Search

Your search keyword '"High Altitude Observatory (HAO)"' showing total 20 results
Start Over Author "High Altitude Observatory (HAO)" Publisher hal ccsd
20 results on '"High Altitude Observatory (HAO)"'

1. A MULTI-SITE CAMPAIGN TO MEASURE SOLAR-LIKE OSCILLATIONS IN PROCYON. II. MODE FREQUENCIES

Author

D. Sosnowska, William J. Chaplin, Hiroyasu Ando, Sylvaine Turck-Chièze, R. P. Butler, T. Appourchaux, Tiago L. Campante, T. H. Dall, J. C. Lebrun, Rafael A. García, Gabrielle Berthomieu, Rosario Cosentino, Saskia Hekker, Silvio Leccia, M. Hartmann, S. Frandsen, B. Mosser, K. Brogaard, Michael Endl, Sabine Reffert, A. P. Hatzes, Jørgen Christensen-Dalsgaard, Christoffer Karoff, Simon J. O'Toole, J. Lundgreen-Nielsen, Janine Provost, Frank Grundahl, E. Michel, László L. Kiss, M. Bazot, H. Bruntt, S. Benatti, Caroline Barban, T. S. Metcalfe, P. Eggenberger, M. Martic, Fabien Carrier, Jean-Loup Bertaux, Robert A. Wittenmyer, B. Sato, Hideyuki Izumiura, Timothy R. Bedding, Eric Stempels, J. H. M. M. Schmitt, Riccardo Claudi, L. Glowienka, Eiji Kambe, Hans Kjeldsen, Torben Arentoft, Alfio Bonanno, Sydney Institute for Astronomy (SIfA), The University of Sydney, Danish AsteroSeismology Centre (DASC), Aarhus University [Aarhus], Centro de Astrofísica da Universidade do Porto (CAUP), Universidade do Porto = University of Porto, Institut d'astrophysique spatiale (IAS), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), INAF - Osservatorio Astrofisico di Catania (OACT), Istituto Nazionale di Astrofisica (INAF), School of Physics and Astronomy [Birmingham], University of Birmingham [Birmingham], Département d'Astrophysique, de physique des Particules, de physique Nucléaire et de l'Instrumentation Associée (DAPNIA), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Observatoire de Paris - Site de Paris (OP), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Department of Terrestrial Magnetism [Carnegie Institution], Carnegie Institution for Science, Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Konkoly Observatory, Research Centre for Astronomy and Earth Sciences [Budapest], Hungarian Academy of Sciences (MTA)-Hungarian Academy of Sciences (MTA), Anglo-Australian Observatory (AAO), Okayama Astrophysical Observatory (OAO), National Astronomical Observatory of Japan (NAOJ), Global Edge Institute, Tokyo Institute of Technology [Tokyo] (TITECH), Thüringer Landessternwarte Tautenburg (TLS), Laboratoire de Cosmologie, Astrophysique Stellaire & Solaire, de Planétologie et de Mécanique des Fluides (CASSIOPEE), Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Observatoire de Haute-Provence (OHP), Institut Pythéas (OSU PYTHEAS), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Centre National de la Recherche Scientifique (CNRS), HELIOS - LATMOS, Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centro di Ateneo di Studi e Attività Spaziali 'Giuseppe Colombo' (CISAS), Università degli Studi di Padova = University of Padua (Unipd), INAF - Osservatorio Astronomico di Padova (OAPD), INAF - Osservatorio Astronomico di Capodimonte (OAC), Department of Physics and Astronomy [Uppsala], Uppsala University, European Southern Observatory (ESO), Institute of Astronomy [Leuven], Catholic University of Leuven - Katholieke Universiteit Leuven (KU Leuven), Observatoire Astronomique de l'Université de Genève (ObsGE), Université de Genève = University of Geneva (UNIGE), University of New South Wales [Sydney] (UNSW), McDonald Observatory, University of Texas at Austin [Austin], High Altitude Observatory (HAO), National Center for Atmospheric Research [Boulder] (NCAR), Landessternwarte Königstuhl [ZAH] (LSW), Universität Heidelberg [Heidelberg] = Heidelberg University, Sydney Institute for Astronomy ( SIfA ), The University of Sydney [Sydney], Danish AsteroSeismology Centre ( DASC ), Centro de Astrofísica da Universidade do Porto ( CAUP ), Universidade do Porto [Porto], Institut d'astrophysique spatiale ( IAS ), Université Paris-Sud - Paris 11 ( UP11 ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ), INAF - Osservatorio Astrofisico di Catania ( OACT ), Istituto Nazionale di Astrofisica ( INAF ), Département d'Astrophysique, de physique des Particules, de physique Nucléaire et de l'Instrumentation Associée ( DAPNIA ), Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ), Laboratoire Atmosphères, Milieux, Observations Spatiales ( LATMOS ), Université de Versailles Saint-Quentin-en-Yvelines ( UVSQ ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ), Observatoire de Paris - Site de Paris ( OP ), Institut national des sciences de l'Univers ( INSU - CNRS ) -Observatoire de Paris-Centre National de la Recherche Scientifique ( CNRS ), Laboratoire d'études spatiales et d'instrumentation en astrophysique ( LESIA ), Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Observatoire de Paris-Université Paris Diderot - Paris 7 ( UPD7 ) -Centre National de la Recherche Scientifique ( CNRS ), Carnegie Institution for Science [Washington], Astrophysique Interactions Multi-échelles ( AIM - UMR 7158 - UMR E 9005 ), Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -Université Paris Diderot - Paris 7 ( UPD7 ), Hungarian Academy of Sciences [Budapest], Anglo-Australian Observatory ( AAO ), Okayama Astrophysical Observatory ( OAO ), National Astronomical Observatory of Japan ( NAOJ ), National Astronomical Observatory of Japan, National Institutes of Natural Sciences, Tokyo Institute of Technology [Tokyo] ( TITECH ), Thüringer Landessternwarte Tautenburg ( TLS ), Laboratoire de Cosmologie, Astrophysique Stellaire & Solaire, de Planétologie et de Mécanique des Fluides ( CASSIOPEE ), Université Nice Sophia Antipolis ( UNS ), Université Côte d'Azur ( UCA ) -Université Côte d'Azur ( UCA ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Observatoire de la Côte d'Azur, Université Côte d'Azur ( UCA ) -Centre National de la Recherche Scientifique ( CNRS ), Observatoire de Haute-Provence ( OHP ), Institut Pythéas ( OSU PYTHEAS ), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture ( IRSTEA ) -Institut de Recherche pour le Développement ( IRD ) -Aix Marseille Université ( AMU ) -Centre National de la Recherche Scientifique ( CNRS ) -Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture ( IRSTEA ) -Institut de Recherche pour le Développement ( IRD ) -Aix Marseille Université ( AMU ) -Centre National de la Recherche Scientifique ( CNRS ), HEPPI - LATMOS, Université de Versailles Saint-Quentin-en-Yvelines ( UVSQ ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Versailles Saint-Quentin-en-Yvelines ( UVSQ ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ), Centro di Ateneo di Studi e Attività Spaziali 'Giuseppe Colombo' ( CISAS ), Universita degli Studi di Padova = University of Padua = Université de Padoue, INAF - Osservatorio Astronomico di Padova ( OAPD ), INAF - Osservatorio Astronomico di Capodimonte ( OAC ), European Southern Observatory ( ESO ), Katholieke Universiteit Leuven ( KU Leuven ), Observatoire Astronomique de l'Université de Genève ( ObsGE ), Université de Genève ( UNIGE ), University of New South Wales [Sydney] ( UNSW ), High Altitude Observatory ( HAO ), National Center for Atmospheric Research [Boulder] ( NCAR ), Landessternwarte Königstuhl [ZAH] ( LSW ), Universität Heidelberg [Heidelberg], Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Université Nice Sophia Antipolis (... - 2019) (UNS), Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Institut de Recherche pour le Développement (IRD), Universita degli Studi di Padova, Université de Genève (UNIGE), Universidade do Porto, Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), and Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Offset (computer science), Oscillations, Granulation, FOS: Physical sciences, Lifetimes, Astrophysics, 01 natural sciences, Asteroseismology, Stellar Oscillations, Photometry, P-Modes, 0103 physical sciences, Solar-like oscillations, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Physics, geography, [ PHYS.ASTR.SR ] Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], geography.geographical_feature_category, 010308 nuclear & particles physics, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Procyon A, Multi site, Sun, Spectral density, Centroid, Astronomy and Astrophysics, [PHYS.ASTR.SR]Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Stars, Corot, Data Reduction, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Ridge, stars: oscillations, stars: individual (Procyon A), [ SDU.ASTR.SR ] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR]
Abstract

We have analyzed data from a multi-site campaign to observe oscillations in the F5 star Procyon. The data consist of high-precision velocities that we obtained over more than three weeks with eleven telescopes. A new method for adjusting the data weights allows us to suppress the sidelobes in the power spectrum. Stacking the power spectrum in a so-called echelle diagram reveals two clear ridges that we identify with even and odd values of the angular degree (l=0 and 2, and l=1 and 3, respectively). We interpret a strong, narrow peak at 446 muHz that lies close to the l=1 ridge as a mode with mixed character. We show that the frequencies of the ridge centroids and their separations are useful diagnostics for asteroseismology. In particular, variations in the large separation appear to indicate a glitch in the sound-speed profile at an acoustic depth of about 1000 s. We list frequencies for 55 modes extracted from the data spanning 20 radial orders, a range comparable to the best solar data, which will provide valuable constraints for theoretical models. A preliminary comparison with published models shows that the offset between observed and calculated frequencies for the radial modes is very different for Procyon than for the Sun and other cool stars. We find the mean lifetime of the modes in Procyon to be 1.29 +0.55/-0.49 days, which is significantly shorter than the 2-4 days seen in the Sun., Comment: accepted for publication in ApJ

Published
2010
Full Text
View/download PDF

2. Properties of 42 Solar-type Kepler Targets from the Asteroseismic Modeling Portal

Author

M. Di Mauro, Timothy R. White, M. Steslicki, Margarida S. Cunha, Karan Molaverdikhani, T. S. Metcalfe, A. M. Serenelli, Benjamin P. Brown, R. Trampedach, Dennis Stello, William J. Chaplin, Sébastien Deheuvels, Derek Buzasi, R. Simoniello, Anwesh Mazumdar, Guy R. Davies, Timothy R. Bedding, Mário J. P. F. G. Monteiro, Jørgen Christensen-Dalsgaard, Rachel Howe, Mutlu Yildiz, O. L. Creevey, Yvonne Elsworth, David B. Guenther, K. B. MacGregor, Othman Benomar, S. Mathur, Yveline Lebreton, Aliz Derekas, Rafael A. García, Christoffer Karoff, G. Doğan, Haiying Xu, D. Pricopi, Tiago L. Campante, D. Salabert, Josefina Montalbán, Z. Celik, M. D. Suran, M. Gruberbauer, C. Aksoy, J. A. Guzik, High Altitude Observatory (HAO), National Center for Atmospheric Research [Boulder] (NCAR), Computational and Information Systems Laboratory (CISL), Stellar Astrophysics Centre [Aarhus] (SAC), Aarhus University [Aarhus], Laboratoire d'Annecy-le-Vieux de Physique Théorique (LAPTH), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Università degli studi di Torino (UNITO), Dept. Electrical and Computer Engineering, University of Minnesota, University of Minnesota [Twin Cities] (UMN), University of Minnesota System-University of Minnesota System, Institut d'Astrophysique et de Géophysique [Liège], Université de Liège, BIT lab (BIT Lab), Université Galatasaray (GSU), Department of Astronomy and Physics [Halifax], Saint Mary's University [Halifax], Inorgan Chem Lab, Galaxies, Etoiles, Physique, Instrumentation (GEPI), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique de Rennes (IPR), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS), Ege Üniversitesi, Università degli studi di Torino = University of Turin (UNITO), and Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS)

Subjects
oscillations [stars], FOS: Physical sciences, Astrophysics, Type (model theory), stars: interiors, 01 natural sciences, Kepler, methods: numerical, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, stars: evolution, 010303 astronomy & astrophysics, Scaling, Solar and Stellar Astrophysics (astro-ph.SR), ComputingMilieux_MISCELLANEOUS, Physics, interiors [stars], [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], 010308 nuclear & particles physics, Oscillation, Subgiant, Mode (statistics), Astronomy and Astrophysics, numerical [methods], Radius, Stars, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, evolution [stars], Astrophysics::Earth and Planetary Astrophysics, stars: oscillations
Abstract

WOS: 000344141500013, Recently the number of main-sequence and subgiant stars exhibiting solar-like oscillations that are resolved into individual mode frequencies has increased dramatically. While only a few such data sets were available for detailed modeling just a decade ago, the Kepler mission has produced suitable observations for hundreds of new targets. This rapid expansion in observational capacity has been accompanied by a shift in analysis and modeling strategies to yield uniform sets of derived stellar properties more quickly and easily. We use previously published asteroseismic and spectroscopic data sets to provide a uniform analysis of 42 solar-type Kepler targets from the Asteroseismic Modeling Portal. We find that fitting the individual frequencies typically doubles the precision of the asteroseismic radius, mass, and age compared to grid-based modeling of the global oscillation properties, and improves the precision of the radius and mass by about a factor of three over empirical scaling relations. We demonstrate the utility of the derived properties with several applications., NASANational Aeronautics & Space Administration (NASA) [NNX13AC44G, NNX13AE91G]; White Dwarf Research Corporation through the Pale Blue Dot project; Danish National Research FoundationDanmarks Grundforskningsfond [DNRF106]; European Research CouncilEuropean Research Council (ERC) [267864]; Scientific and Technological Research Council of TurkeyTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [TUBITAK:112T989]; European Commission grant for the SPACEINN project [FP7-SPACE-2012-312844]; NSF Astronomy and Astrophysics postdoctoral fellowshipNational Science Foundation (NSF) [AST 09-02004]; NSFNational Science Foundation (NSF) [PHY 08-21899, PHY 11-25915]; Investigador FCT contract - FCT/MCTES (Portugal); POPH/FSE (EC)European Commission Joint Research CentreEuropean Social Fund (ESF); Hungarian OTKAOrszagos Tudomanyos Kutatasi Alapprogramok (OTKA) [K83790, KTIA URKUT_10-1-2011-0019]; Lendulet Young Researchers Programme of the Hungarian Academy of Sciences; Janos Bolyai Research Scholarship of the Hungarian Academy of SciencesHungarian Academy of Sciences; City of Szombathely [S-11-1027]; European Community Seventh Framework Programme (FP7) [269194 (IRSES/ASK)]; CNES grant at CEA-Saclay; NIUS programme of HBCSE (TIFR); MICINN grant [AYA2011-24704]; ESF EUROCORES Program EuroGENESIS (MICINN) [EUI2009-04170]; Australian Research CouncilAustralian Research Council; Science and Technology Facilities CouncilScience & Technology Facilities Council (STFC) [ST/J001163/1], We would like to thank Victor Silva Aguirre for helpful discussions. This work was supported in part by NASA grants NNX13AC44G and NNX13AE91G, and by White Dwarf Research Corporation through the Pale Blue Dot project (http://whitedwarf.org/palebluedot/). Computational time on Kraken at the National Institute of Computational Sciences was provided through XSEDE allocation TG-AST090107. Funding for the Stellar Astrophysics Centre is provided by The Danish National Research Foundation (grant DNRF106). We acknowledge the ASTERISK project (ASTERoseismic Investigations with SONG and Kepler) funded by the European Research Council (grant agreement No.: 267864), the Scientific and Technological Research Council of Turkey (TUBITAK:112T989), and a European Commission grant for the SPACEINN project (FP7-SPACE-2012-312844). B.P.B. was supported in part by NSF Astronomy and Astrophysics postdoctoral fellowship AST 09-02004. C.M.S.O. is supported by NSF grant PHY 08-21899 and K.I.T.P. is supported by NSF grant PHY 11-25915. M.S.C. is supported by an Investigador FCT contract funded by FCT/MCTES (Portugal) and POPH/FSE (EC). A.D. has been supported by the Hungarian OTKA grants K83790, KTIA URKUT_10-1-2011-0019 grant, the Lendulet-2009 Young Researchers Programme of the Hungarian Academy of Sciences, the Janos Bolyai Research Scholarship of the Hungarian Academy of Sciences and the City of Szombathely under agreement No. S-11-1027. A.D. and R.A.G. acknowledge the support of the European Community Seventh Framework Programme (FP7/2007-2013) under grant agreement No. 269194 (IRSES/ASK). R.A.G. and D. Salabert acknowledge the support of the CNES grant at CEA-Saclay. A.M. acknowledges support from the NIUS programme of HBCSE (TIFR). A.S. is supported by the MICINN grant AYA2011-24704 and by the ESF EUROCORES Program EuroGENESIS (MICINN grant EUI2009-04170). D. Stello is supported by the Australian Research Council.

Published
2014
Full Text
View/download PDF

3. Seismic constraints on the radial dependence of the internal rotation profiles of six Kepler subgiants and young red giants

Author

Jian-Ning Fu, M. J. Goupil, Alex Lobel, S. Deheuvels, Guy R. Davies, J. Molenda-Żakowicz, Othman Benomar, William J. Chaplin, Patrick Eggenberger, Daniel R. Reese, T. Stahn, Tiago L. Campante, Laurent Gizon, G. Doğan, Rafael A. García, Benoit Mosser, Xiao-Hu Yang, Hans Bruntt, Jesper Schou, P. De Cat, Luca Casagrande, T. Ceillier, Jørgen Christensen-Dalsgaard, C. Régulo, Thierry Appourchaux, S. Mathis, A. O. Thygesen, Marc H. Pinsonneault, Institut de recherche en astrophysique et planétologie (IRAP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), High Altitude Observatory (HAO), National Center for Atmospheric Research [Boulder] (NCAR), Stellar Astrophysics Centre [Aarhus] (SAC), Aarhus University [Aarhus], Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Institut d'astrophysique spatiale (IAS), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Sydney Institute for Astronomy (SIfA), The University of Sydney, School of Physics and Astronomy [Birmingham], University of Birmingham [Birmingham], Research School of Astronomy and Astrophysics [Canberra] (RSAA), Australian National University (ANU), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Royal Observatory of Belgium [Brussels] (ROB), Department of Astronomy, Beijing Normal University, China, Instituto de Astrofisica de Canarias (IAC), Institut d'Astrophysique et de Géophysique [Liège], Université de Liège, Max-Planck-Institut für Sonnensystemforschung (MPS), Max-Planck-Gesellschaft, Institut für Astrophysik [Göttingen], Georg-August-University [Göttingen], Zentrum für Astronomie der Universität Heidelberg (ZAH), Universität Heidelberg [Heidelberg], Observatoire Astronomique de l'Université de Genève (ObsGE), Université de Genève (UNIGE), Instytut Astronomiczny Uniwersytetu Wrocławskiego, Departments of Astronomy and Chemistry, The Ohio State University, Ohio State University [Columbus] (OSU), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Georg-August-University = Georg-August-Universität Göttingen, Universität Heidelberg [Heidelberg] = Heidelberg University, Université de Genève = University of Geneva (UNIGE), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), and Royal Observatory of Belgium [Brussels]

Subjects
Angular momentum, FOS: Physical sciences, Context (language use), Astrophysics, asteroseismology, Classification of discontinuities, stars: interiors, Rotation, Spectral line, stars: rotation, Astrophysics::Solar and Stellar Astrophysics, stars: evolution, rotation, stars, interiors, evolution, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, Envelope (waves), Physics, interiors [stars], Subgiant, Astronomy and Astrophysics, Stars, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, evolution [stars], rotation [stars], Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

Context : We still do not know which mechanisms are responsible for the transport of angular momentum inside stars. The recent detection of mixed modes that contain the signature of rotation in the spectra of Kepler subgiants and red giants gives us the opportunity to make progress on this issue. Aims: Our aim is to probe the radial dependance of the rotation profiles for a sample of Kepler targets. For this purpose, subgiants and early red giants are particularly interesting targets because their rotational splittings are more sensitive to the rotation outside the deeper core than is the case for their more evolved counterparts. Methods: We first extract the rotational splittings and frequencies of the modes for six young Kepler red giants. We then perform a seismic modeling of these stars using the evolutionary codes CESAM2k and ASTEC. By using the observed splittings and the rotational kernels of the optimal models, we perform inversions of the internal rotation profiles of the six stars. Results: We obtain estimates of the mean rotation rate in the core and in the convective envelope of these stars. We show that the rotation contrast between the core and the envelope increases during the subgiant branch. Our results also suggest that the core of subgiants spins up with time, contrary to the RGB stars whose core has been shown to spin down. For two of the stars, we show that a discontinuous rotation profile with a deep discontinuity reproduces the observed splittings significantly better than a smooth rotation profile. Interestingly, the depths that are found most probable for the discontinuities roughly coincide with the location of the H-burning shell, which separates the layers that contract from those that expand. These results will bring observational constraints to the scenarios of angular momentum transport in stars., Comment: Accepted in A&A, 27 pages, 18 figures

Published
2014
Full Text
View/download PDF

4. Convection and Differential Rotation in F-Type Stars

Author

Mark S. Miesch, Allan Sacha Brun, Kyle C. Augustson, Benjamin P. Brown, Juri Toomre, Joint Institute for Laboratory Astrophysics (JILA), National Institute of Standards and Technology [Gaithersburg] (NIST)-University of Colorado [Boulder], Department of Astronomy [Madison], University of Wisconsin-Madison, Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), High Altitude Observatory (HAO), National Center for Atmospheric Research [Boulder] (NCAR), European Project: 207430,EC:FP7:ERC,ERC-2007-StG,STARS2(2008), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Département d'Astrophysique (ex SAP) (DAP), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, and STARS2

Subjects
Physics, Spherical harmonics, Astronomy and Astrophysics, stars: solar-type, Astrophysics, Type (model theory), stars: interiors, Rotation, Coupling (probability), [PHYS.ASTR.SR]Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], 01 natural sciences, Radiation zone, 010305 fluids & plasmas, Computational physics, Convection zone, Space and Planetary Science, stars: rotation, 0103 physical sciences, hydrodynamics, Differential rotation, 010303 astronomy & astrophysics, Main sequence, convection
Abstract

International audience; Differential rotation is a common feature of main-sequence spectral F-type stars. In seeking to make contact with observations and to provide a self-consistent picture of how differential rotation is achieved in the interiors of these stars, we use the three-dimensional anelastic spherical harmonic (ASH) code to simulate global-scale turbulent flows in 1.2 and 1.3 $M_\odot$ F-type stars at varying rotation rates. The simulations are carried out in spherical shells that encompass most of the convection zone and a portion of the stably stratified radiative zone below it, allowing us to explore the effects of overshooting convection. We examine the scaling of the mean flows and thermal state with rotation rate and mass and link these scalings to fundamental parameters of the simulations. Indeed, we find that the differential rotation becomes much stronger with more rapid rotation and larger mass, scaling as $\Delta\Omega$ $\alpha$ $M^{3.9}$$\Omega_0^{0.6}$. Accompanying the growing differential rotation is a significant latitudinal temperature contrast, with amplitudes of 1000 K or higher in the most rapidly rotating cases. This contrast in turn scales with mass and rotation rate as $\Delta$$T$ $\alpha$ $M^{6.4}$$\Omega_0^{1.6}$. On the other hand, the meridional circulations become much weaker with more rapid rotation and with higher mass, with their kinetic energy decreasing as KE$_{MC}$ $\alpha$ $M^{-1.2}$$\Omega_0^{-0.8}$. Additionally, three of our simulations exhibit a global-scale shear instability within their stable regions that persists for the duration of the simulations. The flow structures associated with the instabilities have a direct coupling to and impact on the flows within the convection zone.

Published
2013
Full Text
View/download PDF

5. Solar magnetism eXplorer (SolmeX)

Author

Peter, Hardi, Abbo, L., Andretta, V., Auchère, F., Bemporad, A., Berrilli, F., Bommier, V., Braukhane, A., Casini, R., Curdt, W., Davila, J., Dittus, H., Fineschi, S., Fludra, A., Gandorfer, A., Griffin, D., Inhester, B., Lagg, A., Degl’innocenti, E. Landi, Maiwald, V., Sainz, R. Manso, Pillet, V. Martínez, Matthews, S., Moses, D., Parenti, S., Pietarila, A., Quantius, D., Raouafi, N. -E., Raymond, J., Rochus, P., Romberg, O., Schlotterer, M., Schühle, U., Solanki, S., Spadaro, D., Teriaca, L., Tomczyk, S., Bueno, J. Trujillo, Vial, J. -C., INAF - Osservatorio Astronomico di Capodimonte (OAC), Istituto Nazionale di Astrofisica (INAF), Institut d'astrophysique spatiale (IAS), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Dipartimento di Astronomia e Scienza dello Spazio, Università di Firenze, Università degli Studi di Firenze = University of Florence [Firenze] (UNIFI), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), High Altitude Observatory (HAO), National Center for Atmospheric Research [Boulder] (NCAR), Max-Planck-Institut für Sonnensystemforschung (MPS), Max-Planck-Gesellschaft, NASA Goddard Space Flight Center (GSFC), DLR Institute of Space Systems, German Aerospace Center (DLR), INAF - Osservatorio Astrofisico di Torino (OATo), Space Science and Technology Department [Didcot] (RAL Space), STFC Rutherford Appleton Laboratory (RAL), Science and Technology Facilities Council (STFC)-Science and Technology Facilities Council (STFC), Centre Spatial de Liège (CSL), Université de Liège, Max Planck Institute for Solar System Research (MPS), Università degli Studi di Firenze [Firenze], Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Università degli Studi di Firenze = University of Florence (UniFI), and Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS)

Subjects
[PHYS]Physics [physics], [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Space Physics (physics.space-ph), Physics - Plasma Physics, Plasma Physics (physics.plasm-ph), Astrophysics - Solar and Stellar Astrophysics, Physics - Space Physics, [SDU]Sciences of the Universe [physics], Physics::Space Physics, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Solar and Stellar Astrophysics (astro-ph.SR), ComputingMilieux_MISCELLANEOUS
Abstract

The magnetic field plays a pivotal role in many fields of Astrophysics. This is especially true for the physics of the solar atmosphere. Measuring the magnetic field in the upper solar atmosphere is crucial to understand the nature of the underlying physical processes that drive the violent dynamics of the solar corona -- that can also affect life on Earth. SolmeX, a fully equipped solar space observatory for remote-sensing observations, will provide the first comprehensive measurements of the strength and direction of the magnetic field in the upper solar atmosphere. The mission consists of two spacecraft, one carrying the instruments, and another one in formation flight at a distance of about 200m carrying the occulter to provide an artificial total solar eclipse. This will ensure high-quality coronagraphic observations above the solar limb. Solmex integrates two spectro-polarimetric coronagraphs for off-limb observations, one in the EUV and one in the IR, and three instruments for observations on the disk. The latter comprises one imaging polarimeter in the EUV for coronal studies, a spectro-polarimeter in the EUV to investigate the low corona, and an imaging spectro-polarimeter in the UV for chromospheric studies. SOHO and other existing missions have investigated the emission of the upper atmosphere in detail (not considering polarization), and as this will be the case also for missions planned for the near future. Therefore it is timely that SolmeX provides the final piece of the observational quest by measuring the magnetic field in the upper atmosphere through polarimetric observations., Submitted to Experimental Astronomy. 30 pages, 19 figures

Published
2012
Full Text
View/download PDF

6. Magnetic Braking Formulation for Sun-Like Stars: Dependence on Dipole Field Strength and Rotation Rate

Author

Sean P. Matt, Thomas P. Greene, Marc H. Pinsonneault, K. B. MacGregor, Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), High Altitude Observatory (HAO), National Center for Atmospheric Research [Boulder] (NCAR), Department of Astronomy, Ohio State University [Columbus] (OSU), NASA Ames Research Center (ARC), European Project: 207430,EC:FP7:ERC,ERC-2007-StG,STARS2(2008), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), and Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)

Subjects
Physics, Angular momentum, FOS: Physical sciences, Astronomy and Astrophysics, Rotation, 01 natural sciences, Computational physics, Magnetic field, Stars, Dipole, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Magnetohydrodynamics, 010306 general physics, 010303 astronomy & astrophysics, Magnetic dipole, Solar and Stellar Astrophysics (astro-ph.SR), Main sequence
Abstract

We use two-dimensional axisymmetric magnetohydrodynamic simulations to compute steady-state solutions for solar-like stellar winds from rotating stars with dipolar magnetic fields. Our parameter study includes 50 simulations covering a wide range of relative magnetic field strengths and rotation rates, extending from the slow- and approaching the fast-magnetic-rotator regimes. Using the simulations to compute the angular momentum loss, we derive a semi-analytic formulation for the external torque on the star that fits all of the simulations to a precision of a few percents. This formula provides a simple method for computing the magnetic braking of sun-like stars due to magnetized stellar winds, which properly includes the dependence on the strength of the magnetic field, mass loss rate, stellar radius, suface gravity, and spin rate and which is valid for both slow and fast rotators., Accepted for publication in ApJ Letters, 6 pages, 4 figures

Published
2012
Full Text
View/download PDF

7. Modeling the Dynamical Coupling of Solar Convection With the Radiative Interior

Author

Brun, A.S., S. Miesch, Mark, Toomre, Juri, Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), High Altitude Observatory (HAO), National Center for Atmospheric Research [Boulder] (NCAR), Joint Institute for Laboratory Astrophysics (JILA), National Institute of Standards and Technology [Gaithersburg] (NIST)-University of Colorado [Boulder], STARS2, European Project: 207430,EC:FP7:ERC,ERC-2007-StG,STARS2(2008), Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics::Fluid Dynamics, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Physics::Atmospheric and Oceanic Physics
Abstract

International audience; The global dynamics of a rotating star like the Sun involves the coupling of a highly turbulent convective envelope overlying a seemingly benign radiative interior. We use the anelastic spherical harmonic code to develop a new class of three-dimensional models that nonlinearly couple the convective envelope to a deep stable radiative interior. The numerical simulation assumes a realistic solar stratification from r = 0.07 up to 0.97R (with R the solar radius), thus encompassing part of the nuclear core up through most of the convection zone. We find that a tachocline naturally establishes itself between the differentially rotating convective envelope and the solid body rotation of the interior, with a slow spreading that is here diffusively controlled. The rapid angular momentum redistribution in the convective envelope leads to a fast equator and slow poles, with a conical differential rotation achieved at mid-latitudes, much as has been deduced by helioseismology. The convective motions are able to overshoot downward about 0.04R into the radiative interior. However, the convective meridional circulation there is confined to a smaller penetration depth and is directed mostly equatorward at the base of the convection zone. Thermal wind balance is established in the lower convection zone and tachocline but departures are evident in the upper convection zone. Internal gravity waves are excited by the convective overshooting, yielding a complex wave field throughout the radiative interior.

Published
2011
Full Text
View/download PDF

8. Buoyant Magnetic Loops in a Global Dynamo Simulation of a Young Sun

Author

Nicholas J. Nelson, Mark S. Miesch, Juri Toomre, Benjamin P. Brown, Allan Sacha Brun, Joint Institute for Laboratory Astrophysics (JILA), National Institute of Standards and Technology [Gaithersburg] (NIST)-University of Colorado [Boulder], Department of Astronomy [Madison], University of Wisconsin-Madison, Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), High Altitude Observatory (HAO), National Center for Atmospheric Research [Boulder] (NCAR), European Project: 207430,EC:FP7:ERC,ERC-2007-StG,STARS2(2008), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), and Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)

Subjects
Convection, FOS: Physical sciences, 01 natural sciences, Physics::Fluid Dynamics, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, 010306 general physics, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Physics, magnetic field -Sun, Photosphere, Sunspot, activity, Starspot, Stellar atmosphere, Astronomy and Astrophysics, Mechanics, [PHYS.ASTR.SR]Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Physics - Plasma Physics, Plasma Physics (physics.plasm-ph), convection -magnetohydrodynamics (MHD) -stars, Convection zone, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Physics::Space Physics, Astrophysics::Earth and Planetary Astrophysics, interiors -stars, Magnetohydrodynamics, Dynamo
Abstract

The current dynamo paradigm for the Sun and sun-like stars places the generation site for strong toroidal magnetic structures deep in the solar interior. Sunspots and star-spots on sun-like stars are believed to arise when sections of these magnetic structures become buoyantly unstable and rise from the deep interior to the photosphere. Here we present the first 3-D global magnetohydrodynamic (MHD) simulation in which turbulent convection, stratification, and rotation combine to yield a dynamo that self-consistently generates buoyant magnetic loops. We simulate stellar convection and dynamo action in a spherical shell with solar stratification, but rotating three times faster than the current solar rate. Strong wreaths of toroidal magnetic field are realized by dynamo action in the convection zone. By turning to a dynamic Smagorinsky model for subgrid-scale turbulence, we here attain considerably reduced diffusion in our simulation. This permits the regions of strongest magnetic field in these wreaths to rise toward the top of the convection zone via a combination of magnetic buoyancy instabilities and advection by convective giant cells. Such a global simulation yielding buoyant loops represents a significant step forward in combining numerical models of dynamo action and flux emergence., 6 pages, 3 figures, accepted in ApJ Letters

Published
2011
Full Text
View/download PDF

9. Simulation of electric field and current during the 11 June 1993 disturbance dynamo event: Comparison with the observations

Author

Zaka, K.Z., Kobea, A. T., Doumbia, V., Richmond, A.D., Maute, A., Mene, N.M., Obrou, O.K., Assamoi, P., Boka, K., Adohi, J.P., Amory-Mazaudier, Christine, Laboratoire de Physique de l'Atmosphère, Université de Cocody, 22 BP 582 Abidjan 22, High Altitude Observatory (HAO), and National Center for Atmospheric Research [Boulder] (NCAR)

Subjects
[SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, [SDE.MCG]Environmental Sciences/Global Changes, Physics::Space Physics, Astrophysics::Solar and Stellar Astrophysics, Physics::Atmospheric and Oceanic Physics, Physics::Geophysics
Abstract

International audience; The ionospheric disturbance dynamo signature in geomagnetic variations is investigated using the National Center for Atmospheric Research Thermosphere‐ Ionosphere‐Electrodynamics General Circulation Model. The model results are tested against reference magnetically quiet time observations on 21 June 1993, and disturbance effects were observed on 11 June 1993. The model qualitatively reproduces the observed diurnal and latitude variations of the geomagnetic horizontal intensity and declination for the reference quiet day in midlatitude and low‐latitude regions but underestimates their amplitudes. The patterns of the disturbance dynamo signature and its source "anti‐Sq" current system are well reproduced in the Northern Hemisphere. However, the model significantly underestimates the amplitude of disturbance dynamo effects when compared with observations. Furthermore, the largest simulated disturbances occur at different local times than the observations. The discrepancies suggest that the assumed high‐latitude storm time energy inputs in the model were not quantitatively accurate for this storm.

Published
2010
Full Text
View/download PDF

10. The Asteroseismic Potential of Kepler: First Results for Solar-Type Stars

Author

W. J. Chaplin, T. Appourchaux, Y. Elsworth, R. A. García, G. Houdek, C. Karoff, T. S. Metcalfe, J. Molenda-Żakowicz, M. J. P. F. G. Monteiro, M. J. Thompson, T. M. Brown, J. Christensen-Dalsgaard, R. L. Gilliland, H. Kjeldsen, W. J. Borucki, D. Koch, J. M. Jenkins, J. Ballot, S. Basu, M. Bazot, T. R. Bedding, O. Benomar, A. Bonanno, I. M. Brandão, H. Bruntt, T. L. Campante, O. L. Creevey, M. P. Di Mauro, G. Doğan, S. Dreizler, P. Eggenberger, L. Esch, S. T. Fletcher, S. Frandsen, N. Gai, P. Gaulme, R. Handberg, S. Hekker, R. Howe, D. Huber, S. G. Korzennik, J. C. Lebrun, S. Leccia, M. Martic, S. Mathur, B. Mosser, R. New, P.-O. Quirion, C. Régulo, I. W. Roxburgh, D. Salabert, J. Schou, S. G. Sousa, D. Stello, G. A. Verner, T. Arentoft, C. Barban, K. Belkacem, S. Benatti, K. Biazzo, P. Boumier, P. A. Bradley, A.-M. Broomhall, D. L. Buzasi, R. U. Claudi, M. S. Cunha, F. D'Antona, S. Deheuvels, A. Derekas, A. García Hernández, M. S. Giampapa, M. J. Goupil, M. Gruberbauer, J. A. Guzik, S. J. Hale, M. J. Ireland, L. L. Kiss, I. N. Kitiashvili, K. Kolenberg, H. Korhonen, A. G. Kosovichev, F. Kupka, Y. Lebreton, B. Leroy, H.-G. Ludwig, S. Mathis, E. Michel, A. Miglio, J. Montalbán, A. Moya, A. Noels, R. W. Noyes, P. L. Pallé, L. Piau, H. L. Preston, T. Roca Cortés, M. Roth, K. H. Sato, J. Schmitt, A. M. Serenelli, V. Silva Aguirre, I. R. Stevens, J. C. Suárez, M. D. Suran, R. Trampedach, S. Turck-Chièze, K. Uytterhoeven, R. Ventura, P. A. Wilson, School of Physics and Astronomy [Birmingham], University of Birmingham [Birmingham], Institut d'astrophysique spatiale (IAS), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Département d'Astrophysique, de physique des Particules, de physique Nucléaire et de l'Instrumentation Associée (DAPNIA), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Institute for Astronomy [Vienna], University of Vienna [Vienna], High Altitude Observatory (HAO), National Center for Atmospheric Research [Boulder] (NCAR), Astronomical Institute [Wroclaw], University of Wrocław [Poland] (UWr), Centro de Astrofísica da Universidade do Porto (CAUP), Universidade do Porto, School of Mathematics and Statistics [Sheffield] (SoMaS), University of Sheffield [Sheffield], Las Cumbres Observatory (LCO), Department of Physics and Astronomy [Aarhus], Aarhus University [Aarhus], Space Telescope Science Institute (STSci), NASA Ames Research Center (ARC), SETI Institute, Laboratoire Astrophysique de Toulouse-Tarbes (LATT), Centre National de la Recherche Scientifique (CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, Department of Astronomy [New Haven], Yale University [New Haven], Sydney Institute for Astronomy (SIfA), The University of Sydney, INAF - Osservatorio Astrofisico di Catania (OACT), Istituto Nazionale di Astrofisica (INAF), Observatoire de Paris, Université Paris sciences et lettres (PSL), Departamento de Astrofísica [La laguna], Universidad de La Laguna [Tenerife - SP] (ULL), Instituto de Astrofisica de Canarias (IAC), Istituto di Astrofisica Spaziale e Fisica cosmica - Roma (IASF-Roma), Institut für Astrophysik [Göttingen], Georg-August-University [Göttingen], Observatoire Astronomique de l'Université de Genève (ObsGE), Université de Genève (UNIGE), Materials and Engineering Research Institute [Sheffield] (MERI), Sheffield Hallam University, Beijing Normal University (BNU), National Solar Observatory [Tucson] (NSO/Tucson), National Science Foundation [Arlington] (NSF)-Association of Universities for Research in Astronomy (AURA), Harvard-Smithsonian Center for Astrophysics (CfA), Harvard University [Cambridge]-Smithsonian Institution, HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), INAF - Osservatorio Astronomico di Capodimonte (OAC), Indian Institute of Astrophysics (IIA), Observatoire de Paris - Site de Paris (OP), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Canadian Space Agency (CSA), Astronomy Unit [London] (AU), Queen Mary University of London (QMUL), Hansen Experimental Physics Lab [Stanford] (HEPL), Stanford University, Département d'astrophysique, Géophysique et Océanographie (AGO), Université de Liège, Centro di Ateneo di Studi e Attività Spaziali 'Giuseppe Colombo' (CISAS), Universita degli Studi di Padova, INAF - Osservatorio Astrofisico di Arcetri (OAA), Los Alamos National Laboratory (LANL), Eureka Scientific, INAF - Osservatorio Astronomico di Padova (OAPD), INAF - Osservatorio Astronomico di Roma (OAR), Konkoly Observatory, Research Centre for Astronomy and Earth Sciences [Budapest], Hungarian Academy of Sciences (MTA)-Hungarian Academy of Sciences (MTA), Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Department of Astronomy and Physics [Halifax], Saint Mary's University [Halifax], Galaxies, Etoiles, Physique, Instrumentation (GEPI), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Institut d'Astrophysique et de Géophysique [Liège], Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Universidade do Porto = University of Porto, Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Georg-August-University = Georg-August-Universität Göttingen, Université de Genève = University of Geneva (UNIGE), Harvard University-Smithsonian Institution, Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Università degli Studi di Padova = University of Padua (Unipd), and Faculdade de Ciências

Subjects
oscillations [stars], Física [Ciências exactas e naturais], FOS: Physical sciences, Astrophysics, Type (model theory), Star (graph theory), stars: interiors, 01 natural sciences, Kepler, Spectral line, Physical sciences [Natural sciences], Astrophysics, Astronomy, Physical sciences, Physical sciences, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Astrofísica, Astronomia, Ciências Físicas, Física, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, Physics, interiors [stars], 010308 nuclear & particles physics, Oscillation, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], stars: late-type, Astronomy and Astrophysics, Stars, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, late-type [stars], Astrophysics::Earth and Planetary Astrophysics, stars: oscillations
Abstract

We present preliminary asteroseismic results from Kepler on three G-type stars. The observations, made at one-minute cadence during the first 33.5d of science operations, reveal high signal-to-noise solar-like oscillation spectra in all three stars: About 20 modes of oscillation may be clearly distinguished in each star. We discuss the appearance of the oscillation spectra, use the frequencies and frequency separations to provide first results on the radii, masses and ages of the stars, and comment in the light of these results on prospects for inference on other solar-type stars that Kepler will observe., Comment: 16 pages, 3 figures, 1 table; now accepted for publication in ApJ Letters

Published
2010
Full Text
View/download PDF

11. The correlation of longitudinal/seasonal variations of evening equatorial pre-reversal drift and of plasma bubbles

Author

G. Li, B. Ning, L. Liu, Z. Ren, J. Lei, S.-Y. Su, Institute of Geology and Geophysics [Beijing] (IGG), Chinese Academy of Sciences [Beijing] (CAS), Wuhan Institute of Physics and Mathematics, Graduate School of the Chinese Academy of Sciences (GSCAS), Chinese Academy of Sciences [Changchun Branch] (CAS), High Altitude Observatory (HAO), National Center for Atmospheric Research [Boulder] (NCAR), Institute of Space Science [Taiwan], National Central University [Taiwan] (NCU), and EGU, Publication

Subjects
Atmospheric Science, Evening, Drift velocity, Magnetic dip, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Atmospheric sciences, F region, Earth and Planetary Sciences (miscellaneous), Solstice, lcsh:Science, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, [SDU.OCEAN] Sciences of the Universe [physics]/Ocean, Atmosphere, lcsh:QC801-809, Geology, Astronomy and Astrophysics, Geophysics, Solar maximum, lcsh:QC1-999, lcsh:Geophysics. Cosmic physics, Space and Planetary Science, Physics::Space Physics, [SDU.STU] Sciences of the Universe [physics]/Earth Sciences, lcsh:Q, Ionosphere, Longitude, lcsh:Physics
Abstract

The evening pre-reversal vertical drift velocity enhancement (PRE) constitutes an important seeding mechanism for the generation of F region irregularities. Ion density and drift measurements from ROCSAT-1 and DMSP satellites are used to examine the correlation of longitudinal/seasonal (l/s) variations in the evening pre-reversal vertical drift velocity at the magnetic equator in the topside ionosphere and the plasma bubble (PB) occurrence probability. The analysis performed for three years 2000–2002 (solar maximum), provides consistent evidence as the ground observations that the equatorial PB occurrence is dependent on and increases approximately linearly with PRE, and the l/s variations of PRE play an important role in the global l/s distribution of PB occurrence. The solstitial evening PRE and equatorial PB occurrence show similar longitudinal variations: During June solstice, two peaks appear in the African and Pacific longitude sectors, and two minimums are observed in the Indian and American regions; During December solstice, the situation is approximately opposite. The equinoctial longitudinal effects are comparably small. It is concluded that the large-scale l/s variations of equatorial PB occurrence can be closely related to the l/s variations of PRE.

Published
2008

12. Assessment of ionospheric Joule heating by GUMICS-4 MHD simulation, AMIE, and satellite-based statistics: towards a synthesis

Author

M. Palmroth, P. Janhunen, T. I. Pulkkinen, A. Aksnes, G. Lu, N. Østgaard, J. Watermann, G. D. Reeves, G. A. Germany, Finnish Meteorological Institute (FMI), University of Bergen (UiB), High Altitude Observatory (HAO), National Center for Atmospheric Research [Boulder] (NCAR), Danish Meteorological Institute (DMI), Los Alamos National Laboratory (LANL), Center for Space Plasma and Aeronomic Research [Huntsville] (CSPAR), University of Alabama in Huntsville (UAH), and EGU, Publication

Subjects
Atmospheric Science, 010504 meteorology & atmospheric sciences, Magnetosphere, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, 01 natural sciences, 7. Clean energy, 010305 fluids & plasmas, 0103 physical sciences, Substorm, Earth and Planetary Sciences (miscellaneous), Magnetohydrodynamic drive, lcsh:Science, 0105 earth and related environmental sciences, Physics, Geomagnetic storm, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, [SDU.OCEAN] Sciences of the Universe [physics]/Ocean, Atmosphere, lcsh:QC801-809, Geology, Astronomy and Astrophysics, Geophysics, lcsh:QC1-999, lcsh:Geophysics. Cosmic physics, Solar wind, 13. Climate action, Space and Planetary Science, Physics::Space Physics, [SDU.STU] Sciences of the Universe [physics]/Earth Sciences, lcsh:Q, Ionosphere, Magnetohydrodynamics, Joule heating, lcsh:Physics
Abstract

We investigate the Northern Hemisphere Joule heating from several observational and computational sources with the purpose of calibrating a previously identified functional dependence between solar wind parameters and ionospheric total energy consumption computed from a global magnetohydrodynamic (MHD) simulation (Grand Unified Magnetosphere Ionosphere Coupling Simulation, GUMICS-4). In this paper, the calibration focuses on determining the amount and temporal characteristics of Northern Hemisphere Joule heating. Joule heating during a substorm is estimated from global observations, including electric fields provided by Super Dual Auroral Network (SuperDARN) and Pedersen conductances given by the ultraviolet (UV) and X-ray imagers on board the Polar satellite. Furthermore, Joule heating is assessed from several activity index proxies, large statistical surveys, assimilative data methods (AMIE), and the global MHD simulation GUMICS-4. We show that the temporal and spatial variation of the Joule heating computed from the GUMICS-4 simulation is consistent with observational and statistical methods. However, the different observational methods do not give a consistent estimate for the magnitude of the global Joule heating. We suggest that multiplying the GUMICS-4 total Joule heating by a factor of 10 approximates the observed Joule heating reasonably well. The lesser amount of Joule heating in GUMICS-4 is essentially caused by weaker Region 2 currents and polar cap potentials. We also show by theoretical arguments that multiplying independent measurements of averaged electric fields and Pedersen conductances yields an overestimation of Joule heating. Keywords. Ionosphere (Auroral ionosphere; Modeling and forecasting; Electric fields and currents)

Published
2005

13. IRIS ++ database: Merging of IRIS + Mark-1 + LOWL

Author

M. Lazrek, Eric Fossat, François-Xavier Schmider, S. J. Jiménez-Reyes, J. T. Hoeksema, S. Kholikov, Steven Tomczyk, Sh. A. Ehgamberdiev, A. Cacciani, Pere L. Palle, G. Grec, D. Salabert, Thierry Corbard, B. Gelly, Joseph Louis LAGRANGE (LAGRANGE), Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Télescope héliographique pour l'étude du magnétisme et des instabilites solaires (THEMIS), Centre National de la Recherche Scientifique (CNRS), National Solar Observatory [Tucson] (NSO/Tucson), National Science Foundation [Arlington] (NSF)-Association of Universities for Research in Astronomy (AURA), High Altitude Observatory (HAO), National Center for Atmospheric Research [Boulder] (NCAR), and Université Cadi Ayyad [Marrakech] (UCA)

Subjects
Physics, 010504 meteorology & atmospheric sciences, Real-time computing, Network data, Astronomy and Astrophysics, Astrophysics, [PHYS.ASTR.SR]Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], 01 natural sciences, Space and Planetary Science, Duty cycle, 0103 physical sciences, 010303 astronomy & astrophysics, Merge (version control), ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Remote sensing
Abstract

The IRIS network has been operated continuously since July 1st 1989. To date, it has acquired more than a complete solar cycle of full-disk helioseismic data which has been used to constrain the structure and rotation of the deep solar interior. However, the duty cycle of the network data has never reached initial expectations. To improve this situation, several cooperations have been developed with teams collecting observations with similar instruments. This paper demonstrates that we are able to merge data from these different instruments in a consistent manner resulting in a very significant improvement in network duty cycle over more than one solar cycle initiating what we call the IRIS + + network.

Published
2002
Full Text
View/download PDF

14. Analysis of the solar cycle and core rotation using 15 years of Mark-I observations: 1984-1999

Author

Jiménez-Reyes, S., Corbard, T., Pallé, P., Roca Cortes, T., Tomczyk, S., High Altitude Observatory (HAO), National Center for Atmospheric Research [Boulder] (NCAR), Departamento de Astrofísica [La laguna], and Universidad de La Laguna [Tenerife - SP] (ULL)

Subjects
[PHYS.ASTR.SR]Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2001
Full Text
View/download PDF

15. Coordinated Cluster and ground-based instrument observations of transient changes in the magnetopause boundary layer during an interval of predominantly northward IMF: relation to reconnection pulses and FTE signatures

Author

M. Lockwood, A. Fazakerley, H. Opgenoorth, J. Moen, A. P. van Eyken, M. Dunlop, J.-M. Bosqued, G. Lu, C. Cully, P. Eglitis, I. W. McCrea, M. A. Hapgood, M. N. Wild, R. Stamper, W. Denig, M. Taylor, J. A. Wild, G. Provan, O. Amm, K. Kauristie, T. Pulkkinen, A. Strømme, P. Prikryl, F. Pitout, A. Balogh, H. Rème, R. Behlke, T. Hansen, R. Greenwald, H. Frey, S. K. Morley, D. Alcaydé, P.-L. Blelly, E. Donovan, M. Engebretson, M. Lester, J. Watermann, M. F. Marcucci, Solar Terrestrial Physics Division, Department of Space Science and Technology, School of Physics and Astronomy [Southampton], University of Southampton, Mullard Space Science Laboratory (MSSL), University College of London [London] (UCL), IRF, Department of Physics [Oslo], Faculty of Mathematics and Natural Sciences [Oslo], University of Oslo (UiO)-University of Oslo (UiO), EISCAT Scientific Association, Blackett Laboratory, Imperial College London, Centre d'étude spatiale des rayonnements (CESR), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), High Altitude Observatory (HAO), National Center for Atmospheric Research [Boulder] (NCAR), University of Calgary, AFRL Hanscom Research Base (AFB), Air Force Research Laboratory (AFRL), United States Air Force (USAF)-United States Air Force (USAF), Department of Physics and Astonomy, Finnish Meteorological Institute (FMI), University of Tromsø (UiT), Communications Research Centre Canada (CRC), Remote Sensing Group, Johns Hopkins University Applied Physics Laboratory [Laurel, MD] (APL), Space Science Centre, Department of Physics [Minneapolis], Augsburg College, Danish Meteorological Institute (DMI), Istituto di Fisica dello Spazio Interplanetario (IFSI), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, and Consiglio Nazionale delle Ricerche (CNR)

Subjects
Atmospheric Science, 010504 meteorology & atmospheric sciences, Field line, Magnetosphere, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Noon, 01 natural sciences, Magnetosheath, 0103 physical sciences, Earth and Planetary Sciences (miscellaneous), Interplanetary magnetic field, lcsh:Science, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Physics, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, lcsh:QC801-809, Geology, Astronomy and Astrophysics, Geophysics, lcsh:QC1-999, lcsh:Geophysics. Cosmic physics, Boundary layer, Space and Planetary Science, Physics::Space Physics, Flux transfer event, Magnetopause, lcsh:Q, lcsh:Physics
Abstract

We study a series of transient entries into the low-latitude boundary layer (LLBL) of all four Cluster spacecraft during an outbound pass through the mid-afternoon magnetopause ( [ XGSM, YGSM, ZGSM ] ≈ [ 2, 7, 9 ] RE). The events take place during an interval of northward IMF, as seen in the data from the ACE satellite and lagged by a propagation delay of 75 min that is welldefined by two separate studies: (1) the magnetospheric variations prior to the northward turning (Lockwood et al., 2001, this issue) and (2) the field clock angle seen by Cluster after it had emerged into the magnetosheath (Opgenoorth et al., 2001, this issue). With an additional lag of 16.5 min, the transient LLBL events correlate well with swings of the IMF clock angle (in GSM) to near 90°. Most of this additional lag is explained by ground-based observations, which reveal signatures of transient reconnection in the pre-noon sector that then take 10–15 min to propagate eastward to 15 MLT, where they are observed by Cluster. The eastward phase speed of these signatures agrees very well with the motion deduced by the cross-correlation of the signatures seen on the four Cluster spacecraft. The evidence that these events are reconnection pulses includes: transient erosion of the noon 630 nm (cusp/cleft) aurora to lower latitudes; transient and travelling enhancements of the flow into the polar cap, imaged by the AMIE technique; and poleward-moving events moving into the polar cap, seen by the EISCAT Svalbard Radar (ESR). A pass of the DMSP-F15 satellite reveals that the open field lines near noon have been opened for some time: the more recently opened field lines were found closer to dusk where the flow transient and the poleward-moving event intersected the satellite pass. The events at Cluster have ion and electron characteristics predicted and observed by Lockwood and Hapgood (1998) for a Flux Transfer Event (FTE), with allowance for magnetospheric ion reflection at Alfvénic disturbances in the magnetopause reconnection layer. Like FTEs, the events are about 1 RE in their direction of motion and show a rise in the magnetic field strength, but unlike FTEs, in general, they show no pressure excess in their core and hence, no characteristic bipolar signature in the boundary-normal component. However, most of the events were observed when the magnetic field was southward, i.e. on the edge of the interior magnetic cusp, or when the field was parallel to the magnetic equatorial plane. Only when the satellite begins to emerge from the exterior boundary (when the field was northward), do the events start to show a pressure excess in their core and the consequent bipolar signature. We identify the events as the first observations of FTEs at middle altitudes.Key words. Magnetospheric physics (magnetopause, cusp and boundary layers; magnetosphere-ionosphere interactions; solar wind-magnetosphere interactions)

Published
2001

16. Electrodynamic coupling of high and low latitudes' Observations on May 27, 1993

Author

C. Peymirat, Arthur D. Richmond, Marc R. Hairston, Christine Amory-Mazaudier, Barbara A. Emery, Therese Moretto, H. Lühr, A. T. Kobea, Laboratoire de Physique de l'Atmosphère, Université de Cocody, 22 BP 582 Abidjan 22, High Altitude Observatory (HAO), National Center for Atmospheric Research [Boulder] (NCAR), Centre d'étude spatiale des rayonnements (CESR), Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, GeoForschungsZentrum - Helmholtz-Zentrum Potsdam (GFZ), Danish Space Research Institute (DSRI), William B. Hanson Center for Space Sciences, University of Texas at Dallas [Richardson] (UT Dallas), Centre d'étude des environnements terrestre et planétaires (CETP), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), and Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)

Subjects
Atmospheric Science, 010504 meteorology & atmospheric sciences, [SDE.MCG]Environmental Sciences/Global Changes, Equator, Soil Science, Magnetic dip, Aquatic Science, Noon, Oceanography, Atmospheric sciences, 01 natural sciences, Latitude, Physics::Geophysics, Geochemistry and Petrology, 0103 physical sciences, Earth and Planetary Sciences (miscellaneous), 010303 astronomy & astrophysics, Physics::Atmospheric and Oceanic Physics, 0105 earth and related environmental sciences, Earth-Surface Processes, Water Science and Technology, Geomagnetic storm, Ecology, Paleontology, Forestry, Equatorial electrojet, Geophysics, Earth's magnetic field, 13. Climate action, Space and Planetary Science, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, Middle latitudes, Physics::Space Physics, Astrophysics::Earth and Planetary Astrophysics, Geology
Abstract

International audience; The penetration of disturbance electric fields from the polar region to the magnetic equator on the dayside of the Earth is examined with geomagnetic data on May 27, 1993. First, we examine a dayside equatorial disturbance that followed the rapid recovery of magnetic activity from a storm and that has the characteristics of overshielding caused by persistent region-2 field-aligned currents. It lasted *0 3 hours. Second, we analyze a series of fluctuations with periods of 25-75 min, to determine the variations of amplitude and phase with magnetic latitude and magnetic local time. The fluctuations were highly coherent at all latitudes between the magnetic equator and the auroral zone, but the coherency decreasedin the polar cap. A northward fluctuation at the equator during midday hours accompanied auroral zone fluctuations that were southward before noon, eastward around noon, and northward after noon. The amplitudes decreased away from the auroral zone toward midlatitudes but were amplified under the equatorial electrojet. No detectablep hased ifferencesa re found, indicating that any temporal lags which might be inducedb y persistencein the region-2f ield-alignedc urrentsa re less than i min for fluctuations having periods like those examined here. A synoptic inversion analysis of the high-latitude magnetic data to estimate the time-varying high-latitude electric potential patterns shows that fluctuations of the high-latitude east-west potential gradient tended to be concentrated around midday, where they were in phase with fluctuations in the midday east-west potential gradient at the magnetic equator.

Published
2000

17. The Solar Cycle and the Tachocline: Theories and Observations

Author

Corbard, T., Jimenez-Reyes, S.J., Tomoczyk, S., Dikpati, M., Gilman, P., High Altitude Observatory (HAO), National Center for Atmospheric Research [Boulder] (NCAR), and Corbard, Thierry

Subjects
[PHYS.ASTR.SR] Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], [PHYS.ASTR.SR]Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], ComputingMilieux_MISCELLANEOUS
Abstract

International audience; Not Available

Published
2000

18. First Results from SWAN Lyman α solar wind mapper on SOHO

Author

Bertaux, Jean-Loup, Quémerais, Eric, Lallement, Rosine, Kyrölä, E., Schmidt, Walter, Summanen, T., Goutail, Jean-Pierre, Berthé, Michell, Costa, Jorge, HOLZER, T., Service d'aéronomie (SA), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Finnish Meteorological Institute (FMI), High Altitude Observatory (HAO), and National Center for Atmospheric Research [Boulder] (NCAR)

Subjects
[SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Physics::Space Physics, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Physics::Atmospheric and Oceanic Physics, Astrophysics::Galaxy Astrophysics
Abstract

International audience; After one year of almost flawless operation on board the SOHO spacecraft poised at L1 Lagrange point, we report the main features of SWAN observations. SWAN is mainly dedicated to the monitoring of the latitude distribution of the solar wind by the Lα method. Maps of sky Lα emissions were recorded througout the year. The region of maximum emission, located in the upwind hemisphere, deviates strongly from the pattern that could be expected from a solar wind constant with latitude. It is divided into two lobes by a depression aligned with the solar equatorial plane called the Lyα groove already noted in 1976 Prognoz data. The north lobe is much brighter than the south lobe. These two characteristics can be explained qualitatively by an enhanced ionization along the neutral sheet where the slow solar wind is concentrated, which results from the higher low-latitude solar wind mass flux as measured by Ulysses. The groove is the direct imprint on the sky of the enhanced carving by the slow solar wind, at this time of solar minimum, when the tilt angle of the neutral sheet is small. The question is still pending to predict what will happen with the ascending phase of the solar cycle. Observations of comets are briefly mentioned, with the ability of SWAN to monitor the H2O production of many comets. Operations of the instrument are briefly described, including some instrumental problems which could be solved by software modifications sent to the instrument.

Published
1997
Full Text
View/download PDF

19. Long-Term Variation of the Interplanetary H Lyα Glow: Voyager UVS Measurements and Implications for the Solar H Lyα Irradiance

Author

Bill R. Sandel, Eric Quémerais, Giuliana de Toma, High Altitude Observatory (HAO), National Center for Atmospheric Research [Boulder] (NCAR), Service d'aéronomie (SA), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Lunar and Planetary Laboratory [Tucson] (LPL), and University of Arizona

Subjects
Physics, 010504 meteorology & atmospheric sciences, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Irradiance, Interplanetary medium, Flux, Astronomy and Astrophysics, Astrophysics, Solar irradiance, Atmospheric sciences, 01 natural sciences, Atmosphere, Atmospheric radiative transfer codes, 13. Climate action, Space and Planetary Science, Physics::Space Physics, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Solstice, Astrophysics::Earth and Planetary Astrophysics, Interplanetary spaceflight, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences
Abstract

International audience; In this paper we study interplanetary (IP) Lya data taken with the Voyager 1 and Voyager 2 spacecraft from 1980 to 1995. The coverage in time is equal to about 156 and 220 points yr~1 for Voyager 1 and Voyager 2, respectively, with almost no gaps. The IP Lya data are normalized for spatial changes in the emissivity, which arise from variations in observing geometry, by using a radiative transfer model. The normalized data show the variation of the solar H Lya line-center Ñux during the solar cycle. We compare this variation with the solar H Lya irradiance measurements of integrated Ñux from the Solar Mesosphere Explorer and the Upper Atmosphere Research Satellite/Solar-Stellar Irradiance Comparison Experiment (SOLSTICE), and, when direct solar measurements are not available, we use estimated irra-diances from magnesium and helium indices. The comparison between Voyager IP data and solar data shows that the best agreement is found with the SOLSTICE set of measurements, when no di †erences in the variation of the line-center Ñux and the integrated Ñux are taken into account.

Published
1997
Full Text
View/download PDF

20. The discovery of nonradial pulsation in the λ Bootis star HD 111604

Author

Bohlender, David A., Gonzalez, Jean-François, Kennelly, E., Canada-France-Hawaii Telescope Corporation (CFHT), National Research Council of Canada (NRC)-Centre National de la Recherche Scientifique (CNRS)-University of Hawai'i [Honolulu] (UH), Centre de Recherche Astrophysique de Lyon (CRAL), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), High Altitude Observatory (HAO), and National Center for Atmospheric Research [Boulder] (NCAR)

Subjects
stars: individual: HD 111604, stars: λ Boo, stars: oscillations, stars: peculiar A, [PHYS.ASTR.SR]Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], stars: δ Scuti
Abstract

International audience; Evidence for high order nonradial pulsation (NRP) has been discovered in the λ Boo star HD 111604. Analysis of a limited number of spectra of the NaID lines indicate that the mode of oscillation, |m|, is approximately 20 and NRP features circumnavigate the star every 0.71 days. Current models suggest that these objects should be near the ZAMS, and the detection of nonradial pulsation in at least one member of the class presents the exciting possibility of performing a direct measurement of its evolutionary state to test this hypothesis.

Published
1996

Catalog

Books, media, physical & digital resources
See catalog results