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Towards DIB mapping in galaxies beyond 100 Mpc [...] (Monreal-Ibero et al.)
Monday, 16 March 2015 08:00

Vol. 575
In section 1. Letters

Towards DIB mapping in galaxies beyond 100 Mpc. A radial profile of the lambda 5780.5 diffuse interstellar band in AM1353-272 B

by A. Monreal-Ibero, P. M. Weilbacher, M. Wendt, et al., A&A 575, L3


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Thanks to MUSE on the ESO-VLT, the authors have been able to detect and resolve the absorption of diffuse interstellar bands (DIBs) from the interstellar medium (ISM) of two interacting galaxies known by the name of the Dentist’s Chair. This is the first time that DIBs are resolved in galaxies outside the Local Group. The radial profile of the DIBS decreases in correlation with extinction, as expected because the same behaviour is observed in the Milky Way. These observations open new means for studying the ISM of remote galaxies and quasars.

 
V444 Cygni X-ray and polarimetric variability (Lomax et al.)
Friday, 12 December 2014 08:00

Vol. 573
In section 8. Stellar atmospheres

V444 Cygni X-ray and polarimetric variability: Radiative and Coriolis forces shape the wind collision region

by J.R. Lomax, Y. Naze, J.L. Hoffman, et al., A&A 573, A43


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Colliding winds have almost become a vogue in studies of massive binaries and none are better documented than those for the WN+O star binary V444 Cyg. The authors present a comprehensive, multiwavelength picture of the system's behavior including phase-resolved X-ray and optical spectrophotometry. A particularly novel feature of the study is their use of optical spectropolarimetry to constrain the scattering geometry. Then using hydrodynamic modeling they determine the respective roles of radiative braking on the structure of the standing shock, and the phase distortions of the variations due to the dynamics. They also constrain the soft X-ray emission to be beyond the substellar collision point.

 
The GAPS programme with HARPS-N at TNG .V. (Damasso et al.)
Thursday, 05 March 2015 07:18

Vol. 575
In section 10. Planets and planetary systems

The GAPS programme with HARPS-N at TNG .V. A comprehensive analysis of the XO-2 stellar and planetary systems

by M. Damasso, K. Biazzo, A.S. Bonomo, et al., A&A 575, A111


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The XO-2 system is peculiar and extremely interesting. It is a binary star with two solar-like components, XO-2N and XO-2S, each one possessing a system of giant planets. XO-2N has one giant planet of 0.6 times the mass of Jupiter in a 2.6-day orbit that was discovered in transit in 2007. XO-2S has two giant planets that were discovered by the radial-velocimetry technique: planet b has 0.26 Mjup for a 18-day orbital period, while planet c has 1.4 Mjup for a 121-day orbital period. Damasso et al. observed the two components both in radial velocimetry and photometry. They find that XO-2N seems to be spinning faster than XO-2S, which could be a consequence of a tidal spin-up of XO-2N by its planet. Even more intriguing, they find that the abundance of iron in XO-2N is 0.054 dex greater than in XO-2S. Given that the two stars were born from the same molecular cloud core, this difference in abundance seems to confirm that the formation of planets affects the stellar compositions.

 
ALMA detection of [C II] 158 mic. emission [...] (Schaerer et al.)
Thursday, 12 March 2015 13:45

Vol. 575
In section 1. Letters

ALMA detection of [C II] 158 μm emission from a strongly lensed z = 2.013 star-forming galaxy?

by D. Schaerer, F. Boone, T. Jones, et al., A&A 575, L2


Understanding the structure and kinematics of the interstellar medium (ISM) of distant galaxies is one of the ultimate goals of present day galaxy evolution studies. These issues can now begin to be addressed thanks to a combination of sub-millimetric observations, hunting for rest-frame far-IR atomic lines (as the forbidden 158um line from ionized carbon) carrying away a large fraction of the energy budget of the galaxy ISM, and gravitational lensing techniques. The latter are necessary to amplify (by about 50 times in this case) the feeble emission line signal. The authors of this paper present one of the first successful experiments of this kind, finding that the structure of the ISM in these early systems closely resembles that observed in local, normal galaxies.

 
The elemental composition of the Sun (Scott et al.; Grevese et al.)
Thursday, 11 December 2014 01:04

Vol. 573
In section 9. The Sun

The elemental composition of the Sun I. The intermediate mass elements Na to Ca

by P. Scott, N. Grevesse, M. Asplund, et al. A&A 573, A25


The elemental composition of the Sun II. The iron group elements Sc to Ni

by P. Scott, M. Asplund, N. Grevesse, M. Bergemann, and A. J. Sauval A&A 573, A26


The elemental composition of the Sun. III. The heavy elements Cu to Th

by N. Grevesse, P. Scott, M. Asplund, and A. J. Sauval A&A 573, A27


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The chemical composition of the Sun is an essential piece of reference data for astronomy, cosmology, astroparticle physics, space physics, and geophysics: elemental abundances of essentially all astronomical objects refer to the solar composition, and basically every process involving the Sun depends on its composition. In this set of three papers, the authors present a comprehensive redetermination of the solar composition for the intermediate-mass elements (Na to Ca) in Paper I, all the iron group nuclei (Sc to Ni) in Paper II, and the heavy elements (from Cu to Th) in Paper III. In these papers the authors present the most accurate, homogeneous, and reliable results possible by employing a highly realistic 3D hydrodynamic model of the solar photosphere, which has successfully passed an arsenal of observational tests. They also carefully assess each transition probability, partition function, isotopic and hyperfine-splitting constant, and the observed spectrum of every line, making certain to only employ the best possible input data. This analysis provides a complete description and update of the results presented in Asplund, Grevesse, Sauval, & Scott (2009, ARA&A), including full details of all the lines and input data used.

 
The effect of external environment (E. I. Vorobyov et al.)
Wednesday, 10 December 2014 08:00

Vol. 573
In section 6. Interstellar and circumstellar matter

The effect of external environment on the evolution of protostellar disks

by E.I. Vorobyov, D.N.C. Lin, and M. Guedel A&A 573, A5


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The authors study the gravitational collapse of prestellar cores of subsolar mass embedded in a low-density external environment. They find that the infall of matter from the external environment can significantly alter the disk properties as compared to those seen in the isolated model. Depending on the magnitude and direction of rotation of the external environment, a variety of disks can form including both (i) compact disks (< 200 AU) shrinking in size because of the infall of external matter with low angular momentum and (ii) extended disks forming because of the infall of external matter with high angular momentum. The former are usually stable against gravitational fragmentation, while the latter are prone to fragmentation and formation of stellar systems with substellar or very-low-mass companions. In the case of counter-rotating external environment with high angular momentum, counter-rotating inner and outer disks separated by a deep gap at a few tens of AU can be formed. This model may lead to the emergence of a transient stellar system with substellar or very-low-mass components counterrotating with respect to the star.

 

Editor-in-Chief: T. Forveille
Letters Editor-in-Chief: J. Alves
Managing Editor: N. Aghanim

ISSN: 0004-6361 ; e-ISSN: 1432-0746
Frequency: 12 volumes per year
Published by: EDP Sciences

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