Andrew Yee[_1_]
February 22nd 07, 04:12 AM
ESO Education and Public Relations Dept.
----------------------------------------------------------------------------
Text with all links and the photos are available on the ESO Website at URL:
http://www.eso.org/outreach/press-rel/pr-2007/pr-06-07.html
----------------------------------------------------------------------------
Contacts:
Jorge Melnick
ESO
Phone: +49 89 3200 6297
Romain Petrov
LUAN/CNRS/UNSA, Nice, France
Phone: +33 4 92 07 63 47
Fabien Malbet
LAOG/CNRS/UJF, Grenoble, France
Phone: +33 4 76 63 58 33
For Immediate Release: 21 February 2007
ESO Instrument Release 06/07
The Sky Through Three Giant Eyes
AMBER Instrument on VLT Delivers a Wealth of Results
The ESO Very Large Telescope Interferometer, which allows astronomers to
scrutinise objects with a precision equivalent to that of a 130-m telescope,
is proving itself an unequalled success every day. One of the latest
instruments installed, AMBER, has led to a flurry of scientific results, an
anthology of which is being published this week as special features in the
research journal Astronomy & Astrophysics.
"With its unique capabilities, the VLT Interferometer (VLTI) has created
itself a niche in which it provide answers to many astronomical questions,
from the shape of stars, to discs around stars, to the surroundings of the
supermassive black holes in active galaxies," says Jorge Melnick (ESO), the
VLT Project Scientist. The VLTI has led to 55 scientific papers already and
is in fact producing more than half of the interferometric results
worldwide.
"With the capability of AMBER to combine up to three of the 8.2-m VLT Unit
Telescopes, we can really achieve what nobody else can do," added Fabien
Malbet, from the LAOG (France) and the AMBER Project Scientist.
Eleven articles will appear this week in Astronomy & Astrophysics' special
AMBER section. Three of them describe the unique instrument, while the other
eight reveal completely new results about the early and late stages in the
life of stars.
The first results presented in this issue cover various fields of stellar
and circumstellar physics. Two papers deal with very young solar-like stars,
offering new information about the geometry of the surrounding discs and
associated outflowing winds. Other articles are devoted to the study of hot
active stars of particular interest: Alpha Arae, Kappa Canis Majoris, and
CPD:57o2874. They provide new, precise information about their rotating gas
envelopes.
An important new result concerns the enigmatic object Eta Carinae. Using
AMBER with its high spatial and spectral resolution, it was possible to zoom
into the very heart of this very massive star. In this innermost region, the
observations are dominated by the extremely dense stellar wind that totally
obscures the underlying central star. The AMBER observations show that this
dense stellar wind is not spherically symmetric, but exhibits a clearly
elongated structure. Overall, the AMBER observations confirm that the
extremely high mass loss of Eta Carinae's massive central star is
non-spherical and much stronger along the poles than in the equatorial
plane. This is in agreement with theoretical models that predict such an
enhanced polar mass-loss in the case of rapidly rotating stars.
Several papers from this special feature focus on the later stages in a
star's life. One looks at the binary system Gamma 2 Velorum, which contains
the closest example of a star known as a Wolf-Rayet. A single AMBER
observation allowed the astronomers to separate the spectra of the two
components, offering new insights in the modeling of Wolf-Rayet stars, but
made it also possible to measure the separation between the two stars. This
led to a new determination of the distance of the system, showing that
previous estimates were incorrect. The observations also revealed
information on the region where the winds from the two stars collide.
The famous binary system RS Ophiuchi, an example of a recurrent nova, was
observed just 5 days after it was discovered to be in outburst on 12
February 2006, an event that has been expected for 21 years. AMBER was able
to detect the extension of the expanding nova emission. These observations
show a complex geometry and kinematics, far from the simple interpretation
of a spherical fireball in extension. AMBER has detected a high velocity jet
probably perpendicular to the orbital plane of the binary system, and
allowed a precise and careful study of the wind and the shockwave coming
from the nova.
The stream of results from the VLTI and AMBER is no doubt going to increase
in the coming years with the availability of new functionalities.
"In addition to the 8.2-m Unit Telescopes, the VLTI can also combine the
light from up to 4 movable 1.8-m Auxiliary Telescopes. AMBER fed by three of
these AT's will be offered to the user community as of April this year, and
from October we will also make FINITO available," said Melnick. "This
'fringe-tracking' device allows us to stabilise changes in the atmospheric
conditions and thus to substantially improve the efficiency of the
observations. By effectively 'freezing' the interferometric fringes, FINITO
allows astronomers to significantly increase the exposure times."
The Astronomy & Astrophysics special feature (volume 464: March II 2007) on
AMBER first results includes 11 articles. They are freely available on the
A&A web site,
http://www.aanda.org/articles/aa/abs/2007/10/contents/contents.html
More Information
The AMBER consortium, led by Romain Petrov (Nice, France), includes
researchers from the Laboratoire d'Astrophysique de Grenoble (France),
Laboratoire d'Astrophysique Universitaire de Nice (France), Max-Planck
Institut f Radioastronomie (Bonn, Germany), INAF-Osservatorio Astrofisico di
Arcetri (Italy), and the Observatoire de la Ce d'Azur (Nice, France).
In March 2004, the first on-line tests of AMBER (Astronomical Multiple BEam
Recombiner) were completed, when astronomers combined the two beams of light
from the southern star Theta Centauri from two test 40-cm aperture
telescopes (ESO 07/04). It was later used to combine light from two, then
three Unit Telescopes of ESO's VLT and light from the Auxiliary Telescopes.
AMBER is part of the VLT Interferometer (VLTI) and completes the planned set
of first-generation instruments for this facility. It continues the success
story of the interferometric mode of the VLT, following the unique initial
scientific results obtained by the VINCI and MIDI instruments, the
installation of the four MACAO adaptive optics systems and the recent
arrival of the last of the four 1.8-m Auxiliary Telescopes at Paranal.
The principle of the interferometric technique is to combine the light
collected by two or more telescopes. The greater the distance between the
telescopes, the more details one can detect. For the VLTI, this distance can
be up to 200 metres, providing observers with milli-arcsecond spatial
resolution. With such a high spatial resolution, one would be able to
distinguish between the headlights of a car located on the Moon. In
addition, AMBER also provides astronomers with spectroscopic measurements,
allowing the structure and the physics of the source to be constrained by
comparing the measures at different wavelengths.
AMBER combines the light beams from three telescopes: this is a world first
for large telescopes such as the VLT. The ability to combine three beams,
rather than just two as in a conventional interferometer, provides a
substantial increase in the efficiency of observations, permitting
astronomers to obtain three baselines simultaneously instead of one. The
combination of these three baselines also permits the computation of the
so-called closure phase, an important mathematical quantity that can be used
in imaging applications.
The AMBER instrument is mounted on a 4.2 x 1.5-m precision optical table,
placed in the VLT Interferometric Laboratory at the top of the Paranal
mountain. The total shipping weight of the instrument and its extensive
associated electronics was almost 4 tons.
Two of the results discussed here were already presented as ESO press
releases in ESO 29/05 and 35/06.
National contacts for the media:
Belgium: Dr. Rodrigo Alvarez, +32-2-474 70 50
Finland: Ms. Riitta Tirronen, +358 9 7748 8369
Denmark: Dr. Michael Linden-Vnle, +45-33-18 19 97
France: Dr. Daniel Kunth, +33-1-44 32 80 85
Germany: Dr. Jakob Staude, +49-6221-528229
Italy: Dr. Leopoldo Benacchio, +39-357-230 26 51
The Netherlands: Ms. Marieke Baan, +31-20-525 74 80
Portugal: Prof. Teresa Lago, +351-22-089 833
Sweden: Dr. Jesper Sollerman, +46-8-55 37 85 54
Switzerland: Dr. Martin Steinacher, +41-31-324 23 82
United Kingdom: Mr. Peter Barratt, +44-1793-44 20 25
----------------------------------------------------------------------------
ESO Press Information is available on Receive email notification
the WWW at about important news from
http://www.eso.org/outreach/press-rel/ ESO - subscribe to the
ESO-NEWS Mailing List.
----------------------------------------------------------------------------
Copyright ESO Education & Public Relations Department
Karl-Schwarzschild-Strasse 2, D-85748 Garching, Germany
----------------------------------------------------------------------------
----------------------------------------------------------------------------
Text with all links and the photos are available on the ESO Website at URL:
http://www.eso.org/outreach/press-rel/pr-2007/pr-06-07.html
----------------------------------------------------------------------------
Contacts:
Jorge Melnick
ESO
Phone: +49 89 3200 6297
Romain Petrov
LUAN/CNRS/UNSA, Nice, France
Phone: +33 4 92 07 63 47
Fabien Malbet
LAOG/CNRS/UJF, Grenoble, France
Phone: +33 4 76 63 58 33
For Immediate Release: 21 February 2007
ESO Instrument Release 06/07
The Sky Through Three Giant Eyes
AMBER Instrument on VLT Delivers a Wealth of Results
The ESO Very Large Telescope Interferometer, which allows astronomers to
scrutinise objects with a precision equivalent to that of a 130-m telescope,
is proving itself an unequalled success every day. One of the latest
instruments installed, AMBER, has led to a flurry of scientific results, an
anthology of which is being published this week as special features in the
research journal Astronomy & Astrophysics.
"With its unique capabilities, the VLT Interferometer (VLTI) has created
itself a niche in which it provide answers to many astronomical questions,
from the shape of stars, to discs around stars, to the surroundings of the
supermassive black holes in active galaxies," says Jorge Melnick (ESO), the
VLT Project Scientist. The VLTI has led to 55 scientific papers already and
is in fact producing more than half of the interferometric results
worldwide.
"With the capability of AMBER to combine up to three of the 8.2-m VLT Unit
Telescopes, we can really achieve what nobody else can do," added Fabien
Malbet, from the LAOG (France) and the AMBER Project Scientist.
Eleven articles will appear this week in Astronomy & Astrophysics' special
AMBER section. Three of them describe the unique instrument, while the other
eight reveal completely new results about the early and late stages in the
life of stars.
The first results presented in this issue cover various fields of stellar
and circumstellar physics. Two papers deal with very young solar-like stars,
offering new information about the geometry of the surrounding discs and
associated outflowing winds. Other articles are devoted to the study of hot
active stars of particular interest: Alpha Arae, Kappa Canis Majoris, and
CPD:57o2874. They provide new, precise information about their rotating gas
envelopes.
An important new result concerns the enigmatic object Eta Carinae. Using
AMBER with its high spatial and spectral resolution, it was possible to zoom
into the very heart of this very massive star. In this innermost region, the
observations are dominated by the extremely dense stellar wind that totally
obscures the underlying central star. The AMBER observations show that this
dense stellar wind is not spherically symmetric, but exhibits a clearly
elongated structure. Overall, the AMBER observations confirm that the
extremely high mass loss of Eta Carinae's massive central star is
non-spherical and much stronger along the poles than in the equatorial
plane. This is in agreement with theoretical models that predict such an
enhanced polar mass-loss in the case of rapidly rotating stars.
Several papers from this special feature focus on the later stages in a
star's life. One looks at the binary system Gamma 2 Velorum, which contains
the closest example of a star known as a Wolf-Rayet. A single AMBER
observation allowed the astronomers to separate the spectra of the two
components, offering new insights in the modeling of Wolf-Rayet stars, but
made it also possible to measure the separation between the two stars. This
led to a new determination of the distance of the system, showing that
previous estimates were incorrect. The observations also revealed
information on the region where the winds from the two stars collide.
The famous binary system RS Ophiuchi, an example of a recurrent nova, was
observed just 5 days after it was discovered to be in outburst on 12
February 2006, an event that has been expected for 21 years. AMBER was able
to detect the extension of the expanding nova emission. These observations
show a complex geometry and kinematics, far from the simple interpretation
of a spherical fireball in extension. AMBER has detected a high velocity jet
probably perpendicular to the orbital plane of the binary system, and
allowed a precise and careful study of the wind and the shockwave coming
from the nova.
The stream of results from the VLTI and AMBER is no doubt going to increase
in the coming years with the availability of new functionalities.
"In addition to the 8.2-m Unit Telescopes, the VLTI can also combine the
light from up to 4 movable 1.8-m Auxiliary Telescopes. AMBER fed by three of
these AT's will be offered to the user community as of April this year, and
from October we will also make FINITO available," said Melnick. "This
'fringe-tracking' device allows us to stabilise changes in the atmospheric
conditions and thus to substantially improve the efficiency of the
observations. By effectively 'freezing' the interferometric fringes, FINITO
allows astronomers to significantly increase the exposure times."
The Astronomy & Astrophysics special feature (volume 464: March II 2007) on
AMBER first results includes 11 articles. They are freely available on the
A&A web site,
http://www.aanda.org/articles/aa/abs/2007/10/contents/contents.html
More Information
The AMBER consortium, led by Romain Petrov (Nice, France), includes
researchers from the Laboratoire d'Astrophysique de Grenoble (France),
Laboratoire d'Astrophysique Universitaire de Nice (France), Max-Planck
Institut f Radioastronomie (Bonn, Germany), INAF-Osservatorio Astrofisico di
Arcetri (Italy), and the Observatoire de la Ce d'Azur (Nice, France).
In March 2004, the first on-line tests of AMBER (Astronomical Multiple BEam
Recombiner) were completed, when astronomers combined the two beams of light
from the southern star Theta Centauri from two test 40-cm aperture
telescopes (ESO 07/04). It was later used to combine light from two, then
three Unit Telescopes of ESO's VLT and light from the Auxiliary Telescopes.
AMBER is part of the VLT Interferometer (VLTI) and completes the planned set
of first-generation instruments for this facility. It continues the success
story of the interferometric mode of the VLT, following the unique initial
scientific results obtained by the VINCI and MIDI instruments, the
installation of the four MACAO adaptive optics systems and the recent
arrival of the last of the four 1.8-m Auxiliary Telescopes at Paranal.
The principle of the interferometric technique is to combine the light
collected by two or more telescopes. The greater the distance between the
telescopes, the more details one can detect. For the VLTI, this distance can
be up to 200 metres, providing observers with milli-arcsecond spatial
resolution. With such a high spatial resolution, one would be able to
distinguish between the headlights of a car located on the Moon. In
addition, AMBER also provides astronomers with spectroscopic measurements,
allowing the structure and the physics of the source to be constrained by
comparing the measures at different wavelengths.
AMBER combines the light beams from three telescopes: this is a world first
for large telescopes such as the VLT. The ability to combine three beams,
rather than just two as in a conventional interferometer, provides a
substantial increase in the efficiency of observations, permitting
astronomers to obtain three baselines simultaneously instead of one. The
combination of these three baselines also permits the computation of the
so-called closure phase, an important mathematical quantity that can be used
in imaging applications.
The AMBER instrument is mounted on a 4.2 x 1.5-m precision optical table,
placed in the VLT Interferometric Laboratory at the top of the Paranal
mountain. The total shipping weight of the instrument and its extensive
associated electronics was almost 4 tons.
Two of the results discussed here were already presented as ESO press
releases in ESO 29/05 and 35/06.
National contacts for the media:
Belgium: Dr. Rodrigo Alvarez, +32-2-474 70 50
Finland: Ms. Riitta Tirronen, +358 9 7748 8369
Denmark: Dr. Michael Linden-Vnle, +45-33-18 19 97
France: Dr. Daniel Kunth, +33-1-44 32 80 85
Germany: Dr. Jakob Staude, +49-6221-528229
Italy: Dr. Leopoldo Benacchio, +39-357-230 26 51
The Netherlands: Ms. Marieke Baan, +31-20-525 74 80
Portugal: Prof. Teresa Lago, +351-22-089 833
Sweden: Dr. Jesper Sollerman, +46-8-55 37 85 54
Switzerland: Dr. Martin Steinacher, +41-31-324 23 82
United Kingdom: Mr. Peter Barratt, +44-1793-44 20 25
----------------------------------------------------------------------------
ESO Press Information is available on Receive email notification
the WWW at about important news from
http://www.eso.org/outreach/press-rel/ ESO - subscribe to the
ESO-NEWS Mailing List.
----------------------------------------------------------------------------
Copyright ESO Education & Public Relations Department
Karl-Schwarzschild-Strasse 2, D-85748 Garching, Germany
----------------------------------------------------------------------------