51 research outputs found
Astrophysics datamining in the classroom: Exploring real data with new software tools and robotic telescopes
Within the efforts to bring frontline interactive astrophysics and astronomy
to the classroom, the Hands on Universe (HOU) developed a set of exercises and
platform using real data obtained by some of the most advanced ground and space
observatories. The backbone of this endeavour is a new free software Web tool -
Such a Lovely Software for Astronomy based on Image J (Salsa J). It is
student-friendly and developed specifically for the HOU project and targets
middle and high schools. It allows students to display, analyze, and explore
professionally obtained astronomical images, while learning concepts on
gravitational dynamics, kinematics, nuclear fusion, electromagnetism. The
continuous evolving set of exercises and tutorials is being completed with real
(professionally obtained) data to download and detailed tutorials. The
flexibility of the Salsa J platform tool enables students and teachers to
extend the exercises with their own observations. The software developed for
the HOU program has been designed to be a multi-platform, multi-lingual
experience for image manipulation and analysis in the classroom. Its design
enables easy implementation of new facilities (extensions and plugins), minimal
in-situ maintenance and flexibility for exercise plugin. Here, we describe some
of the most advanced exercises about astrophysics in the classroom, addressing
particular examples on gravitational dynamics, concepts currently introduced in
most sciences curricula in middle and high schools.Comment: 10 pages, 12 images, submitted to the special theme issue Using
Astronomy and Space Science Research in Physics Courses of the American
Journal of Physic
Analytical approximations of K-corrections in optical and near-infrared bands
To compare photometric properties of galaxies at different redshifts, the
fluxes need to be corrected for the changes of effective rest-frame wavelengths
of filter bandpasses, called K-corrections. Usual approaches to compute them
are based on the template fitting of observed spectral energy distributions
(SED) and, thus, require multi-colour photometry. Here, we demonstrate that, in
cases of widely used optical and near-infrared filters, K-corrections can be
precisely approximated as two-dimensional low-order polynomials of only two
parameters: redshift and one observed colour. With this minimalist approach, we
present the polynomial fitting functions for K-corrections in SDSS ugriz, UKIRT
WFCAM YJHK, Johnson-Cousins UBVR_cI_c, and 2MASS JHK_s bands for galaxies at
redshifts Z<0.5 based on empirically-computed values obtained by fitting
combined optical-NIR SEDs of a set of 10^5 galaxies constructed from SDSS DR7
and UKIDSS DR5 photometry using the Virtual Observatory. For luminous red
galaxies we provide K-corrections as functions of their redshifts only. In two
filters, g and r, we validate our solutions by computing K-corrections directly
from SDSS DR7 spectra. We also present a K-corrections calculator, a web-based
service for computing K-corrections on-line.Comment: 13 pages, 7 figures, 25 tables. Accepted for publication in MNRAS.
This version contains low-resolution figures. The "K-corrections calculator"
service is available at http://kcor.sai.msu.ru
Int J Mol Sci
The placenta is a key organ for fetal and brain development. Its epigenome can be regarded as a biochemical record of the prenatal environment and a potential mechanism of its association with the future health of the fetus. We investigated associations between placental DNA methylation levels and child behavioral and emotional difficulties, assessed at 3 years of age using the Strengths and Difficulties Questionnaire (SDQ) in 441 mother-child dyads from the EDEN cohort. Hypothesis-driven and exploratory analyses (on differentially methylated probes (EWAS) and regions (DMR)) were adjusted for confounders, technical factors, and cell composition estimates, corrected for multiple comparisons, and stratified by child sex. Hypothesis-driven analyses showed an association of cg26703534 () with emotional symptoms, and exploratory analyses identified two probes, cg09126090 (intergenic region) and cg10305789 (), as negatively associated with peer relationship problems, as well as 33 DMRs, mostly positively associated with at least one of the SDQ subscales. Among girls, most associations were seen with emotional difficulties, whereas in boys, DMRs were as much associated with emotional than behavioral difficulties. This study provides the first evidence of associations between placental DNA methylation and child behavioral and emotional difficulties. Our results suggest sex-specific associations and might provide new insights into the mechanisms of neurodevelopment.Exposition prénatale au tabac et à la pollution atmosphérique et effets sur la santé respiratoire et le neurodévelopment de l'enfant: rôle de la méthylation placentaireHorizon 2020 research and innovation programm
Ultimate merging at z ∼ 0.1
International audienceWe present a study of 58 double-peaked emission line galaxies for which one of the components is suppressed in [OIII]λ5008 or is significantly weaker than the other one. Accordingly, the two components are classified differently in the BPT diagram. We show that the strong [OIII] component coincides with the stellar velocity and the suppressed component is off-centred in 66% of the galaxies, while in 12% of them it is the opposite. The analysis of their morphology reveals that about half of the sample is composed of S0, and the rest is composed of mergers and late-type galaxies in equal measure. We discuss the hypothesis that these characteristics exclude rotating discs and suggest different stages of merging. It is possible that the number of mergers is underestimated if the double nuclei are not resolved. Tidal features are detected in the outskirts of some S0 galaxies. This high fraction of S0 is surprising, as in addition most of the galaxies are isolated and the others are in small groups. All these galaxies that host an AGN component are massive, lie on the star forming sequence, and exhibit an enhanced star formation at their centre. While we cannot exclude outflows, these galaxies exhibit spectra that do not correspond to usual outflow observations characterised by high gas velocities, and the standard deviations of the two peaks are comparable. In parallel, these characteristics are compatible with ultimate stages of galaxy merging, where the two nuclei are either too close to be detected, or dynamical disturbances might be present in post-mergers like massive S0 galaxies
Exhaustion of the gas next to the supermassive black hole of M31
International audienc
The surface brightness of the Galaxy at the solar neighbourhood
International audienceWe present a new determination of the surface brightness of our Galaxy at the Solar Neighbourhood as observed from outside the Galaxy. We rely on various existing optical and infra-red surveys to obtain a multiwavelength estimate. On the one hand, scattered light does not contribute significantly to the surface brightness. On the other hand, optical and infrared integrated all-sky surveys (Pioneer 10/11 and COBE/DIRBE) show a systematically larger value than our synthetic local estimate based on Hipparcos data. This local estimate is also compatible with our Galactic simulations normalised at the Solar Neighbourhood and assuming a homogeneous stellar distribution. We interpret this disagreement as a signature of the presence of a local minimum of the stellar density compatible with Gould's belt. According to this result, the global luminosity of the Milky Way should follow the Tully-Fisher relation established for external galaxies
The surface brightness of the Galaxy at the solar neighbourhood
International audienceWe present a new determination of the surface brightness of our Galaxy at the Solar Neighbourhood as observed from outside the Galaxy. We rely on various existing optical and infra-red surveys to obtain a multiwavelength estimate. On the one hand, scattered light does not contribute significantly to the surface brightness. On the other hand, optical and infrared integrated all-sky surveys (Pioneer 10/11 and COBE/DIRBE) show a systematically larger value than our synthetic local estimate based on Hipparcos data. This local estimate is also compatible with our Galactic simulations normalised at the Solar Neighbourhood and assuming a homogeneous stellar distribution. We interpret this disagreement as a signature of the presence of a local minimum of the stellar density compatible with Gould's belt. According to this result, the global luminosity of the Milky Way should follow the Tully-Fisher relation established for external galaxies
A SITELLE view of M31’s central region – I. Calibrations and radial velocity catalogue of nearly 800 emission-line point-like sources
International audienc
Supernova rates and host galaxies properties in the Local Universe
International audienceWe present a short overview of a systematic study performed on supernovae (SN) in the Local Universe, collected from the IAU circulars. We estimate empirical selection biases on the host galaxy and SN detection luminosities. The correction of these biases enables us to derive SN rates and to study their dependency with the galaxy luminosity. We show for the first time a clear correlation of the number of detected supernovae with the LB luminosity of the host galaxy. We do not detect any significant difference in this correlation between type-Ia and core-collapse SN
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