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Magnetic fields of opposite polarity in sunspot penumbrae
Franz, M.; Schmidt, W.; Solanki, S. K. +25 more
Context. A significant part of the penumbral magnetic field returns below the surface in the very deep photosphere. For lines in the visible, a large portion of this return field can only be detected indirectly by studying its imprints on strongly asymmetric and three-lobed Stokes V profiles. Infrared lines probe a narrow layer in the very deep ph…
Distance-dependent Offsets between Parallaxes for Nearby Stars and Gaia DR1 Parallaxes
Gies, Douglas R.; Henry, Todd J.; Winters, Jennifer G. +3 more
We use 612 single stars with previously published trigonometric parallaxes placing them within 25 pc to evaluate parallaxes released in Gaia’s first data release (DR1). We find that the Gaia parallaxes are, on average, 0.24 ± 0.02 mas smaller than the weighted mean trigonometric parallax values for these stars in the solar neighborhood. We also fi…
Applications for edge detection techniques using Chandra and XMM-Newton data: galaxy clusters and beyond
Fabian, A. C.; Sanders, J. S.; Walker, S. A.
The unrivalled spatial resolution of the Chandra X-ray observatory has allowed many breakthroughs to be made in high-energy astrophysics. Here we explore applications of Gaussian gradient magnitude (GGM) filtering to X-ray data, which dramatically improves the clarity of surface brightness edges in X-ray observations, and maps gradients in X-ray s…
Ion chemistry in the coma of comet 67P near perihelion
Gunell, H.; Wurz, P.; Altwegg, K. +33 more
The coma and the comet-solar wind interaction of comet 67P/Churyumov-Gerasimenko changed dramatically from the initial Rosetta spacecraft encounter in 2014 August through perihelion in 2015 August. Just before equinox (at 1.6 au from the Sun), the solar wind signal disappeared and two regions of different cometary ion characteristics were observed…
A multi-epoch spectroscopic study of the BAL quasar APM 08279+5255. II. Emission- and absorption-line variability time lags
Dadina, M.; Perna, M.; Trevese, D. +2 more
Context. The study of high-redshift bright quasars is crucial to gather information about the history of galaxy assembly and evolution. Variability analyses can provide useful data on the physics of quasar processes and their relation with the host galaxy.
Aims: In this study, we aim to measure the black hole mass of the bright lensed BAL QSO…
A porosity gradient in 67P/C-G nucleus suggested from CONSERT and SESAME-PP results: an interpretation based on new laboratory permittivity measurements of porous icy analogues
Thomas, N.; Brouet, Y.; Pommerol, A. +12 more
The Rosetta spacecraft made a rendezvous with comet 67P/Churyumov-Gerasimenko (67P) in 2014 August, soon after the Philae module landed on the small lobe of the nucleus on 2014 November 12. The CONSERT instrument, onboard Rosetta and Philae, sounded the upper part of the interior of 67P with radiowaves at 90 MHz and determined an average of the re…
f (R )-gravity model of the Sunyaev-Zeldovich profile of the Coma cluster compatible with Planck data
De Martino, I.
In the weak-field limit, analytic f (R ) models of gravity introduce a Yukawa-like correction to the Newtonian gravitational potential. These models have been widely tested at galactic scales and provide an alternative explanation to the dynamics of galaxies without Dark Matter. We study if the temperature anisotropies due to the thermal Sunyaev-Z…
Bayesian analysis of inflationary features in Planck and SDSS data
Benetti, Micol; Alcaniz, Jailson S.
We perform a Bayesian analysis to study possible features in the primordial inflationary power spectrum of scalar perturbations. In particular, we analyze the possibility of detecting the imprint of these primordial features in the anisotropy temperature power spectrum of the cosmic microwave background (CMB) and also in the matter power spectrum …
Stellar laboratories. VI. New Mo iv-vii oscillator strengths and the molybdenum abundance in the hot white dwarfs G191-B2B and RE 0503-289
Hoyer, D.; Rauch, T.; Werner, K. +3 more
Context. For the spectral analysis of high-resolution and high signal-to-noise (S/N) spectra of hot stars, state-of-the-art non-local thermodynamic equilibrium (NLTE) model atmospheres are mandatory. These are strongly dependent on the reliability of the atomic data that is used for their calculation.
Aims: To identify molybdenum lines in the…
Deep imaging of the shell elliptical galaxy NGC 3923 with MegaCam
Cuillandre, J. -C.; Gwyn, S.; Ebrová, I. +4 more
Context. The elliptical galaxy NGC 3923 is known to be surrounded by a number of stellar shells, probable remnants of an accreted galaxy. Despite its uniqueness, the deepest images of its outskirts come from the 1980s. On the basis of the modified Newtonian dynamics (MOND), it has recently been predicted that a new shell lies in this region.
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