To better understand the hot chemically peculiar group of HgMn stars, we have considered a compilation of a large number of recently published data obtained for these stars from spectroscopy. We ...compare these data to the previous compilation by Smith. We confirm the main trends of the abundance peculiarities, namely the increasing overabundances with increasing atomic number of heavy elements, and their large spread from star to star. For all the measured elements, we have looked for correlations between abundances and effective temperature (T
eff). In addition to the known correlation for Mn, some other elements are found to show some connection between their abundances and T
eff. We have also checked if multiplicity is a determinant parameter for abundance peculiarities determined for these stars. A statistical analysis using a Kolmogorov–Smirnov test shows that the abundances anomalies in the atmosphere of HgMn stars do not present significant dependence on the multiplicity.
In this paper, we present a new catalogue of chemically peculiar (CP) stars obtained by compiling publications in which abundances of metals are provided. Our catalogue includes 428 stars for which ...the data were obtained through spectroscopic observations. Most of them (416) are AmFm, HgMn, and ApBp stars. We have used this compilation to proceed to a statistical overview of the abundance anomalies versus the physical parameters of the stars. Spearman’s rank correlation test has been applied, and a significant number of correlations of abundance peculiarities with respect to effective temperature, surface gravity, and rotation velocity have been found. Four interesting cases are discussed in details: the Mn peculiarities in HgMn stars, the Ca correlation with respect to effective temperature in AmFm stars, the case of helium and iron in ApBp stars. Furthermore, we checked for ApBp stars using Anderson–Darling test whether the belonging to a multiple system is a determinant parameter or not for abundance peculiarities.
Abstract
To enlarge our data base of chemically peculiar stars, we compiled published data concerning the He-weak and He-rich stars observed by high-resolution spectroscopy techniques during last ...decades. Twenty He-weak and 28 He-rich stars have been added to the data base. We have also distinguished roAp stars from stars previously identified as Ap stars. To deepen our knowledge on statistical overview of the abundance anomalies versus the physical parameters of stars, we compared our data with previous compilations. We applied statistical tests on our data and found interesting correlations for effective temperature and surface gravity for all type of stars and a few correlations for projected rotation velocity only for He-rich stars. Because of the lack of the data, we could not check whether being a member of binary system is affecting on chemical peculiarities of those stars.
This document constitutes an excerpt of the Technical Design Report for the second stage of the "Any Light Particle Search" (ALPS-II) at DESY as submitted to the DESY PRC in August 2012 and reviewed ...in November 2012. ALPS-II is a "Light Shining through a Wall" experiment which searches for photon oscillations into weakly interacting sub-eV particles. These are often predicted by extensions of the Standard Model and motivated by astrophysical phenomena. The first phases of the ALPS-II project were approved by the DESY management on 21 February, 2013.
We have developed a solid state probe for an absolute irradiance calibration of the Thomson scattering system on the Large Plasma Device (LAPD), based on Raman scattering off silica. Measurements ...performed with a triple-grating spectrometer have investigated the intensities of a pulsed laser beam Raman scattered off crystalline and amorphous silica over a range of temperatures of relevance to the LAPD (299–498 K). The data were compared with Rayleigh and Raman scattering intensities in gaseous nitrogen. The measurements show that Raman scattering off quartz allows rapid and accurate alignment and calibration of Thomson scattering systems in plasma physics experiments that cannot be calibrated using conventional methods.
In the current study the chemical abundances available for HgMn stars and published since 1993 were combined. The compilation results show that overabundance in the atmospheres of HgMn stars ...increases for heavy elements.
HgMn stars are affected by atomic diffusion processes. Because theoretical models based on atomic diffusion require that the atmospheres of ApBp stars have to be much more stable than those of normal ...stars, the detection or the absence of detection of granulation in them should be an interesting information for the modelling. We would like to address the question of the stability of the atmospheres of HgMn stars by analysing the light curves provided by the Convection Rotation and planetary Transits (CoRoT) satellite. We used the CoRoT light curves of the bright HgMn star HD 175640 observed through asteroseismology channel, to look for granulation signature. We have developed a new quasi-automatic idl procedure, which allows us to correct abnormal jumps and variations which exist in CoRoT N2 data. The earlier results show that this procedure is an appropriate tool for the analysis of data obtained through asteroseismology and exoplanet channels. Calculations we carried out for this target show that granulation signature in this HgMn star is not detected from CoRoT light curves. On the other hand, we do not detect clear pulsation signal for this star. That shows that even if some HgMn stars are pulsating, this is not a general property of the group.
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