TY  - JOUR
A1  - Chougule, Abhishek
A1  - Przybilla, Norbert
A1  - Dimitrijevic, Milan S.
A1  - Schaffenroth, Veronika
T1  - The impact of improved Stark-broadening widths on the modeling of double-ionized chromium lines in hot stars
JF  - Contributions of the Astronomical Observatory Skalnate Pleso = Práce Astronomického Observatória na Skalnatom Plese
N2  - 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.
KW  - line: profiles
KW  - stars: abundances
Y1  - 2020
U6  - https://doi.org/10.31577/caosp.2020.50.1.139
SN  - 1335-1842
SN  - 1336-0337
VL  - 50
IS  - 1
SP  - 139
EP  - 146
PB  - Astronomický Ústav SAV
CY  - Tatranská Lomnica
ER  - 
TY  - JOUR
A1  - Devarapalli, Shanti Priya
A1  - Jagirdar, Rukmini
A1  - Prasad, Manjunath R.
A1  - Thomas, Vineet S.
A1  - Ahmed, Syed Aslam
A1  - Gralapally, Raghavendra
A1  - Das, Jesmin Permala Lohy
T1  - Comprehensive study of a neglected contact binary TYC 5532-1333-1
JF  - Monthly notices of the Royal Astronomical Society
N2  - 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.
KW  - line: profiles
KW  - methods: observational
KW  - techniques: photometric
KW  - techniques: spectroscopic
KW  - stars: activity
KW  - binaries: eclipsing
Y1  - 2019
U6  - https://doi.org/10.1093/mnras/staa031
SN  - 0035-8711
SN  - 1365-2966
VL  - 493
IS  - 2
SP  - 1565
EP  - 1573
PB  - Oxford Univ. Press
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Gonzalez Manrique, Sergio Javier
A1  - Kuckein, Christoph
A1  - Pastor Yabar, A.
A1  - Collados Vera, M.
A1  - Denker, Carsten
A1  - Fischer, C. E.
A1  - Gömöry, P.
A1  - Diercke, Andrea
A1  - Gonzalez, N. Bello
A1  - Schlichenmaier, R.
A1  - Balthasar, H.
A1  - Berkefeld, T.
A1  - Feller, A.
A1  - Hoch, S.
A1  - Hofmann, A.
A1  - Kneer, F.
A1  - Lagg, A.
A1  - Nicklas, H.
A1  - Orozco Suarez, D.
A1  - Schmidt, D.
A1  - Schmidt, W.
A1  - Sigwarth, M.
A1  - Sobotka, M.
A1  - Solanki, S. K.
A1  - Soltau, D.
A1  - Staude, J.
A1  - Strassmeier, Klaus G.
A1  - Verma, Meetu
A1  - Volkmer, R.
A1  - von der Lühe, O.
A1  - Waldmann, T.
T1  - Fitting peculiar spectral profiles in He I 10830 angstrom absorption features
JF  - Astronomische Nachrichten = Astronomical notes
N2  - 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
KW  - Sun: chromosphere
KW  - methods: data analysis
KW  - techniques: spectroscopic
KW  - line: profiles
Y1  - 2016
U6  - https://doi.org/10.1002/asna.201512433
SN  - 0004-6337
SN  - 1521-3994
VL  - 337
SP  - 1057
EP  - 1063
PB  - Wiley-VCH
CY  - Weinheim
ER  -