Search Publications
VLT/X-Shooter Near-infrared Spectroscopy and HST Imaging of Gravitationally Lensed z ~ 2 Compact Quiescent Galaxies
Geier, S.; Toft, S.; Fynbo, J. P. U. +4 more
Quiescent massive galaxies at z ~ 2 are thought to be the progenitors of present-day massive ellipticals. Observations revealed them to be extraordinarily compact. Until now, the determination of stellar ages, star formation rates, and dust properties via spectroscopic measurements has been feasible only for the most luminous and massive specimens…
Signatures of Multiple Stellar Populations in Unresolved Extragalactic Globular/Young Massive Star Clusters
Zepf, Stephen E.; Peacock, Mark B.; Finzell, Thomas
We present an investigation of potential signatures of the formation of multiple stellar populations in recently formed extragalactic star clusters. All of the Galactic globular clusters for which good samples of individual stellar abundances are available show evidence for multiple populations. This appears to require that multiple episodes of st…
A 3D general circulation model for Pluto and Triton with fixed volatile abundance and simplified surface forcing
Michaels, Timothy I.; Zalucha, Angela M.
We present a 3D general circulation model of Pluto and Triton's atmospheres, which uses radiative-conductive-convective forcing. In both the Pluto and Triton models, an easterly (prograde) jet is present at the equator with a maximum magnitude of 10-12 m s-1 and 4 m s-1, respectively. Neither atmosphere shows any significant …
HD 45314: a new γ Cassiopeiae analog among Oe stars
Morel, T.; Nazé, Y.; Rauw, G. +2 more
Context. Oe stars possibly form an extension to higher temperatures of the Be phenomenon, but it is still unclear whether these stars have disks.
Aims: X-ray spectra could provide hints for interactions of the star with a putative surrounding disk.
Methods: We obtained XMM-Newton observations of two Oe stars, HD 45314 and HD 60848. Spect…
X-ray emission regimes and rotation sequences in M 35 . An updated model of stellar activity evolution on the main sequence
Gondoin, P.
Context. Late-type stars in young open clusters show two kinds of dependence of their X-ray emission on rotation. They also tend to group into two main sub-populations that lie on narrow sequences in diagrams where their rotation periods are plotted against their (B - V) colour indices. A correlation between these two regimes of X-ray emission and…
Increasing the Fine Structure Visibility of the Hinode SOT Ca II H Filtergrams
Koutchmy, S.; Tavabi, E.; Ajabshirizadeh, A.
We present an image processing technique, the improved OMC filter (also called Madmax), which selects maxima of convexities of intensity modulations of an image. The filter computes second derivatives of the image in multiple directions around each pixel. It is shown to be efficient for pattern recognition, and bright hair-like or small anisotropi…
Saturn suprathermal O2+ and mass-28+ molecular ions: Long-term seasonal and solar variation
Krimigis, S. M.; Mitchell, D. G.; Hamilton, D. C. +3 more
Suprathermal singly charged molecular ions, O2+ (at ~32 Da/e) and the Mass-28 ion group 28M+ (ions at ~28 Da/e, with possible contributions from C2H5+, HCNH+, N2+, and/or CO+), are present throughout Saturn's ~4-20 Rs (1 Saturn …
ROSINA/DFMS capabilities to measure isotopic ratios in water at comet 67P/Churyumov-Gerasimenko
Altwegg, K.; Balsiger, H.; Berthelier, J. J. +7 more
The likelihood that comets may have delivered part of the water to Earth has been reinforced by the recent observation of the earth-like D/H ratio in Jupiter-family comet 103P/Hartley 2 by Hartogh et al. (2012). Prior to this observation, results from several Oort cloud comets indicated a factor of 2 enrichment of deuterium relative to the abundan…
X-ray properties of the young open clusters HM1 and IC 2944/2948
Corcoran, M. F.; Nazé, Y.; Rauw, G. +1 more
Using XMM-Newton data, we study for the first time the X-ray emission of HM1 and IC 2944/2948. Low-mass, pre-main-sequence objects with an age of a few Myr are detected, as well as a few background or foreground objects. Most massive stars in both clusters display the usual high-energy properties of that type of objects, though with log [LX
Evidence of extensive glaciation in Deuteronilus Mensae, Mars: Inferences towards multiple glacial events in the past epochs
Sinha, Rishitosh K.; Murty, S. V. S.
In this study, we examine the existence of multiple episodes of glacial activities in Deuteronilus Mensae region on Mars from the analysis of high-resolution remote sensing images acquired by Mars Reconnaissance Orbiter (MRO) ConText Camera (CTX) and High resolution imaging science experiment (HiRISE). The investigated portion from northern mid-la…