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CoRoT, asteroseismology, spectroscopic observations with HARPS

CoRoT, asteroseismology, spectroscopic observations with HARPS. Ennio PORETTI INAF – Osservatorio Astronomico di Brera. Italian community selected part of the asteroseismic targets New targets proposed to the COROT Scientific Committee

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CoRoT, asteroseismology, spectroscopic observations with HARPS

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  1. CoRoT, asteroseismology, spectroscopic observations with HARPS Ennio PORETTI INAF – OsservatorioAstronomico di Brera

  2. Italian community selected part of the asteroseismictargets New targetsproposedto the COROT ScientificCommittee (December 2002, Corot Week 3)

  3. Jean Baptiste Camille COROT (1795-1875) The Bridge at Nantes Louvre

  4. USING HARPS-ESO TO MONITOR THE COROT ASTEROSEISMIC TARGETS PI : INAF-OA Brera, on behalf of the CoRoT Consortium : Meudon Observatory, Leuven University and Bruxelles Observatory, Instituto de Astrofisica Andalucia , IA Canarias, Vienna University, Mid-Pyrenees Observatory, … GOAL: to combine CoRoT photometry from space with high-resolution Spectroscopy from ground (ESO, OHP, Calar Alto, Canary Islands). In particular, three consecutive Large Programmes LP178.D-0256 FEROS 2.2m 60 nights in 4 semesters (2007-08) LP182.D-0365 HARPS 3.6m 45 nights in 3 semesters (2009-10) LP185.D-0056 HARPS 3.6m 90 nights in 6 semesters (2010-13) Two observers each semester, mostly PhD or Post-doc students e.g., Anne-Laure Huat, Thierry Semaan, Markus Hareter, Juan Gutierrez Soto, Monica Rainer, Katrien Uytterhoeven, …

  5. Eachpulsational mode isdefined bythreenumbersn , l , m n : radialnumber l : nodes on the surface m : howmanynodesfrom the poles NON RADIAL MODES

  6. The spectroscopic counterpart of the COROT observations FG Vir (Zima et al. 2006)

  7. Nonradial pulsations in Delta Sct stars

  8. The “check” star The Delta Sct star Amplitudes of peaks at 10 c/d: 100-th: 0.200 mmag 250-th: 0.100 mmag 500-th: 0.060 mmag 900-th: 0.030 mmag Expected WHITE noise : 0.0000075 mag 0.0075 mmag 7.5 micromag Frequency search by means of iterative sine-wave least-squares fitting(Vanicek 1971)

  9. HOW SPECTROSCOPY CAN HELP ? • Line profile variations allow us : • to separate radial modes from • nonradial modes • to break the degeneracy in m • due to the rotational splitting LPV observed in the HARPS spectra of HD 50870. It is a spectroscopic binary (SB2) , having a very long period (> 1y). Component A is the Delta Sct (Vsini=37.5 km/s). Component B is slightly cooler (Vsini i =8.0 km/s) (Mantegazza et al., in prep)

  10. MODE IDENTIFICATION HD 50844 (l,m couples) V sin i = 55 km/s; inclination angle: 82° Porettiet al., 2009

  11. SUMMARY OF THE RESULTS ON THE PHYSICS OF DELTA SCT STARS The light curves usually show hundreds of independent terms. Spectroscopic observations suggest the presence of modes up to l=14. The cancellation effects are not sufficient in removing the flux variations associated to these high degree modes (as Daszynska-Daskiewicz, Dziembowski, Pamyatnykh, 2006, Mem SAIt, 77, 113 correctly predicted). Hundreds of frequencies. There are some implications : - high l degree modes excited; - rotational splitting; - different radial order; - cancellation effects are not effective at the 0.05 mmag level.

  12. CoRoT light curve spanning 1 day Predominant term. One cycle disappears. Short and long term oscillations. Rapid oscillations. They continuous beating Peak-to-peak still 5 mmag. Short term oscillations, very small amplitude, still beating.

  13. (2010)

  14. IF THEY SHOW GRANULATION, THEN THE ONSET OF NON-NEGLIGIBLE CONVECTION SHOULD BE CONSIDERED IN THE STELLAR MODELS OF HOT STARS !

  15. By the way, high-amplitude Delta Sct stars show just few independent modes and a lot of linear combinations (CoRoT 101155810, Poretti et al. 2011)

  16. A cooler “check” star The Delta Sct star The Delta Sct star A hotter “check” star … non pulsating stars do not show granulation ….

  17. HD 171586 No pulsation, but Rotational effects Sp. type A2 Prot = 2.10553 d (Luftinger et al., in prep.) Rms residual 40 micromag Noise level: 2 micromag

  18. THE BETA CEPHEI VARIABLE HD 180642 (Briquetet al. 2009) Identification of modes thanks to line profile variations: ell=0, ell=2 No shock-waves, the stellar atmosphere is a single velocity field. It is not a fast rotator, only Veq=38 km/s. Solar-like oscillations detected, but questioned.

  19. O, B, Be stars BINARITY, MASS LOSS, PULSATIONS HD 51756 : SB2. The star is not pulsating, but it should be. (Papics et al. 2011) HD 46149 : Binary, solar-like oscillations in a massive O-type star. Compatible with predictions (Degroote et al. 2010) AU Mon : eclipsing binary. Emission lines are not of photospheric origin. Circumstellar disk, no pulsation (Desmet et al. 2010) HD 181231: Be. Beating phenomenon. Related to mass ejection ? (Neiner et al. 2009) HD 49430: Be. Spectroscopic monitoring of a pre-outburst phase. Changes in the line-profiles and amplitude of modes (Floquet et al. 2009) HD 50209: Be. Evidences of nonradial pulsations (Diago et al. 2009)

  20. THE HERITAGE OF THE SPECTROSCOPIC OBSERVATIONS … and still more to come ….

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