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EI2GYB > ASTRO 10.11.25 14:11l 111 Lines 6352 Bytes #47 (0) @ WW
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Subj: Laser trial at ESO kickstarts new era of interferometry
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Laser trial at ESO kickstarts new era of interferometry
Last week, four lasers were projected into the sky above the European Southern
Observatory (ESO) Paranal site in Chile. The lasers successfully created an
"artificial star" that astronomers can use to measure and then correct the blur
caused by Earth's atmosphere, ESO announced today.
The striking launch of these lasers from each of the eight-meter telescopes at
Paranal is a significant milestone of the GRAVITY+ project-a complex upgrade to
ESO's Very Large Telescope Interferometer (VLTI).
GRAVITY+ unlocks a greater observing power and much wider sky coverage for the
VLTI than previously possible, enabling the study of even fainter and more
distant objects.
The first target for the GRAVITY+ and ESO teams at Paranal performing test
observations using the new lasers was a cluster of massive stars at the center
of the Tarantula Nebula-a star-forming region in our neighboring galaxy, the
Large Magellanic Cloud. These first observations revealed that a bright object
in the nebula, thought to be an extremely massive single star, is actually a
binary of two stars close together, which showcases the capabilities and
scientific potential of the upgraded VLTI.
Dr. Rebeca Garcia Lopez, who is an expert in star and planet formation at UCD
School of Physics, is an associate partner in the GRAVITY+ consortium, in
charge of the instrument spectrograph upgrade. She said, "This opens a new era
in optical interferometry and it will allow us to understand how solar systems
similar to our own form with unprecedented detail."
The VLTI combines light from several individual telescopes using
interferometry. GRAVITY is a very successful VLTI instrument that has been used
to generate images of exoplanets, observe near and far stars and perform
detailed observations of faint objects orbiting the Milky Way's supermassive
black hole.
GRAVITY+ is implementing infrastructural changes to the telescopes and upgrades
to the VLTI underground tunnels, where the light beams are brought together.
The installation of a laser at each of the previously unequipped telescopes is
a key achievement of this long-term project, transforming the VLTI into the
most powerful optical interferometer in the world.
Principal Investigator Professor Frank Einsenhauer, of Max-Planck Institute for
Extraterrestrial Physics (MPE), Germany, which led the consortium, said, "The
VLTI with GRAVITY has already enabled so many unpredicted discoveries. We are
excited to see how GRAVITY+ will push the boundaries even further."
Dr. Taro Shimizu, MPE astronomer and consortium member, said, "This opens up
the instrument to observations of objects in the early distant universe, less
than a few hundred million years after the Big Bang."
The series of upgrades has been ongoing for a few years and includes revised
adaptive-optics technology-a system to correct the blur caused by Earth's
atmosphere-with advanced state-of-the-art sensors and deformable mirrors.
Until now, for the VLTI, adaptive-optics corrections have been done by pointing
to bright reference stars that need to be close to the target, limiting the
number of objects we can observe. With the installation of a laser at each of
the telescopes, a bright artificial star is created 90km above Earth's surface,
enabling the correction of atmospheric blur anywhere in the sky. This unlocks
the whole southern sky to the VLTI and dramatically enhances its observing
power.
With the addition of these lasers, astronomers will be able to study distant
active galaxies and directly measure the mass of the supermassive black holes
that power them, as well as observe young stars and the planet-forming disks
around them.
GRAVITY has made significant breakthroughs in astrophysics in the last decade.
It successfully tested Einstein's Theory of General Relativity (through the
measurement of gravitational redshift), earning Professor Reinhard Genzel, MPE,
and Professor Andrea Ghez, University of California, the Nobel Prize for
Physics in 2020. UCD's Dr. Garcia Lopez is co-author on the 2018 paper
"Detection of the gravitational redshift in the orbit of the star S2 near the
Galactic centre massive black hole," published in Astronomy & Astrophysics.
In addition, astronomers also used GRAVITY to find the first observational
evidence of magnetospheric accretion, the process by which matter is "fed" into
newborn stars. The results were published in 2020 in Nature, titled, "A measure
of the size of the magnetospheric accretion region in TW Hydrae," with Dr.
Garcia Lopez as first author.
Through Dr. Garcia Lopez, UCD is involved in the upgrade of the GRAVITY
spectrograph, in charge of the spectral-resolution upgrade. In collaboration
with Universidad National Autonoma de Mexico (UNAM), they have designed a
holographic grating prism to be installed in the spectrograph and are also
responsible for testing and installation at the VTLI.
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