Search Publications
Dense gas in M 33 (HerM33es)
Boquien, M.; Braine, J.; van der Werf, P. +13 more
Aims: We aim to better understand the emission of molecular tracers of the diffuse and dense gas in giant molecular clouds and the influence that metallicity, optical extinction, density, far-UV field, and star formation rate have on these tracers.
Methods: Using the IRAM 30 m telescope, we detected HCN, HCO+, 12CO,…
Comparison of geoeffectiveness of coronal mass ejections and corotating interaction regions
Vršnak, B.; Verbanac, G.; Bandić, M. +2 more
Context. A detailed comparison of the geomagnetic responses to interplanetary coronal mass ejection (ICMEs) and corotating interaction regions (CIRs) during solar cycle 23 was performed using geomagnetic indices Dst, Ap, and AE.
Aims: We aim to find out if there are relative differences in the response of various magnetospheric current system…
Luminosities of carbon-rich asymptotic giant branch stars in the Milky Way
Cristallo, S.; Guandalini, R.
Context. Stars evolving along the asymptotic giant branch can become carbon-rich in the final part of their evolution. They replenish the inter-stellar medium with nuclear processed material via strong radiative stellar winds. The determination of the luminosity function of these stars, even if far from being conclusive, is extremely important for…
Chromospheric evaporation in sympathetic coronal bright points
Ji, H. S.; Zhang, Q. M.
Context. Chromospheric evaporation is a key process in solar flares that has been extensively investigated using spectroscopic observations. However, direct soft X-ray (SXR) imaging of the process is rare, especially in remote brightenings associated with the primary flares that have recently attracted a great deal of attention.
Aims: We inte…
A self-consistent chemically stratified atmosphere model for the roAp star 10 Aquilae
Shulyak, D.; Kochukhov, O.; Weiss, W. +3 more
Context. Chemically peculiar A-type (Ap) stars are a subgroup of the CP2 stars that exhibit anomalous overabundances of numerous elements, e.g. Fe, Cr, Sr, and rare earth elements. The pulsating subgroup of Ap stars, the roAp stars, present ideal laboratories to observe and model pulsational signatures, as well as the interplay of the pulsations w…
A multi-wavelength view of AB Doradus outer atmosphere . Simultaneous X-ray and optical spectroscopy at high cadence
Wieringa, M. H.; Schmitt, J. H. M. M.; Wolter, U. +3 more
Aims: We study the chromosphere and corona of the ultra-fast rotator
What do the Mt. Wilson stars tell us about solar activity?
Schmitt, J. H. M. M.; Schröder, K. -P.; Mittag, M. +2 more
We relate the evolutionary status and mass of the Mt. Wilson project stars with the type and strength of stellar activity as established in decades of monitoring their chromospheric Ca II K line emission. We specifically derive their positions in the Hertzsprung-Russell-diagram (HRD) from Hipparcos parallaxes and SIMBAD B - V data, considering and…
A study of the starless dark cloud LDN 1570: Distance, dust properties, and magnetic field geometry
Maheswar, G.; Bhatt, H. C.; Ramaprakash, A. N. +3 more
Aims: We aim to map the magnetic field geometry and to study the dust properties of the starless cloud, L1570, using multi-wavelength optical polarimetry and photometry of the stars projected on the cloud.
Methods: The direction of the magnetic field component parallel to the plane of the sky of a cloud can be obtained using polarimetry …
X-ray emission from the luminous O-type subdwarf HD 49798 and its compact companion
Tiengo, A.; Mereghetti, S.; Stella, L. +4 more
The X-ray source RX J0648.0-4418 is the only confirmed binary system in which a compact object, most likely a massive white dwarf, accretes from a hot subdwarf companion, the bright sdO star HD 49798. The X-ray emission from this system is characterized by two periodic modulations caused by an eclipse, at the orbital period of 1.55 d, and by the r…
The filtering of interstellar dust in the solar system
Kempf, S.; Krüger, H.; Srama, R. +4 more
Context. Theoretical predictions demonstrate that small (<0.1 µm) interstellar grains are mostly excluded from reaching the planetary system by electromagnetic interactions in the heliopause region and in the inner heliosphere. Bigger interstellar grains have been recorded in the planetary system by dust measurements on board Ulysses and …