Search Publications
Variation of the temperature gradient in the solar photosphere with magnetic activity
Faurobert, M.; Ricort, G.; Balasubramanian, R.
Context. The contribution of quiet-Sun regions to the solar irradiance variability is currently unclear. Some solar-cycle variations of the quiet-Sun physical structure, such as the temperature gradient or the photospheric radius, might affect the irradiance.
Aims: We intend to investigate possible variations of the photospheric temperature g…
New insights into the quasi-periodic X-ray burster GS 0836-429
Sánchez-Fernández, C.; Kuulkers, E.; Aranzana, E.
GS 0836-429 is a neutron star X-ray transient that displays Type-I X-ray bursts. In 2003 and 2004 it experienced two outbursts in X-rays. We present here an analysis of the system's bursting properties during these outbursts. We studied the evolution of the 2003-2004 outbursts in soft X-rays using RXTE (2.5-12 keV; ASM) and in hard X-rays with INT…
Pseudomagnitude distances: Application to the Pleiades cluster
Duvert, G.; Chelli, A.
The concept of pseudomagnitude has recently been introduced to estimate apparent stellar diameters using a strictly observational methodology. Pseudomagnitudes are distance indicators which have the remarkable property of being reddening free. In this study, we use Hipparcos parallax measurements to compute the mean absolute pseudomagnitudes of so…
Polar cap magnetic field reversals during solar grand minima: could pores play a role?
Švanda, Michal; Brun, Allan Sacha; Roudier, Thierry +1 more
We study the magnetic flux carried by pores located outside active regions with sunspots and investigate their possible contribution to the reversal of the global magnetic field of the Sun. We find that they contain a total flux of comparable amplitude to the total magnetic flux contained in polar caps. The pores located at distances of 40-100 Mm …
Effects of disc asymmetries on astrometric measurements. Can they mimic planets?
Schneider, J.; Souami, D.; Kral, Q. +1 more
Astrometry covers a parameter space that cannot be reached by RV or transit methods to detect terrestrial planets on wide orbits. In addition, high accuracy astrometric measurements are necessary to measure the inclination of the planet's orbits. Here we investigate the principles of an artefact of the astrometric approach, namely the displacement…
The structure and early evolution of massive star forming regions. Substructure in the infrared dark cloud SDC13
Avison, A.; Peretto, N.; Fuller, G. A. +4 more
Context. Investigations into the substructure of massive star forming regions are essential for understanding the observed relationships between core mass distributions and mass distributions in stellar clusters, differentiating between proposed mechanisms of massive star formation.
Aims: We study the substructure in the two largest fragments…
Large-scale latitude distortions of the inner Milky Way disk from the Herschel/Hi-GAL Survey
Moore, T. J. T.; Testi, L.; Benedettini, M. +9 more
Aims: We use the Herschel Hi-GAL survey data to study the spatial distribution in Galactic longitude and latitude of the interstellar medium (ISM) and of dense, star-forming clumps in the inner Galaxy.
Methods: We assemble a complete mosaic of the inner Galaxy between l = -70° and +68° in the far-infrared continuum from Hi-GAL. The peak …
Compact stellar systems in the polar ring galaxies NGC 4650A and NGC 3808B: Clues to polar disk formation
Georgiev, Iskren Y.; Goudfrooij, Paul; Puzia, Thomas H. +2 more
Context. Polar ring galaxies (PRGs) are composed of two kinematically distinct and nearly orthogonal components, a host galaxy (HG) and a polar ring/disk (PR). The HG usually contains an older stellar population than the PR. The suggested formation channel of PRGs is still poorly constrained. Suggested options are merger, gas accretion, tidal inte…
Multilayer modeling of the aureole photometry during the Venus transit: comparison between SDO/HMI and VEx/SOIR data
Vandaele, A. C.; Wilquet, V.; Mahieux, A. +4 more
Context. The mesosphere of Venus is a critical range of altitudes in which complex temperature variability has been extensively studied by the space mission Venus Express (VEx) during its eight-year mission (2006-2014). In particular, the Solar Occultation in the InfraRed (SOIR) instrument probed the morning and evening terminator in the 70-170 km…
Properties of galaxies at the faint end of the Hα luminosity function at z ~ 0.62
Villar, Víctor; Gallego, Jesús; Gómez-Guijarro, Carlos +3 more
Context. Studies measuring the star formation rate density, luminosity function, and properties of star-forming galaxies are numerous. However, it exists a gap at 0.5 < z < 0.8 in Hα-based studies.
Aims: Our main goal is to study the properties of a sample of faint Hα emitters at z ~ 0.62. We focus on their contribution to the faint end…