Rotational modulation and single g-mode pulsation in the B9pSi star HD 174356?

Chemically peculiar (CP) stars of the upper main sequence are characterized by specific anomalies in the photospheric abundances of some chemical elements. The group of CP2 stars, which encompasses classical Ap and Bp stars, exhibits strictly periodic light, spectral, and spectropolarimetric variations that can be adequately explained by the model of a rigidly rotating star with persistent surface structures and a stable global magnetic field. Using observations from the Kepler K2 mission, we find that the B9pSi star HD 174356 displays a light curve variable in both amplitude and shape, which is not expected in a CP2 star. Employing archival and new photometric and spectroscopic observations, we carry out a detailed abundance analysis of HD 174356 and discuss its photometric and astrophysical properties in detail. We employ phenomenological modelling to decompose the light curve and the observed radial velocity variability. Our abundance analysis confirms that HD 174356 is a silicon-type CP2 star. No magnetic field stronger than 110 G was found. The star's light curve can be interpreted as the sum of two independent strictly periodic signals with and. The periods have remained stable over 17 yr of observations. In all spectra, HD 174356 appears to be single-lined. From the simulation of the variability characteristics and investigation of stars in the close angular vicinity, we put forth the hypothesis that the peculiar light variability of HD 174356 arises in a single star and is caused by rotational modulation due to surface abundance patches (P1) and g-mode pulsation (P2).Fil: Mikulaek, Z. Masaryk University; República ChecaFil: Paunzen, E.. Masaryk University; República ChecaFil: Hümmerich, S.. Masaryk University; República ChecaFil: Niemczura, E.. University of Wrocław; PoloniaFil: Walczak, P.. University of Wrocław; PoloniaFil: Fraga, L.. Masaryk University; República ChecaFil: Bernhard, K.. American Association of Variable Star Observers ; Estados UnidosFil: Janik, J.. Masaryk University; República ChecaFil: Hubrig, S.. Leibniz-Institut für Astrophysik Potsdam; AlemaniaFil: Järvinen, S.. Masaryk University; República ChecaFil: Jagelka, M.. Leibniz Institute For Astrophysics Potsdam; AlemaniaFil: Pintado, Olga Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Correlación Geológica. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Departamento de Geología. Cátedra Geología Estructural. Instituto Superior de Correlación Geológica; Argentina. Universidad San Pablo Tucumán; ArgentinaFil: Krticka, J.. Masaryk University; República ChecaFil: Prisegen, M.. Masaryk University; República ChecaFil: Skarka, M.. Masaryk University; República ChecaFil: Zejda, M.. Masaryk University; República ChecaFil: Ilyin, I.. Leibniz-Institut für Astrophysik Potsdam; AlemaniaFil: Pribulla, T.. Masaryk University; República ChecaFil: Kaminski, K.. Adam Mickiewicz University; PoloniaFil: Kaminska, M. K.. Adam Mickiewicz University; PoloniaFil: Tokarek, J.. Adam Mickiewicz University; PoloniaFil: Zielinski, P.. Astronomical Observatory University of Warsaw; Poloni

Tau Ori and Tau Lib: Two New Massive Heartbeat Binaries

We report the discovery of two massive eccentric systems with BRITE data, tau Ori and tau Lib, showing heartbeat effects close to the periastron passage. τ Lib exhibits shallow eclipses that will soon vanish due to the apsidal motion in the system. In neither system, tidally excited oscillations were detected

Principal component analysis of summertime ground site measurements in the Athabasca oil sands with a focus on analytically unresolved intermediate-volatility organic compounds

In this paper, measurements of air pollutants made at a ground site near Fort McKay in the Athabasca oil sands region as part of a multi-platform campaign in the summer of 2013 are presented. The observations included measurements of selected volatile organic compounds (VOCs) by a gas chromatograph–ion trap mass spectrometer (GC-ITMS). This instrument observed a large, analytically unresolved hydrocarbon peak (with a retention index between 1100 and 1700) associated with intermediate-volatility organic compounds (IVOCs). However, the activities or processes that contribute to the release of these IVOCs in the oil sands region remain unclear. Principal component analysis (PCA) with varimax rotation was applied to elucidate major source types impacting the sampling site in the summer of 2013. The analysis included 28 variables, including concentrations of total odd nitrogen (NOy), carbon dioxide (CO2), methane (CH4), ammonia (NH3), carbon monoxide (CO), sulfur dioxide (SO2), total reduced-sulfur compounds (TRSs), speciated monoterpenes (including α- and β-pinene and limonene), particle volume calculated from measured size distributions of particles less than 10 and 1&thinsp;µm in diameter (PM10−1 and PM1), particle-surface-bound polycyclic aromatic hydrocarbons (pPAHs), and aerosol mass spectrometer composition measurements, including refractory black carbon (rBC) and organic aerosol components. The PCA was complemented by bivariate polar plots showing the joint wind speed and direction dependence of air pollutant concentrations to illustrate the spatial distribution of sources in the area. Using the 95&thinsp;% cumulative percentage of variance criterion, 10 components were identified and categorized by source type. These included emissions by wet tailing ponds, vegetation, open pit mining operations, upgrader facilities, and surface dust. Three components correlated with IVOCs, with the largest associated with surface mining and likely caused by the unearthing and processing of raw bitumen.</p

A gas chromatograph for quantification of peroxycarboxylic nitric anhydrides calibrated by thermal dissociation cavity ring-down spectroscopy

The peroxycarboxylic nitric anhydrides (PANs, molecular formula: RC(O)O2NO2) can readily be observed by gas chromatography (PAN-GC) coupled to electron capture detection. Calibration of a PAN-GC remains a challenge, because the response factors differ for each of the PANs, and because their synthesis in sufficiently high purity is non-trivial, in particular for PANs containing unsaturated side chains. In this manuscript, a PAN-GC and its calibration using diffusion standards, whose output was quantified by blue diode laser thermal dissociation cavity ring-down spectroscopy (TD-CRDS), are described. The PAN-GC peak areas correlated linearly with total peroxy nitrate (ΣPN) mixing ratios measured by TD-CRDS (r > 0.96). Accurate determination of response factors required the concentrations of PAN impurities in the synthetic standards to be subtracted from ΣPN. The PAN-GC and its TD-CRDS calibration method were deployed during ambient air measurement campaigns in Abbotsford, BC, from 20 July to 5 August 2012, and during the Fort McMurray Oil Sands Strategic Investigation of Local Sources (FOSSILS) campaign at the AMS13 ground site in Fort McKay, AB, from 10 August to 5 September 2013. The PAN-GC limits of detection for PAN, PPN, and MPAN during FOSSILS were 1, 2, and 3 pptv, respectively. For the Abbotsford data set, the PAN-GC mixing ratios were compared, and agreed with those determined in parallel by thermal dissociation chemical ionization mass spectrometry (TD-CIMS). Advantages and disadvantages of the PAN measurement techniques used in this work and the utility of TD-CRDS as a PAN-GC calibration method are discussed.Natural Sciences and Engineering Research Council (NSERC

Characteristics of patients presenting with myocardial infarction with non-obstructive coronary arteries (MINOCA) in Poland: data from the ORPKI national registry

Myocardial infarction (MI) with non-obstructive coronary arteries (MINOCA) is an important clinical problem especially in the era of extensive utilization of coronary angiography in MI patients. Its pathophysiology is poorly understood which makes diagnostics and treatment of MINOCA challenging in everyday clinical practice. The aim of the study was to assess characteristics of MINOCA patients in Poland based on data from the Polish National ORPKI Registry. In 2016, 49,893 patients with non-ST-segment elevation (NSTEMI) or ST-segment elevation (STEMI) myocardial infarction entered the ORPKI registry. MINOCA was defined as a non-obstructive coronary artery disease (CAD) and a lack of previous coronary revascularization. MINOCA was identified in 3924 (7.8%) patients and clinical presentation was more often NSTEMI than STEMI (MINOCA: 78 vs. 22%; obstructive CAD 51.1 vs. 48.9%; p\u2009<\u20090.0001). MINOCA patients were younger and more often females with significantly lower rates of diabetes, smoking, arterial hypertension, kidney disease, previous MI and previous stroke comparing to patients with obstructive CAD. Myocardial bridge was visualized in angiography more often in the MINOCA group (2.2 vs. 0.4%; p\u2009<\u20090.0001). Additional coronary assessment inducing fractional flow reserve, intravascular ultrasound, optical coherence tomography was marginally (<\u20091%) used in both groups. Periprocedural mortality was lower in MINOCA group (0.13% vs. 0.95%; p\u2009<\u20090.0001). MINOCA patients represent a significant proportion of MI patients in Poland. Due to multiple potential causes, MINOCA should be considered rather as a working diagnosis after coronary angiography and further efforts should be taken to define the cause of MI in each individual patient

Stable sulfur isotope measurements to trace the fate of SO2 in the Athabasca oil sands region

Concentrations and δ34S values for SO2 and size-segregated sulfate aerosols were determined for air monitoring station 13 (AMS 13) at Fort MacKay in the Athabasca oil sands region, northeastern Alberta, Canada as part of the Joint Canada-Alberta Implementation Plan for Oil Sands Monitoring (JOSM) campaign from 13 August to 5 September 2013. Sulfate aerosols and SO2 were collected on filters using a high-volume sampler, with 12 or 24ĝ€h time intervals. Sulfur dioxide (SO2) enriched in 34S was exhausted by a chemical ionization mass spectrometer (CIMS) operated at the measurement site and affected isotope samples for a portion of the sampling period. It was realized that this could be a useful tracer and samples collected were divided into two sets. The first set includes periods when the CIMS was not running (CIMS-OFF) and no 34SO2 was emitted. The second set is for periods when the CIMS was running (CIMS-ON) and 34SO2 was expected to affect SO2 and sulfate high-volume filter samples. δ34S values for sulfate aerosols with diameter D \u3e 0.49ĝ€μm during CIMS-OFF periods (no tracer 34SO2 present) indicate the sulfur isotope characteristics of secondary sulfate in the region. Such aerosols had δ34S values that were isotopically lighter (down to ĝ\u275.3ĝ€‰) than what was expected according to potential sulfur sources in the Athabasca oil sands region (+3.9 to +11.5ĝ€‰). Lighter δ34S values for larger aerosol size fractions are contrary to expectations for primary unrefined sulfur from untreated oil sands (+6.4ĝ€‰) mixed with secondary sulfate from SO2 oxidation and accompanied by isotope fractionation in gas phase reactions with OH or the aqueous phase by H2O2 or O3. Furthermore, analysis of 34S enhancements of sulfate and SO2 during CIMS-ON periods indicated rapid oxidation of SO2 from this local source at ground level on the surface of aerosols before reaching the high-volume sampler or on the collected aerosols on the filters in the high-volume sampler. Anti-correlations between δ34S values of dominantly secondary sulfate aerosols with D \u3c ĝ€†0.49ĝ€μm and the concentrations of Fe and Mn (rĝ€ Combining double low line ĝ€ĝ\u270.80 and rĝ€ Combining double low line ĝ€ĝ\u270.76, respectively) were observed, suggesting that SO2 was oxidized by a transition metal ion (TMI) catalyzed pathway involving O2 and Fe3+ and/or Mn2+, an oxidation pathway known to favor lighter sulfur isotopes. Correlations between SO2 to sulfate conversion ratio (F(s)) and the concentrations of α-pinene (rĝ€ Combining double low line ĝ€0.85), β-pinene (rĝ€ Combining double low line ĝ€0.87), and limonene (rĝ€ Combining double low line ĝ€0.82) during daytime suggests that SO2 oxidation by Criegee biradicals may be a potential oxidation pathway in the study region. © Author(s) 2018