NOVA/LEIDEN/NEVEC/ESO/ESA
Workshop:
School on Space and Ground Based
Optical/InfraRed Interferometry
Leiden, The Netherlands, September 18-22,
2000
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You can find general information on publications dealing with interferometry
at the OLBIN website
(http://huey.jpl.nasa.gov/olbin/ ). Optical long baseline interferometry news,
edited by P. Lawson (JPL).
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Monday: Introduction to interferometric
techniques
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| Pierre Lena |
Principles of interferometry (I) |
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- General Fourier optics and aperture synthesis
- Atmospheric effects
- Beam combination
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| Pierre Lena |
Principles of interferometry (II) |
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- Fringe detection
- Imaging, deconvolution techniques
- S/N consideration, principle limits
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Both this lecture and the previous lecture will establish the basic
physical principles on which astronomical interferometry is based :
coherence of light, combination of beams, sampling of image spatial
frequency content. The effects of atmospheric perturbations will be
analyzed with the limitations they impose on ground based observations,
including the role of adaptive optics. Signal detection principles and
practical realizations will be presented, with discussion of noise sources,
sensitivity limits for various wavelengths and observing conditions
(ground and space) of interest. Example of current astronomical results
shall be given. |
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Related publications |
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For both parts of the lecture ``Principles of interferometry''.
- ``Diffraction limited imaging with Very Large
Telescopes'', Cargese, NATO ASI 274, Kluwer, 1998
- ``High Angular resolution in Astrophysics?'',
Cargese, NATO ASI 501, 1996
- ``Science with the VLTI'', Springer 1997
- ``Observational astrophysics'', Léna et al.
Springer 1998
- ``Adaptive optics in astronomy'', Cambridge
Univ. Press, 1999
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| Andreas Quirrenbach |
Interferometry and astrometry |
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Astrometric observables (delay, fringe phase, differential delay),
metrology, baseline solutions, wide-angle astrometry, narrow-angle astrometry,
atmospheric limits, astrometry from space. |
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Tuesday: Major current facilities
and scientific expectations
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| Andreas Quirrenbach |
Overview of existing and past instruments
around the world |
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Brief descriptions and major achievements of: Michelson and Pease
20-foot and 50-foot, Hanbury Brown intensity interferometer, I2T, GI2T,
MarkIII, COAST, PTI, NPOI, IRMA, IOTA, CHARA, Mira, SUSI, ISI. |
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| Chris Haniff |
The COAST interferometer |
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| Part I : |
Actual implementation of the COAST interferometer telescopes,
beam pipes, delay lines, beam combination, and detection. |
| Part II : |
Science with the COAST interferometer. |
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| Francesco Paresce |
A science overview of optical interferometry |
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The accurate determination of fundamental stellar parameters ( diameter,
effective temperature, mass, distance) by optical/IR interferometry
and how this will affect our knowledge of stellar astrophysics. |
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Related publications |
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See the publications listed below the next talk. |
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| Rens Waters |
Interferometric studies of circumstellar
matter. |
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Circumstellar matter plays an important role in the formation and
the late phases of evolution of stars. In the star formation process,
observations of the geometry and physical conditions in the proto-stellar
cloud are needed to constrain star and planet formation models. One
of the key issues in this field is the structure of the circumstellar
disk, which forms around young stars as a result of the conservation
of angular momentum. High angular resolution observations are needed
to resolve the inner disk structure. In the final stages of stellar
evolution, both massive stars as well as low mass stars go through a
phase of extensive mass loss, through a dense, dusty, and slowly expanding
wind. The physics of this wind is poorly understood, but is of importance
for stellar evolution: mass loss virtually terminates the evolution
by the removal of the entire hydrogen-rich envelope of the star. The
processes that govern the formation of dust, the interplay of dust formation
with pulsation, and the geometry of the wind, are important points to
be clarified, and require high angular resolution imaging. The lecture
will address the potential of interferometry, particularly at near-IR
and mid-IR wavelengths, to address these issues. |
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Related publications |
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Overviews on the subject of this lecture and the previous lecture
by Francesco Paresce can be found in
- the Proceedings of the ESO Astrophysics Symposium
``Science with the VLTI'' ed. F.Paresce, Springer, 1997 and
- the Proceedings of the conference ``Working
on the fringe'' , eds. S.Unwin and R.Stachnik, ASO COnf.Ser., Vol.194
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Wednesday: An overview of future space
missions
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| Alain Leger |
Scientific Goals of DARWIN |
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- Two goals
- Planets: basic, but remote, driver: search
for exo-live
- General astrophysics: proto-planetary
disks, AGN cores, young galaxies... (not developed in present
lecture)
- Means (for planets): spectroscopy of their
atmosphere
- Mission challenges
- Expected results (for planets)
- Major enlargement of planetary science:
determination of atmospheric composition for many planets (different
ages, size, distance to star, stellar spectral type...)
- Search for life: atmospheric compositions
as ingredients to atmospheric models that will decide how significant
are observations regarding the presence of biological activity.
- Next: similar missions but with higher spectral
resolution and S/N for a major increase of the information potential.
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Related publications |
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- Owen T., 1980: The Search for Early Forms
of Life in Other Planetary Systems - Future Possibilities Afforded
by Spectroscopic Techniques, in ``Strategies for the Search
of Life in the Universe'', Papagiannis ed., pp 177-185, Reidel,
Dordrecht
- Angel R. et al., 1986: Detecting Earth-Like
Planets, Nature 322, 341-343
- Leger A. et al., 1996: Could We Search
for Primitive Life on Extrasolar Planets in the Near Future?
Icarus, 123, 249-255
Click here
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| Glenn Lund |
The infrared space interferometer: DARWIN |
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Description of the talk |
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| Rudolf Le Poole |
Global astrometry with GAIA |
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Description of the talk |
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Thursday: Coherent arrays of large
ground-based telescopes
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| Andreas Glindemann |
A VLTI overview |
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The VLTI with its subsystems (telescopes, delay lines, adaptive optics,
fringe tracker) will be presented as well as the instruments (VINCI,
MIDI, AMBER). Imaging techniques - phase closure and dual feed - will
be explained and the instrumentation (PRIMA) for imaging will be discussed.
The needs for a ground based nulling instrument in the mid infrared
will be outlined. An overview over concepts for the second generation
instrumentation will be given. |
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Related publications |
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The papers presented at the SPIE conference 25-31 March 2000, provide
an excellent overview of the VLTI. Most of them are available as PDF
files at: http://www.eso.org/projects/vlti/publink/ |
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| Christoph Leinert |
The VLTI Mid IR Instrument: MIDI |
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Description of the talk |
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| Bill Cotton |
What the experience of radio-interferometry
tells us |
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- Brief description of heterodyne interferometry
esp. VLBI
- Comparison of heterodyne and direct interferometry
- Phase closure: keeping coherent in an incoherent
world
- Resolution: too much of a good thing?
- Delay - frequency relationship
- Imaging versus modeling
- Demonstration of VLBI data analysis and results
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Related publications: |
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- ``Very Long Baseline Interferometry'', eds.
M. Felli and R. E. Spencer, (1989), (NATO) ASI Series C, no. 283,
Kluwer Academic Publishers.
- ``Synthesis Imaging in Radio Astronomy'',
eds. R. A. Perley, F. R. Schwab, and A. H. Bridle, (1989) ASP Conference
Series, vol. 6, pp. 233-245.
- ``Very Long Baseline Interferometry and the
VLBA'', A.Zensus, P. Napier and P. Diamond eds. (1995) ASP Conference
series ASP, vol. 82, pp. 190 - 207.
- ``Synthesis Imaging in Radio Astronomy II'',
Volume 180 of the ASP Conference Series Proceedings, eds. G.B. Taylor,
C.L. Carilli, and R.A. Perley (NRAO) A Collection of Lectures from
the Sixth NRAO/NMIMT Synthesis Imaging Summer School held at Socorro,
New Mexico, USA June 17-23, 1998 Published July 1999, 688 pgs.,
ISBN 1-58381-005-6
A more technically oriented work is:
- ``Interferometry and Synthesis in Radio Astronomy'',
by A. Richard Thompson, James M. Moran and George W. Swenson, Jr,
(1986), John Wiley & Sons, New York.
The authors of this last book are revising it. The previous edition
is out of print. |
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