Thermonuclear reaction rates are calculated for three oxygen isotopes 14,15,16O in CNO cycles reactions occurring in red giant stars. These reactions are:, , , , and . Reaction rates have been calculated using Matlab codes, and related comparisons were made with NACRE II and Reaclib libraries, and the ratios of production to the destruction of 15,16O isotopes were found. Present reaction rate results were close to most of the selected reactions, and in some cases larger with a factor of 1-3. 15,16O production to destruction ratios indicated a special tendency to saturate at temperatures higher than ~ 2 GK, and these ratios were in general larger than 1 indicating an excess of producing such isotopes in red giant stars.
Mackereth, J. Ted, et al. ; The NASA Transiting Exoplanet Survey Satellite (NASA-TESS) mission presents a treasure trove for understanding the stars it observes and the Milky Way, in which they reside. We present a first look at the prospects for Galactic and stellar astrophysics by performing initial asteroseismic analyses of bright (G < 11) red giant stars in the TESS southern continuous viewing zone (SCVZ). Using three independent pipelines, we detect νmax and Δν in 41 per cent of the 15 405 star parent sample (6388 stars), with consistency at a level of ∼2 per cent in νmax and ∼5 per cent in Δν. Based on this, we predict that seismology will be attainable for ∼3 × 105 giants across the whole sky and at least 104 giants with ≥1 yr of observations in the TESS-CVZs, subject to improvements in analysis and data reduction techniques. The best quality TESS-CVZ data, for 5574 stars where pipelines returned consistent results, provide high-quality power spectra across a number of stellar evolutionary states. This makes possible studies of, for example, the asymptotic giant branch bump. Furthermore, we demonstrate that mixed ℓ = 1 modes and rotational splitting are cleanly observed in the 1-yr data set. By combining TESS-CVZ data with TESS-HERMES, SkyMapper, APOGEE, and Gaia, we demonstrate its strong potential for Galactic archaeology studies, providing good age precision and accuracy that reproduces well the age of high [α/Fe] stars and relationships between mass and kinematics from previous studies based on e.g. Kepler. Better quality astrometry and simpler target selection than the Kepler sample makes this data ideal for studies of the local star formation history and evolution of the Galactic disc. These results provide a strong case for detailed spectroscopic follow-up in the CVZs to complement that which has been (or will be) collected by current surveys. ; JTM and AM acknowledge support from the ERC Consolidator Grant funding scheme (project ASTEROCHRONOMETRY, G.A. n. 772293). JTM acknowledges support from the Banting Postdoctoral Fellowship programme administered by the Government of Canada, and a CITA/Dunlap Institute fellowship. The Dunlap Institute is funded through an endowment established by the David Dunlap family and the University of Toronto. SM acknowledges support from the Spanish Ministry with the Ramon y Cajal fellowship number RYC-2015-17697. RAG acknowledges the support from the PLATO CNES grant. DB acknowledges supported by FCT through the research grants UIDB/04434/2020, UIDP/04434/2020, and PTDC/FIS-AST/30389/2017, and by FEDER – Fundo Europeu de Desenvolvimento Regional through COMPETE2020 – Programa Operacional Competitividade e Internacionalização (grant: POCI-01-0145-FEDER-030389). LC acknowledges support from the Australian Research Council grant FT160100402. TC acknowledges support from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement no. 792848 (PULSATION). AS is partially supported by grants ESP2017-82674-R (Spanish Government) and 2017-SGR-1131 (Generalitat de Catalunya). MHP and MV acknowledge support from NASA grant 80NSSC18K1582.
[Context] Thanks to ongoing efforts to compute accurate stellar ages, we are able to characterise stars in different regions of the Milky Way. The Gaia and Kepler space-missions, along with ground-based spectroscopic surveys such as APOGEE, provide a unique way to study the chemo-kinematics relations as a function of age through the Galactic stellar populations and provide new constraints to Galactic evolution models. [Aims] We investigate the properties of the double sequences of the Milky Way discs visible in the [α/Fe] versus [Fe/H] diagram, which are usually associated to the chemical thin and thick discs at the solar circle. In the framework of Galactic formation and evolution, we discuss the complex relationships between age, metallicity, [α/Fe], and the radial, azimuthal, and vertical components of the space velocities. [Methods] We study stars with measured chemical and seismic properties from the APOGEE spectroscopic survey and the Kepler satellite, respectively. In addition, astrometry from the Gaia satellite is available for the majority of the sample. We separate the [α/Fe]-[Fe/H] diagram into three stellar populations: the thin disc, the high-α metal-poor thick disc, and the high-α metal-rich thick disc and characterise each of these in the age-chemo-kinematics parameter space. Because of the model-dependent nature of the ages inferred from asteroseismology, and because they depend on the quality of the input spectroscopic information, we compare results obtained from different APOGEE data releases (DR14 and DR16). We also use age determinations from two recent works in the literature. In addition, we use the Besançon stellar populations synthesis model to highlight selection biases and mechanisms (such as mergers and secular evolution) not included in the model. [Results] The thin disc exhibits a flat age-metallicity relation while [α/Fe] increases with stellar age. We confirm no correlation between radial and vertical velocities with [Fe/H], [α/Fe], and age for each stellar population. Considering both samples, Vφ decreases with age for the thin disc, while Vφ increases with age for the high-α metal-poor thick disc. We show that this difference is not due to sample selection. Although the age distribution of the high-α metal-rich thick disc is very close to that of the high-α metal-poor thick disc between 7 and 14 Gyr, its kinematics seems to follow that of the thin disc. This feature, not predicted by the hypotheses included in the Besançon Galaxy Model, suggests a different origin and history for this population. Finally, we show that there is a maximum dispersion of the vertical velocity, σZ, with age for the high-α metal-poor thick disc around 8 Gyr. The comparisons with the Besançon Galaxy Model simulations suggest a more complex chemo-dynamical scheme to explain this feature, most likely including mergers and radial migration effects. ; F.F., A.F., R.M., M.R., T.A. acknowledge support by the Spanish Ministry of Science, Innovation and University (MICIU/FEDER, UE) through grant RTI2018-095076-B-C21, the Institute of Cosmos Sciences University of Barcelona (ICCUB, Unidad de Excelencia "María de Maeztu") through grant CEX2019-000918-M, the Ramon y Cajal Fellowship RYC2018-025968-I. This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 800502. AM acknowledges funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement No. 772293 – project ASTEROCHRONOMETRY, https://www.asterochronometry.eu.
Context. The intermediate-mass pre-main sequence Herbig Ae/Be stars are key to understanding the differences in formation mechanisms between low-and high-mass stars. The study of the general properties of these objects is hampered by the lack of a well-defined, homogeneous sample, and because few and mostly serendipitously discovered sources are known. Aims. Our goal is to identify new Herbig Ae/Be candidates to create a homogeneous and well defined catalogue of these objects. Methods. We have applied machine learning techniques to 4 150 983 sources with data from Gaia DR2, 2MASS, WISE, and IPHAS or VPHAS+. Several observables were chosen to identify new Herbig Ae/Be candidates based on our current knowledge of this class, which is characterised by infrared excesses, photometric variabilities, and Hα emission lines. Classical techniques are not efficient for identifying new Herbig Ae/Be stars mainly because of their similarity with classical Be stars, with which they share many characteristics. By focusing on disentangling these two types of objects, our algorithm has also identified new classical Be stars. Results. We have obtained a large catalogue of 8470 new pre-main sequence candidates and another catalogue of 693 new classical Be candidates with a completeness of 78.8ℓ ±ℓ 1.4% and 85.5ℓ ±ℓ 1.2%, respectively. Of the catalogue of pre-main sequence candidates, at least 1361 sources are potentially new Herbig Ae/Be candidates according to their position in the Hertzsprung-Russell diagram. In this study we present the methodology used, evaluate the quality of the catalogues, and perform an analysis of their flaws and biases. For this assessment, we make use of observables that have not been accounted for by the algorithm and hence are selection-independent, such as coordinates and parallax based distances. The catalogue of new Herbig Ae/Be stars that we present here increases the number of known objects of the class by an order of magnitude. ; With funding from the Spanish government through the "María de Maeztu Unit of Excellence" accreditation (MDM-2017-0737)
Monteiro, Mario J. P. F. G./0000-0003-0513-8116; Suarez, Juan Carlos/0000-0003-3649-8384; Serenelli, Aldo/0000-0001-6359-2769; Jiang, Chen/0000-0002-7614-1665; Slumstrup, Ditte/0000-0003-4538-9518; Mathur, Savita/0000-0002-0129-0316; Christensen-Dalsgaard, Jorgen/0000-0001-5137-0966; Bodi, Attila/0000-0002-8585-4544; Pereira, Filipe/0000-0002-2157-7146; YILDIZ, Mutlu/0000-0002-7772-7641; Di Mauro, Maria Pia/0000-0001-7801-7484; Ball, Warrick/0000-0002-4773-1017; Spitoni, Emanuele/0000-0001-9715-5727; Handberg, Rasmus/0000-0001-8725-4502; Lustosa de Moura, Bruno/0000-0001-6295-3526; Lund, Mikkel Norup/0000-0001-9214-5642; Rodriguez Diaz, Luisa Fernanda/0000-0002-0588-1375; Basu, Sarbani/0000-0002-6163-3472; Stokholm, Amalie/0000-0002-5496-365X; Cunha, Margarida/0000-0001-8237-7343; miglio, andrea/0000-0001-5998-8533; BUGNET, Lisa/0000-0003-0142-4000; Buzasi, Derek/0000-0002-1988-143X; Van Eylen, Vincent/0000-0001-5542-8870; Stello, Dennis/0000-0002-4879-3519; Lysgaard Rorsted, Jakob/0000-0001-9234-430X; Angelou, George/0000-0003-4463-1907; Mosser, Benoit/0000-0002-7547-1208; Verma, Kuldeep/0000-0003-0970-6440; Kuszlewicz, James/0000-0002-3322-5279; Bell, Keaton/0000-0002-0656-032X; Huber, Daniel/0000-0001-8832-4488; Lundkvist, Mia Sloth/0000-0002-8661-2571 ; WOS: 000520956000001 ; Since the onset of the "space revolution" of high-precision high-cadence photometry, asteroseismology has been demonstrated as a powerful tool for informing Galactic archeology investigations. the launch of the NASA Transiting Exoplanet Survey Satellite (TESS) mission has enabled seismic-based inferences to go full sky-providing a clear advantage for large ensemble studies of the different Milky Way components. Here we demonstrate its potential for investigating the Galaxy by carrying out the first asteroseismic ensemble study of red giant stars observed by TESS. We use a sample of 25 stars for which we measure their global asteroseimic observables and estimate their fundamental stellar properties, such as radius, mass, and age. Significant improvements are seen in the uncertainties of our estimates when combining seismic observables from TESS with astrometric measurements from the Gaia mission compared to when the seismology and astrometry are applied separately. Specifically, when combined we show that stellar radii can be determined to a precision of a few percent, masses to 5%-10%, and ages to the 20% level. This is comparable to the precision typically obtained using end-of-mission Kepler data. ; NASA's Science Mission directorate; Danish National Research FoundationDanmarks Grundforskningsfond [DNRF106]; ESA PRODEXEuropean Space Agency [PEA 4000119301]; Stellar Astrophysics Centre (SAC) at Aarhus University; Independent Research Fund Denmark [7027-00096B]; FCT/MCTESPortuguese Foundation for Science and Technology [UID/FIS/04434/2019, PTDC/FIS-AST/30389/2017, POCI-01-0145-FEDER-030389, CEECIND/02619/2017]; FEDER through COMPETE2020 [UID/FIS/04434/2019, PTDC/FIS-AST/30389/2017, POCI-01-0145-FEDER-030389, CEECIND/02619/2017]; CNES/PLATO grant; NASANational Aeronautics & Space Administration (NASA) [NNX16AB76G]; European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreementEuropean Union (EU) [792848, 664931]; ESA PRODEX programme; Premiale 2015 MITiC; National Science FoundationNational Science Foundation (NSF) [AST-1903828]; Carlsberg FoundationCarlsberg Foundation [CF17-0760]; European Research Council under the European Community's Seventh Framework Programme (FP7/2007-2013)/ERC grant [338251]; European Research CouncilEuropean Research Council (ERC) [772293]; MINECO [ESP2017-82674R]; Spanish public funds for research [ESP2017-87676-2-2]; Spanish Ministry of Science and EducationSpanish Government [RYC-2012-09913] ; This Letter includes data collected by the TESS mission, which are publicly available from the Mikulski Archive for Space Telescopes (MAST). Funding for the TESS mission is provided by NASA's Science Mission directorate. Funding for the TESS Asteroseismic Science Operations Centre is provided by the Danish National Research Foundation (grant agreement No. DNRF106), ESA PRODEX (PEA 4000119301), and Stellar Astrophysics Centre (SAC) at Aarhus University. V.S. A. acknowledges support from the Independent Research Fund Denmark (Research grant 7027-00096B). D.B. is supported in the form of work contract FCT/MCTES through national funds and by FEDER through COMPETE2020 in connection to these grants: UID/FIS/04434/2019; PTDC/FIS-AST/30389/2017 & POCI-01-0145-FEDER-030389. L.B., R.A.G., and B.M. acknowledge the support from the CNES/PLATO grant. D.B. acknowledges NASA grant NNX16AB76G. T.L.C. acknowledges support from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No.792848 (PULSATION). This work was supported by FCT/MCTES through national funds (UID/FIS/04434/2019). E.C. is funded by the European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement No. 664931. R.H. and M.N.L. acknowledge the support of the ESA PRODEX programme. T.S.R. acknowledges financial support from Premiale 2015 MITiC (PI B. Garilli). K.J.B. is supported by the National Science Foundation under Award AST-1903828. M. S.L. is supported by the Carlsberg Foundation (grant agreement No. CF17-0760). M.C. is funded by FCT//MCTES through national funds and by FEDER through COMPETE2020 through these grants: UID/FIS/04434/2019, PTDC/FIS-AST/30389/2017 & POCI-01-0145-FEDER-030389, CEECIND/02619/2017. the research leading to the presented results has received funding from the European Research Council under the European Community's Seventh Framework Programme (FP7/2007-2013)/ERC grant agreement no 338251 (StellarAges). A.M. acknowledges support from the European Research Council Consolidator Grant funding scheme (project ASTEROCHRONOMETRY, grant agreement No. 772293,.http://www.asterochronometry.eu).A.M.S.is partially supported by MINECO grant ESP2017-82674R. J.C.S. acknowledges funding support from Spanish public funds for research under projects ESP2017-87676-2-2, and from project RYC-2012-09913 under the `Ramon y Cajal' program of the Spanish Ministry of Science and Education. Resources supporting this work were provided by the NASA High-End Computing (HEC) Program through the NASA Advanced Supercomputing (NAS) Division at Ames Research Center for the production of the SPOC data products.
[Contact] The large quantity of high-quality asteroseismic data that have been obtained from space-based photometric missions and the accuracy of the resulting frequencies motivate a careful consideration of the accuracy of computed oscillation frequencies of stellar models, when applied as diagnostics of the model properties. ; [Aims] Based on models of red-giant stars that have been independently calculated using different stellar evolution codes, we investigate the extent to which the differences in the model calculation affect the model oscillation frequencies and other asteroseismic diagnostics. ; [Methods] For each of the models, which cover four different masses and different evolution stages on the red-giant branch, we computed full sets of low-degree oscillation frequencies using a single pulsation code and, from these frequencies, typical asteroseismic diagnostics. In addition, we carried out preliminary analyses to relate differences in the oscillation properties to the corresponding model differences. ; [Results] In general, the differences in asteroseismic properties between the different models greatly exceed the observational precision of these properties. This is particularly true for the nonradial modes whose mixed acoustic and gravity-wave character makes them sensitive to the structure of the deep stellar interior and, hence, to details of their evolution. In some cases, identifying these differences led to improvements in the final models presented here and in Paper I; here we illustrate particular examples of this. ; [Conclusions] Further improvements in stellar modelling are required in order fully to utilise the observational accuracy to probe intrinsic limitations in the modelling and improve our understanding of stellar internal physics. However, our analysis of the frequency differences and their relation to stellar internal properties provides a striking illustration of the potential, in particular, of the mixed modes of red-giant stars for the diagnostics of stellar interiors. ; Funding for the Stellar Astrophysics Centre is provided by The Danish National Research Foundation (Grant agreement No. DNRF106). The research was supported by the ASTERISK project (ASTERoseismic Investigations with SONG and Kepler) funded by the European Research Council (Grant agreement No. 267864). This research was supported in part by the National Science Foundation under Grant No. NSF PHY-1748958. VSA acknowledges support from VILLUM FONDEN (research grant 10118) and the Independent Research Fund Denmark (Research grant 7027-00096B). DS is the recipient of an Australian Research Council Future Fellowship (project number FT1400147). SC acknowledges support from Premiale INAF MITiC, from INAF "Progetto mainstream" (PI: S. Cassisi), and grant AYA2013-42781P from the Ministry of Economy and Competitiveness of Spain. AMS is partially supported by grants ESP2017-82674-R (Spanish Government) and 2017-SGR-1131 (General-itat de Catalunya). TC acknowledges support from the European Research Council AdG No 320478-TOFU and the STFC Consolidated Grant ST/R000395/1. SH received funding for this research from the European Research Council under the European Community's Seventh Framework Programme (FP7/2007-2013)/ERC grant agreement no 338251 (StellarAges). AM acknowledges the support of the Government of India, Department of Atomic Energy, under Project No. 12-R&D-TFR-6.04-0600. DB is supported in the form of work contract FCT/MCTES through national funds and by FEDER through COMPETE2020 in connection to these grants: UID/FIS/04434/2019; PTDC/FIS-AST/30389/2017 & POCI-01-0145-FEDER-030389.
Orhan, Zeynep Celik/0000-0002-9424-2339; Serenelli, Aldo/0000-0001-6359-2769; Monteiro, Mario J. P. F. G./0000-0003-0513-8116; Huber, Daniel/0000-0001-8832-4488; Adibekyan, Vardan/0000-0002-0601-6199; Reffert, Sabine/0000-0002-0460-8289; Stock, Stephan/0000-0002-1166-9338; Stassun, Keivan/0000-0002-3481-9052; Cunha, Margarida/0000-0001-8237-7343; Kuszlewicz, James/0000-0002-3322-5279; Lund, Mikkel Norup/0000-0001-9214-5642; Mathur, Savita/0000-0002-0129-0316; Nielsen, Martin Bo/0000-0001-9169-2599; Mosser, Benoit/0000-0002-7547-1208; Pereira, Filipe/0000-0002-2157-7146; Lucas, Miles/0000-0001-6341-310X; miglio, andrea/0000-0001-5998-8533; Ball, Warrick/0000-0002-4773-1017; Basu, Sarbani/0000-0002-6163-3472; Veras, Dimitri/0000-0001-8014-6162; Handberg, Rasmus/0000-0001-8725-4502; Christensen-Dalsgaard, Jorgen/0000-0001-5137-0966; Delgado Mena, Elisa/0000-0003-4434-2195 ; WOS: 000498546800001 ; The Transiting Exoplanet Survey Satellite (TESS) is performing a near all-sky survey for planets that transit bright stars. in addition, its excellent photometric precision enables asteroseismology of solar-type and red-giant stars, which exhibit convection-driven, solar-like oscillations. Simulations predict that TESS will detect solar-like oscillations in nearly 100 stars already known to host planets. in this paper, we present an asteroseismic analysis of the known red-giant host stars HD;212771 and HD;203949, both systems having a long-period planet detected through radial velocities. These are the first detections of oscillations in previously known exoplanet-host stars by TESS, further showcasing the mission?s potential to conduct asteroseismology of red-giant stars. We estimate the fundamental properties of both stars through a grid-based modeling approach that uses global asteroseismic parameters as input. We discuss the evolutionary state of HD;203949 in depth and note the large discrepancy between its asteroseismic mass (M-* = 1.23 0.15 MM* = 1.00 0.16 M if in the clump) and the mass quoted in the discovery paper (M-* = 2.1 0.1 M), implying a change >30% in the planet?s mass. Assuming HD;203949 to be in the clump, we investigate the planet?s past orbital evolution and discuss how it could have avoided engulfment at the tip of the red-giant branch. Finally, HD;212771 was observed by K2 during its Campaign 3, thus allowing for a preliminary comparison of the asteroseismic performances of TESS and K2. We estimate the ratio of the observed oscillation amplitudes for this star to be
We assess the consequences for consumers in 76 countries of multinational acquisitions in beer and spirits. Outcomes depend on how changes in ownership affect markups versus efficiency. We find that owner fixed effects contribute very little to the performance of brands. On average, foreign ownership tends to raise costs and lower appeal. Using the estimated model, we simulate the consequences of counter-factual national merger regulation. The US beer price index would have been 4-7% higher without divestitures. Up to 30% savings could have been obtained in Latin America by emulating the pro-competition policies of the US and EU.
We assess the consequences for consumers in 76 countries of multinational acquisitions in beer and spirits. Outcomes depend on how changes in ownership affect markups versus efficiency. We find that owner fixed effects contribute very little to the performance of brands. On average, foreign ownership tends to raise costs and lower appeal. Using the estimated model, we simulate the consequences of counterfactual national merger regulation. The US beer price index would have been 4–7% higher without divestitures. Up to 30% savings could have been obtained in Latin America by emulating the pro-competition policies of the US and EU.
We assess the consequences for consumers in 76 countries of multinational acquisitions in beer and spirits. Outcomes depend on how changes in ownership affect markups versus efficiency. We find that owner fixed effects contribute very little to the performance of brands. On average, foreign ownership tends to raise costs and lower appeal. Using the estimated model, we simulate the consequences of counterfactual national merger regulation. The US beer price index would have been 4–7% higher without divestitures. Up to 30% savings could have been obtained in Latin America by emulating the pro-competition policies of the US and EU.
A Li-rich red giant (RG) star (2M19411367+4003382) recently discovered in the direction of NGC 6819 belongs to the rare subset of Li-rich stars that have not yet evolved to the luminosity bump, an evolutionary stage where models predict Li can be replenished. The currently favored model to explain Li enhancement in first-ascent RGs like 2M19411367+4003382 requires deep mixing into the stellar interior. Testing this model requires a measurement of C-12/C-13, which is possible to obtain from Apache Point Observatory Galactic Evolution Experiment (APOGEE) spectra. However, the Li-rich star also has abnormal asteroseismic properties that call into question its membership in the cluster, even though its radial velocity and location on color-magnitude diagrams are consistent with membership. To address these puzzles, we have measured a wide array of abundances in the Li-rich star and three comparison stars using spectra taken as part of the APOGEE survey to determine the degree of stellar mixing, address the question of membership, and measure the surface gravity. We confirm that the Li-rich star is a RG with the same overall chemistry as the other cluster giants. However, its log g is significantly lower, consistent with the asteroseismology results and suggestive of a very low mass if the star is indeed a cluster member. Regardless of the cluster membership, the C-12/C-13 and C/N ratios of the Li-rich star are consistent with standard first dredge-up, indicating that Li dilution has already occurred, and inconsistent with internal Li enrichment scenarios that require deep mixing. ; National Science Foundation AST1109888 ; NSF AST-1358862, AST 1109718, AST 1312863 ; Alfred P. Sloan Foundation ; National Science Foundation ; U.S. Department of Energy Office of Science ; University of Arizona ; Brazilian Participation Group ; Brookhaven National Laboratory ; Carnegie Mellon University ; University of Florida ; French Participation Group ; German Participation Group ; Harvard University ; Instituto de Astrofisica de Canarias ; Michigan State/NotreDame/JINA Participation Group ; Johns Hopkins University ; Lawrence Berkeley National Laboratory ; Max Planck Institute for Astrophysics ; Max Planck Institute for Extraterrestrial Physics ; New Mexico State University ; New York University ; Ohio State University ; Pennsylvania State University ; University of Portsmouth ; Princeton University ; Spanish Participation Group ; University of Tokyo ; University of Utah ; Vanderbilt University ; University of Virginia ; University of Washington ; Yale University ; National Aeronautics and Space Administration ; Two Micron All Sky Survey ; University of Massachusetts ; Infrared Processing and Analysis Center/California Institute of Technology ; U.S. Government NAG W-2166 ; Astronomy
