Science case for 1 mas spectro-imaging in the near-infrared
Garcia, P.J.V., Berger, J.-P., Marconi, A., Krivov, A., AChiavassa, A., Aringer, B., Nisini, B., Defrére, D., Mawet, D., Schertl, D., Tatuli, E., Thiébaut, E., Baron, F., Malbet, F.,
Duchéne, G., Weigelt, G., Duvert, G., Henri, G., Klahr, H., Surdej, J., Augereau, J-C., Claeskens, J.-F., Young, J., Hron, J., Perraut, K., Hofmann, K.-H., Testi, L., Cunha, M., Filho, M., De Becker, M., Absil, O.,
Chesneau, O., Collette, P., Petrucci, P.-O., Neuhaeuser, R., Corradi, R., Antón, S., Wolf, S., Hoenig, S., Renard, S., Forveille, T., Beckert, T., Lebzelter, T., Harries, T., Borkowski, V., and Bonfils, X.
Proceedings of the SPIE conference "Astronomical Instrumentation"
held in Marseille, France from June 23-28, 2008
SPIE Proceedings, Volume 7013, pg.70134N (1-14)(2008)
Abstract
We present the work developed within the science team of the Very Large Telescope Interferometer Spectro-
Imager (VSI) during the Phase A studies. VSI aims at delivering ~ 1 milliarcsecond resolution data cubes
in the near-infrared, with several spectral resolutions up to 12 000, by combining up to 8 VLTI telescopes. In
the design of an instrument, the science case plays a central role by supporting the instrument construction
decision, defining the top-level requirements and balancing design options. The overall science philosophy of
VSI was that of a general user instrument serving a broad community. The science team addressed themes
which included several areas of astrophysics and illustrated specific modes of operation of the instrument: a)
YSO disks and winds; b) Multiplicity of young stars; c) Exoplanets; d) Debris disks; e) Stellar surface imaging;
f) The environments of evolved stars; g) AGN tori; h) AGN's Broad Line Region; i) Supermassive black-holes;
and j) Microlensing. The main conclusions can be summarized as follows: a) The accessible targets and related
science are extremely sensitive to the instrument limiting magnitude; the instrument should be optimized for
sensitivity and have its own fringe tracker. b) Most of the science cases are readily achievable with on-axis fringe
tracking, off-axis fringe tracking enabling extra science. c) In most targets (YSOs, evolved stars and AGNs), the
interpretation and analysis of circumstellar/nuclear dust morphology requires direct access to the gas via spectral
resolved studies of emission lines, requiring at least a spectral resolution of 2 500. d) To routinely deliver images
at the required sensitivity, the number of telescopes in determinant, with 6 telescopes being favored. e) The
factorial increase in the number of closure phases and visibilities, gained in a single observation, makes massive
surveys of parameters and related science for the first time possible. f) High dynamic range imaging and very
high dynamic range differential closure phase are possible allowing the study of debris disks and characterization
of pegasides. g) Spectro-imaging in the near-infrared is highly complementary to ALMA, adaptive optics and
interferometric imaging in the thermal infrared.
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