714 research outputs found
Impact of micro-telluric lines on precise radial velocities and its correction
Context: In the near future, new instruments such as ESPRESSO will arrive,
allowing us to reach a precision in radial-velocity measurements on the order
of 10 cm/s. At this level of precision, several noise sources that until now
have been outweighed by photon noise will start to contribute significantly to
the error budget. The telluric lines that are not neglected by the masks for
the radial velocity computation, here called micro-telluric lines, are one such
noise source. Aims: In this work we investigate the impact of micro-telluric
lines in the radial velocities calculations. We also investigate how to correct
the effect of these atmospheric lines on radial velocities. Methods: The work
presented here follows two parallel lines. First, we calculated the impact of
the micro-telluric lines by multiplying a synthetic solar-like stellar spectrum
by synthetic atmospheric spectra and evaluated the effect created by the
presence of the telluric lines. Then, we divided HARPS spectra by synthetic
atmospheric spectra to correct for its presence on real data and calculated the
radial velocity on the corrected spectra. When doing so, one considers two
atmospheric models for the synthetic atmospheric spectra: the LBLRTM and TAPAS.
Results: We find that the micro-telluric lines can induce an impact on the
radial velocities calculation that can already be close to the current
precision achieved with HARPS, and so its effect should not be neglected,
especially for future instruments such as ESPRESSO. Moreover, we find that the
micro-telluric lines' impact depends on factors, such as the radial velocity of
the star, airmass, relative humidity, and the barycentric Earth radial velocity
projected along the line of sight at the time of the observation.Comment: Accepted in A&
Determination of Acaricide Resistance in Rhipicephalus (Boophilus) microplus (Acari: Ixodidae) Field Populations of Argentina, South Africa, and Australia With the Larval Tarsal Test
Infestations with ticks have an important economic impact on the cattle industry worldwide and resistance to acaricides has become a widespread phenomenon. To optimize their treatment strategy, farmers need to know if and against which classes potential acaricide-resistance does occur. Bioassays are used to assess the resistance level and pattern of Rhipicephalus (Boophilus) microplus populations. The objective of the current study was to assess the susceptibility of field populations originating from Argentina (8), South Africa (3), and Australia (2) using the Larval Tarsal Test. Nine acaricidal compounds from five major classes were tested: organosphosphates, synthetic pyrethroids (SP), macrocyclic lactones, phenylpyrazols, and amidines. The resistance ratios at concentrations inducing 50 and 90% mortality were used to detect established and emerging resistance. This study confirmed the newly reported presence of amitraz resistance in populations from Argentina. In addition, resistance to SP appeared to be widespread (88%) in the Argentinean farms, which had been selected based on the observation of lack of treatment efficacy by farmers. In South Africa one of the three populations was found to be resistant to SP and to a phenylpyrazol compound (pyriprol). Furthermore, resistance to organosphosphates and SP was observed in Australia. Finally, the Larval Tarsal Test proved to be a suitable test to evaluate the susceptibility of R. microplus field populations to the most relevant acaricidal classe
The Earth transiting the Sun as seen from Jupiter's moons: detection of an inverse Rossiter-McLaughlin effect produced by the opposition surge of the icy Europa
We report on a multiwavelength observational campaign which followed the Earth's transit on the Sun as seen from Jupiter on 2014 January 2014. Simultaneous observations of Jupiter's moons Europa and Ganymede obtained with high accuracy radial velocity planetary searcher (HARPS) from La Silla, Chile and HARPS-N from La Palma, Canary Islands were performed to measure the Rossiter-McLaughlin effect due to the Earth's passage using the same technique successfully adopted for the 2012 Venus Transit. The expected modulation in radial velocities was of ≈20cm s−1 but an anomalous drift as large as ≈38m s−1, i.e. more than two orders of magnitude higher and opposite in sign, was detected instead. The consistent behaviour of the two spectrographs rules out instrumental origin of the radial velocity drift and Birmingham Solar Oscillations Network observations rule out the possible dependence on the Sun's magnetic activity. We suggest that this anomaly is produced by the opposition surge on Europa's icy surface, which amplifies the intensity of the solar radiation from a portion of the solar surface centred around the crossing Earth which can then be observed as a sort of inverse Rossiter-McLaughlin effect. in fact, a simplified model of this effect can explain in detail most features of the observed radial velocity anomalies, namely the extensions before and after the transit, the small differences between the two observatories and the presence of a secondary peak closer to Earth passage. This phenomenon, observed here for the first time, should be observed every time similar Earth alignments occur with rocky bodies without atmospheres. We predict that it should be observed again during the next conjunction of Earth and Jupiter in 202
Search for giant planets in M67 IV: survey results
We present the results of a seven-year-long radial velocity survey of a
sample of 88 main-sequence and evolved stars to reveal signatures of
Jupiter-mass planets in the solar-age and solar-metallicity open cluster M67.
We aim at studying the frequency of giant planets in this cluster with respect
to the field stars. In addition, our sample is also ideal to perform a
long-term study to compare the chemical composition of stars with and without
giant planets in detail. We analyzed precise radial velocity (RV) measurements
obtained with five different instruments. We conducted Monte Carlo simulations
to estimate the occurrence rate of giant planets in our radial velocity survey.
All the planets previously announced in this RV campaign with their properties
are summarized here: 3 hot Jupiters around the main-sequence stars YBP1194,
YBP1514, and YBP401, and 1 giant planet around the evolved star S364. Two
additional planet candidates around the stars YBP778 and S978 are also analyzed
in the present work. We discuss stars that exhibit large RV variability or
trends individually. For 2 additional stars, long-term trends are compatible
with new binary candidates or substellar objects, which increases the total
number of binary candidates detected in our campaign to 14. Based on the
Doppler-detected planets discovered in this survey, we find an occurrence of
giant planets of ~18.0%(+12.0/-8.0%) in the selected period-mass range. This
frequency is slightly higher but consistent within the errors with the estimate
for the field stars, which leads to the general conclusion that open cluster
and field statistics agree. However, we find that the rate of hot Jupiters in
the cluster (~5.7%(+5.5/-3.0%)) is substantially higher than in the field.Comment: Accepted by A&
A possibly inflated planet around the bright, young star DS Tuc A
The origin of the observed diversity of planetary system architectures is one
of the main topic of the exoplanetary research. The detection of a
statistically significant sample of planets around young stars allows us to
study the early stages of planet formation and evolution, but only a handful of
them is known so far. In this regard, a considerable contribution is expected
from the NASA TESS satellite, which is now performing a survey of
of the sky to search for short-period transiting planets In its first month of
operations, TESS found a planet candidate with an orbital period of 8.14 days
around a member of the Tuc-Hor young association ( 40 Myr), the G6V main
component of the binary system DS\,Tuc. If confirmed, it would be the first
transiting planet around a young star suitable for radial velocity and/or
atmospheric characterization. We aim to validate the planetary nature of this
companion and to measure its orbital and physical parameters. We obtain
accurate planet parameters by coupling an independent reprocessing of the TESS
light curve with improved stellar parameters and the dilution caused by the
binary companion; we analyse high precision archival radial velocities to
impose an upper limit of about 0.1 M on the planet mass; we finally
rule out the presence of external companions beyond 40 au with adaptive optics
images. We confirm the presence of a young, giant ( R) planet having a not negligible possibility to be inflated (theoretical
mass M) around DS\,Tuc~A. We discuss the feasibility
of mass determination, Rossiter-McLaughlin analysis and atmosphere
characterization, allowed by the brightness of the star.Comment: 12 pages, 11 figures. Accepted for publication in A&
The HARPS search for southern extra-solar planets. XVII. Super-Earth and Neptune-mass planets in multiple planet systems HD47186 and HD181433
This paper reports on the detection of two new multiple planet systems around
solar-like stars HD47186 and HD181433. The first system includes a hot Neptune
of 22.78 M_Earth at 4.08-days period and a Saturn of 0.35 M_Jup at 3.7-years
period. The second system includes a Super-Earth of 7.5 M_Earth at 9.4-days
period, a 0.64 M$_Jup at 2.6-years period as well as a third companion of 0.54
M_Jup with a period of about 6 years. These detections increase to 20 the
number of close-in low-mass exoplanets (below 0.1 M_Jup) and strengthen the
fact that 80% of these planets are in a multiple planetary systems.Comment: 5 pages, 5 figures, accepted in A&
Identification and weighting of the most critical "real-life” drug-drug interactions with acenocoumarol in a tertiary care hospital
Purpose: The objective of this study was to identify the most clinically relevant drug-drug interactions (DDIs) at risk of affecting acenocoumarol safety in our tertiary care university hospital, a 2,000 bed institution. Methods: We identified DDIs occurring with acenocoumarol by combining two different sources of information: a 1-year retrospective analysis of acenocoumarol prescriptions and comedications from our Computerized Physician Order Entry (CPOE) system (n = 2,439 hospitalizations) and a retrospective study of clinical pharmacology consultations involving acenocoumarol over the past 14 years (1994-2007) (n = 407). We classified these DDIs using an original risk-analysis method. A criticality index was calculated for each associated drug by multiplying three scores based on mechanism of interaction, involvement in a supratherapeutic international normalized ratio (INR) (≥ 6) and involvement in a severe bleeding. Results: One hundred and twenty-six DDIs were identified and weighted. Twenty-eight drugs had a criticality index ≥ 20 and were therefore considered at high risk for interacting with acenocoumarol by increasing its effect: 75% of these drugs involved a pharmacokinetic mechanism and 14 % a pharmacodynamic mechanism. An unknown mechanism of interaction was involved in 11 % of drugs. Conclusion: Twenty-eight specific drugs were identified as being at high risk for interacting with acenocoumarol in our hospital using an original risk-analysis method. Most analyzed drugs interact with acenocoumarol via a pharmacokinetic mechanism. Actions such as the implementation of alerts in our CPOE system should be specifically developed for these drug
Identification and weighting of the most critical "real-life” drug-drug interactions with acenocoumarol in a tertiary care hospital
Purpose: The objective of this study was to identify the most clinically relevant drug-drug interactions (DDIs) at risk of affecting acenocoumarol safety in our tertiary care university hospital, a 2,000 bed institution. Methods: We identified DDIs occurring with acenocoumarol by combining two different sources of information: a 1-year retrospective analysis of acenocoumarol prescriptions and comedications from our Computerized Physician Order Entry (CPOE) system (n = 2,439 hospitalizations) and a retrospective study of clinical pharmacology consultations involving acenocoumarol over the past 14 years (1994-2007) (n = 407). We classified these DDIs using an original risk-analysis method. A criticality index was calculated for each associated drug by multiplying three scores based on mechanism of interaction, involvement in a supratherapeutic international normalized ratio (INR) (≥ 6) and involvement in a severe bleeding. Results: One hundred and twenty-six DDIs were identified and weighted. Twenty-eight drugs had a criticality index ≥ 20 and were therefore considered at high risk for interacting with acenocoumarol by increasing its effect: 75% of these drugs involved a pharmacokinetic mechanism and 14 % a pharmacodynamic mechanism. An unknown mechanism of interaction was involved in 11 % of drugs. Conclusion: Twenty-eight specific drugs were identified as being at high risk for interacting with acenocoumarol in our hospital using an original risk-analysis method. Most analyzed drugs interact with acenocoumarol via a pharmacokinetic mechanism. Actions such as the implementation of alerts in our CPOE system should be specifically developed for these drug
The HARPS search for southern extra-solar planets. XXIV. Companions to HD 85390, HD 90156 and HD 103197: A Neptune analogue and two intermediate mass planets
We report the detection of three new extrasolar planets orbiting the solar
type stars HD 85390, HD 90156 and HD 103197 with the HARPS spectrograph mounted
on the ESO 3.6-m telescope at La Silla observatory. HD 85390 has a planetary
companion with a projected intermediate mass (42.0 Earth masses) on a 788-day
orbit (a=1.52 AU) with an eccentricity of 0.41, for which there is no analogue
in the solar system. A drift in the data indicates the presence of another
companion on a long period orbit, which is however not covered by our
measurements. HD 90156 is orbited by a warm Neptune analogue with a minimum
mass of 17.98 Earth masses (1.05 Neptune masses), a period of 49.8 days (a=0.25
AU) and an eccentricity of 0.31. HD 103197 has an intermediate mass planet on a
circular orbit (P=47.8 d, Msini=31.2 Earth masses). We discuss the formation of
planets of intermediate mass (about 30-100 Earth masses) which should be rare
inside a few AU according to core accretion formation models.Comment: 9 pages, 5 figures. Accepted to A&
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