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Measurement of diameter and rotation of seismology primary targets with AMBER

Measurement of diameter and rotation of seismology primary targets with AMBER. LUAN OCA. F.X Schmider, A. Domiciano, R. Petrov, S. Jankov G. Berthomieu, P. Mathias, J. Provost, F. Thevenin C. Catala. What we want to measure through interferometry. Fundamental parameters Diameter

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Measurement of diameter and rotation of seismology primary targets with AMBER

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  1. Measurement of diameter and rotationof seismology primary targetswith AMBER LUAN OCA F.X Schmider, A. Domiciano, R. Petrov, S. Jankov G. Berthomieu, P. Mathias, J. Provost, F. Thevenin C. Catala

  2. What we want to measure through interferometry • Fundamental parameters • Diameter • Oblateness • Differential rotation • Inclination angle • Detection and characterisation of oscillation modes • Single mode identification • Intermediate degree modes • High degree modes

  3. AMBER/VLTI Present Status • AMBER • characteristics • 3 Telescopes instrument • K, H and J bands • Single mode • Dispersed fringes • Spectral resolutions 35, 1000, 10000 • Limiting magnitude with UTs: K>11 • specification: absolute visibility accuracy <1% • goal: visibility accuracy = 0.1% • specification: differential phase accuracy < 10-3 radians • goal: differential phase accuracy < 10-4 radians • Commissioning in H and K medium resolution in April 2004, high resolution in October 2004 • First open period second semester 2005, with the UT • Fully operational (3 AT, BCD) second semester 2006? • Fringe tracking (FINITO) is not working properly. Magnitude limit is 7 with AT • Relative precision are better than 0.5% for individual measurements • Absolute visibilities are biased by calibration uncertainties

  4. Differential visibilities and diameters(using BCD = Beam Commuter Device) • 3 AT, 3 bases • BCD • low resolution (R=35) • JHK band diameter is calculated as a parameter of a model of the ratio of visibilities for the various bases

  5. Visibilities of COROT targets Uniform disk model baseline =180 m, J Limb darkening model smallest largest diameter of main COROT targets • Precision on visibility limited by: • instrumental stability • limb darkening model HD 43587 HD 49933 Precision on diameter: depends on visibility slope

  6. Parallax and angular diameter of primary targets 2R / d typical relative error on  = 0.2-0.3% for  ≥ 0.3 mas error on diameter dominated by error on parallax BUT small error on  : relation between Teff and mV (independent estimate of Teff)

  7. 5 km/s 10 km/s 25 km/s 5 km/s 10 km/s 25 km/s Spectrum Differential phase measurement and photocenter displacement spectroscopic profile photocenter displacement: depends on diameter, vsini

  8. Proposed set-up for rotation measurement • 3 AT • perpendicular baselines • high resolution spectroscopy (R=15000) photocenter displacement: depends on diameter & vsini if vsini is already known from spectroscopy, we can determine diameter very efficient for stars with high vsini, even for small angular diamaters (e.g. HD181555)

  9. Program summary • 80 hours are necessary to complete the program on all accessible COROT primary targets • 16 h have been granted to the program on LUAN and OCA guaranteed time on 2nd semester 2006 (2x4h for differential visibilities / BCD ) and 1st semester 2007 (2x4h for differential phase / HR) • The complement has to be claimed on open time and on CNRS-INSU guaranteed time (same period)

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