155 research outputs found
The dependence of oxygen and nitrogen abundances on stellar mass from the CALIFA survey
We analysed the optical spectra of HII regions extracted from a sample of 350
galaxies of the CALIFA survey. We calculated total O/H abundances and, for the
first time, N/O ratios using the semi-empirical routine HII-CHI-mistry, which,
according to P\'erez-Montero (2014), is consistent with the direct method and
reduces the uncertainty in the O/H derivation using [NII] lines owing to the
dispersion in the O/H-N/O relation. Then we performed linear fittings to the
abundances as a function of the de-projected galactocentric distances. The
analysis of the radial distribution both for O/H and N/O in the non-interacting
galaxies reveals that both average slopes are negative, but a non-negligible
fraction of objects have a flat or even a positive gradient (at least 10\% for
O/H and 4\% for N/O). The slopes normalised to the effective radius appear to
have a slight dependence on the total stellar mass and the morphological type,
as late low-mass objects tend to have flatter slopes. No clear relation is
found, however, to explain the presence of inverted gradients in this sample,
and there is no dependence between the average slopes and the presence of a
bar. The relation between the resulting O/H and N/O linear fittings at the
effective radius is much tighter (correlation coefficient = 0.80) than
between O/H and N/O slopes ( = 0.39) or for O/H and N/O in the
individual \hii\ regions ( = 0.37). These O/H and N/O values at the
effective radius also correlate very tightly (less than 0.03 dex of dispersion)
with total luminosity and stellar mass. The relation with other integrated
properties, such as star formation rate, colour, or morphology, can be
understood only in light of the found relation with mass.Comment: Accepted for publication in A&A. 20 pages, 19 figure
Characterisation of the hydrodynamic atmospheric escape of HD 209458 b, HD 189733 b, and GJ 3470 b
Interstellar matter and star formatio
Aperture effects on the oxygen abundance determinations from CALIFA data
This paper aims at providing aperture corrections for emission lines in a
sample of spiral galaxies from the Calar Alto Legacy Integral Field Area Survey
(CALIFA) database. In particular, we explore the behavior of the
log([OIII]5007/Hbeta)/([NII]6583/Halpha) (O3N2) and log[NII]6583/Halpha (N2)
flux ratios since they are closely connected to different empirical
calibrations of the oxygen abundances in star forming galaxies.
We compute median growth curves of Halpha, Halpha/Hbeta, O3N2 and N2 up to
2.5R_50 and 1.5 disk R_eff. The growth curves simulate the effect of observing
galaxies through apertures of varying radii. The median growth curve of the
Halpha/Hbeta ratio monotonically decreases from the center towards larger
radii, showing for small apertures a maximum value of ~10% larger than the
integrated one. The median growth curve of N2 shows a similar behavior,
decreasing from the center towards larger radii. No strong dependence is seen
with the inclination, morphological type and stellar mass for these growth
curves. Finally, the median growth curve of O3N2 increases monotonically with
radius. However, at small radii it shows systematically higher values for
galaxies of earlier morphological types and for high stellar mass galaxies.
Applying our aperture corrections to a sample of galaxies from the SDSS
survey at 0.02<=z<=0.3 shows that the average difference between fiber-based
and aperture corrected oxygen abundances, for different galaxy stellar mass and
redshift ranges, reaches typically to ~11%, depending on the abundance
calibration used. This average difference is found to be systematically biased,
though still within the typical uncertainties of oxygen abundances derived from
empirical calibrations. Caution must be exercised when using observations of
galaxies for small radii (e.g. below 0.5R_eff) given the high dispersion shown
around the median growth curves.Comment: Accepted for publication in Ap
CO-CAVITY pilot survey:Molecular gas and star formation in void galaxies
We present the first molecular gas mass survey of void galaxies. We compare
these new data together with data for the atomic gas mass and star formation
rate () from the literature to those of galaxies in filaments and
walls in order to better understand how molecular gas and star formation are
related to the large-scale environment. We observed at the IRAM 30 m telescope
the CO(1-0) and CO(2-1) emission of 20 void galaxies selected from the Void
Galaxy Survey (VGS), with a stellar mass range from to . We detected 15 objects in at least one CO line. We
compared the molecular gas mass (), the star formation efficiency
(), the atomic gas mass, the molecular-to-atomic gas
mass ratio, and the specific star formation rate (sSFR) of the void galaxies
with two control samples of galaxies in filaments and walls, selected from
xCOLD GASS and EDGE-CALIFA, for different stellar mass bins and taking the star
formation activity into account. The results for the molecular gas mass for a
sample of 20 voids galaxies allowed us to make a statistical comparison to
galaxies in filaments and walls for the first time.Comment: 24 pages, 15 figures, accepted in A&A, language corrected versio
Detection of He I \AA{} absorption on HD 189733 b with CARMENES high-resolution transmission spectroscopy
We present three transit observations of HD 189733 b obtained with the
high-resolution spectrograph CARMENES at Calar Alto. A strong absorption signal
is detected in the near-infrared He I triplet at 10830 \AA{} in all three
transits. During mid-transit, the mean absorption level is %
measured in a 10 km s range at a net blueshift of km
s (10829.84--10830.57 \AA{}). The absorption signal exhibits radial
velocities of km s and km s during
ingress and egress, respectively; measured in the planetary rest frame. We show
that stellar activity related pseudo-signals interfere with the planetary
atmospheric absorption signal. They could contribute as much as 80% of the
observed signal and might also affect the radial velocity signature, but
pseudo-signals are very unlikely to explain the entire signal. The observed
line ratio between the two unresolved and the third line of the He I triplet is
, which strongly deviates from the value expected for an optically
thin atmospheres. When interpreted in terms of absorption in the planetary
atmosphere, this favors a compact helium atmosphere with an extent of only 0.2
planetary radii and a substantial column density on the order of cm. The observed radial velocities can be understood either in
terms of atmospheric circulation with equatorial superrotation or as a sign of
an asymmetric atmospheric component of evaporating material. We detect no clear
signature of ongoing evaporation, like pre- or post-transit absorption, which
could indicate material beyond the planetary Roche lobe, or radial velocities
in excess of the escape velocity. These findings do not contradict planetary
evaporation, but only show that the detected helium absorption in HD 189733 b
does not trace the atmospheric layers that show pronounced escape signatures.Comment: 13 pages, 12 figures, accepted for publication in A&
Estudio piloto de metilfenidato y entrenamiento a padres en el tratamiento de niños con trastorno por déficit de atención hiperactividad [A pilot study of methylphenidate and parent training in the treatment of children with attention-deficit hiperactivity disorder]
Objetivo. Este estudio comunica la eficacia de un programa de entrenamiento a padres y un ensayo clínico con medicación estimulante (metilfenidato), en la disminución de síntomas de trastorno por déficit de atención-hiperactividad (TDAH) en una muestra de niños venezolanos.Pacientes y métodos. 24 niños, con edades entre 6 y 10 años, con diagnóstico de TDAH, identificados en unas jornadas de cribado de TDAH, se asignaron aleatoriamente a los dos grupos de tratamiento: entrenamiento a padres y medicación estimulante (metilfenidato).Resultados. Ambos grupos mostraron reducción de síntomas al finalizar la fase de intervención terapéutica en diferentes grados. Estas diferencias fueron estadísticamente significativas para las valoraciones de los padres en ambos grupos, en los síntomas de falta de atención, hiperactividad e impulsividad. Las valoraciones de los profesores mostraron disminución de síntomas significativos en el grupo de medicación para las medidas de hiperactividad e impulsividad, pero no para las de falta de atención, mientras que para el grupo de entrenamiento a padres sólo hubo diferencias significativas en el índice de TDAH. No hubo diferencia en cuanto a la efectividad de ambas intervenciones.Conclusiones. Al comparar ambos programas de tratamiento, se observa que tanto el entrenamiento a padres como la medicación psicoestimulante son tratamientos efectivos para la disminución de los síntomas del TDAH. A pesar de que no existen diferencias entre la efectividad de ambas intervenciones, se observa una tendencia a que la medicación sea más efectiva.
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OBJECTIVE. This study gives information about a parent training program and a clinical trial with a stimulant drug (methylphenidate) to reduce the symptoms of attention deficit hiperactivity disorder (ADHD) in a group of children in Venezuela.PATIENTS AND METHODS. 24 children, aged between 6 and 10 years and diagnosed as having ADHD, identified in ADHD screening days, were randomly assigned to two groups of treatment: parent training and a stimulant drug (methylphenidate).RESULTS. Both groups showed an improvement in their symptoms, to different degrees, after treatment. The differences were statistically significant, as evaluated by their parents, regarding the symptoms of inattention, hyperactivity and impulsivity. The teachers observed a significant improvement for the medication group with respect to the symptoms of hyperactivity and impulsivity, but no change in the inattention, whilst in the parent training group there was only significant difference in the ADHD index. There was no difference in the effectiveness of the two types of treatment.CONCLUSIONS. When the two programs of treatment were compared it was observed that both parent training and psychostimulant medication were effective in reducing the symptoms of ADHD. Although there was no difference in the effectiveness of the two programs, there was a tendency for medication to be more effectiv
Atmospheric characterization of the ultra-hot Jupiter WASP-33b: Detection of Ti and V emission lines and retrieval of a broadened line profile
Ultra-hot Jupiters are highly irradiated gas giant exoplanets on close-in
orbits around their host stars. We analyzed high-resolution spectra from
CARMENES, HARPS-N, and ESPaDOnS taken over eight observation nights to study
the emission spectrum of WASP-33b and draw conclusions about its atmosphere. By
applying the cross-correlation technique, we detected the spectral signatures
of Ti I, V I, and a tentative signal of Ti II for the first time via emission
spectroscopy. These detections are an important finding because of the
fundamental role of Ti- and V-bearing species in the planetary energy balance.
Moreover, we assessed and confirm the presence of OH, Fe I, and Si I from
previous studies. The spectral lines are all detected in emission, which
unambiguously proves the presence of an inverted temperature profile in the
planetary atmosphere. By performing retrievals on the emission lines of all the
detected species, we determined a relatively weak atmospheric thermal inversion
extending from approximately 3400 K to 4000 K. We infer a supersolar
metallicity close to 1.5 dex in the planetary atmosphere, and find that its
emission signature undergoes significant line broadening with a Gaussian FWHM
of about 4.5 km/s. Also, we find that the atmospheric temperature profile
retrieved at orbital phases far from the secondary eclipse is about 300 K to
700 K cooler than that measured close to the secondary eclipse, which is
consistent with different day- and nightside temperatures. Moreover, retrievals
performed on the emission lines of the individual chemical species lead to
consistent results, which gives additional confidence to our retrieval method.
Increasing the number of species included in the retrieval and expanding the
set of retrieved atmospheric parameters will further advance our understanding
of exoplanet atmospheres.Comment: Accepted for publication in A&
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