Institution
European Southern Observatory
Facility•Garching bei München, Germany•
About: European Southern Observatory is a facility organization based out in Garching bei München, Germany. It is known for research contribution in the topics: Galaxy & Stars. The organization has 3594 authors who have published 16157 publications receiving 823095 citations. The organization is also known as: The European Southern Observatory,ESO & ESO.
Topics: Galaxy, Stars, Star formation, Redshift, Population
Papers published on a yearly basis
Papers
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TL;DR: In this article, the authors used a wavelet analysis of the Lyα forest region of quasar spectra to demonstrate that there is a relatively sudden increase in the line widths between redshifts z ≈ 3.5 and 3.0, which they associate with entropy injection resulting from the reionization of He II.
Abstract: The temperature of the diffuse, photoheated intergalactic medium (IGM) depends on its reionization history because the thermal timescales are long. The widths of the hydrogen Lyα absorption lines seen in the spectra of distant quasars that arise in the IGM can be used to determine its temperature. We use a wavelet analysis of the Lyα forest region of quasar spectra to demonstrate that there is a relatively sudden increase in the line widths between redshifts z ≈ 3.5 and 3.0, which we associate with entropy injection resulting from the reionization of He II. The subsequent falloff in temperature after z ≈ 3.5 is consistent with a thermal evolution dominated by adiabatic expansion. If, as expected, the temperature also drops rapidly after hydrogen reionization, then the high temperatures inferred from the line widths before He II reionization imply that hydrogen reionization occurred below redshift z = 9.
192 citations
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192 citations
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Max Planck Society1, University of Grenoble2, University of Chile3, Paris Diderot University4, University of Oxford5, Space Telescope Science Institute6, University of Geneva7, INAF8, Université Paris-Saclay9, Aix-Marseille University10, ETH Zurich11, Stockholm University12, École normale supérieure de Lyon13, University of Atacama14, University of Michigan15, Leiden University16, University of Bern17, Hungarian Academy of Sciences18, European Southern Observatory19, Diego Portales University20
TL;DR: In this article, the spectral properties of PDS 70 b have been characterized using spectrophotometry of the entire near-infrared range (0.96-3.8 μ m).
Abstract: Context . The observation of planets in their formation stage is a crucial but very challenging step in understanding when, how, and where planets form. PDS 70 is a young pre-main sequence star surrounded by a transition disk, in the gap of which a planetary-mass companion has recently been discovered. This discovery represents the first robust direct detection of such a young planet, possibly still at the stage of formation.Aims . We aim to characterize the orbital and atmospheric properties of PDS 70 b, which was first identified on May 2015 in the course of the SHINE survey with SPHERE, the extreme adaptive-optics instrument at the VLT.Methods . We obtained new deep SPHERE/IRDIS imaging and SPHERE/IFS spectroscopic observations of PDS 70 b. The astrometric baseline now covers 6 yr, which allowed us to perform an orbital analysis. For the first time, we present spectrophotometry of the young planet which covers almost the entire near-infrared range (0.96–3.8 μ m). We use different atmospheric models covering a large parameter space in temperature, log g , chemical composition, and cloud properties to characterize the properties of the atmosphere of PDS 70 b.Results . PDS 70 b is most likely orbiting the star on a circular and disk coplanar orbit at ~22 au inside the gap of the disk. We find a range of models that can describe the spectrophotometric data reasonably well in the temperature range 1000–1600 K and log g no larger than 3.5 dex. The planet radius covers a relatively large range between 1.4 and 3.7 R J with the larger radii being higher than expected from planet evolution models for the age of the planet of 5.4 Myr.Conclusions . This study provides a comprehensive data set on the orbital motion of PDS 70 b, indicating a circular orbit and a motion coplanar with the disk. The first detailed spectral energy distribution of PDS 70 b indicates a temperature typical of young giant planets. The detailed atmospheric analysis indicates that a circumplanetary disk may contribute to the total planetflux.
192 citations
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TL;DR: In this article, the authors present high-resolution spectroscopic observations of GRB 060418, obtained with VLT/UVES, with a resolving power of 7 km s-1, and a signal-to-noise ratio of 10-15.490.
Abstract: We present high-resolution spectroscopic observations of GRB 060418, obtained with VLT/UVES. These observations were triggered using the VLT Rapid-Response Mode (RRM), which allows for automated observations of transient phenomena, without any human intervention. This resulted in the first UVES exposure of GRB 060418 to be started only 10 min after the initial Swift satellite trigger. A sequence of spectra covering 330-670 nm were acquired at 11, 16, 25, 41 and 71 minutes (mid-exposure) after the trigger, with a resolving power of 7 km s-1, and a signal-to-noise ratio of 10-15. This time-series clearly shows evidence for time variability of allowed transitions involving Fe II fine-structure levels (^6D{7/2}, ^6D{5/2}, ^6D{3/2}, and ^6D{1/2}), and metastable levels of both Fe II (^4F{9/2} and ^4D{7/2}) and Ni II (^4F{9/2}), at the host-galaxy redshift z=1.490. This is the first report of absorption lines arising from metastable levels of Fe II and Ni II along any GRB sightline. We model the observed evolution of the level populations with three different excitation mechanisms: collisions, excitation by infra-red photons, and fluorescence following excitation by ultraviolet photons. Our data allow us to reject the collisional and IR excitation scenarios with high confidence. The UV pumping model, in which the GRB afterglow UV photons excite a cloud of atoms with a column density N, distance d, and Doppler broadening parameter b, provides an excellent fit, with best-fit values: log N(Fe II) = 14.75+0.06-0.04, log N(Ni II)=13.84±0.02, d=1.7±0.2 kpc, and b=25±3 km s-1. The success of our UV pumping modeling implies that no significant amount of Fe II or Ni II is present at distances smaller than 1.7 kpc, most likely because it is ionized by the GRB X-ray/UV flash. Because neutral hydrogen is more easily ionized than Fe II and Ni II, this minimum distance also applies to any H I present. Therefore the majority of very large H I column densities typically observed along GRB sightlines may not be located in the immediate environment of the GRB. The UV pumping fit also constrains two GRB afterglow parameters: the spectral slope, beta = -0.5+0.8-1.0, and the total rest-frame UV flux that irradiated the cloud since the GRB trigger, constraining the magnitude of a possible UV flash. Based on observations collected at the European Southern Observatory, Chile; proposal no. 77.D-0661.
192 citations
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TL;DR: The presence of two nearly Earth-sized bodies orbiting the post-red-giant, hot B subdwarf star KIC 05807616 is reported, which may be the dense cores of evaporated giant planets that were transported closer to the star during the engulfment and triggered the mass loss necessary for the formation of the hot B subswarf.
Abstract: Two planets around the post-red-giant star KIC 05807616 are shown to have survived being engulfed by the former red giant
192 citations
Authors
Showing all 3617 results
Name | H-index | Papers | Citations |
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Robert C. Nichol | 187 | 851 | 162994 |
Richard S. Ellis | 169 | 882 | 136011 |
Rob Ivison | 166 | 1161 | 102314 |
Alvio Renzini | 162 | 908 | 95452 |
Timothy C. Beers | 156 | 934 | 102581 |
Krzysztof M. Gorski | 132 | 380 | 105912 |
Emanuele Daddi | 129 | 581 | 63187 |
P. R. Christensen | 127 | 313 | 88445 |
Mark Dickinson | 124 | 389 | 66770 |
Christopher W. Stubbs | 122 | 622 | 109429 |
Eva K. Grebel | 118 | 863 | 83915 |
Martin Asplund | 118 | 612 | 52527 |
Jesper Sollerman | 118 | 726 | 53436 |
E. F. van Dishoeck | 115 | 742 | 49190 |
Jørgen Christensen-Dalsgaard | 114 | 585 | 48272 |