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15 results on '"Roudier, T."'

1. Magnetic Field and Convection in the Cool Supergiant Betelgeuse

Author

Aurière, M., Konstantinova-Antova, R., Petit, P., Charbonnel, C., Van Eck, S., Donati, J.-F., Lignieres, F., Roudier, T., 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), University of Sofia, Observatoire Astronomique de l'Université de Genève (ObsGE), Université de Genève (UNIGE), Institut d'Astronomie et d'Astrophysique, Université libre de Bruxelles (ULB), 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), and Université Fédérale Toulouse Midi-Pyrénées more...

Subjects
[SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], [SDU]Sciences of the Universe [physics], ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2013
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2. Magnetic field and convection in the cool supergiant Betelgeuse

Author

Petit, P., Aurière, M., Konstantinova-Antova, R., Morgenthaler, A., Perrin, G., Roudier, T., and Donati, J. -F.

Subjects
Astrophysics - Solar and Stellar Astrophysics, Astrophysics::Solar and Stellar Astrophysics, FOS: Physical sciences, Solar and Stellar Astrophysics (astro-ph.SR)
Abstract

We present the outcome of a highly-sensitive search for magnetic fields on the cool supergiant Betelgeuse. A time-series of six circularly-polarized spectra was obtained using the NARVAL spectropolarimeter at T\'elescope Bernard Lyot (Pic du Midi Observatory), between 2010 March and April. Zeeman signatures were repeatedly detected in cross-correlation profiles, corresponding to a longitudinal component of about 1 G. The time-series unveils a smooth increase of the longitudinal field from 0.5 to 1.5 G, correlated with radial velocity fluctuations. We observe a strong asymmetry of Stokes V signatures, also varying in correlation with the radial velocity. The Stokes V line profiles are red-shifted by about 9 km/s with respect to the Stokes I profiles, suggesting that the observed magnetic elements may be concentrated in the sinking components of the convective flows., Comment: Submitted to Lecture Notes in Physics (CNRS astronomy school : "From solar environment to stellar environment") more...

Published
2011
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3. Large-scale horizontal flows in the solar photosphere

Author

Roudier, T., Švanda, M., Meunier, N., Keil, S., Rieutord, M., Malherbe, M., Rondi, S., Molodij, G., Bommier, V., Schmieder, B., Laboratoire Astrophysique de Toulouse-Tarbes (LATT), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Centre de Recherche en Nutrition Humaine d'Auvergne (CRNH d'Auvergne), Laboratoire d'Astrophysique de l'Observatoire Midi-Pyrénées (LATT), Center for Astrophysics, Weizmann Institute of Science, Weizmann Institute of Science, Observatoire de Paris - Site de Paris (OP), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and PSL Research University (PSL)-PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS) more...

Subjects
[SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], [SDU]Sciences of the Universe [physics], ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2008
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4. Tracking granules on the Sun's surface and reconstructing velocity fields

Author

Rieutord, M., Roudier, T., Roques, S., Ducottet, C., 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, Institut d'Electronique du Solide et des Systèmes (InESS), Centre National de la Recherche Scientifique (CNRS), Laboratoire Hubert Curien [Saint Etienne] (LHC), and Université Jean Monnet [Saint-Étienne] (UJM)-Centre National de la Recherche Scientifique (CNRS)-Institut d'Optique Graduate School (IOGS) more...

Subjects
[SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], [SDU]Sciences of the Universe [physics], ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2007
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5. Tracking granules on the Sun's surface and reconstructing velocity fields

Author

Tkaczuk, R., Rieutord, M., Meunier, N., Roudier, T., 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, and Centre de Recherche en Nutrition Humaine d'Auvergne (CRNH d'Auvergne) more...

Subjects
[SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], [SDU]Sciences of the Universe [physics], ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2007
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6. Tracking granules on the Sun's surface and reconstructing horizontal velocity fields: I. the CST algorithm

Author

Rieutord, M., Roudier, T., Roques, S., and Ducottet, C.

Subjects
Astrophysics (astro-ph), FOS: Physical sciences, Astrophysics::Solar and Stellar Astrophysics, Astrophysics
Abstract

Determination of horizontal velocity fields on the solar surface is crucial for understanding the dynamics of structures like mesogranulation or supergranulation or simply the distribution of magnetic fields. We pursue here the development of a method called CST for coherent structure tracking, which determines the horizontal motion of granules in the field of view. We first devise a generalization of Strous method for the segmentation of images and show that when segmentation follows the shape of granules more closely, granule tracking is less effective for large granules because of increased sensitivity to granule fragmentation. We then introduce the multi-resolution analysis on the velocity field, based on Daubechies wavelets, which provides a view of this field on different scales. An algorithm for computing the field derivatives, like the horizontal divergence and the vertical vorticity, is also devised. The effects from the lack of data or from terrestrial atmospheric distortion of the images are also briefly discussed., in press in Astronomy and Astrophysics, 9 pages more...

Published
2007

7. A simulation of solar convection at supergranulation scale

Author

Rieutord, M., Ludwig, H. -G., Roudier, T., Nordlund, A., and Stein, R.

Subjects
Astrophysics (astro-ph), Astrophysics::Solar and Stellar Astrophysics, FOS: Physical sciences, Astrophysics
Abstract

We present here numerical simulations of surface solar convection which cover a box of 30$\times30\times$3.2 Mm$^3$ with a resolution of 315$\times315\times$82, which is used to investigate the dynamics of scales larger than granulation. No structure resembling supergranulation is present; possibly higher Reynolds numbers (i.e. higher numerical resolution), or magnetic fields, or greater depth are necessary. The results also show interesting aspects of granular dynamics which are briefly presented, like extensive p-mode ridges in the k-$\omega$ diagram and a ringlike distribution of horizontal vorticity around granules. At large scales, the horizontal velocity is much larger than the vertical velocity and the vertical motion is dominated by p-mode oscillations., Comment: Contribution to the proceedings of the workshop entitled "THEMIS and the new frontiers of solar atmosphere dynamics" (March 2001), 6 pages, to appear in Nuovo Cimento C more...

Published
2001

8. On mesogranulation, network formation and supergranulation

Author

Rieutord, M., Roudier, T., Malherbe, J. M., and Rincon, F.

Subjects
Astrophysics (astro-ph), FOS: Physical sciences, Astrophysics::Solar and Stellar Astrophysics, Astrophysics
Abstract

We present arguments which show that in all likelihood mesogranulation is not a true scale of solar convection but the combination of the effects of both highly energetic granules, which give birth to strong positive divergences (SPDs) among which we find exploders, and averaging effects of data processing. The important role played by SPDs in horizontal velocity fields appears in the spectra of these fields where the scale $\sim$4 Mm is most energetic; we illustrate the effect of averaging with a one-dimensional toy model which shows how two independent non-moving (but evolving) structures can be transformed into a single moving structure when time and space resolution are degraded. The role of SPDs in the formation of the photospheric network is shown by computing the advection of floating corks by the granular flow. The coincidence of the network bright points distribution and that of the corks is remarkable. We conclude with the possibility that supergranulation is not a proper scale of convection but the result of a large-scale instability of the granular flow, which manifests itself through a correlation of the flows generated by SPDs., 10 pages, 11 figures, to appear in Astronomy and Astrophysics more...

Published
2000

9. The dynamics perspective

Author

Turck-Chièze, S., Schmutz, W., Thuillier, G., Jefferies, S., Pallé, P., Dewitt, S., Ballot, J., Berthomieu, G., Bonanno, A., Brun, A. S., Christensen-Dalsgaard, J., Corbard, T., Couvidat, S., Darwich, A. M., Dintrans, B., Domingo, V., Finsterle, W., Fossat, E., García, R. A., Gelly, B., Gough, D., Guzik, J., Jiménez, A. J., Jiménez-Reyes, S., Kosovichev, A., Lambert, P., Lefebvre, S., Ilidio Lopes, Martic, M., Mathis, S., Mathur, S., Nghiem, P. A. P., Piau, L., Provost, J., Rieutord, M., Robillot, J. M., Rogers, T., Roudier, T., Roxburgh, I., Rozelot, J. P., Straka, C., Talon, S., Théado, S., Thompson, M., Vauclair, S., Zahn, J. P., 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), Physikalisch-Meteorologisches Observatorium Davos/World Radiation Center (PMOD/WRC), 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), University of Hawai'i [Honolulu] (UH), Instituto de Astrofisica de Canarias (IAC), Institut Royal Météorologique de Belgique [Bruxelles] - Royal Meteorological Institute (IRM), Max-Planck-Institut für Astrophysik (MPA), Max-Planck-Gesellschaft, Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA), INAF - Osservatorio Astrofisico di Catania (OACT), Istituto Nazionale di Astrofisica (INAF), Aarhus University [Aarhus], Hansen Experimental Physics Lab [Stanford] (HEPL), Stanford University, 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, Universitat de València (UV), Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA), University of Cambridge [UK] (CAM), Los Alamos National Laboratory (LANL), Instituto Superior Técnico, Technical University of Lisbon, Observatoire Astronomique de l'Université de Genève (ObsGE), Université de Genève = University of Geneva (UNIGE), Department of Astronomy and Astrophysics [Chicago], University of Chicago, Observatoire Bordeaux, Université Sciences et Technologies - Bordeaux 1 (UB), Laboratoire Astrophysique de Toulouse-Tarbes (LATT), 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), 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), Queen Mary University of London (QMUL), Yale University [New Haven], Université du Québec à Montréal = University of Québec in Montréal (UQAM), Laboratoire Univers et Théories (LUTH (UMR_8102)), 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), and Karen Fletcher. Scientific Editor: Michael Thompson (eds) more...

Subjects
[SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], ComputingMilieux_MISCELLANEOUS
Abstract

International audience

10. Scientific Objectives of the Novel Formation Flying Mission Aspiics

Author

Turck-Chièze, S., Schmutz, W., Thuillier, G., Jefferies, S., Pallé, Dewitt, S., Ballot, J., Berthomieu, G., Bonanno, A., Brun, A. S., Christensen-Dalsgaard, J., Corbard, T., Couvidat, S., Darwich, A. M., Dintrans, B., Domingo, V., Finsterle, W., Fossat, E., Garcia, R. A., Gelly, B., Gough, D., Guzik, J., Jiménez, A. J., Jiménez-Reyes, S., Kosovichev, A., Lambert, P., Lefebvre, S., Lopes, I., Martic, M., Mathis, S., Mathur, S., Nghiem, P. A. P., Piau, L., Provost, J., Rieutord, M., Robillot, J. M., Rogers, T., Roudier, T., Roxburgh, I., Rozelot, J. P., Straka, C., Talon, S., Théado, S., Thompson, M., Vauclair, S., and Zahn, J. P. more...

12. The EUV Variability Experiment (EVE) on the Solar Dynamics Observatory (SDO): Science Plan and Instrument Overview

Author

Turck-Chièze, S., Schmutz, W., Thuillier, G., Jefferies, S., Pallé, Dewitt, S., Ballot, J., Berthomieu, G., Bonanno, A., Brun, A. S., Christensen-Dalsgaard, J., Corbard, T., Couvidat, S., Darwich, A. M., Dintrans, B., Domingo, V., Finsterle, W., Fossat, E., Garcia, R. A., Gelly, B., Gough, D., Guzik, J., Jiménez, A. J., Jiménez-Reyes, S., Kosovichev, A., Lambert, P., Lefebvre, S., Lopes, I., Martic, M., Mathis, S., Mathur, S., Nghiem, P. A. P., Piau, L., Provost, J., Rieutord, M., Robillot, J. M., Rogers, T., Roudier, T., Roxburgh, I., Rozelot, J. P., Straka, C., Talon, S., Théado, S., Thompson, M., Vauclair, S., and Zahn, J. P. more...

13. The dynamics project

Author

Turck-Chièze, S., Schmutz, W., Thuillier, G., Cacciani, A., Pallé, P., Domingo, V., Ballot, J., Berthomieu, G., Bonanno, A., Brun, A. S., Christensen-Dalsgaard, J., Corbard, T., Couvidat, S., Darwich, A. M., Dintrans, B., Finsterle, W., Fossat, E., García, R. A., Gelly, B., Gough, D., Guzik, J., Jiménez, A. J., Sebastián Jiménez Reyes, Kosovichev, A., Lambert, P., Lefebvre, S., Lopes, I., Martic, M., Mathis, S., Mathur, S., Nghiem, P. A. P., Piau, L., Provost, J., Rieutord, M., Robillot, J. M., Rogers, T., Roudier, T., Roxburgh, I., Rozelot, J. P., Talon, S., Thompson, M., Vauclair, S., and Zahn, J. P. more...

14. Weak magnetic fields in CP stars

Author

Aurière, M., Wade, G. A., Lignières, F., Landstreet, J. D., Donati, J. -F, Hui Bon Hoa, A., Ilian Iliev, Petit, P., Roudier, T., Silvester, J., Theado, S., 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, and University of Western Ontario (UWO) more...

Subjects
[PHYS.ASTR.CO]Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], stars: magnetic fields, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics::Galaxy Astrophysics, stars: chemically peculiar
Abstract

International audience; We present the first results of a magnetic survey of main sequence A and late B stars with NARVAL, the new generation spectropolarimeter available at Telescope Bernard Lyot at Pic du Midi Observatory. We observed 3 HgMn stars, 12 Am stars and the only Ap star for which no Zeeman detection was obtained with MuSiCoS. If we combine our results with those of our previous survey of weak magnetic fields in spectroscopically selected Ap/Bp stars we get the following situation: - Ap/Bp stars: all these stars appear to host a detectable magnetic field. A threshold dipolar magnetic field of 300 G appears to exist, below which fields are very rare and perhaps altogether absent. - Am and HgMn stars: no magnetic field is detected up to now for the 15 observed stars. An accuracy down to 0.3 G (respectively 1 G) is reached on longitudinal magnetic field measurements for Am (respectively HgMn) stars. We propose a possible interpretation of the observed threshold field which naturally explains the magnetic dichotomy: there exists a critical field strength above which stable magnetic configurations exist and below which any large scale field configuration is destroyed by some instability. more...

15. The Dynamics Project

Author

Turck-Chièze, S., Schmutz, W., Thuillier, G., Jefferies, S., Pallé, Dewitt, S., Ballot, J., Berthomieu, G., Bonanno, A., Brun, A. S., Christensen-Dalsgaard, J., Corbard, T., Couvidat, S., Darwich, A. M., Dintrans, B., Domingo, V., Finsterle, W., Fossat, E., Garcia, R. A., Gelly, B., Gough, D., Guzik, J., Jiménez, A. J., Jiménez-Reyes, S., Kosovichev, A., Lambert, P., Lefebvre, S., Lopes, I., Martic, M., Mathis, S., Mathur, S., Nghiem, P. A. P., Piau, L., Provost, J., Rieutord, M., Robillot, J. M., Rogers, T., Roudier, T., Roxburgh, I., Rozelot, J. P., Straka, C., Talon, S., Théado, S., Thompson, M., Vauclair, S., and Zahn, J. P. more...