@article{ChougulePrzybillaDimitrijevicetal.2020, author = {Chougule, Abhishek and Przybilla, Norbert and Dimitrijevic, Milan S. and Schaffenroth, Veronika}, title = {The impact of improved Stark-broadening widths on the modeling of double-ionized chromium lines in hot stars}, series = {Contributions of the Astronomical Observatory Skalnate Pleso = Pr{\´a}ce Astronomick{\´e}ho Observat{\´o}ria na Skalnatom Plese}, volume = {50}, journal = {Contributions of the Astronomical Observatory Skalnate Pleso = Pr{\´a}ce Astronomick{\´e}ho Observat{\´o}ria na Skalnatom Plese}, number = {1}, publisher = {Astronomick{\´y} {\´U}stav SAV}, address = {Tatransk{\´a} Lomnica}, issn = {1335-1842}, doi = {10.31577/caosp.2020.50.1.139}, pages = {139 -- 146}, year = {2020}, abstract = {Stellar atmosphere modeling and chemical abundance determinations require the knowledge of spectral line shapes. Spectral lines of chromium in various ionization stages are common in stellar spectra but detailed data on Stark broadening for them is scarce. Recently we reported on the first calculations of Stark widths for several 4s-4p transitions of double-ionized chromium, employing the Modified Semi-Empirical approach (MSE). In this work we present applications of the data to spectrum synthesis of Cr III lines in the ultraviolet region of hot stars. The Atlas9 model atmosphere code and the line-formation code Surface were used with the assumption of local thermodynamic equilibrium. The improvements of adopting the MSE broadening tables instead of approximate Stark broadening coefficients are investigated for a total of 56 Cr III lines visible in HST/STIS spectra of the B3 subgiant star Iota Herculis and the subdwarf B-star Feige 66.}, language = {en} } @article{DevarapalliJagirdarPrasadetal.2020, author = {Devarapalli, Shanti Priya and Jagirdar, Rukmini and Prasad, Manjunath R. and Thomas, Vineet S. and Ahmed, Syed Aslam and Gralapally, Raghavendra and Das, Jesmin Permala Lohy}, title = {Comprehensive study of a neglected contact binary TYC 5532-1333-1}, series = {Monthly notices of the Royal Astronomical Society}, volume = {493}, journal = {Monthly notices of the Royal Astronomical Society}, number = {2}, publisher = {Oxford Univ. Press}, address = {Oxford}, issn = {0035-8711}, doi = {10.1093/mnras/staa031}, pages = {1565 -- 1573}, year = {2020}, abstract = {A comprehensive photometric and spectroscopic analysis of the variable TYC 5532-1333-1 (TYC) along with an investigation of its orbital period variation is presented for the first time. The B- and V-band photometric study indicates that TYC is an intermediate contact binary with degree of contact and mass ratio of 34 per cent and similar to 0.24, respectively. The derived equivalent widths from the spectroscopic study of H alpha and Na-I lines reveal phase-dependent variation and mutual correlation. Using the available times of minimum light, an investigation of orbital period variation shows a long-term decrease at a rate of 3.98 x 10(-6) d yr(-1). Expected causes for such decline in the orbital period could be angular momentum loss and a quasi-sinusoidal variation due to light-time effect probably caused by a third-body companion. The minimum mass of the third body (M-3) was derived to be 0.65 M-circle dot. Our presented study is an attempt to evaluate and understand the evolutionary state of above-mentioned neglected contact binary.}, language = {en} } @article{GonzalezManriqueKuckeinPastorYabaretal.2016, author = {Gonzalez Manrique, Sergio Javier and Kuckein, Christoph and Pastor Yabar, A. and Collados Vera, M. and Denker, Carsten and Fischer, C. E. and G{\"o}m{\"o}ry, P. and Diercke, Andrea and Gonzalez, N. Bello and Schlichenmaier, R. and Balthasar, H. and Berkefeld, T. and Feller, A. and Hoch, S. and Hofmann, A. and Kneer, F. and Lagg, A. and Nicklas, H. and Orozco Suarez, D. and Schmidt, D. and Schmidt, W. and Sigwarth, M. and Sobotka, M. and Solanki, S. K. and Soltau, D. and Staude, J. and Strassmeier, Klaus G. and Verma, Meetu and Volkmer, R. and von der L{\"u}he, O. and Waldmann, T.}, title = {Fitting peculiar spectral profiles in He I 10830 angstrom absorption features}, series = {Astronomische Nachrichten = Astronomical notes}, volume = {337}, journal = {Astronomische Nachrichten = Astronomical notes}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {0004-6337}, doi = {10.1002/asna.201512433}, pages = {1057 -- 1063}, year = {2016}, abstract = {The new generation of solar instruments provides better spectral, spatial, and temporal resolution for a better understanding of the physical processes that take place on the Sun. Multiple-component profiles are more commonly observed with these instruments. Particularly, the He i 10830 triplet presents such peculiar spectral profiles, which give information on the velocity and magnetic fine structure of the upper chromosphere. The purpose of this investigation is to describe a technique to efficiently fit the two blended components of the He i 10830 triplet, which are commonly observed when two atmospheric components are located within the same resolution element. The observations used in this study were taken on 2015 April 17 with the very fast spectroscopic mode of the GREGOR Infrared Spectrograph (GRIS) attached to the 1.5-m GREGOR solar telescope, located at the Observatorio del Teide, Tenerife, Spain. We apply a double-Lorentzian fitting technique using Levenberg-Marquardt least-squares minimization. This technique is very simple and much faster than inversion codes. Line-of-sight Doppler velocities can be inferred for a whole map of pixels within just a few minutes. Our results show sub-and supersonic downflow velocities of up to 32 km s(-1) for the fast component in the vicinity of footpoints of filamentary structures. The slow component presents velocities close to rest. (C) 2016 WILEY-VCH Verlag GmbH\& Co. KGaA, Weinheim}, language = {en} }