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Surface Brightness Asymmetries of LPV stars probed by NIR-Interferometric measurements

Surface Brightness Asymmetries of LPV stars probed by NIR-Interferometric measurements Prospects for the correction on the GAIA parallax. S. Sacuto, Vienna Institute of Astronomy. Jorissen P. Cruzalèbes, E. Pasquato, A. Chiavassa, A. Spang, O. Chesneau & Y. Rabbia. VLTI-AMBER observations.

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Surface Brightness Asymmetries of LPV stars probed by NIR-Interferometric measurements

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  1. Surface Brightness Asymmetries of LPV stars probed by NIR-Interferometric measurements Prospects for the correction on the GAIA parallax S. Sacuto, Vienna Institute of Astronomy • Jorissen P. Cruzalèbes, E. Pasquato, A. Chiavassa, • A. Spang, O. Chesneau & Y. Rabbia GAIA/VLTI - 25 Janvier 2010

  2. VLTI-AMBER observations (Proposals P83 and P84: Mid-resolution / l0=2.3µm) GAIA/VLTI - 25 Janvier 2010

  3. Observation and calibration process GAIA/VLTI - 25 Janvier 2010

  4. Calibrated Squared Visibility GAIA/VLTI - 25 Janvier 2010

  5. Calibrated Cloture Phases GAIA/VLTI - 25 Janvier 2010

  6. Categories • Clear evidence of SBA (119 Tau / Alp Tra / Tx Psc) • Evidence of SBA (Del Oph / R Scl / W Ori) • Poor evidence of SBA (Alp Car / Zet Ara*) • First lobe* (Omi1 Cma / TW Oph) • Peculiar cases (L2 Pup / T Cet) * : Use of larger baselines GAIA/VLTI - 25 Janvier 2010

  7. 1. Clear evidence of SBA (119 Tau / Alp Tra / Tx Psc) GAIA/VLTI - 25 Janvier 2010

  8. 119 Tau 119 Tau TX Psc TX Psc GAIA/VLTI - 25 Janvier 2010

  9. 2. Evidence of SBA (Del Oph / R Scl / W Ori) GAIA/VLTI - 25 Janvier 2010

  10. Del Oph GAIA/VLTI - 25 Janvier 2010

  11. A0-H0(p)=79m A0-K0=128m 3. Poor evidence of SBA (Alp Car / Zet Ara) GAIA/VLTI - 25 Janvier 2010

  12. Circumstellar environment? D0-K0(p)=81m A0-H0(p)=55m A0-K0=128m A0-K0=128m 4. First lobe (Omi1 Cma / TW Oph) GAIA/VLTI - 25 Janvier 2010

  13. 5. Peculiar cases (L2 Pup / T Cet) GAIA/VLTI - 25 Janvier 2010

  14. ~3 times larger than the 13 mas catalog value ! Uniform disk Binary (Hipparcos) L2 Pup UD=35mas Prim.=40mas Comp.=4mas Sep=27.5mas Fc/Fp=2.8% baseline GAIA/VLTI - 25 Janvier 2010

  15. H0 D0 G1 Summary and conclusion • 12 Objects (5 categories): The P86 proposal (recently submited) uses the triplet D0-G1-H0 and will constraint this result GAIA/VLTI - 25 Janvier 2010

  16. GBOG Nice, 18 Novembre 2009 GAIA/VLTI - 25 Janvier 2010

  17. Deviation from the UD model in the 2nd lobe Presence of asymmetries in the second lobe The example of the M0.5III Giant: d Oph (Teff = 3679 K; log g = 1.4) Visibility: Interferometric measurements of d Oph reveal asymmetric structures on its photosphere. As the signature of these asymmetries appears in the second lobe of visibility, it means that structures of 10 to 30% (1-3 mas) size of the star are detected. Therefore, the size of the spots is about 10 times larger than the one predicted from the simulations of Svensson et al., 2005. This means that SBA could affect the astrometry of LPVs located closer than 300 pc at the level of accuracy of GAIA (~10 µas). We can thus re-evaluate the number of possible threats to the parallax to maybe half of the LPVs observablewith GAIA. 2.3µm 1st lobe Uniform Disk of 10 mas 2nd lobe Measurements Closure phase: 2.3µm

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