44 results on '"Boumier, P"'
Search Results
2. The CoRoT target HD 175726: an active star with weak solar-like oscillations*
- Author
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Mosser, B., Michel, E., Appourchaux, T., Barban, C., Baudin, F., Boumier, P., Bruntt, H., Catala, C., Deheuvels, S., García, R. A., Gaulme, P., Regulo, C., Roxburgh, I., Samadi, R., Verner, G., Auvergne, M., Baglin, A., Ballot, J., Benomar, O., Mathur, S., Mosser, B., Michel, E., Appourchaux, T., Barban, C., Baudin, F., Boumier, P., Bruntt, H., Catala, C., Deheuvels, S., García, R. A., Gaulme, P., Regulo, C., Roxburgh, I., Samadi, R., Verner, G., Auvergne, M., Baglin, A., Ballot, J., Benomar, O., and Mathur, S.
- Abstract
Context. The CoRoT short runs give us the opportunity to observe a large variety of late-type stars through their solar-like oscillations. We report observations of the star HD 175726 that lasted for 27 days during the first short run of the mission. The time series reveals a high-activity signal and the power spectrum presents an excess due to solar-like oscillations with a low signal-to-noise ratio.
- Published
- 2009
- Full Text
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3. Solar-like oscillations in HD 181420: data analysis of 156 days of CoRoT data*
- Author
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Barban, C., Deheuvels, S., Baudin, F., Appourchaux, T., Auvergne, M., Ballot, J., Boumier, P., Chaplin, W. J., García, R. A., Gaulme, P., Michel, E., Mosser, B., Régulo, C., Roxburgh, I. W., Verner, G., Baglin, A., Catala, C., Samadi, R., Bruntt, H., Elsworth, Y., Mathur, S., Barban, C., Deheuvels, S., Baudin, F., Appourchaux, T., Auvergne, M., Ballot, J., Boumier, P., Chaplin, W. J., García, R. A., Gaulme, P., Michel, E., Mosser, B., Régulo, C., Roxburgh, I. W., Verner, G., Baglin, A., Catala, C., Samadi, R., Bruntt, H., Elsworth, Y., and Mathur, S.
- Abstract
Context. The estimate of solar-like oscillation properties, such as their frequencies, amplitudes and lifetimes, is challenging because of their low amplitudes and will benefit from long and uninterrupted observing runs. The space telescope CoRoT allows us to obtain high-performance photometric data over a long and quasi continuous period. Among its main targets are stars for which we expect solar-like oscillations.
- Published
- 2009
- Full Text
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4. The CoRoT satellite in flight: description and performance*
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Auvergne, M., Bodin, P., Boisnard, L., Buey, J.-T., Chaintreuil, S., Epstein, G., Jouret, M., Lam-Trong, T., Levacher, P., Magnan, A., Perez, R., Plasson, P., Plesseria, J., Peter, G., Steller, M., Tiphène, D., Baglin, A., Agogué, P., Appourchaux, T., Barbet, D., Beaufort, T., Bellenger, R., Berlin, R., Bernardi, P., Blouin, D., Boumier, P., Bonneau, F., Briet, R., Butler, B., Cautain, R., Chiavassa, F., Costes, V., Cuvilho, J., Cunha-Parro, V., De Oliveira Fialho, F., Decaudin, M., Defise, J.-M., Djalal, S., Docclo, A., Drummond, R., Dupuis, O., Exil, G., Fauré, C., Gaboriaud, A., Gamet, P., Gavalda, P., Grolleau, E., Gueguen, L., Guivarc'h, V., Guterman, P., Hasiba, J., Huntzinger, G., Hustaix, H., Imbert, C., Jeanville, G., Johlander, B., Jorda, L., Journoud, P., Karioty, F., Kerjean, L., Lafond, L., Lapeyrere, V., Landiech, P., Larqué, T., Laudet, P., Le Merrer, J., Leporati, L., Leruyet, B., Levieuge, B., Llebaria, A., Martin, L., Mazy, E., Mesnager, J.-M., Michel, J.-P., Moalic, J.-P., Monjoin, W., Naudet, D., Neukirchner, S., Nguyen-Kim, K., Ollivier, M., Orcesi, J.-L., Ottacher, H., Oulali, A., Parisot, J., Perruchot, S., Piacentino, A., Pinheiro da Silva, L., Platzer, J., Pontet, B., Pradines, A., Quentin, C., Rohbeck, U., Rolland, G., Rollenhagen, F., Romagnan, R., Russ, N., Samadi, R., Schmidt, R., Schwartz, N., Sebbag, I., Smit, H., Sunter, W., Tello, M., Toulouse, P., Ulmer, B., Vandermarcq, O., Vergnault, E., Wallner, R., Waultier, G., Zanatta, P., Auvergne, M., Bodin, P., Boisnard, L., Buey, J.-T., Chaintreuil, S., Epstein, G., Jouret, M., Lam-Trong, T., Levacher, P., Magnan, A., Perez, R., Plasson, P., Plesseria, J., Peter, G., Steller, M., Tiphène, D., Baglin, A., Agogué, P., Appourchaux, T., Barbet, D., Beaufort, T., Bellenger, R., Berlin, R., Bernardi, P., Blouin, D., Boumier, P., Bonneau, F., Briet, R., Butler, B., Cautain, R., Chiavassa, F., Costes, V., Cuvilho, J., Cunha-Parro, V., De Oliveira Fialho, F., Decaudin, M., Defise, J.-M., Djalal, S., Docclo, A., Drummond, R., Dupuis, O., Exil, G., Fauré, C., Gaboriaud, A., Gamet, P., Gavalda, P., Grolleau, E., Gueguen, L., Guivarc'h, V., Guterman, P., Hasiba, J., Huntzinger, G., Hustaix, H., Imbert, C., Jeanville, G., Johlander, B., Jorda, L., Journoud, P., Karioty, F., Kerjean, L., Lafond, L., Lapeyrere, V., Landiech, P., Larqué, T., Laudet, P., Le Merrer, J., Leporati, L., Leruyet, B., Levieuge, B., Llebaria, A., Martin, L., Mazy, E., Mesnager, J.-M., Michel, J.-P., Moalic, J.-P., Monjoin, W., Naudet, D., Neukirchner, S., Nguyen-Kim, K., Ollivier, M., Orcesi, J.-L., Ottacher, H., Oulali, A., Parisot, J., Perruchot, S., Piacentino, A., Pinheiro da Silva, L., Platzer, J., Pontet, B., Pradines, A., Quentin, C., Rohbeck, U., Rolland, G., Rollenhagen, F., Romagnan, R., Russ, N., Samadi, R., Schmidt, R., Schwartz, N., Sebbag, I., Smit, H., Sunter, W., Tello, M., Toulouse, P., Ulmer, B., Vandermarcq, O., Vergnault, E., Wallner, R., Waultier, G., and Zanatta, P.
- Abstract
Context. CoRoT is a space telescope dedicated to stellar seismology and the search for extrasolar planets. The mission is led by the CNES in association with French laboratories and has a large international participation. The European Space Agency (ESA), Austria, Belgium, and Germany contribute to the payload, and Spain and Brazil contribute to the ground segment. Development of the spacecraft, which is based on a PROTEUS low earth orbit (LEO) recurrent platform, commenced in October 2000, and the satellite was launched on December 27, 2006.
- Published
- 2009
- Full Text
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5. Hydrodynamical simulations of convection-related stellar micro-variability***
- Author
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Ludwig, H.-G., Samadi, R., Steffen, M., Appourchaux, T., Baudin, F., Belkacem, K., Boumier, P., Goupil, M.-J., Michel, E., Ludwig, H.-G., Samadi, R., Steffen, M., Appourchaux, T., Baudin, F., Belkacem, K., Boumier, P., Goupil, M.-J., and Michel, E.
- Abstract
Context. Local-box hydrodynamical model atmospheres provide statistical information about a star's emergent radiation field which allows one to predict the level of its granulation-related micro-variability. Space-based photometry is now sufficiently accurate to test model predictions.
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- 2009
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6. Solar-like oscillations with low amplitude in the CoRoT target HD 181906*
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García, R. A., Régulo, C., Samadi, R., Ballot, J., Barban, C., Benomar, O., Chaplin, W. J., Gaulme, P., Appourchaux, T., Mathur, S., Mosser, B., Toutain, T., Verner, G. A., Auvergne, M., Baglin, A., Baudin, F., Boumier, P., Bruntt, H., Catala, C., Deheuvels, S., Elsworth, Y., Jiménez-Reyes, S. J., Michel, E., Pérez Hernández, F., Roxburgh, I. W., Salabert, D., García, R. A., Régulo, C., Samadi, R., Ballot, J., Barban, C., Benomar, O., Chaplin, W. J., Gaulme, P., Appourchaux, T., Mathur, S., Mosser, B., Toutain, T., Verner, G. A., Auvergne, M., Baglin, A., Baudin, F., Boumier, P., Bruntt, H., Catala, C., Deheuvels, S., Elsworth, Y., Jiménez-Reyes, S. J., Michel, E., Pérez Hernández, F., Roxburgh, I. W., and Salabert, D.
- Abstract
Context. The F8 star HD 181906 (effective temperature ${\sim}6300$K) was observed for 156 days by the CoRoT satellite during the first long run in the direction of the galactic centre. Analysis of the data reveals a spectrum of solar-like acoustic oscillations. However, the faintness of the target (mv= 7.65) means the signal-to-noise (S/N) in the acoustic modes is quite low, and this low S/N leads to complications in the analysis.
- Published
- 2009
- Full Text
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7. Magnetic activity in the photosphere of CoRoT-Exo-2a*
- Author
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Lanza, A. F., Pagano, I., Leto, G., Messina, S., Aigrain, S., Alonso, R., Auvergne, M., Baglin, A., Barge, P., Bonomo, A. S., Boumier, P., Collier Cameron, A., Comparato, M., Cutispoto, G., De Medeiros, J. R., Foing, B., Kaiser, A., Moutou, C., Parihar, P. S., Silva-Valio, A., Weiss, W. W., Lanza, A. F., Pagano, I., Leto, G., Messina, S., Aigrain, S., Alonso, R., Auvergne, M., Baglin, A., Barge, P., Bonomo, A. S., Boumier, P., Collier Cameron, A., Comparato, M., Cutispoto, G., De Medeiros, J. R., Foing, B., Kaiser, A., Moutou, C., Parihar, P. S., Silva-Valio, A., and Weiss, W. W.
- Abstract
Context. The space experiment CoRoT has recently detected transits by a hot Jupiter across the disc of an active G7V star (CoRoT-Exo-2a) that can be considered as a good proxy for the Sun at an age of approximately 0.5 Gyr.
- Published
- 2009
- Full Text
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8. CoRoT sounds the stars: p-mode parameters of Sun-like oscillations on HD 49933*
- Author
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Appourchaux, T., Michel, E., Auvergne, M., Baglin, A., Toutain, T., Baudin, F., Benomar, O., Chaplin, W. J., Deheuvels, S., Samadi, R., Verner, G. A., Boumier, P., García, R. A., Mosser, B., Hulot, J.-C., Ballot, J., Barban, C., Elsworth, Y., Jiménez-Reyes, S. J., Kjeldsen, H., Régulo, C., Roxburgh, I. W., Appourchaux, T., Michel, E., Auvergne, M., Baglin, A., Toutain, T., Baudin, F., Benomar, O., Chaplin, W. J., Deheuvels, S., Samadi, R., Verner, G. A., Boumier, P., García, R. A., Mosser, B., Hulot, J.-C., Ballot, J., Barban, C., Elsworth, Y., Jiménez-Reyes, S. J., Kjeldsen, H., Régulo, C., and Roxburgh, I. W.
- Abstract
Context. The first asteroseismology results from CoRoT are presented, on a star showing Sun-like oscillations. We have analyzed a 60 day lightcurve of high-quality photometric data collected by CoRoT on the F5 V star HD 49933. The data reveal a rich spectrum of overtones of low-degree p modes.
- Published
- 2008
- Full Text
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9. Searching for p-modes in MOST Procyon data: another view*
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Baudin, F., Appourchaux, T., Boumier, P., Kuschnig, R., Leibacher, J. W., Matthews, J. M., Baudin, F., Appourchaux, T., Boumier, P., Kuschnig, R., Leibacher, J. W., and Matthews, J. M.
- Abstract
Context.Photometry of Procyon obtained by the MOST satellite in 2004 has been searched for p modes by several groups, with sometimes contradictory interpretations.
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- 2008
- Full Text
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10. On cross-spectrum capabilities for detecting stellar oscillation modes
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Appourchaux, T., Leibacher, J., Boumier, P., Appourchaux, T., Leibacher, J., and Boumier, P.
- Abstract
Aims.Long-lived stellar oscillation modes are usually detected using Fourier transforms of time series of stellar radial velocities or brightness. It is commonly thought that one could use the cross spectrum of the two signals, or alternatively use the interleaved series of a single signal, to considerably improve the detection level by reducing the noise level.
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- 2007
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11. Global solar Doppler velocity determination with the GOLF/SoHO instrument
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García, R. A., Turck-Chièze, S., Boumier, P., Robillot, J. M., Bertello, L., Charra, J., Dzitko, H., Gabriel, A. H., Jiménez-Reyes, S. J., Pallé, P. L., Renaud, C., Roca Cortés, T., Ulrich, R. K., García, R. A., Turck-Chièze, S., Boumier, P., Robillot, J. M., Bertello, L., Charra, J., Dzitko, H., Gabriel, A. H., Jiménez-Reyes, S. J., Pallé, P. L., Renaud, C., Roca Cortés, T., and Ulrich, R. K.
- Abstract
The Global Oscillation at Low Frequencies (GOLF) experiment is a resonant scattering spectrophotometer on board the Solar and Heliospheric Observatory (SoHO) mission, originally designed to measure the disk-integrated solar oscillations of the Sun. This instrument was designed in a relative photometric mode involving both wings of the neutral sodium doublet (D1at λ5896 and D2at λ5890 Å). However, a “one-wing” photometric mode has been selected to ensure 100% continuity in the measurements after a problem in the polarization mechanisms. Thus the velocity is obtained from only two points on the same wing of the lines. This operating configuration imposes tighter constraints on the stability of the instrument with a higher sensitivity to instrumental variations. In this paper we discuss the evolution of the instrument during the last 8 years in space and the corrections applied to the measured counting rates due to known instrumental effects. We also describe a scaling procedure to obtain the variation of the Doppler velocity based on our knowledge of the sodium profile slope and we compare it to previous velocity estimations.
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- 2005
- Full Text
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12. Inferred acoustic rates of solar pmodes from several helioseismic instruments
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Baudin, F., Samadi, R., Goupil, M.-J., Appourchaux, T., Barban, C., Boumier, P., Chaplin, W. J., Gouttebroze, P., Baudin, F., Samadi, R., Goupil, M.-J., Appourchaux, T., Barban, C., Boumier, P., Chaplin, W. J., and Gouttebroze, P.
- Abstract
Acoustic rates of excitation of solar pmodes can be estimated from observations in order to place constraints on the modelling of the excitation process and the layers where it occurs in the star. For several reasons (including a poor signal to noise ratio and mode overlap), this estimation is difficult. In this work, we use three completely independent datasets to obtain robust estimates in the solar case for $\ell=1$modes. We also show that the height in the solar atmosphere where the modes are observed must be taken into account. Our three sets of results are shown to be consistent, particularly in the lower part of the p-mode spectrum (from 1.8 mHz to 2.8 mHz). At higher frequencies, the agreement is not as good, because of a larger dispersion of the measurements and also because of some systematic differences which might be due to observation height estimation or to a systematic influence of the noise.
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- 2005
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13. Advances in the development of a Mach-Zehnder interferometric Doppler imager for seismology of giant planets
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Evans, Christopher J., Simard, Luc, Takami, Hideki, Gonçalves, Ivan, Schmider, François-Xavier, Bresson, Yves, Dejonghe, Julien, Preis, Olivier, Robbe-Dubois, Sylvie, Appourchaux, Thierry, Boumier, Patrick, Leclec'h, Jean-Christophe, Morinaud, Gilles, Gaulme, Patrick, and Jackiewicz, Jason
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- 2016
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14. Main results of the PICARD mission
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MacEwen, Howard A., Fazio, Giovanni G., Lystrup, Makenzie, Batalha, Natalie, Siegler, Nicholas, Tong, Edward C., Meftah, M., Corbard, T., Hauchecorne, A., Irbah, A., Boumier, P., Chevalier, A., Schmutz, W., Ikhlef, R., Morand, F., Renaud, C., Hochedez, J.-F., Cessateur, G., Turck-Chièze, S., Salabert, D., Rouzé, M., van Ruymbeke, M., Zhu, P., Kholikov, S., Koller, S., Conscience, C., Dewitte, S., Damé, L., and Djafer, D.
- Published
- 2016
- Full Text
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15. A search for solar $\vec{g}$modes in the GOLF data
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Gabriel, A. H., Baudin, F., Boumier, P., García, R. A., Turck-Chièze, S., Appourchaux, T., Bertello, L., Berthomieu, G., Charra, J., Gough, D. O., Pallé, P. L., Provost, J., Renaud, C., Robillot, J.-M., Roca Cortés, T., Thiery, S., Ulrich, R. K., Gabriel, A. H., Baudin, F., Boumier, P., García, R. A., Turck-Chièze, S., Appourchaux, T., Bertello, L., Berthomieu, G., Charra, J., Gough, D. O., Pallé, P. L., Provost, J., Renaud, C., Robillot, J.-M., Roca Cortés, T., Thiery, S., and Ulrich, R. K.
- Abstract
With over 5 years of GOLF data having some 90% continuity, a new attempt has been made to search for possible solar gmodes. Statistical methods are used, based on the minimum of assumptions regarding the solar physics; namely that mode line-widths are small compared with the inverse of the observing time, and that modes are sought in the frequency interval 150 to 400 μHz. A number of simulations are carried out in order to understand the expected behaviour of a system consisting principally of a solar noise continuum overlaid with some weak sharp resonances. The method adopted is based on the FFT analysis of a time series with zero-padding by a factor of 5. One prominent resonance at 284.666 μHz coincides with a previous tentative assignment as one member of an $n=1$, $l=1$, p-mode multiplet. Components of two multiplets, previously tentatively identified as possible g-mode candidates from the GOLF data in 1998, continue to be found, although their statistical significance is shown to be insufficient, within the present assumption regarding the nature of the signal. An upper limit to the amplitude of any gmode present is calculated using two different statistical approaches, according to either the assumed absence (H0 hypothesis) or the assumed presence (H1 hypothesis) of a signal. The former yields a slightly lower limit of around 6 mm/s.
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- 2002
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16. Application of Fano profiles to asymmetric resonances in helioseismology
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Gabriel, A. H., Connerade, J.-P., Thiery, S., Boumier, P., Gabriel, A. H., Connerade, J.-P., Thiery, S., and Boumier, P.
- Abstract
Parallels are drawn between the asymmetric resonance profiles observed in global helioseismology and the Fano theory for autoionisation profiles in atomic spectroscopy. We show that the underlying physics of the interaction of a discrete resonance with a correlated continuum is common to both systems. The approximate formula normally used for fitting to profiles in helioseismology is essentially similar to that developed for atomic spectroscopy by Fano. We propose that the two systems are in reality equivalent. This proposition enables us to understand better which resonances in helioseismology will be correlated with each other and with which solar background "continua". We also question whether the two interacting influences of excitation sourcesand correlated solar background, are really separate independent processes.
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- 2001
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17. Basic concepts in solar magnetohydrodynamics.
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Araki, H., Beig, R., Ehlers, J., Frisch, U., Hepp, K., Jaffe, R. L., Kippenhahn, R., Weidenmüller, H. A., Wess, J., Zittartz, J., Beiglböck, W., Vial, Jean Claude, Bocchialini, Karine, Boumier, Patrick, and Walsh, Robert W.
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- 1998
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18. Future ESA Projects.
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Araki, H., Beig, R., Ehlers, J., Frisch, U., Hepp, K., Jaffe, R. L., Kippenhahn, R., Weidenmüller, H. A., Wess, J., Zittartz, J., Beiglböck, W., Vial, Jean Claude, Bocchialini, Karine, Boumier, Patrick, and Bonnet, Roger-M.
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- 1998
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19. SOHO: an example of Project Management.
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Araki, H., Beig, R., Ehlers, J., Frisch, U., Hepp, K., Jaffe, R. L., Kippenhahn, R., Weidenmüller, H. A., Wess, J., Zittartz, J., Beiglböck, W., Vial, Jean Claude, Bocchialini, Karine, Boumier, Patrick, and Felici, Fabrizio
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- 1998
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20. A SOHO user manual.
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Araki, H., Beig, R., Ehlers, J., Frisch, U., Hepp, K., Jaffe, R. L., Kippenhahn, R., Weidenmüller, H. A., Wess, J., Zittartz, J., Beiglböck, W., Vial, Jean Claude, Bocchialini, Karine, Boumier, Patrick, and Martens, Petrus C.
- Abstract
This paper is intended to serve as the first version of the "SOHO User Manual", a "how to" guide for those interested in analyzing existing SOHO data, or proposing new SOHO observations. Questions addressed are, how to use the SOHO catalogs, where to find the appropriate data analysis software, how to request permission to use proprietary data, how to propose and prepare SOHO observing programs. In an outlook to the future I will emphasize the potential for joint observations during the rising phase of the cycle in the extended SOHO mission, collaborations with Yohkoh, Ulysses, and TRACE, as well as with the ISTP spacecraft. [ABSTRACT FROM AUTHOR]
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- 1998
- Full Text
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21. Instrumentation: Spectroscopy.
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Araki, H., Beig, R., Ehlers, J., Frisch, U., Hepp, K., Jaffe, R. L., Kippenhahn, R., Weidenmüller, H. A., Wess, J., Zittartz, J., Beiglböck, W., Vial, Jean Claude, Bocchialini, Karine, Boumier, Patrick, and Lemaire, Philippe
- Abstract
Our knowledge of the the solar atmosphere comes from the light analysis. The ultraviolet wavelength is the privileged spectral range to study the solar plasma in several stages of ionization emitted from the chromosphere to the corona. Starting with basic notions of spectroscopy, an overview of important parameters is given. Then, after a short description of classical spectrometers, a detailed analysis of the properties of the mountings used on SOHO is performed; some examples are shown. I discuss how to separate the real solar signal from the instrumental contribution. From what has been learnt on the Sun during the last two decades, I make a prospective for future solar spectrometers developments. [ABSTRACT FROM AUTHOR]
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- 1998
- Full Text
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22. Heliospheric plasma physics: an introduction.
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Araki, H., Beig, R., Ehlers, J., Frisch, U., Hepp, K., Jaffe, R. L., Kippenhahn, R., Weidenmüller, H. A., Wess, J., Zittartz, J., Beiglböck, W., Vial, Jean Claude, Bocchialini, Karine, Boumier, Patrick, and Velli, Marco
- Abstract
A selection of topics in plasma physics and hydrodynamics relevant to the heliosphere is presented. The first three sections cover basic defining properties of a plasma, the essentials of particle orbit theory, including conservation of magnetic moment and the various drifts, and an introduction to kinetic theory, with an heuristic derivation of relaxation times. The fourth section is devoted to the hydrodynamic description of the solar wind, and is a pedagogical introduction to Parker's theory as well as to the methods of hydrodynamic and plasma stability. In the fifth and final section we return to the kinetic description of the solar wind plasmas and explore recent versions of the collisionless, or exospheric, models of wind acceleration, and compare their predictive merits and faults with those of the more widely studied fluid theories vis à vis in situ and remote observations of the corona and wind. [ABSTRACT FROM AUTHOR]
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- 1998
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23. Radiative transfer and radiation hydrodynamics.
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Araki, H., Beig, R., Ehlers, J., Frisch, U., Hepp, K., Jaffe, R. L., Kippenhahn, R., Weidenmüller, H. A., Wess, J., Zittartz, J., Beiglböck, W., Vial, Jean Claude, Bocchialini, Karine, Boumier, Patrick, and Carlsson, Mats
- Abstract
Radiation plays an important role, firstly in determining the structure of stars through the dominant role radiation plays in the energy balance (in some objects also in the momentum balance), secondly because we diagnose astrophysical plasma through the emitted electromagnetic radiation. These lectures discuss the diagnostic use of optically thick spectral lines and continua with special emphasis on the Sun. Modern methods to solve the equations of radiative transfer and statistical equilibrium are outlined. We stress the importance of solving self-consistently for the coupling between radiation and hydrodynamics for understanding the dynamic outer atmosphere of the Sun and review some results from such radiation hydrodynamics simulations. [ABSTRACT FROM AUTHOR]
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- 1998
- Full Text
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24. Plasma diagnostics for the solar atmosphere.
- Author
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Araki, H., Beig, R., Ehlers, J., Frisch, U., Hepp, K., Jaffe, R. L., Kippenhahn, R., Weidenmüller, H. A., Wess, J., Zittartz, J., Beiglböck, W., Vial, Jean Claude, Bocchialini, Karine, Boumier, Patrick, and Mason, Helen E.
- Abstract
Superb observations are now being obtained with the ESA/NASA Solar Heliospheric Observatory (SOHO). In these lectures, I discuss the spectroscopic diagnostic techniques used to analyse ultraviolet and X-ray spectra. Intensities of the spectral emission lines can be used to determine the electron density and temperature structure, element abundances and dynamic nature of different features in the solar transition region and corona. To ensure that these techniques are accurate it is necessary to model all the important atomic processes with the best available atomic data calculations. I discuss the analysis of SOHO spectra and look towards other astrophysical UV and X-ray observations. [ABSTRACT FROM AUTHOR]
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- 1998
- Full Text
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25. Solar wind.
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Araki, H., Beig, R., Ehlers, J., Frisch, U., Hepp, K., Jaffe, R. L., Kippenhahn, R., Weidenmüller, H. A., Wess, J., Zittartz, J., Beiglböck, W., Vial, Jean Claude, Bocchialini, Karine, Boumier, Patrick, and Marsch, Eckart
- Abstract
A concise tutorial review is given of solar wind observations and theory with emphasis on the more recent findings from the Ulysses and SOHO missions, in particular about the plasma state and structure of the polar coronal holes, and on theoretical efforts to model the coronal hole flows and the fast solar wind emanating therefrom. The structure of the large-scale corona is discussed and the microstate of the solar wind in terms of particle and wave observations is analysed. Observational evidence is mounting that the magnetically open coronal holes are far away from a state of local thermodynamic equilibrium, as is the associated interplanetary solar wind, and that they differ substantially in their plasma parameters from the low-latitude streamers with closed magnetic fields, which only open intermittently to release the slow solar wind. The coronal sources and their plasma boundary conditions as well as the interplanetary constraints on the wind models are presented and discussed. Modern theories and models of the solar wind are reviewed. First the basic concept of the single-fluid Parker-type model is outlined, and then two-fluid models are described, in particular those incorporating strong heating of protons close to the Sun, which yields fast acceleration with the terminal wind speed being attained within 10 R⊙. Finally, the most recent modelling efforts to generate the wind plasma through ionization in the chromospheric network are presented. [ABSTRACT FROM AUTHOR]
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- 1998
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26. Heating of chromospheres and coronae.
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Araki, H., Beig, R., Ehlers, J., Frisch, U., Hepp, K., Jaffe, R. L., Kippenhahn, R., Weidenmüller, H. A., Wess, J., Zittartz, J., Beiglböck, W., Vial, Jean Claude, Bocchialini, Karine, Boumier, Patrick, and Ulmschneider, Peter
- Abstract
Chromospheres and coronae owe their existence to mechanical heating. In the present work the mechanisms which are thought to provide steady mechanical heating are reviewed. These mechanisms can be classified as hydrodynamical- and magnetic heating mechanisms and each of these can be subdivided further on basis of the fluctuation frequency. Rapid fluctuations generated by the turbulence in the convection zones lead to acoustic waves and to mhd waves (AC-mechanisms), slow fluctuations to pulsational waves and to stressed fields with current sheets (DC-mechanisms). Solar and stellar observations, as well as acoustic and mhd wave generation rate computations on basis of convection zone models and a Kolmogorov-type energy spectrum representation for the turbulence, provide great progress towards the understanding of the complete dependence of the chromospheres and coronae on the properties of the underlying stars. [ABSTRACT FROM AUTHOR]
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- 1998
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27. Solar magnetic fields: an introduction.
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Araki, H., Beig, R., Ehlers, J., Frisch, U., Hepp, K., Jaffe, R. L., Kippenhahn, R., Weidenmüller, H. A., Wess, J., Zittartz, J., Beiglböck, W., Vial, Jean Claude, Bocchialini, Karine, Boumier, Patrick, and Solanki, S. K.
- Abstract
The magnetic field of the Sun is thought to be produced by a dynamo in the solar interior and exhibits its greatest influence on the solar plasma in the tenuous outer layers of the solar atmosphere, where it lies at the heart of almost every major phenomenon. Most direct observations of the magnetic field are restricted to the solar surface, however. Both observational and theoretical methods have been employed heavily to obtain information on and an understanding of solar magnetism. It is the aim of these lecture notes to impart some of this knowledge to the reader: knowledge both of the magnetic field and of some of the methods used to investigate it. First a short overview of the structure of magnetic fields in the observable layers of the Sun is given. This is followed by an introduction to the Zeeman effect and polarized light, which are fundamental to the measurement of the solar magnetic field, and to the magnetohydrostatic description of solar magnetic fields. Finally, current understanding of the small (magnetic elements) and large (sunspots) magnetic features observed in the solar photosphere is summarized. [ABSTRACT FROM AUTHOR]
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- 1998
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28. Methods and techniques in helioseismology.
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Araki, H., Beig, R., Ehlers, J., Frisch, U., Hepp, K., Jaffe, R. L., Kippenhahn, R., Weidenmüller, H. A., Wess, J., Zittartz, J., Beiglböck, W., Vial, Jean Claude, Bocchialini, Karine, Boumier, Patrick, and Cortés, Teodoro Roca
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In the last two decades, the study of global solar oscillations has provided the only effective method to probe the structure of stars, and particularly that of our Sun. As will be seen throughout this short course, we now know the Sun much better than before thanks to Helioseismology. However, the detection of such normal modes of vibration of the Sun has only been possible recently due to the combination of two factors: first the signals to measure, although almost periodic, have very small amplitudes as compared to noise, and second, instrumental and observing techniques have not reached the required sensitivity until now. Here we will look at the observational parameters that can be best measured, in terms of S/N, as well as the ultimate noise that is required in order to observe the solar oscillations. Further, we will review the current instruments and techniques that are able to do so with special emphasis on those onboard the SOHO satellite. However, getting the observations is not the end of the story; it is only after waiting for the acquisition of long time series and after applying sophisticated analysis techniques, that a comprehensive picture can be seen and observational parameters can be compared to theoretical predictions in what is known as the Forward Problem of Helioseismology. We will also see how the differences between the predictions and the actual Sun lead us to calculate the internal structure of the models through what is called the Inverse Problem in Helioseismology. [ABSTRACT FROM AUTHOR]
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- 1998
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29. Prediction of Radiographic Damage in Early Arthritis by Sonographic Erosions and Power Doppler Signal: A Longitudinal Observational Study
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Funck‐Brentano, Thomas, Gandjbakhch, Frédérique, Etchepare, Fabien, Jousse‐Joulin, Sandrine, Miquel, Anne, Cyteval, Catherine, Lukas, Cédric, Tobón, Gabriel J., Saraux, Alain, Boumier, Patrick, Goupille, Philippe, Bourgeois, Pierre, and Fautrel, Bruno
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- 2013
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30. Challenges of Cardiovascular Risk Assessment in the Routine Rheumatology Outpatient Setting: An Observational Study of 110 Rheumatoid Arthritis Patients
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Gossec, L., Salejan, F., Nataf, H., Nguyen, M., Gaud‐Listrat, V., Hudry, C., Breuillard, P., Dernis, E., Boumier, P., Durandin‐Truffinet, M., Fannius, J., Fechtenbaum, J., Izou‐Fouillot, M.‐A., Labatide‐Alanore, S., Lebrun, A., LeDevic, P., LeGoux, P., Sacchi, A., Salliot, C., Sparsa, L., d'André, F. Lecoq, and Dougados, M.
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- 2013
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31. Factors associated with fatigue in early arthritis: Results from a multicenter national French cohort study
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Rat, Anne‐Christine, Pouchot, Jacques, Fautrel, Bruno, Boumier, Patrick, Goupille, Philippe, and Guillemin, Francis
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- 2012
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32. Serum IgA rheumatoid factor and pyridinoline in very early arthritis as predictors of erosion(s) at two years: A simple model of prediction from a conservatively treated community‐based inception cohort
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Loët, Xavier Le, Brazier, Michel, Mejjad, Othmane, Boumier, Patrick, Daragon, Alain, Gayet, Alain, Pouplin, Sophie, Tron, François, Zarnitsky, Charles, Vittecoq, Olivier, Menard, Jean‐François, and Fardellone, Patrice
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- 2010
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33. The CoRoT target HD?175726: an active star with weak solar-like oscillations
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Mosser, B., Michel, E., Appourchaux, T., Barban, C., Baudin, F., Boumier, P., Bruntt, H., Catala, C., Deheuvels, S., Garc?a, R., Gaulme, P., Regulo, C., Roxburgh, I., Samadi, R., Verner, G., Auvergne, M., Baglin, A., Ballot, J., Benomar, O., and Mathur, S.
- Abstract
Context. The CoRoT short runs give us the opportunity to observe a large variety of late-type stars through their solar-like oscillations. We report observations of the star HD?175726 that lasted for 27?days during the first short run of the mission. The time series reveals a high-activity signal and the power spectrum presents an excess due to solar-like oscillations with a low signal-to-noise ratio.Aims. Our aim is to identify the most efficient tools to extract as much information as possible from the power density spectrum.Methods. The most productive method appears to be the autocorrelation of the time series, calculated as the spectrum of the filtered spectrum. This method is efficient, very rapid computationally, and will be useful for the analysis of other targets, observed with CoRoT or with forthcoming missions such as Kepler and Plato.Results. The mean large separation has been measured to be 97.2?0.5???Hz, slightly below the expected value determined from solar scaling laws. We also show strong evidence for variation of the large separation with frequency. The bolometric mode amplitude is only 1.7?0.25?ppm for radial modes, which is 1.7?times less than expected. Due to the low signal-to-noise ratio, mode identification is not possible for the available data set of HD?175726.
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- 2009
34. Helioseismology program for the PICARD satellitehttp://www.picard-mission.cnes.fr
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Corbard, T., Boumier, P., Appourchaux, T., Jiménez-Reyes, S.J., Gelly, B., and team, the PICARD
- Abstract
The PICARD mission is a CNES micro-satellite to be launched in 2009. Its goal is to better understand the Sun and the potential impact of its activity on earth climate by measuring simultaneously the solar total and spectral irradiance, diameter, shape and oscillations. We present the scientific objectives, instrumental requirements and data products of the helioseismology program of PICARD which aims to observe the low to medium lp-mode oscillations in intensity and search for g-mode oscillation signatures at the limb. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
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- 2008
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35. Results from the GOLF instrument on SOHO
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Gabriel, A.H., Turck-Chieze, S., Garcia, R.A., Palle, P.L., Boumier, P., Thiery, S., Baudin, F., Grec, G., Ulrich, R.K., and Bertello, L.
- Published
- 1999
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36. First View of the Solar Core from Golf Acoustic Modes
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Turck-Chièze, S., Basu, S., Brun, A., Christensen-Dalsgaard, J., Eff-Darwich, A., Lopes, I., Pérez Hernández, F., Berthomieu, G., Provost, J., Ulrich, R., Baudin, F., Boumier, P., Charra, J., Gabriel, A., Garcia, R., Grec, G., Renaud, C., Robillot, J., and Roca Cortés, T.
- Abstract
After 8 months of nearly continuous measurements the GOLF instrument, aboard SOHO, has detected acoustic mode frequencies of more than 100 modes, extending from 1.4 mHz to 4.9 mHz. In this paper, we compare these results with the best available predictions coming from solar models. To verify the quality of the data, we examine the asymptotic seismic parameters; this confirms the improvements achieved in solar models during the last decade. Using the GOLF set of frequencies for l=0, 1, 2, 3 combined with the LOWL second year data set for l > 3 we then carry out inversions to infer properties of the solar core. This largely confirms the previous results down to around 0.1 R⊙, while there remain differences, even closer to the centre, where the present study shows an extreme sensitivity of the inversion results to the values of the frequencies. We finally consider physical processes which may influence directly or indirectly the solar core structure.
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- 1997
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37. Performance and Early Results from the Golf Instrument Flown on the Soho Mission
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Gabriel, A., Charra, J., Grec, G., Robillot, J.-M., Roca Cortés, T., Turck-Chièze, S., Ulrich, R., Basu, S., Baudin, F., Bertello, L., Boumier, P., Charra, M., Christensen-Dalsgaard, J., Decaudin, M., Dzitko, H., Foglizzo, T., Fossat, E., García, R., Herreros, J., Lazrek, M., Pallé, P., Pétrou, N., Renaud, C., and Régulo, C.
- Abstract
GOLF in-flight commissioning and calibration was carried out during the first four months, most of which represented the cruise phase of SOHO towards its final L1 orbit. The initial performance of GOLF is shown to be within the design specification, for the entire instrument as well as for the separate sub-systems. Malfunctioning of the polarising mechanisms after 3 to 4 months operation has led to the adoption of an unplanned operating sequence in which these mechanisms are no longer used. This mode, which measures only the blue wing of the solar sodium lines, detracts little from the detection and frequency measurements of global oscillations, but does make more difficult the absolute velocity calibration, which is currently of the order of 20%. Data continuity in the new mode is extremely high and the instrument is producing exceptionally noise-free p-mode spectra. The data set is particularly well suited to the study of effects due to the excitation mechanism of the modes, leading to temporal variations in their amplitudes. The g modes have not yet been detected in this limited data set. In the present mode of operation, there are no indications of any degradation which would limit the use of GOLF for up to 6 years or more.
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- 1997
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38. First Results on it p Modes from GOLF Experiment
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Lazrek, M., Baudin, F., Bertello, L., Boumier, P., Charra, J., Fierry-Fraillon, D., Fossat, E., Gabriel, A., García, R., Gelly, B., Gouiffes, C., Grec, G., Pallé, P., Pérez Hernández, F., Régulo, C., Renaud, C., Robillot, J.-M., Roca Cortés, T., Turck-Chièze, S., and Ulrich, R.
- Abstract
The GOLF experiment on the SOHO mission aims to study the internal structure of the Sun by measuring the spectrum of global oscillations in the frequency range 10-7to 10-2Hz. Here we present the results of the analysis of the first 8 months of data. Special emphasis is put into the frequency determination of the p modes, as well as the splitting in the multiplets due to rotation. For both, we show that the improvement in S/N level with respect to the ground-based networks and other experiments is essential in achieving a very low-degree frequency table with small errors ∼ 2 parts in 10-5). On the other hand, the splitting found seems to favour a solar core which does not rotate slower than its surface. The line widths do agree with theoretical expectations and other observations.
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- 1997
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39. Golf: A resonance spectrometer for the observation of solar oscillations
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Boumier, P., Decaudin, M., Jones, A. R., Grec, G., and Tamiatto, C.
- Abstract
GOLF (Global Oscillations at Low Frequencies) is an instrument to study the line-of-sight velocity of the solar photosphere, to be flown on the SOHO satellite in 1995. It uses a sodium vapour cell in resonance scattering mode, in order to measure the absolute Doppler shift of the solar sodium absorption lines. We detail laboratory tests to determine the performances of the cell built for the experiment. The results are in good agreement with numerical simulations of the resonance processes. As a final result, we can conclude that the level of performances required for the flight instrument will be obtained.
- Published
- 1994
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40. Golf: A resonance spectrometer for the observation of solar oscillations I) Numerical model of the sodium cell response
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Boumier, P. and Dame, L.
- Abstract
GOLF (Global Oscillations at Low Frequencies) is an instrument to study the line-of-sight velocity of the solar photosphere, to be flown on the SOHO satellite in 1995. It uses a sodium vapour cell in resonance scattering mode, in order to measure the absolute Doppler shift of the solar sodium absorption lines. We have developed a model of the resonance cell performance. We describe here the main characteristics of the model, and report the most important results concerning the performance of the cell and its dependance on temperature.
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- 1993
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41. Global Oscillations at Low Frequency from the SOHO mission (GOLF)
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Gabriel, A. H., Grec, G., Charra, J., Robillot, J. -M., Roca Cortés, T., Turck-Chièze, S., Bocchia, R., Boumier, P., Cantin, M., Cespédes, E., Cougrand, B., Crétolle, J., Damé, L., Decaudin, M., Delache, P., Denis, N., Duc, R., Dzitko, H., Fossat, E., Fourmond, J. -J., García, R. A., Gough, D., Grivel, C., Herreros, J. M., Lagardère, H., Moalic, J. -P., Pallé, P. L., Pétrou, N., Sanchez, M., Ulrich, R., and Raay, H. B.
- Abstract
The GOLF experiment on the SOHO mission aims to study the internal structure of the sun by measuring the spectrum of global oscillations in the frequency range 10
-7 to 10-2 Hz. Bothp andg mode oscillations will be investigated, with the emphasis on the low order long period waves which penetrate the solar core. The instrument employs an extension to space of the proven ground-based technique for measuring the mean line-of-sight velocity of the viewed solar surface. By avoiding the atmospheric disturbances experienced from the ground, and choosing a non-eclipsing orbit, GOLF aims to improve the instrumental sensitivity limit by an order of magnitude to 1 mm s-1 over 20 days for frequencies higher than 2.10-4 Hz. A sodium vapour resonance cell is used in a longitudinal magnetic field to sample the two wings of the solar absorption line. The addition of a small modulating field component enables the slope of the wings to be measured. This provides not only an internal calibration of the instrument sensitivity, but also offers a further possibility to recognise, and correct for, the solar background signal produced by the effects of solar magnetically active regions. The use of an additional rotating polariser enables measurement of the mean solar line-of-sight magnetic field, as a secondary objective.- Published
- 1995
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42. MADE IN FRANCE OUVRE LE BAL DE LA RENTREE DES SALONS: En pleine lumière depuis la crise du covid-19, la fabrication française sera au cœur du premier rendez-vous de la filière, qui est organisé début septembre par...
- Author
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DE L'ECLUSE, SOPHIE BOUMIER
- Subjects
TRADE shows ,FASHION exhibitions - Abstract
The article offers information on the tenth edition of Made in France, event to be held from September 1 to 2, 2020 at the Carreau du Temple in Paris, France.
- Published
- 2020
43. Seismic and spectroscopic characterization of the solar-like pulsating CoRoT target HD 49385***
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Deheuvels, S., Bruntt, H., Michel, E., Barban, C., Verner, G., Régulo, C., Mosser, B., Mathur, S., Gaulme, P., Garcia, R. A., Boumier, P., Appourchaux, T., Samadi, R., Catala, C., Baudin, F., Baglin, A., Auvergne, M., Roxburgh, I. W., and Pérez Hernández, F.
- Abstract
Context. The star HD 49385 is the first G-type solar-like pulsator observed in the seismology field of the space telescope CoRoT. The satellite collected 137 days of high-precision photometric data on this star, confirming that it presents solar-like oscillations. HD 49385 was also observed in spectroscopy with the NARVAL spectrograph in January 2009.Aims. Our goal is to characterize HD 49385 using both spectroscopic and seismic data.Methods. The fundamental stellar parameters of HD 49385 are derived with the semi-automatic software VWA, and the projected rotational velocity is estimated by fitting synthetic profiles to isolated lines in the observed spectrum. A maximum likelihood estimation is used to determine the parameters of the observed p modes. We perform a global fit, in which modes are fitted simultaneously over nine radial orders, with degrees ranging from $\ell$= 0 to $\ell$= 3 (36 individual modes).Results. Precise estimates of the atmospheric parameters (Teff, [M/H], log g) and of the νsin iof HD 49385 are obtained. The seismic analysis of the star leads to a clear identification of the modes for degrees $\ell$= 0,1,2. Around the maximum of the signal (ν$\simeq$1013 μHz), some peaks are found significant and compatible with the expected characteristics of $\ell$= 3 modes. Our fit yields robust estimates of the frequencies, linewidths and amplitudes of the modes. We find amplitudes of ~5.6 ±0.8 ppm for radial modes at the maximum of the signal. The lifetimes of the modes range from one day (at high frequency) to a bit more than two days (at low frequency). Significant peaks are found outside the identified ridges and are fitted. They are attributed to mixed modes.
- Published
- 2010
44. Seismic and spectroscopic characterization of the solar-like pulsating CoRoT target HD 49385***
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Deheuvels, S., Bruntt, H., Michel, E., Barban, C., Verner, G., Régulo, C., Mosser, B., Mathur, S., Gaulme, P., Garcia, R. A., Boumier, P., Appourchaux, T., Samadi, R., Catala, C., Baudin, F., Baglin, A., Auvergne, M., Roxburgh, I. W., and Pérez Hernández, F.
- Abstract
Context. The star HD 49385 is the first G-type solar-like pulsator observed in the seismology field of the space telescope CoRoT. The satellite collected 137 days of high-precision photometric data on this star, confirming that it presents solar-like oscillations. HD 49385 was also observed in spectroscopy with the NARVAL spectrograph in January 2009.
- Published
- 2010
- Full Text
- View/download PDF
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