Search Publications
A statistical analysis of two-dimensional patterns and its application to astrometry
Zavada, Petr; Píška, Karel
Here we develop a general statistical procedure for the analysis of finite two-dimensional (2D) patterns inspired by the analysis of heavy-ion data. The method is used in the study of publicly available data obtained by the Gaia-ESA mission. We prove that the procedure can be sensitive to the limits of accuracy of measurement, and can also clearly…
Raman-scattered laser guide-star photons to monitor the scatter of astronomical telescope mirrors
Mieske, Steffen; Milli, Julien; Kuntschner, Harald +26 more
The first observations of laser guide-star photons that are Raman-scattered by air molecules above the Very Large Telescope (VLT) were reported in June 2017. The initial detection came from the Multi-Unit Spectroscopic Explorer (MUSE) optical integral field spectrograph, following the installation of the 4 Laser Guide Star Facility (4LGSF) on Unit…
Temperature gradient in the solar photosphere. Test of a new spectroscopic method and study of its feasibility for ground-based telescopes
Chiavassa, A.; Faurobert, M.; Carbillet, M. +2 more
Context. The contribution of quiet-Sun regions to the solar irradiance variability is currently unclear. Some solar-cycle variations of the quiet-Sun physical structure, such as the temperature gradient, might affect the irradiance. The synoptic measurement of this quantity along the activity cycle would improve our understanding of long-term irra…
X-ray and UV emission of the ultrashort-period, low-mass eclipsing binary system BX Trianguli
Schmitt, J. H. M. M.; Czesla, S.; Robrade, J. +2 more
Context.Close binary systems provide an excellent tool for determining stellar parameters such as radii and masses with a high degree of precision. Due to the high rotational velocities, most of these systems exhibit strong signs of magnetic activity, postulated to be the underlying reason for radius inflation in many of the components. Aims.We ex…
The possible common origin of M 16 and M 17
Comerón, F.; Torra, J.
Context. It has been suggested that the well-studied giant HII regions M 16 and M 17 may have had a common origin, being an example of large-scale triggered star formation. While some features of the distribution of the interstellar medium in the region support this interpretation, no definitive detection of an earlier population of massive stars …
Determining the accuracy of VLBI radio source catalogs
Liu, N.; Zhu, Z.; Lambert, S. B.
Aims: We propose to estimate the accuracy of current very long baseline interferometry (VLBI) catalogs.
Methods: The difference of source position estimated from two decimation solutions was analyzed to estimate the scale factor and noise floor for the formal error of radio source positions by two different methods. In one method, we inv…
Interstellar bromine abundance is consistent with cometary ices from Rosetta
Kama, M.; Ligterink, N. F. W.
Context. Cometary ices are formed during star and planet formation, and their molecular and elemental makeup can be related to the early solar system via the study of inter- and protostellar material.
Aims: We set out to place the first observational constraints on the interstellar gas-phase abundance of bromine (Br). We further aim to compar…
The mass of Albireo Aa and the nature of Albireo AB. New aspects from Gaia DR2
Bastian, U.; Anton, R.
Aims: We aim to clarify the nature of Albireo AB and specifically to decipher whether it is an optical or physical pair. We also try to determine the mass of Albireo Aa.
Methods: We scrutinize and compare the available absolute astrometric data (from HIPPARCOS and Gaia DR2) of Albireo A and B, and we investigate the relative orbit of the…
Detection of a 23.6 min periodic modulation in the optical counterpart of 3XMMJ051034.6-670353
Dhillon, V. S.; Marsh, T. R.; Groot, P. +4 more
We present high speed optical photometric observations made using the NTT and ULTRACAM of the optical counterpart of 3XMMJ051034.6-670353, which was recently identified as an X-ray source showing a modulation on a period of 23.6 min. Although the optical counterpart is faint (g = 21.4), we find that the u'g'r' light curves show a periodic modulati…
Revisiting the case of R Monocerotis: Is CO removed at R < 20 au
Montesinos, B.; Bachiller, R.; Fuente, A. +4 more
Context. To our knowledge, R Mon is the only B0 star in which a gaseous Keplerian disk has been detected. However, there is some controversy about the spectral type of R Mon. Some authors propose that it could be a later B8e star, where disks are more common.
Aims: Our goal is to re-evaluate the R Mon spectral type and characterize its protop…