127 research outputs found
High precision radial velocities with GIANO spectra
Radial velocities (RV) measured from near-infrared (NIR) spectra are a
potentially excellent tool to search for extrasolar planets around cool or
active stars. High resolution infrared (IR) spectrographs now available are
reaching the high precision of visible instruments, with a constant improvement
over time. GIANO is an infrared echelle spectrograph at the Telescopio
Nazionale Galileo (TNG) and it is a powerful tool to provide high resolution
spectra for accurate RV measurements of exoplanets and for chemical and
dynamical studies of stellar or extragalactic objects. No other high spectral
resolution IR instrument has GIANO's capability to cover the entire NIR
wavelength range (0.95-2.45 micron) in a single exposure. In this paper we
describe the ensemble of procedures that we have developed to measure high
precision RVs on GIANO spectra acquired during the Science Verification (SV)
run, using the telluric lines as wavelength reference. We used the Cross
Correlation Function (CCF) method to determine the velocity for both the star
and the telluric lines. For this purpose, we constructed two suitable digital
masks that include about 2000 stellar lines, and a similar number of telluric
lines. The method is applied to various targets with different spectral type,
from K2V to M8 stars. We reached different precisions mainly depending on the H
-magnitudes: for H ~ 5 we obtain an rms scatter of ~ 10 m s-1, while for H ~ 9
the standard deviation increases to ~ 50 - 80 m s-1. The corresponding
theoretical error expectations are ~4 m s-1 and 30 m s-1, respectively. Finally
we provide the RVs measured with our procedure for the targets observed during
GIANO Science Verification.Comment: 26 pages, 15 figures, 6 table
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
Smooth Muscle Cell Phenotypic Switch Induced by Traditional Cigarette Smoke Condensate: A Holistic Overview
Cigarette smoke (CS) is a risk factor for inflammatory diseases, such as atherosclerosis. CS condensate (CSC) contains lipophilic components that may represent a systemic cardiac risk factor. To better understand CSC effects, we incubated mouse and human aortic smooth muscle cells (SMCs) with CSC. We evaluated specific markers for contractile [i.e., actin, aortic smooth muscle (ACTA2), calponin-1 (CNN1), the Kruppel-like factor 4 (KLF4), and myocardin (MYOCD) genes] and inflammatory [i.e., IL-1 beta, and IL-6, IL-8, and galectin-3 (LGALS-3) genes] phenotypes. CSC increased the expression of inflammatory markers and reduced the contractile ones in both cell types, with KLF4 modulating the SMC phenotypic switch. Next, we performed a mass spectrometry-based differential proteomic approach on human SMCs and could show 11 proteins were significantly affected by exposition to CSC (FC >= 2.7, p <= 0.05). These proteins are active in signaling pathways related to expression of pro-inflammatory cytokines and IFN, inflammasome assembly and activation, cy-toskeleton regulation and SMC contraction, mitochondrial integrity and cellular response to oxidative stress, proteostasis control via ubiquitination, and cell proliferation and epithelial-to-mesenchymal transition. Through specific bioinformatics resources, we showed their tight functional correlation in a close interaction niche mainly orchestrated by the interferon-induced double-stranded RNA-activated protein kinase (alternative name: protein kinase RNA-activated; PKR) (EIF2AK2/PKR). Finally, by combining gene expression and protein abundance data we obtained a hybrid network showing reciprocal integration of the CSC-deregulated factors and indicating KLF4 and PKR as the most relevant factors
Atmospheric mass loss and stellar wind effects in young and old systems I: comparative 3D study of TOI-942 and TOI-421 systems
Stars and planetary system
Atmospheric mass loss and stellar wind effects in young and old systems II: is TOI-942 the past of TOI-421 system?
Stars and planetary system
Atmospheric mass loss and stellar wind effects in young and old systems - II.: Is TOI-942 the past of TOI-421 system?
Stars and planetary system
Atmospheric mass-loss and stellar wind effects in young and old systems - I.: Comparative 3D study of TOI-942 and TOI-421 systems
Stars and planetary system
Spectroscopic follow-up of TESS candidates with KESPRINT 1.5 - 3-m telescopes network
We report on the spectroscopic follow-up of TESS planetary candidates with a network of 2-3 meter telescopes located in Ondrejov, CZ, Tautenburg, DE, McDonald observatory, US and SMARTS telescope, CL, which use spectrographs with high resolving power. We coordinate our observing campaigns within the KESPRINT consortium and we significantly contribute to validation and characterization of mostly gas giant planets but not only. We briefly present involved observatories and their current observing campaigns
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&
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