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Measurement of diameter and rotation of seismology primary targets with AMBER

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with AMBER. What we want to measure through interferometry. Fundamental ... AMBER. characteristics. 3 Telescopes instrument. K, H and J bands. Single ... AMBER ... – PowerPoint PPT presentation

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Title: Measurement of diameter and rotation of seismology primary targets with AMBER


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 K11
  • specification absolute visibility accuracy
  • goal visibility accuracy 0.1
  • specification differential phase accuracy radians
  • goal differential phase accuracy
  • 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 (R35)
  • 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
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 (R15000)

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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