[{"year":"2022","publisher":"EDP Sciences","doi":"10.1051/0004-6361/202142956","language":[{"iso":"eng"}],"type":"journal_article","_id":"11621","oa":1,"author":[{"last_name":"Dhouib","first_name":"H.","full_name":"Dhouib, H."},{"last_name":"Mathis","full_name":"Mathis, S.","first_name":"S."},{"orcid":"0000-0003-0142-4000","id":"d9edb345-f866-11ec-9b37-d119b5234501","last_name":"Bugnet","full_name":"Bugnet, Lisa Annabelle","first_name":"Lisa Annabelle"},{"last_name":"Van Reeth","full_name":"Van Reeth, T.","first_name":"T."},{"last_name":"Aerts","first_name":"C.","full_name":"Aerts, C."}],"date_published":"2022-05-19T00:00:00Z","acknowledgement":"We thank the referee for her/his positive and constructive report, which has allowed us to improve the quality of our article. H.D. and S.M. acknowledge support from the CNES PLATO grant at CEA/DAp. T.V.R. gratefully acknowledges support from the Research Foundation Flanders (FWO) under grant agreement No. 12ZB620N and V414021N. This research was supported in part by the National Science Foundation under Grant No. NSF PHY-1748958. C.A. is supported by the KU Leuven Research Council (grant C16/18/005: PARADISE) as well as from the BELgian federal Science Policy Office (BELSPO) through a PLATO PRODEX grant.","date_created":"2022-07-19T08:04:15Z","article_number":"A133","intvolume":"       661","keyword":["Space and Planetary Science","Astronomy and Astrophysics","magnetohydrodynamics (MHD) / waves / stars","rotation / stars: magnetic field / stars","oscillations / methods"],"article_processing_charge":"No","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","extern":"1","publication_identifier":{"issn":["0004-6361"],"eissn":["1432-0746"]},"quality_controlled":"1","month":"05","volume":661,"article_type":"original","date_updated":"2022-08-22T07:58:54Z","status":"public","abstract":[{"text":"Context. Asteroseismology has revealed small core-to-surface rotation contrasts in stars in the whole Hertzsprung–Russell diagram. This is the signature of strong transport of angular momentum (AM) in stellar interiors. One of the plausible candidates to efficiently carry AM is magnetic fields with various topologies that could be present in stellar radiative zones. Among them, strong axisymmetric azimuthal (toroidal) magnetic fields have received a lot of interest. Indeed, if they are subject to the so-called Tayler instability, the accompanying triggered Maxwell stresses can transport AM efficiently. In addition, the electromotive force induced by the fluctuations of magnetic and velocity fields could potentially sustain a dynamo action that leads to the regeneration of the initial strong axisymmetric azimuthal magnetic field.\r\n\r\nAims. The key question we aim to answer is whether we can detect signatures of these deep strong azimuthal magnetic fields. The only way to answer this question is asteroseismology, and the best laboratories of study are intermediate-mass and massive stars with external radiative envelopes. Most of these are rapid rotators during their main sequence. Therefore, we have to study stellar pulsations propagating in stably stratified, rotating, and potentially strongly magnetised radiative zones, namely magneto-gravito-inertial (MGI) waves.\r\n\r\nMethods. We generalise the traditional approximation of rotation (TAR) by simultaneously taking general axisymmetric differential rotation and azimuthal magnetic fields into account. Both the Coriolis acceleration and the Lorentz force are therefore treated in a non-perturbative way. Using this new formalism, we derive the asymptotic properties of MGI waves and their period spacings.\r\n\r\nResults. We find that toroidal magnetic fields induce a shift in the period spacings of gravity (g) and Rossby (r) modes. An equatorial azimuthal magnetic field with an amplitude of the order of 105 G leads to signatures that are detectable in period spacings for high-radial-order g and r modes in γ Doradus (γ Dor) and slowly pulsating B (SPB) stars. More complex hemispheric configurations are more difficult to observe, particularly when they are localised out of the propagation region of MGI modes, which can be localised in an equatorial belt.\r\n\r\nConclusions. The magnetic TAR, which takes into account toroidal magnetic fields in a non-perturbative way, is derived. This new formalism allows us to assess the effects of the magnetic field in γ Dor and SPB stars on g and r modes. We find that these effects should be detectable for equatorial fields thanks to modern space photometry using observations from Kepler, TESS CVZ, and PLATO.","lang":"eng"}],"day":"19","publication_status":"published","oa_version":"Preprint","arxiv":1,"citation":{"chicago":"Dhouib, H., S. Mathis, Lisa Annabelle Bugnet, T. Van Reeth, and C. Aerts. “Detecting Deep Axisymmetric Toroidal Magnetic Fields in Stars: The Traditional Approximation of Rotation for Differentially Rotating Deep Spherical Shells with a General Azimuthal Magnetic Field.” <i>Astronomy &#38; Astrophysics</i>. EDP Sciences, 2022. <a href=\"https://doi.org/10.1051/0004-6361/202142956\">https://doi.org/10.1051/0004-6361/202142956</a>.","ieee":"H. Dhouib, S. Mathis, L. A. Bugnet, T. Van Reeth, and C. Aerts, “Detecting deep axisymmetric toroidal magnetic fields in stars: The traditional approximation of rotation for differentially rotating deep spherical shells with a general azimuthal magnetic field,” <i>Astronomy &#38; Astrophysics</i>, vol. 661. EDP Sciences, 2022.","ista":"Dhouib H, Mathis S, Bugnet LA, Van Reeth T, Aerts C. 2022. Detecting deep axisymmetric toroidal magnetic fields in stars: The traditional approximation of rotation for differentially rotating deep spherical shells with a general azimuthal magnetic field. Astronomy &#38; Astrophysics. 661, A133.","apa":"Dhouib, H., Mathis, S., Bugnet, L. A., Van Reeth, T., &#38; Aerts, C. (2022). Detecting deep axisymmetric toroidal magnetic fields in stars: The traditional approximation of rotation for differentially rotating deep spherical shells with a general azimuthal magnetic field. <i>Astronomy &#38; Astrophysics</i>. EDP Sciences. <a href=\"https://doi.org/10.1051/0004-6361/202142956\">https://doi.org/10.1051/0004-6361/202142956</a>","short":"H. Dhouib, S. Mathis, L.A. Bugnet, T. Van Reeth, C. Aerts, Astronomy &#38; Astrophysics 661 (2022).","mla":"Dhouib, H., et al. “Detecting Deep Axisymmetric Toroidal Magnetic Fields in Stars: The Traditional Approximation of Rotation for Differentially Rotating Deep Spherical Shells with a General Azimuthal Magnetic Field.” <i>Astronomy &#38; Astrophysics</i>, vol. 661, A133, EDP Sciences, 2022, doi:<a href=\"https://doi.org/10.1051/0004-6361/202142956\">10.1051/0004-6361/202142956</a>.","ama":"Dhouib H, Mathis S, Bugnet LA, Van Reeth T, Aerts C. Detecting deep axisymmetric toroidal magnetic fields in stars: The traditional approximation of rotation for differentially rotating deep spherical shells with a general azimuthal magnetic field. <i>Astronomy &#38; Astrophysics</i>. 2022;661. doi:<a href=\"https://doi.org/10.1051/0004-6361/202142956\">10.1051/0004-6361/202142956</a>"},"scopus_import":"1","main_file_link":[{"url":"https://arxiv.org/abs/2202.10026","open_access":"1"}],"title":"Detecting deep axisymmetric toroidal magnetic fields in stars: The traditional approximation of rotation for differentially rotating deep spherical shells with a general azimuthal magnetic field","external_id":{"arxiv":["2202.10026"]},"publication":"Astronomy & Astrophysics"},{"publication":"Astronomy & Astrophysics","external_id":{"arxiv":["2102.01216"]},"title":"Magnetic signatures on mixed-mode frequencies: I. An axisymmetric fossil field inside the core of red giants","main_file_link":[{"open_access":"1","url":"https://arxiv.org/abs/2102.01216"}],"scopus_import":"1","arxiv":1,"citation":{"ama":"Bugnet LA, Prat V, Mathis S, et al. Magnetic signatures on mixed-mode frequencies: I. An axisymmetric fossil field inside the core of red giants. <i>Astronomy &#38; Astrophysics</i>. 2021;650. doi:<a href=\"https://doi.org/10.1051/0004-6361/202039159\">10.1051/0004-6361/202039159</a>","mla":"Bugnet, Lisa Annabelle, et al. “Magnetic Signatures on Mixed-Mode Frequencies: I. An Axisymmetric Fossil Field inside the Core of Red Giants.” <i>Astronomy &#38; Astrophysics</i>, vol. 650, A53, EDP Sciences, 2021, doi:<a href=\"https://doi.org/10.1051/0004-6361/202039159\">10.1051/0004-6361/202039159</a>.","ista":"Bugnet LA, Prat V, Mathis S, Astoul A, Augustson K, García RA, Mathur S, Amard L, Neiner C. 2021. Magnetic signatures on mixed-mode frequencies: I. An axisymmetric fossil field inside the core of red giants. Astronomy &#38; Astrophysics. 650, A53.","apa":"Bugnet, L. A., Prat, V., Mathis, S., Astoul, A., Augustson, K., García, R. A., … Neiner, C. (2021). Magnetic signatures on mixed-mode frequencies: I. An axisymmetric fossil field inside the core of red giants. <i>Astronomy &#38; Astrophysics</i>. EDP Sciences. <a href=\"https://doi.org/10.1051/0004-6361/202039159\">https://doi.org/10.1051/0004-6361/202039159</a>","short":"L.A. Bugnet, V. Prat, S. Mathis, A. Astoul, K. Augustson, R.A. García, S. Mathur, L. Amard, C. Neiner, Astronomy &#38; Astrophysics 650 (2021).","ieee":"L. A. Bugnet <i>et al.</i>, “Magnetic signatures on mixed-mode frequencies: I. An axisymmetric fossil field inside the core of red giants,” <i>Astronomy &#38; Astrophysics</i>, vol. 650. EDP Sciences, 2021.","chicago":"Bugnet, Lisa Annabelle, V. Prat, S. Mathis, A. Astoul, K. Augustson, R. A. García, S. Mathur, L. Amard, and C. Neiner. “Magnetic Signatures on Mixed-Mode Frequencies: I. An Axisymmetric Fossil Field inside the Core of Red Giants.” <i>Astronomy &#38; Astrophysics</i>. EDP Sciences, 2021. <a href=\"https://doi.org/10.1051/0004-6361/202039159\">https://doi.org/10.1051/0004-6361/202039159</a>."},"publication_status":"published","oa_version":"Preprint","day":"07","abstract":[{"text":"Context. The discovery of moderate differential rotation between the core and the envelope of evolved solar-like stars could be the signature of a strong magnetic field trapped inside the radiative interior. The population of intermediate-mass red giants presenting surprisingly low-amplitude mixed modes (i.e. oscillation modes that behave as acoustic modes in their external envelope and as gravity modes in their core) could also arise from the effect of an internal magnetic field. Indeed, stars more massive than about 1.1 solar masses are known to develop a convective core during their main sequence. The field generated by the dynamo triggered by this convection could be the progenitor of a strong fossil magnetic field trapped inside the core of the star for the remainder of its evolution.\r\n\r\nAims. Observations of mixed modes can constitute an excellent probe of the deepest layers of evolved solar-like stars, and magnetic fields in those regions can impact their propagation. The magnetic perturbation on mixed modes may therefore be visible in asteroseismic data. To unravel which constraints can be obtained from observations, we theoretically investigate the effects of a plausible mixed axisymmetric magnetic field with various amplitudes on the mixed-mode frequencies of evolved solar-like stars.\r\n\r\nMethods. First-order frequency perturbations due to an axisymmetric magnetic field were computed for dipolar and quadrupolar mixed modes. These computations were carried out for a range of stellar ages, masses, and metallicities.\r\n\r\nConclusions. We show that typical fossil-field strengths of 0.1 − 1 MG, consistent with the presence of a dynamo in the convective core during the main sequence, provoke significant asymmetries on mixed-mode frequency multiplets during the red giant branch. We provide constraints and methods for the detectability of such magnetic signatures. We show that these signatures may be detectable in asteroseismic data for field amplitudes small enough for the amplitude of the modes not to be affected by the conversion of gravity into Alfvén waves inside the magnetised interior. Finally, we infer an upper limit for the strength of the field and the associated lower limit for the timescale of its action in order to redistribute angular momentum in stellar interiors.","lang":"eng"}],"status":"public","date_updated":"2022-08-19T10:06:33Z","article_type":"original","volume":650,"month":"06","quality_controlled":"1","publication_identifier":{"eissn":["1432-0746"],"issn":["0004-6361"]},"article_processing_charge":"No","extern":"1","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","keyword":["Space and Planetary Science","Astronomy and Astrophysics","stars","oscillations / stars","magnetic field / stars","interiors / stars","evolution / stars","rotation"],"intvolume":"       650","date_created":"2022-07-18T12:10:59Z","article_number":"A53","date_published":"2021-06-07T00:00:00Z","author":[{"first_name":"Lisa Annabelle","full_name":"Bugnet, Lisa Annabelle","last_name":"Bugnet","id":"d9edb345-f866-11ec-9b37-d119b5234501","orcid":"0000-0003-0142-4000"},{"last_name":"Prat","first_name":"V.","full_name":"Prat, V."},{"full_name":"Mathis, S.","first_name":"S.","last_name":"Mathis"},{"full_name":"Astoul, A.","first_name":"A.","last_name":"Astoul"},{"last_name":"Augustson","first_name":"K.","full_name":"Augustson, K."},{"last_name":"García","full_name":"García, R. A.","first_name":"R. A."},{"last_name":"Mathur","full_name":"Mathur, S.","first_name":"S."},{"last_name":"Amard","full_name":"Amard, L.","first_name":"L."},{"first_name":"C.","full_name":"Neiner, C.","last_name":"Neiner"}],"oa":1,"_id":"11605","type":"journal_article","language":[{"iso":"eng"}],"doi":"10.1051/0004-6361/202039159","publisher":"EDP Sciences","year":"2021"},{"month":"03","quality_controlled":"1","publication_identifier":{"eissn":["1432-0746"],"issn":["0004-6361"]},"article_type":"original","volume":647,"date_created":"2022-07-18T12:21:32Z","article_number":"A125","acknowledgement":"We thank Suzanne Aigrain and Joe Llama for providing us with the simulated data used in Aigrain et al. (2015). S. N. B., L. B. and R. A. G. acknowledge the support from PLATO and GOLF CNES grants. A. R. G. S. acknowledges the support from NASA under grant NNX17AF27G. S. M. acknowledges the support from the Spanish Ministry of Science and Innovation with the Ramon y Cajal fellowship number RYC-2015-17697. P. L. P. and S. M. acknowledge support from the Spanish Ministry of Science and Innovation with the grant number PID2019-107187GB-I00. This research has made use of the NASA Exoplanet Archive, which is operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program. Software: Python (Van Rossum & Drake 2009), numpy (Oliphant 2006), pandas (The pandas development team 2020; McKinney 2010), matplotlib (Hunter 2007), scikit-learn (Pedregosa et al. 2011). The source code used to obtain the present results can be found at: https://gitlab.com/sybreton/pushkin ; https://gitlab.com/sybreton/ml_surface_rotation_paper .","article_processing_charge":"No","extern":"1","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","keyword":["Space and Planetary Science","Astronomy and Astrophysics","methods: data analysis / stars: solar-type / stars: activity / stars: rotation / starspots"],"intvolume":"       647","author":[{"full_name":"Breton, S. N.","first_name":"S. N.","last_name":"Breton"},{"last_name":"Santos","full_name":"Santos, A. R. G.","first_name":"A. R. G."},{"orcid":"0000-0003-0142-4000","id":"d9edb345-f866-11ec-9b37-d119b5234501","last_name":"Bugnet","full_name":"Bugnet, Lisa Annabelle","first_name":"Lisa Annabelle"},{"first_name":"S.","full_name":"Mathur, S.","last_name":"Mathur"},{"last_name":"García","first_name":"R. A.","full_name":"García, R. A."},{"first_name":"P. L.","full_name":"Pallé, P. L.","last_name":"Pallé"}],"oa":1,"_id":"11608","date_published":"2021-03-19T00:00:00Z","language":[{"iso":"eng"}],"doi":"10.1051/0004-6361/202039947","publisher":"EDP Sciences","year":"2021","type":"journal_article","main_file_link":[{"url":"https://arxiv.org/abs/2101.10152","open_access":"1"}],"publication":"Astronomy & Astrophysics","external_id":{"arxiv":["2101.10152"]},"title":"ROOSTER: A machine-learning analysis tool for Kepler stellar rotation periods","citation":{"mla":"Breton, S. N., et al. “ROOSTER: A Machine-Learning Analysis Tool for Kepler Stellar Rotation Periods.” <i>Astronomy &#38; Astrophysics</i>, vol. 647, A125, EDP Sciences, 2021, doi:<a href=\"https://doi.org/10.1051/0004-6361/202039947\">10.1051/0004-6361/202039947</a>.","ista":"Breton SN, Santos ARG, Bugnet LA, Mathur S, García RA, Pallé PL. 2021. ROOSTER: A machine-learning analysis tool for Kepler stellar rotation periods. Astronomy &#38; Astrophysics. 647, A125.","apa":"Breton, S. N., Santos, A. R. G., Bugnet, L. A., Mathur, S., García, R. A., &#38; Pallé, P. L. (2021). ROOSTER: A machine-learning analysis tool for Kepler stellar rotation periods. <i>Astronomy &#38; Astrophysics</i>. EDP Sciences. <a href=\"https://doi.org/10.1051/0004-6361/202039947\">https://doi.org/10.1051/0004-6361/202039947</a>","short":"S.N. Breton, A.R.G. Santos, L.A. Bugnet, S. Mathur, R.A. García, P.L. Pallé, Astronomy &#38; Astrophysics 647 (2021).","ama":"Breton SN, Santos ARG, Bugnet LA, Mathur S, García RA, Pallé PL. ROOSTER: A machine-learning analysis tool for Kepler stellar rotation periods. <i>Astronomy &#38; Astrophysics</i>. 2021;647. doi:<a href=\"https://doi.org/10.1051/0004-6361/202039947\">10.1051/0004-6361/202039947</a>","chicago":"Breton, S. N., A. R. G. Santos, Lisa Annabelle Bugnet, S. Mathur, R. A. García, and P. L. Pallé. “ROOSTER: A Machine-Learning Analysis Tool for Kepler Stellar Rotation Periods.” <i>Astronomy &#38; Astrophysics</i>. EDP Sciences, 2021. <a href=\"https://doi.org/10.1051/0004-6361/202039947\">https://doi.org/10.1051/0004-6361/202039947</a>.","ieee":"S. N. Breton, A. R. G. Santos, L. A. Bugnet, S. Mathur, R. A. García, and P. L. Pallé, “ROOSTER: A machine-learning analysis tool for Kepler stellar rotation periods,” <i>Astronomy &#38; Astrophysics</i>, vol. 647. EDP Sciences, 2021."},"arxiv":1,"scopus_import":"1","oa_version":"Preprint","publication_status":"published","day":"19","abstract":[{"text":"In order to understand stellar evolution, it is crucial to efficiently determine stellar surface rotation periods. Indeed, while they are of great importance in stellar models, angular momentum transport processes inside stars are still poorly understood today. Surface rotation, which is linked to the age of the star, is one of the constraints needed to improve the way those processes are modelled. Statistics of the surface rotation periods for a large sample of stars of different spectral types are thus necessary. An efficient tool to automatically determine reliable rotation periods is needed when dealing with large samples of stellar photometric datasets. The objective of this work is to develop such a tool. For this purpose, machine learning classifiers constitute relevant bases to build our new methodology. Random forest learning abilities are exploited to automate the extraction of rotation periods in Kepler light curves. Rotation periods and complementary parameters are obtained via three different methods: a wavelet analysis, the autocorrelation function of the light curve, and the composite spectrum. We trained three different classifiers: one to detect if rotational modulations are present in the light curve, one to flag close binary or classical pulsators candidates that can bias our rotation period determination, and finally one classifier to provide the final rotation period. We tested our machine learning pipeline on 23 431 stars of the Kepler K and M dwarf reference rotation catalogue for which 60% of the stars have been visually inspected. For the sample of 21 707 stars where all the input parameters are provided to the algorithm, 94.2% of them are correctly classified (as rotating or not). Among the stars that have a rotation period in the reference catalogue, the machine learning provides a period that agrees within 10% of the reference value for 95.3% of the stars. Moreover, the yield of correct rotation periods is raised to 99.5% after visually inspecting 25.2% of the stars. Over the two main analysis steps, rotation classification and period selection, the pipeline yields a global agreement with the reference values of 92.1% and 96.9% before and after visual inspection. Random forest classifiers are efficient tools to determine reliable rotation periods in large samples of stars. The methodology presented here could be easily adapted to extract surface rotation periods for stars with different spectral types or observed by other instruments such as K2, TESS or by PLATO in the near future.","lang":"eng"}],"date_updated":"2022-08-22T08:47:47Z","status":"public"},{"type":"journal_article","doi":"10.1051/0004-6361/202038654","language":[{"iso":"eng"}],"year":"2021","publisher":"EDP Sciences","date_published":"2021-02-08T00:00:00Z","author":[{"last_name":"Park","full_name":"Park, J.","first_name":"J."},{"last_name":"Prat","full_name":"Prat, V.","first_name":"V."},{"last_name":"Mathis","first_name":"S.","full_name":"Mathis, S."},{"full_name":"Bugnet, Lisa Annabelle","first_name":"Lisa Annabelle","id":"d9edb345-f866-11ec-9b37-d119b5234501","last_name":"Bugnet","orcid":"0000-0003-0142-4000"}],"_id":"11609","oa":1,"article_processing_charge":"No","extern":"1","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","intvolume":"       646","keyword":["Space and Planetary Science","Astronomy and Astrophysics","hydrodynamics / turbulence / stars","rotation / stars","evolution"],"date_created":"2022-07-18T13:24:32Z","article_number":"A64","acknowledgement":"The authors acknowledge support from the European Research Council through ERC grant SPIRE 647383 and from GOLF and PLATO CNES grants at the Department of Astrophysics at CEA Paris-Saclay. We thank the referee, Prof. A. J. Barker, for his constructive comments that allow us to improve the article.","volume":646,"article_type":"original","month":"02","publication_identifier":{"eissn":["1432-0746"],"issn":["0004-6361"]},"quality_controlled":"1","status":"public","date_updated":"2022-08-19T10:18:03Z","day":"08","publication_status":"published","oa_version":"Preprint","abstract":[{"text":"Context. Stellar interiors are the seat of efficient transport of angular momentum all along their evolution. In this context, understanding the dependence of the turbulent transport triggered by the instabilities of the vertical and horizontal shears of the differential rotation in stellar radiation zones as a function of their rotation, stratification, and thermal diffusivity is mandatory. Indeed, it constitutes one of the cornerstones of the rotational transport and mixing theory, which is implemented in stellar evolution codes to predict the rotational and chemical evolutions of stars.\r\n\r\nAims. We investigate horizontal shear instabilities in rotating stellar radiation zones by considering the full Coriolis acceleration with both the dimensionless horizontal Coriolis component f̃ and the vertical component f.\r\n\r\nMethods. We performed a linear stability analysis using linearized equations derived from the Navier-Stokes and heat transport equations in the rotating nontraditional f-plane. We considered a horizontal shear flow with a hyperbolic tangent profile as the base flow. The linear stability was analyzed numerically in wide ranges of parameters, and we performed an asymptotic analysis for large vertical wavenumbers using the Wentzel-Kramers-Brillouin-Jeffreys (WKBJ) approximation for nondiffusive and highly-diffusive fluids.\r\n\r\nResults. As in the traditional f-plane approximation, we identify two types of instabilities: the inflectional and inertial instabilities. The inflectional instability is destabilized as f̃ increases and its maximum growth rate increases significantly, while the thermal diffusivity stabilizes the inflectional instability similarly to the traditional case. The inertial instability is also strongly affected; for instance, the inertially unstable regime is also extended in the nondiffusive limit as 0 < f < 1 + f̃ 2/N2, where N is the dimensionless Brunt-Väisälä frequency. More strikingly, in the high thermal diffusivity limit, it is always inertially unstable at any colatitude θ except at the poles (i.e., 0° < θ <  180°). We also derived the critical Reynolds numbers for the inertial instability using the asymptotic dispersion relations obtained from the WKBJ analysis. Using the asymptotic and numerical results, we propose a prescription for the effective turbulent viscosities induced by the inertial and inflectional instabilities that can be possibly used in stellar evolution models. The characteristic time of this turbulence is short enough so that it is efficient to redistribute angular momentum and to mix chemicals in stellar radiation zones.","lang":"eng"}],"scopus_import":"1","citation":{"ieee":"J. Park, V. Prat, S. Mathis, and L. A. Bugnet, “Horizontal shear instabilities in rotating stellar radiation zones: II. Effects of the full Coriolis acceleration,” <i>Astronomy &#38; Astrophysics</i>, vol. 646. EDP Sciences, 2021.","chicago":"Park, J., V. Prat, S. Mathis, and Lisa Annabelle Bugnet. “Horizontal Shear Instabilities in Rotating Stellar Radiation Zones: II. Effects of the Full Coriolis Acceleration.” <i>Astronomy &#38; Astrophysics</i>. EDP Sciences, 2021. <a href=\"https://doi.org/10.1051/0004-6361/202038654\">https://doi.org/10.1051/0004-6361/202038654</a>.","ama":"Park J, Prat V, Mathis S, Bugnet LA. Horizontal shear instabilities in rotating stellar radiation zones: II. Effects of the full Coriolis acceleration. <i>Astronomy &#38; Astrophysics</i>. 2021;646. doi:<a href=\"https://doi.org/10.1051/0004-6361/202038654\">10.1051/0004-6361/202038654</a>","apa":"Park, J., Prat, V., Mathis, S., &#38; Bugnet, L. A. (2021). Horizontal shear instabilities in rotating stellar radiation zones: II. Effects of the full Coriolis acceleration. <i>Astronomy &#38; Astrophysics</i>. EDP Sciences. <a href=\"https://doi.org/10.1051/0004-6361/202038654\">https://doi.org/10.1051/0004-6361/202038654</a>","mla":"Park, J., et al. “Horizontal Shear Instabilities in Rotating Stellar Radiation Zones: II. Effects of the Full Coriolis Acceleration.” <i>Astronomy &#38; Astrophysics</i>, vol. 646, A64, EDP Sciences, 2021, doi:<a href=\"https://doi.org/10.1051/0004-6361/202038654\">10.1051/0004-6361/202038654</a>.","short":"J. Park, V. Prat, S. Mathis, L.A. Bugnet, Astronomy &#38; Astrophysics 646 (2021).","ista":"Park J, Prat V, Mathis S, Bugnet LA. 2021. Horizontal shear instabilities in rotating stellar radiation zones: II. Effects of the full Coriolis acceleration. Astronomy &#38; Astrophysics. 646, A64."},"arxiv":1,"publication":"Astronomy & Astrophysics","title":"Horizontal shear instabilities in rotating stellar radiation zones: II. Effects of the full Coriolis acceleration","external_id":{"arxiv":["2006.10660"]},"main_file_link":[{"url":"https://arxiv.org/abs/2006.10660","open_access":"1"}]},{"external_id":{"arxiv":["1908.05222"]},"title":"Surface rotation and photometric activity for Kepler targets. I. M and K main-sequence stars","publication":"The Astrophysical Journal Supplement Series","main_file_link":[{"url":"https://arxiv.org/abs/1908.05222","open_access":"1"}],"issue":"1","scopus_import":"1","arxiv":1,"citation":{"ama":"Santos ARG, García RA, Mathur S, et al. Surface rotation and photometric activity for Kepler targets. I. M and K main-sequence stars. <i>The Astrophysical Journal Supplement Series</i>. 2019;244(1). doi:<a href=\"https://doi.org/10.3847/1538-4365/ab3b56\">10.3847/1538-4365/ab3b56</a>","short":"A.R.G. Santos, R.A. García, S. Mathur, L.A. Bugnet, J.L. van Saders, T.S. Metcalfe, G.V.A. Simonian, M.H. Pinsonneault, The Astrophysical Journal Supplement Series 244 (2019).","ista":"Santos ARG, García RA, Mathur S, Bugnet LA, van Saders JL, Metcalfe TS, Simonian GVA, Pinsonneault MH. 2019. Surface rotation and photometric activity for Kepler targets. I. M and K main-sequence stars. The Astrophysical Journal Supplement Series. 244(1), 21.","mla":"Santos, A. R. G., et al. “Surface Rotation and Photometric Activity for Kepler Targets. I. M and K Main-Sequence Stars.” <i>The Astrophysical Journal Supplement Series</i>, vol. 244, no. 1, 21, IOP Publishing, 2019, doi:<a href=\"https://doi.org/10.3847/1538-4365/ab3b56\">10.3847/1538-4365/ab3b56</a>.","apa":"Santos, A. R. G., García, R. A., Mathur, S., Bugnet, L. A., van Saders, J. L., Metcalfe, T. S., … Pinsonneault, M. H. (2019). Surface rotation and photometric activity for Kepler targets. I. M and K main-sequence stars. <i>The Astrophysical Journal Supplement Series</i>. IOP Publishing. <a href=\"https://doi.org/10.3847/1538-4365/ab3b56\">https://doi.org/10.3847/1538-4365/ab3b56</a>","ieee":"A. R. G. Santos <i>et al.</i>, “Surface rotation and photometric activity for Kepler targets. I. M and K main-sequence stars,” <i>The Astrophysical Journal Supplement Series</i>, vol. 244, no. 1. IOP Publishing, 2019.","chicago":"Santos, A. R. G., R. A. García, S. Mathur, Lisa Annabelle Bugnet, J. L. van Saders, T. S. Metcalfe, G. V. A. Simonian, and M. H. Pinsonneault. “Surface Rotation and Photometric Activity for Kepler Targets. I. M and K Main-Sequence Stars.” <i>The Astrophysical Journal Supplement Series</i>. IOP Publishing, 2019. <a href=\"https://doi.org/10.3847/1538-4365/ab3b56\">https://doi.org/10.3847/1538-4365/ab3b56</a>."},"abstract":[{"lang":"eng","text":"Brightness variations due to dark spots on the stellar surface encode information about stellar surface rotation and magnetic activity. In this work, we analyze the Kepler long-cadence data of 26,521 main-sequence stars of spectral types M and K in order to measure their surface rotation and photometric activity level. Rotation-period estimates are obtained by the combination of a wavelet analysis and autocorrelation function of the light curves. Reliable rotation estimates are determined by comparing the results from the different rotation diagnostics and four data sets. We also measure the photometric activity proxy Sph using the amplitude of the flux variations on an appropriate timescale. We report rotation periods and photometric activity proxies for about 60% of the sample, including 4431 targets for which McQuillan et al. did not report a rotation period. For the common targets with rotation estimates in this study and in McQuillan et al., our rotation periods agree within 99%. In this work, we also identify potential polluters, such as misclassified red giants and classical pulsator candidates. Within the parameter range we study, there is a mild tendency for hotter stars to have shorter rotation periods. The photometric activity proxy spans a wider range of values with increasing effective temperature. The rotation period and photometric activity proxy are also related, with Sph being larger for fast rotators. Similar to McQuillan et al., we find a bimodal distribution of rotation periods."}],"oa_version":"Preprint","publication_status":"published","day":"19","status":"public","date_updated":"2022-08-22T08:10:38Z","article_type":"original","volume":244,"quality_controlled":"1","publication_identifier":{"issn":["0067-0049"]},"month":"09","keyword":["Space and Planetary Science","Astronomy and Astrophysics","methods: data analysis","stars: activity","stars: low-mass","stars: rotation","starspots","techniques: photometric"],"intvolume":"       244","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","extern":"1","article_processing_charge":"No","acknowledgement":"The authors thank Róbert Szabó Paul G. Beck, Katrien Kolenberg, and Isabel L. Colman for helping on the classification of stars. This paper includes data collected by the Kepler mission and obtained from the MAST data archive at the Space Telescope Science Institute (STScI). Funding for the Kepler mission is provided by the National Aeronautics and Space Administration (NASA) Science Mission Directorate. STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5–26555. A.R.G.S. acknowledges the support from NASA under grant NNX17AF27G. R.A.G. and L.B. acknowledge the support from PLATO and GOLF CNES grants. S.M. acknowledges the support from the Ramon y Cajal fellowship number RYC-2015-17697. T.S.M. acknowledges support from a Visiting Fellowship at the Max Planck Institute for Solar System Research. This research has made use of the NASA Exoplanet Archive, which is operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program.\r\n\r\nSoftware: KADACS (García et al. 2011), NumPy (van der Walt et al. 2011), SciPy (Jones et al. 2001), Matplotlib (Hunter 2007).\r\n\r\nFacilities: MAST - , Kepler Eclipsing Binary Catalog - , Exoplanet Archive. -","date_created":"2022-07-19T09:21:58Z","article_number":"21","date_published":"2019-09-19T00:00:00Z","oa":1,"_id":"11623","author":[{"last_name":"Santos","first_name":"A. R. G.","full_name":"Santos, A. R. G."},{"last_name":"García","full_name":"García, R. A.","first_name":"R. A."},{"first_name":"S.","full_name":"Mathur, S.","last_name":"Mathur"},{"first_name":"Lisa Annabelle","full_name":"Bugnet, Lisa Annabelle","orcid":"0000-0003-0142-4000","last_name":"Bugnet","id":"d9edb345-f866-11ec-9b37-d119b5234501"},{"first_name":"J. L.","full_name":"van Saders, J. L.","last_name":"van Saders"},{"last_name":"Metcalfe","full_name":"Metcalfe, T. S.","first_name":"T. S."},{"last_name":"Simonian","first_name":"G. V. A.","full_name":"Simonian, G. V. A."},{"last_name":"Pinsonneault","full_name":"Pinsonneault, M. H.","first_name":"M. H."}],"type":"journal_article","publisher":"IOP Publishing","year":"2019","language":[{"iso":"eng"}],"doi":"10.3847/1538-4365/ab3b56"},{"author":[{"first_name":"S. N.","full_name":"Breton, S. N.","last_name":"Breton"},{"full_name":"Bugnet, Lisa Annabelle","first_name":"Lisa Annabelle","id":"d9edb345-f866-11ec-9b37-d119b5234501","last_name":"Bugnet","orcid":"0000-0003-0142-4000"},{"full_name":"Santos, A. R. G.","first_name":"A. R. G.","last_name":"Santos"},{"full_name":"Saux, A. Le","first_name":"A. Le","last_name":"Saux"},{"last_name":"Mathur","full_name":"Mathur, S.","first_name":"S."},{"full_name":"Palle, P. L.","first_name":"P. L.","last_name":"Palle"},{"last_name":"Garcia","first_name":"R. A.","full_name":"Garcia, R. A."}],"oa":1,"_id":"11627","publication_status":"submitted","oa_version":"Preprint","date_published":"2019-06-23T00:00:00Z","day":"23","abstract":[{"lang":"eng","text":"For a solar-like star, the surface rotation evolves with time, allowing in principle to estimate the age of a star from its surface rotation period. Here we are interested in measuring surface rotation periods of solar-like stars observed by the NASA mission Kepler. Different methods have been developed to track rotation signals in Kepler photometric light curves: time-frequency analysis based on wavelet techniques, autocorrelation and composite spectrum. We use the learning abilities of random forest classifiers to take decisions during two crucial steps of the analysis. First, given some input parameters, we discriminate the considered Kepler targets between rotating MS stars, non-rotating MS stars, red giants, binaries and pulsators. We then use a second classifier only on the MS rotating targets to decide the best data analysis treatment."}],"language":[{"iso":"eng"}],"doi":"10.48550/arXiv.1906.09609","date_updated":"2022-08-22T08:16:53Z","year":"2019","status":"public","type":"preprint","month":"06","main_file_link":[{"url":"https://arxiv.org/abs/1906.09609","open_access":"1"}],"publication":"arXiv","external_id":{"arxiv":["1906.09609"]},"title":"Determining surface rotation periods of solar-like stars observed by the Kepler mission using machine learning techniques","date_created":"2022-07-20T11:18:53Z","article_number":"1906.09609","arxiv":1,"citation":{"ieee":"S. N. Breton <i>et al.</i>, “Determining surface rotation periods of solar-like stars observed by the Kepler mission using machine learning techniques,” <i>arXiv</i>. .","chicago":"Breton, S. N., Lisa Annabelle Bugnet, A. R. G. Santos, A. Le Saux, S. Mathur, P. L. Palle, and R. A. Garcia. “Determining Surface Rotation Periods of Solar-like Stars Observed by the Kepler Mission Using Machine Learning Techniques.” <i>ArXiv</i>, n.d. <a href=\"https://doi.org/10.48550/arXiv.1906.09609\">https://doi.org/10.48550/arXiv.1906.09609</a>.","ama":"Breton SN, Bugnet LA, Santos ARG, et al. Determining surface rotation periods of solar-like stars observed by the Kepler mission using machine learning techniques. <i>arXiv</i>. doi:<a href=\"https://doi.org/10.48550/arXiv.1906.09609\">10.48550/arXiv.1906.09609</a>","short":"S.N. Breton, L.A. Bugnet, A.R.G. Santos, A.L. Saux, S. Mathur, P.L. Palle, R.A. Garcia, ArXiv (n.d.).","ista":"Breton SN, Bugnet LA, Santos ARG, Saux AL, Mathur S, Palle PL, Garcia RA. Determining surface rotation periods of solar-like stars observed by the Kepler mission using machine learning techniques. arXiv, 1906.09609.","apa":"Breton, S. N., Bugnet, L. A., Santos, A. R. G., Saux, A. L., Mathur, S., Palle, P. L., &#38; Garcia, R. A. (n.d.). Determining surface rotation periods of solar-like stars observed by the Kepler mission using machine learning techniques. <i>arXiv</i>. <a href=\"https://doi.org/10.48550/arXiv.1906.09609\">https://doi.org/10.48550/arXiv.1906.09609</a>","mla":"Breton, S. N., et al. “Determining Surface Rotation Periods of Solar-like Stars Observed by the Kepler Mission Using Machine Learning Techniques.” <i>ArXiv</i>, 1906.09609, doi:<a href=\"https://doi.org/10.48550/arXiv.1906.09609\">10.48550/arXiv.1906.09609</a>."},"user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","extern":"1","article_processing_charge":"No","keyword":["asteroseismology","rotation","solar-like stars","kepler","machine learning","random forest"]}]