Search Publications
Spectral observations of X Persei: Connection between Hα and X-ray emission
Zamanov, R.; Stoyanov, K. A.; Wolter, U. +2 more
We present spectroscopic observations of the Be/X-ray binary X Per obtained during the period 1999-2018. Using new and published data, we found that during "disc-rise" the expansion velocity of the circumstellar disc is 0.4-0.7 km s-1. Our results suggest that the disc radius in recent decades show evidence of resonant truncation of the…
Detection of spike-like structures near the front of type-II bursts
Hillaris, A.; Preka-Papadema, P.; Moussas, X. +6 more
Aims: We examine high time resolution dynamic spectra for fine structures in type II solar radio bursts
Methods: We used data obtained with the acousto-optic spectrograph receiver of the Artemis-JLS (ARTEMIS-IV) solar radio spectrograph in the 450-270 MHz range at 10 ms cadence and identified more than 600 short, narrowband features. The…
Interpretation through experimental simulations of phase functions revealed by Rosetta in 67P/Churyumov-Gerasimenko dust coma
Lasue, J.; Fulle, M.; Bertini, I. +3 more
Context. The dust-brightness phase curves that have been measured by the OSIRIS cameras on board the Rosetta spacecraft within the coma of comet 67P/Churyumov-Gerasimenko (67P) present a remarkable flattened u-shape.
Aims: Our goal is to compare these phase curves with those of tentatively analog dust samples to assess the key dust properties…
A VLBI study of the wind-wind collision region in the massive multiple HD 167971
Galván-Madrid, R.; Brandner, W.; Herrero-Illana, R. +7 more
Context. Colliding winds in massive binaries are able to accelerate particles up to relativistic speeds as the result of the interaction between the winds of the different stellar components. HD 167971 exhibits this phenomenon which makes it a strong radio source.
Aims: We aim at characterizing the morphology of the radio emission and its dep…
Chromospheric observations and magnetic configuration of a supergranular structure
Leenaarts, Jorrit; Robustini, Carolina; de la Cruz Rodríguez, Jaime +1 more
Context. Unipolar magnetic regions are often associated with supergranular cells. The chromosphere above these regions is regulated by the magnetic field, but the field structure is poorly known. In unipolar regions, the fibrillar arrangement does not always coincide with magnetic field lines, and polarimetric observations are needed to establish …
The discovery of a Li/Na-rich giant star in Omega Centauri: formed from the pure ejecta of super-AGB stars?
Salaris, M.; Bonifacio, P.; Monaco, L. +3 more
We report the discovery of two Li-rich giant stars (fainter than the red giant branch (RGB) bump) in the stellar system Omega Centauri using GIRAFFE-FLAMES spectra. These two stars have A(Li) = 1.65 and 2.40 dex and they belong to the main population of the system ([Fe/H] = -1.70 and -1.82, respectively). The most Li-rich of them (#25664) has [Na/…
Estimating the mass of CMEs from the analysis of EUV dimmings
Cremades, H.; Balmaceda, L. A.; Nuevo, F. A. +2 more
Context. Reliable estimates of the mass of coronal mass ejections (CMEs) are required to quantify their energy and predict how they affect space weather. When a CME propagates near the observer's line of sight, these tasks involve considerable errors, which motivated us to develop alternative means for estimating the CME mass.
Aims: We aim at…
ULX contribution to stellar feedback: an intermediate-mass black hole candidate and the population of ULXs in the low-metallicity starburst galaxy ESO 338-4
Östlin, G.; Hayes, M.; Mas-Hesse, J. M. +5 more
Context. X-ray radiation from accreting compact objects is an important part of stellar feedback. The metal-poor galaxy ESO 338-4 has experienced vigorous starburst during the last <40 Myr and contains some of the most massive super star clusters in the nearby Universe. Given its starburst age and its star-formation rate, ESO 338-4 is one of th…
Gaia-assisted selection of a quasar reddened by dust in an extremely strong damped Lyman-α absorber at z = 2.226
Milvang-Jensen, B.; Fynbo, J. P. U.; Christensen, L. +7 more
Damped Lyman-α absorbers (DLAs) as a class of quasi-stellar object (QSO) absorption-line systems are currently our most important source of detailed information on the cosmic chemical evolution of galaxies. However, the degree to which this information is biased by dust remains to be understood. One strategy is to specifically search for QSOs that…
Constraining the orbit of the planet-hosting binary τ Boötis. Clues about planetary formation and migration
Albrecht, S.; Justesen, A. B.
Context. The formation of planets in compact or highly eccentric binaries and the migration of hot Jupiters are two outstanding problems in planet formation. Detailed characterisation of known systems is important for informing and testing models. The hot Jupiter τ Boo Ab orbits the primary star in the long-period (P ≳ 1000 yr), highly eccentric (…