249 research outputs found
Exoplanet atmospheres with GIANO II. Detection of molecular absorption in the dayside spectrum of HD 102195b
The study of exoplanetary atmospheres is key to understand the differences
between their physical, chemical and dynamical processes. Up to now, the bulk
of atmospheric characterization analysis has been conducted on transiting
planets. On some sufficiently bright targets, high-resolution spectroscopy
(HRS) has also been successfully tested for non-transiting planets. We study
the dayside of the non-transiting planet HD 102195b using the GIANO
spectrograph mounted at TNG, demonstrating the feasibility of atmospheric
characterization measurements and molecular detection for non-transiting
planets with the HRS technique using 4-m class telescopes. The Doppler-shifted
planetary signal changes on the order of many km/s during the observations, in
contrast with the telluric absorption which is stationary in wavelength,
allowing us to remove the contamination from telluric lines while preserving
the features of the planetary spectrum. The emission signal from HD 102195b's
atmosphere is then extracted by cross-correlating the residual spectra with
atmospheric models. We detect molecular absorption from water vapor at
4.4 level. We also find convincing evidence for the presence of
methane, which is detected at the 4.1 level. The two molecules are
detected with a combined significance of 5.3, at a semi-amplitude of
the planet radial velocity km/s. We estimate a planet true mass
of and orbital inclination between 72.5 and
84.79 (1). Our analysis indicates a non-inverted atmosphere
for HD 102195b, as expected given the relatively low temperature of the planet,
inefficient to keep TiO/VO in gas phase. Moreover, a comparison with
theoretical expectations and chemical model predictions corroborates our
methane detection and suggests that the detected and signatures
could be consistent with a low C/O ratio.Comment: 12 pages, 12 figures, accepted for publication in A&
Exoplanet atmospheres with GIANO. I. Water in the transmission spectrum of HD 189733b
High-resolution spectroscopy (R 20,000) at near-infrared wavelengths
can be used to investigate the composition, structure, and circulation patterns
of exoplanet atmospheres. However, up to now it has been the exclusive dominion
of the biggest telescope facilities on the ground, due to the large amount of
photons necessary to measure a signal in high-dispersion spectra. Here we show
that spectrographs with a novel design - in particular a large spectral range -
can open exoplanet characterisation to smaller telescope facilities too. We aim
to demonstrate the concept on a series of spectra of the exoplanet HD 189733 b
taken at the Telescopio Nazionale Galileo with the near-infrared spectrograph
GIANO during two transits of the planet. In contrast to absorption in the
Earth's atmosphere (telluric absorption), the planet transmission spectrum
shifts in radial velocity during transit due to the changing orbital motion of
the planet. This allows us to remove the telluric spectrum while preserving the
signal of the exoplanet. The latter is then extracted by cross-correlating the
residual spectra with template models of the planet atmosphere computed through
line-by-line radiative transfer calculations, and containing molecular
absorption lines from water and methane. By combining the signal of many
thousands of planet molecular lines, we confirm the presence of water vapour in
the atmosphere of HD 189733 b at the 5.5- level. This signal was
measured only in the first of the two observing nights. By injecting and
retrieving artificial signals, we show that the non-detection on the second
night is likely due to an inferior quality of the data. The measured strength
of the planet transmission spectrum is fully consistent with past CRIRES
observations at the VLT, excluding a strong variability in the depth of
molecular absorption lines.Comment: 10 pages, 8 figures. Accepted for publication in Astronomy &
Astrophysics. v2 includes language editin
AMPK alpha 1-induced RhoA phosphorylation mediates vasoprotective effect of estradiol
OBJECTIVE: Estradiol (E2) mediates numerous beneficial effects assigned to estrogens, but whereas mechanisms have been described at the endothelial level, direct effects on vascular smooth muscle cells (VSMC) are poorly documented. As evidence accumulates regarding the role of RhoA in vascular pathophysiology and the benefit of RhoA-Rho associated protein kinase (Rock) pathway inhibition, we analyzed if E2 could inhibit it in VSMC. METHODS AND RESULTS: We show that in VSMC, E2 inhibits the RhoA-Rock pathway in a time- and concentration-dependent manner. The inhibition of RhoA-Rock pathway results from E2-induced phosphorylation of the Ser188 of RhoA. Using pharmacological, transfection, and in vitro phosphorylation experiments, we demonstrate that AMP-activated protein kinase subunit alpha 1 (AMPKalpha1) is activated by estrogen receptor stimulation and catalyzes RhoA phosphorylation induced by E2. Ex vivo, ovariectomy leads to an increase in the amplitude of phenylephrine- or serotonine-induced contractions of aortic rings in wild-type mice but not in AMPKalpha1-knock-out mice or E2-supplemented animals. These functional effects were correlated with a reduced level of RhoA phosphorylation in the aorta of ovariectomized female, male, and AMPKalpha1 knock-out mice. CONCLUSION: Our work thus defines AMPKalpha1 as (1) a new kinase for RhoA and (2) a new mediator of the vasoprotective effects of estrogen
On the origin of the non-detection of metastable HeI in the upper atmosphere of the hot Jupiter WASP-80b
We aim to narrow down the origin of the non-detection of the metastable HeI
triplet at about 10830 A obtained for the hot Jupiter WASP-80b. We measure the
X-ray flux of WASP-80 from archival observations and use it as input to scaling
relations accounting for the coronal [Fe/O] abundance ratio to infer the
extreme-ultraviolet (EUV) flux in the 200-504 A range, which controls the
formation of metastable HeI. We run three dimensional (magneto) hydrodynamic
simulations of the expanding planetary upper atmosphere interacting with the
stellar wind to study the impact on the HeI absorption of the stellar
high-energy emission, the He/H abundance ratio, the stellar wind, and the
possible presence of a planetary magnetic field up to 1 G. For a low stellar
EUV emission, which is favoured by the measured logR'HK value, the HeI
non-detection can be explained by a solar He/H abundance ratio in combination
with a strong stellar wind, or by a sub-solar He/H abundance ratio, or by a
combination of the two. For a high stellar EUV emission, the non-detection
implies a sub-solar He/H abundance ratio. A planetary magnetic field is
unlikely to be the cause of the non-detection. The low EUV stellar flux, driven
by the low [Fe/O] coronal abundance, is the likely primary cause of the HeI
non-detection. High-quality EUV spectra of nearby stars are urgently needed to
improve the accuracy of high-energy emission estimates, which would then enable
one to employ the observations to constrain the planetary He/H abundance ratio
and the stellar wind strength. This would greatly enhance the information that
can be extracted from HeI atmospheric characterisation observations.Comment: Accepted for publication on A&A, 20 page
DREAM: III.A helium survey in exoplanets on the edge of the hot Neptune desert with GIANO-B@TNG
The population of close-in exoplanets features a desert of hot Neptunes whose
origin is uncertain. These planets may have lost their atmosphere, eroding into
mini-Neptunes and super-Earths. Direct observations of evaporating atmospheres
are essential to derive mass-loss estimates and constrain this scenario. The
metastable 1083.3nm HeI triplet represents a powerful diagnostic of atmospheric
evaporation since it traces the hot gas in extended exoplanet atmospheres, is
observable from the ground, and is weakly affected by interstellar medium
absorption. We conducted a uniform HeI transmission spectroscopy survey,
focusing on 9 planets located at the edges of the Neptunian desert, aiming to
gain insights into the role of photo-evaporation in its formation. We observed
one transit per planet using the high-resolution, near-infrared spectrograph
GIANO-B on the Telescopio Nazionale Galileo. We focused our analysis on the HeI
triplet by computing high-resolution transmission spectra. We then employed the
p-winds model to interpret the observed transmission spectra. We found no sign
of planetary absorption in the HeI triplet in any of the investigated targets.
We thus provided 3sigma upper-limit estimations on the thermosphere absorption,
temperature, and mass loss, and combined them with past measurements to search
for correlations with parameters thought to be drivers in the formation of the
HeI triplet. Our results strengthen the importance of performing homogeneous
surveys and analyses to bring clarification in the HeI detection and hence in
the Neptunian desert origin. Our findings corroborate the literature
expectations that the HeI absorption signal correlates with the stellar mass
and the received XUV flux. However, these trends seem to disappear in terms of
mass-loss rates; further studies are essential to shed light on this aspect and
to understand better the photo-evaporation process.Comment: 23 pages, 13 figures, accepted for publication in A&A, after language
editin
The GAPS programme at TNG XXII. The GIARPS view of the extended helium atmosphere of HD189733 b accounting for stellar activity
Exoplanets orbiting very close to their host star are strongly irradiated.
This can lead the upper atmospheric layers to expand and evaporate into space.
The metastable helium (HeI) triplet at 1083.3nm has recently been shown to be a
powerful diagnostic to probe extended and escaping exoplanetary atmosphere. We
perform high-resolution transmission spectroscopy of the transiting hot Jupiter
HD189733b with the GIARPS (GIANO-B + HARPS-N) observing mode of the Telescopio
Nazionale Galileo, taking advantage of the simultaneous optical+near infrared
spectral coverage to detect HeI in the planet's extended atmosphere and to
gauge the impact of stellar magnetic activity on the planetary absorption
signal. Observations were performed during five transit events of HD189733b. By
comparison of the in- and out-of-transit GIANO-B observations we compute
high-resolution transmission spectra, on which we perform equivalent width
measurements and light-curves analyses to gauge the excess in-transit
absorption in the HeI triplet. We detect an absorption signal during all five
transits. The mean in-transit absorption depth amounts to 0.75+/-0.03%. We
detect night-to-night variations in the HeI absorption signal likely due to the
transit events occurring in presence of stellar surface inhomogeneities. We
evaluate the impact of stellar-activity pseudo-signals on the true planetary
absorption using a comparative analysis of the HeI and the H lines. We
interpret the time-series of the HeI absorption lines in the three nights not
affected by stellar contamination -exhibiting a mean in-transit absorption
depth of 0.77+/-0.04%- using a 3-d atmospheric code. Our simulations suggest
that the helium layers only fill part of the Roche lobe. Observations can be
explained with a thermosphere heated to 12000 K, expanding up to
1.2 planetary radii, and losing 1 g/s of metastable helium.Comment: 17 pages, 17 figures, accepted for publication in A&
Contextual effects of immigrant presence on populist radical right support: testing the ‘halo effect’ on Front National voting in France
This paper examines the relationship between immigration and populist radical right (PRR) support, based on an analysis of the contextual effects of immigrant presence on Front National vote in France in 2017. Using a unique set of survey data geolocalising respondents at the subcommunal level, it finds evidence for the existence of a curvilinear “halo effect,” with substantial increases in the probability of PRR vote in areas surrounding communities with significantly higher-than-average immigrant populations, and independent of other socio-economic context, as well as individual socio-demographic characteristics. Most importantly, a path analysis confirms the presence of individual attitudinal mediators of this halo effect on PRR vote, thus testing the foundation of the halo, namely that the contextual effects of immigrant presence act on attitudes which drive PRR support. These findings provide a significant step forward in understanding the mechanisms linking subjective experience of immigration with voting for the populist radical right
The GAPS programme at TNG. XLV. HI Balmer lines transmission spectroscopy and NLTE atmospheric modelling of the ultra-hot Jupiter KELT-20b/MASCARA-2b
We aim at extracting the transmission spectrum of the HI Balmer lines of the
ultra-hot Jupiter (UHJ) KELT-20b/MASCARA-2b from observations and to further
compare the results with what obtained through forward modelling accounting for
non-local thermodynamic equilibrium (NLTE) effects. We extract the line
profiles from six transits obtained with the HARPS-N high-resolution
spectrograph attached to the Telescopio Nazionale Galileo telescope. We compute
the temperature-pressure (TP) profile employing the helios code in the lower
atmosphere and the Cloudy NLTE code in the middle and upper atmosphere. We
further use Cloudy to compute the theoretical planetary transmission spectrum
in LTE and NLTE for comparison with observations. We detected the Halpha
(0.79+/-0.03%; 1.25 Rp), Hbeta (0.52+/-0.03%; 1.17 Rp), and Hgamma
(0.39+/-0.06%; 1.13 Rp) lines, while we detected the Hdelta line at almost 4
sigma (0.27+/-0.07%; 1.09 Rp). The models predict an isothermal temperature of
about2200 K at pressures >10^-2 bar and of about 7700 K at pressures <10^-8
bar, with a roughly linear temperature rise in between. In the middle and upper
atmosphere, the NLTE TP profile is up to about 3000 K hotter than in LTE. The
synthetic transmission spectrum derived from the NLTE TP profile is in good
agreement with the observed HI Balmer line profiles, validating our obtained
atmospheric structure. Instead, the synthetic transmission spectrum derived
from the LTE TP profile leads to significantly weaker absorption compared to
the observations. Metals appear to be the primary agents leading to the
temperature inversion in UHJs and the impact of NLTE effects on them increases
the magnitude of the inversion. We find that the impact of NLTE effects on the
TP profile of KELT-20b/MASCARA-2b is larger than for the hotter UHJ KELT-9b,
and thus NLTE effects might be relevant also for planets cooler than
KELT-20b/MASCARA-2b.Comment: Accepted for publication in Astronomy and Astrophysic
Learning curve and interobserver reproducibility evaluation of liver stiffness measurement by transient elastography:
Background/Aims: Fibroscan allows liver stiffness examination (LSE) that is well correlated with fibrosis stages. Our main objective was to evaluate LSE learning curve.Methods: LSE results of five novice observers with different medical status were compared with those of five expert observers (physicians with >100 examinations) in 250 patients with chronic liver disease. Each novice–expert pair had to blindly examine 50 consecutive patients divided into five consecutive subgroups of 10 patients. Results: In each observer group, novice–expert agreement [intraclass correlation coefficient (Ric)] for LSE results was excellent from the first to the last subgroup. Novice–expert agreement for LSE results varied with liver stiffness level: <9 kPa: Ric=0.49; ≥9 kPa: Ric=0.87. Relative difference (%) between novice and expert LSE results was independently associated with the number of valid LSE measurements, and stabilizes around 20–30% after the fourth valid measurement. In each observer group, novice–expert agreement (Ric) for LSE success rate progressively increased as a function of time. Conclusion: LSE requires no learning curve: a novice is able to obtain a reliable result after a single training session, whatever the professional status. However, success rate will progressively increase. An LSE with less than four valid measurements should not be considered as reliable
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