Publications of the MPIfR
Optical & Infrared
Interferometry Group
Philippe Stee, Denis Mourard, Daniel
Bonneau, Paul Berlioz-Arthaud, Armando Domiciano de Souza, Renaud Foy,
Petr Harmanec, Slobodan Jankov, Pierre Kervella, Pavel Koubsky,
Stéphane Lagarde, Jean-Baptiste Le Bouquin, Philippe Mathias, Antoine
Mérand, Nicolas Nardetto, Romain G. Petrov, Karine Rousselet-Perraut,
Chantal Stehle, and Gerd Weigelt
VEGA: a visible spectrograph and polarimeter
for CHARA - science cases description
Advances in Stellar Interferometry
Proceedings of SPIE: Vol. 6268, p.62683R-(1-22)
Danchi, W., Monnier, J., Schöller, M. (eds.)
Abstract
Interferometry has been intensively done at long wavelengths, starting
with the radio interferometers in the years 50 since it was easier to
guide radio wavelengths in cable while keeping the phase information or
using a local oscillator and a correlator to recombine "a posteriori"
the beams over intercontinental distances. In the optical a lot of work
as been done at IR and near-IR wavelengths since it was technically
easier, or we must say, less difficult to recombine directly the
optical beams since the coherence length is larger and the turbulence
slower than at shorter wavelengths. Therefore, the visible domain of
the electromagnetic spectrum is not covered at the same level than near
or mid infrared. Some very nice and important results have been however
obtained with the GI2T interferometer in south of France, the Mark III
interferometer on the Mount Wilson, USA, the NPOI array in Flagstaff,
USA or the SUSI interferometer in Australia. We will present in this
paper the science cases of a new but already existing and tested
instrument: the REGAIN focal instrument which was designed and built
for the GI2T. This instrument, in his CHARA adaptation, called VEGA
will open new fields in a wide range of Astrophysical topics only
addressable in the visible domain. It will provide a spectral
resolution up to 30000 within the spectral range 0.4-0.9 micron and a
spatial resolution of less than 1mas for up to 4 telescopes in its
X-lambda special configuration. A polarimetric device (SPIN) measuring
simultaneously the polarization in 2 directions either circular or
linear is also implemented in this instrument. Since VEGA was already
tested on the sky on 1.5 m telescopes it is also very well suited for
the 1m CHARA array and will only need minor adaptations for the
injection of the CHARA beams. This paper will focus on some of the most
promising science drivers only possible with this visible instrument.
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