89 research outputs found
The COVID-19 Student Stress Questionnaire: Validation in Spanish university students from health sciences
This study aimed to validate the Spanish version of the COVID-19 Student Stress Questionnaire (CSSQ), a 7-item tool assessing COVID-19-related stressors among university students, namely, Relationships and Academic Life, Isolation, and Fear of Contagion. Participants were 331 Spanish university students. Factor analyses sustained the three factor solution of the original tool. Data also revealed satisfactory convergent and discriminant validity, suitable internal consistency, and significant associations with psychological symptoms, as measured by the Symptom Checklist-90-Revised. The Spanish version of the CSSQ represents a valid tool to be used in clinical settings to timely identify students at high psychological risk and to develop evidence-based interventions during/after the pandemic
The HARPS search for southern extra-solar planets XXXV. The interesting case of HD41248: stellar activity, no planets?
The search for planets orbiting metal-poor stars is of uttermost importance
for our understanding of the planet formation models. However, no dedicated
searches have been conducted so far for very low mass planets orbiting such
objects. Only a few cases of low mass planets orbiting metal-poor stars are
thus known. Amongst these, HD41248 is a metal-poor, solar-type star on which a
resonant pair of super-Earth like planets has In the present paper we present a
new planet search program that is using the HARPS spectrograph to search for
Neptunes and Super-Earths orbiting a sample of metal-poor FGK dwarfs. We then
present a detailed analysis of an additional 162 radial velocity measurements
of HD41248, obtained within this program, with the goal of confirming the
existence of the proposed planetary system. We analyzed the precise radial
velocities, obtained with the HARPS spectrograph, together with several stellar
activity diagnostics and line profile indicators. A careful analysis shows no
evidence for the planetary system previously announced. One of the signals,
with a period of about 25 days, is shown to be related to the rotational period
of the star, and is clearly seen in some of the activity proxies. The remaining
signal (P~18 days) could not be convincingly retrieved in the new data set. We
discuss possible causes for the complex (evolving) signals observed in the data
of HD41248, proposing that they may be explained by the appearance and
disappearance of active regions on the surface of a star with strong
differential rotation, or by a combination of the sparse data sampling and
active region evolution.Comment: Accepted for publication in A&
The SOPHIE search for northern extrasolar planets. V. Follow-up of ELODIE candidates: Jupiter-analogs around Sun-like stars
We present radial-velocity measurements obtained in a programs underway to
search for extrasolar planets with the spectrograph SOPHIE at the 1.93-m
telescope of the Haute-Provence Observatory. Targets were selected from
catalogs observed with ELODIE, mounted previously at the telescope, in order to
detect long-period planets with an extended database close to 15 years. Two new
Jupiter-analog candidates are reported to orbit the bright stars HD150706 and
HD222155 in 16.1 and 10.9 yr at 6.7 (+4.0,-1.4) and 5.1(+0.6,-0.7) AU and to
have minimum masses of 2.71 (+1.44,-0.66) and 1.90 (+0.67,-0.53) M_Jup,
respectively. Using the measurements from ELODIE and SOPHIE, we refine the
parameters of the long-period planets HD154345b and HD89307b, and publish the
first reliable orbit for HD24040b. This last companion has a minimum mass of
4.01 +/- 0.49 M_Jup orbiting its star in 10.0 yr at 4.92 +/- 0.38 AU. Moreover,
the data provide evidence of a third bound object in the HD24040 system. With a
surrounding dust debris disk, HD150706 is an active G0 dwarf for which we
partially corrected the effect of the stellar spot on the SOPHIE
radial-velocities. HD222155 is an inactive G2V star. On the basis of the
previous findings of Lovis and collaborators and since no significant
correlation between the radial-velocity variations and the activity index are
found in the SOPHIE data, these variations are not expected to be only due to
stellar magnetic cycles. Finally, we discuss the main properties of this new
population of long-period Jupiter-mass planets, which for the moment, consists
of fewer than 20 candidates. These stars are preferential targets either for
direct-imaging or astrometry follow-up to constrain the system parameters and
for higher precision radial-velocity to search for lower mass planets, aiming
to find a Solar System twin.Comment: accepted for publication in Astronomy & Astrophysic
The SOPHIE search for northern extrasolar planets. II. A multi-planet system around HD9446
We report the discovery of a planetary system around HD9446, performed from
radial velocity measurements secured with the spectrograph SOPHIE at the 193-cm
telescope of the Haute-Provence Observatory during more than two years. At
least two planets orbit this G5V, active star: HD9446b has a minimum mass of
0.7 M_Jup and a slightly eccentric orbit with a period of 30 days, whereas
HD9446c has a minimum mass of 1.8 M_Jup and a circular orbit with a period of
193 days. As for most of the known multi-planet systems, the HD9446-system
presents a hierarchical disposition, with a massive outer planet and a lighter
inner planet.Comment: 7 pages, 6 figures, 3 tables, accepted for publication in A&
Refined parameters and spectroscopic transit of the super-massive planet HD147506b
In this paper, we report a refined determination of the orbital parameters
and the detection of the Rossiter-McLaughlin effect of the recently discovered
transiting exoplanet HD147506b (HAT-P-2b). The large orbital eccentricity at
the short orbital period of this exoplanet is unexpected and is distinguishing
from other known transiting exoplanets. We performed high-precision radial
velocity spectroscopic observations of HD147506 (HAT-P-2) with the new
spectrograph SOPHIE, mounted on the 1.93 m telescope at the Haute-Provence
observatory (OHP). We obtained 63 new measurements, including 35 on May 14 and
20 on June 11, when the planet was transiting its parent star. The radial
velocity (RV) anomaly observed illustrates that HAT-P-2b orbital motion is set
in the same direction as its parent star spin. The sky-projected angle between
the normal of the orbital plane and the stellar spin axis, \lambda = 0.2 +12.2
-12.5 deg, is consistent with zero. The planetary and stellar radii were
re-determined, yielding R_p = 0.951 +0.039 -0.053 R_Jup, R_s = 1.416 +0.040
-0.062 R_Sun. The mass M_p = 8.62 +0.39 -0.55 M_Jup and radius of HAT-P-2b
indicate a density of 12.5 +2.6 -3.6 g cm^{-3}, suggesting an object in between
the known close-in planets with typical density of the order of 1 g cm^{-3},
and the very low-mass stars, with density greater than 50 g cm^{-3}.Comment: Submitted to A&A; V2: Replaced by accepted versio
Two planets around Kapteyn's star: a cold and a temperate super-Earth orbiting the nearest halo red dwarf
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society - Letters. ©: 2014 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.Exoplanets of a few Earth masses can be now detected around nearby low-mass stars using Doppler spectroscopy. In this Letter, we investigate the radial velocity variations of Kapteyn's star, which is both a sub-dwarf M-star and the nearest halo object to the Sun. The observations comprise archival and new HARPS (High Accuracy Radial velocity Planet Searcher), High Resolution Echelle Spectrometer (HIRES) and Planet Finder Spectrograph (PFS) Doppler measurements. Two Doppler signals are detected at periods of 48 and 120 d using likelihood periodograms and a Bayesian analysis of the data. Using the same techniques, the activity indices and archival All Sky Automated Survey (ASAS-3) photometry show evidence for low-level activity periodicities of the order of several hundred days. However, there are no significant correlations with the radial velocity variations on the same time-scales. The inclusion of planetary Keplerian signals in the model results in levels of correlated and excess white noise that are remarkably low compared to younger G, K and M dwarfs. We conclude that Kapteyn's star is most probably orbited by two super-Earth mass planets, one of which is orbiting in its circumstellar habitable zone, becoming the oldest potentially habitable planet known to date. The presence and long-term survival of a planetary system seem a remarkable feat given the peculiar origin and kinematic history of Kapteyn's star. The detection of super-Earth mass planets around halo stars provides important insights into planet-formation processes in the early days of the Milky Way.Peer reviewe
The SOPHIE search for northern extrasolar planets. IV. Massive companions in the planet-brown dwarf boundary
The mass domain where massive extrasolar planets and brown dwarfs lay is
still poorly understood. Indeed, not even a clear dividing line between massive
planets and brown dwarfs has been established yet. This is partly due to the
paucity of this kind of objects orbiting close to solar-type stars, the
so-called brown dwarf desert, that hinders setting up a strong observational
base to compare to models and theories of formation and evolution.
We search to increase the current sample of massive sub-stellar objects with
precise orbital parameters, and to constrain the true mass of detected
sub-stellar candidates.
The initial identification of sub-stellar candidates is done using precise
radial velocity measurements obtained with the SOPHIE spectrograph at the
1.93-m telescope of the Haute-Provence Observatory. Subsequent characterisation
of these candidates, with the principal aim of identifying stellar companions
in low-inclination orbits, is done by means of different spectroscopic
diagnostics, as the measurement of the bisector velocity span and the study of
the correlation mask effect. With this objective, we also employed astrometric
data from the Hipparcos mission and a novel method of simulating stellar
cross-correlation functions.
Seven new objects with minimum masses between ~ 10 Mjup and ~90 Mjup are
detected. Out of these, two are identified as low-mass stars in low-inclination
orbits, and two others have masses below the theoretical deuterium-burning
limit, and are therefore planetary candidates. The remaining three are brown
dwarf candidates; the current upper limits for their the masses do not allow us
to conclude on their nature. Additionally, we have improved on the parameters
of an already-known brown dwarf (HD137510b), confirmed by astrometry.Comment: 18 pages. Accepted for publication in Astronomy and Astrophysic
Spread of a SARS-CoV-2 variant through Europe in the summer of 2020.
Following its emergence in late 2019, the spread of SARS-CoV-21,2 has been tracked by phylogenetic analysis of viral genome sequences in unprecedented detail3–5. Although the virus spread globally in early 2020 before borders closed, intercontinental travel has since been greatly reduced. However, travel within Europe resumed in the summer of 2020. Here we report on a SARS-CoV-2 variant, 20E (EU1), that was identified in Spain in early summer 2020 and subsequently spread across Europe. We find no evidence that this variant has increased transmissibility, but instead demonstrate how rising incidence in Spain, resumption of travel, and lack of effective screening and containment may explain the variant’s success. Despite travel restrictions, we estimate that 20E (EU1) was introduced hundreds of times to European countries by summertime travellers, which is likely to have undermined local efforts to minimize infection with SARS-CoV-2. Our results illustrate how a variant can rapidly become dominant even in the absence of a substantial transmission advantage in favourable epidemiological settings. Genomic surveillance is critical for understanding how travel can affect transmission of SARS-CoV-2, and thus for informing future containment strategies as travel resumes. © 2021, The Author(s), under exclusive licence to Springer Nature Limited
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