92 research outputs found
Interferometry concepts
This paper serves as an introduction to the current book. It provides the
basic notions of long-baseline optical/infrared interferome-try prior to
reading all the subsequent chapters, and is not an extended introduction to the
field.Comment: 35 pages, 13 figure
Circumstellar matter studied by spectrally-resolved interferometry
This paper describes some generalities about spectro-interferometry and the
role it has played in the last decade for the better understanding of
circumstellar matter. I provide a small history of the technique and its
origins, and recall the basics of differential phase and its central role for
the recent discoveries. I finally provide a small set of simple interpretations
of differential phases for specific astrophysical cases, and intend to provide
a "cookbook" for the other cases.Comment: 12 pages; Circumstellar dynamics at high resolution, Foz do
Igua\c{c}u : Brazil (2012
Olivier Chesneau's work on massive stars
Olivier Chesneau challenged several fields of observational stellar
astrophysics with bright ideas and an impressive amount of work to make them
real in the span of his career, from his first paper on P Cygni in 2000, up to
his last one on V838 Mon in 2014. He was using all the so-called high-angular
resolution techniques since it helped his science to be made, namely study in
details the inner structure of the environments around stars, be it small mass
(AGBs), more massive (supergiant stars), or explosives (Novae). I will focus
here on his work on massive stars.Comment: The Physics of Evolved Stars, Jun 2015, Nice, Franc
Observation of double star by long-baseline interferometry
This paper serves as a reference on how to estimate the parameters of binary
stars and how to combine multiple techniques, namely astrometry, interferometry
and radial velocities.Comment: F. Millour, A. Chiavassa, L. Bigot, O. Chesneau, A. Meilland \& P.
Stee. What can the highest angular resolution bring to stellar astrophysics?,
69-70, EDP sciences, 2015, EAS publication series, 978-2-7598-1833-4.
\<10.1051/eas/1569020\>.
\<http://www.eas-journal.org/articles/eas/abs/2014/04/contents/contents.html\&g
"Advanced" data reduction for the AMBER instrument
The amdlib AMBER data reduction software is meant to produce AMBER data
products from the raw data files that are sent to the PIs of different
proposals or that can be found in the ESO data archive. The way defined by ESO
to calibrate the data is to calibrate one science data file with a calibration
one, observed as close in time as possible. Therefore, this scheme does not
take into account instrumental drifts, atmospheric variations or
visibility-loss corrections, in the current AMBER data processing software,
amdlib. In this article, we present our approach to complement this default
calibration scheme, to perform the final steps of data reduction, and to
produce fully calibrated AMBER data products. These additional steps include:
an overnight view of the data structure and data quality, the production of
night transfer functions from the calibration stars observed during the night,
the correction of additional effects not taken into account in the standard
AMBER data reduction software such as the so-called "jitter" effect and the
visibility spectral coherence loss, and finally, the production of fully
calibrated data products. All these new features are beeing implemented in the
modular pipeline script amdlibPipeline, written to complement the amdlib
software.Comment: 10 pages, will be published in the proceeding of the SPIE conference
"astronomical Telescopes and Instrumentation: Optical and Infrared
Interferometry", held in Marseille from 23 to 27 june 200
AMBER closure and differential phases: accuracy and calibration with a Beam Commutation
The first astrophysical results of the VLTI focal instrument AMBER have shown
the importance of the differential and closure phase measures, which are
supposed to be much less sensitive to atmospheric and instrumental biases than
the absolute visibility. However there are artifacts limiting the accuracy of
these measures which can be substantially overcome by a specific calibration
technique called Beam Commutation. This paper reports the observed accuracies
on AMBER/VLTI phases in different modes, discusses some of the instrumental
biases and shows the accuracy gain provided by Beam Commutation on the
Differential Phase as well as on the Closure Phase.Comment: This paper will be published in the proceeding of SPIE ``astronomical
Telescopes and Instrumentation: Optical and Infrared Interferometry'
Optical interferometry and adaptive optics of bright transients
Bright optical transients (i.e. transients typically visible with the naked
eye) are populated mainly by novae eruptions plus a few supernovae (among which
the SN1987a event). One bright nova happen every two years, either in the North
ot in the South hemisphere. It occurs that current interferometers have
matching sensitivities, with typically visible or infrared limiting magnitude
in the range 5--7. The temporal development of the fireball, followed by a dust
formation phase or the appearance of many coronal lines can be sudied with the
Very Large Telescope Interferometer. The detailed geometry of the first phases
of novae in outburst remains virtually unexplored. This paper summarizes the
work which has been done to date using the VLTI.Comment: Hot-wiring the transien Universe 3, Santa Fe : United States (2013
Imaging "Pinwheel"nebulae with optical long-baseline interferometry
Dusty Wolf-Rayet stars are few but remarkable in terms of dust production
rates (up to one millionth of solar mass per year). Infrared excesses
associated to mass-loss are found in the sub-types WC8 and WC9. Few WC9d stars
are hosting a "pinwheel" nebula, indirect evidence of a companion star around
the primary. While few other WC9d stars have a dust shell which has been barely
resolved so far, the available angular resolution offered by single telescopes
is insufficient to confirm if they also host "pinwheel" nebulae or not. In this
article, we present the possible detection of such nebula around the star
WR118. We discuss about the potential of interferometry to image more
"pinwheel" nebulae around other WC9d stars.Comment: To be published soon in the conference proceedin
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