths.
EUROPEAN PHYSICAL JOURNAL C
(2023)
