4 research outputs found
HARPS3 for a Roboticized Isaac Newton Telescope
We present a description of a new instrument development, HARPS3, planned to
be installed on an upgraded and roboticized Isaac Newton Telescope by end-2018.
HARPS3 will be a high resolution (R = 115,000) echelle spectrograph with a
wavelength range from 380-690 nm. It is being built as part of the Terra
Hunting Experiment - a future 10 year radial velocity measurement programme to
discover Earth-like exoplanets. The instrument design is based on the
successful HARPS spectrograph on the 3.6m ESO telescope and HARPS-N on the TNG
telescope. The main changes to the design in HARPS3 will be: a customised fibre
adapter at the Cassegrain focus providing a stabilised beam feed and on-sky
fibre diameter ~ 1.4 arcsec, the implementation of a new continuous flow
cryostat to keep the CCD temperature very stable, detailed characterisation of
the HARPS3 CCD to map the effective pixel positions and thus provide an
improved accuracy wavelength solution, an optimised integrated polarimeter and
the instrument integrated into a robotic operation. The robotic operation will
optimise our programme which requires our target stars to be measured on a
nightly basis. We present an overview of the entire project, including a
description of our anticipated robotic operation.Comment: 13 pages, 8 figures, SPIE conference proceeding
Nightside condensation of iron in an ultra-hot giant exoplanet
Ultra-hot giant exoplanets receive thousands of times Earth's insolation.
Their high-temperature atmospheres (>2,000 K) are ideal laboratories for
studying extreme planetary climates and chemistry. Daysides are predicted to be
cloud-free, dominated by atomic species and substantially hotter than
nightsides. Atoms are expected to recombine into molecules over the nightside,
resulting in different day-night chemistry. While metallic elements and a large
temperature contrast have been observed, no chemical gradient has been measured
across the surface of such an exoplanet. Different atmospheric chemistry
between the day-to-night ("evening") and night-to-day ("morning") terminators
could, however, be revealed as an asymmetric absorption signature during
transit. Here, we report the detection of an asymmetric atmospheric signature
in the ultra-hot exoplanet WASP-76b. We spectrally and temporally resolve this
signature thanks to the combination of high-dispersion spectroscopy with a
large photon-collecting area. The absorption signal, attributed to neutral
iron, is blueshifted by -11+/-0.7 km s-1 on the trailing limb, which can be
explained by a combination of planetary rotation and wind blowing from the hot
dayside. In contrast, no signal arises from the nightside close to the morning
terminator, showing that atomic iron is not absorbing starlight there. Iron
must thus condense during its journey across the nightside.Comment: Published in Nature (Accepted on 24 January 2020.) 33 pages, 11
figures, 3 table
ESPRESSO: the Echelle spectrograph for rocky exoplanets and stable spectroscopic observations
International audienceESPRESSO, the Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations, will combine the efficiency of modern echelle spectrograph design with extreme radial-velocity precision. It will be installed on ESO's VLT in order to achieve a gain of two magnitudes with respect to its predecessor HARPS, and the instrumental radialvelocity precision will be improved to reach cm/s level. Thanks to its characteristics and the ability of combining incoherently the light of 4 large telescopes, ESPRESSO will offer new possibilities in various fields of astronomy. The main scientific objectives will be the search and characterization of rocky exoplanets in the habitable zone of quiet, nearby G to M-dwarfs, and the analysis of the variability of fundamental physical constants. We will present the ambitious scientific objectives, the capabilities of ESPRESSO, and the technical solutions of this challenging project