| 1. |
- Mikulasek, Z., et al.
(författare)
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On the Nature of Rotation Period Variability of Magnetic Stars
- 2017
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Ingår i: Stars. - 9781583819043 ; , s. 220-223
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Konferensbidrag (refereegranskat)abstract
- The magnetic chemically peculiar (mCP) stars of the upper main sequence exhibit periodic light, magnetic, radio, and spectroscopic variations that can be adequately explained by a model of a rigidly rotating magnetized star with persistent surface structures. The majority of mCP stars rotate at strictly constant periods. However, there are a few mCP stars whose rotation periods vary on timescales of decades while the shape of their phase curves remains unchanged. In the case of CU Vir and V901 Ori, we have detected cyclic period variations. We demonstrate that the period oscillations of CU Vir may be a consequence of the interaction of the internal magnetic field and differential rotation.
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| 2. |
- Pakhomov, Yu, et al.
(författare)
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VALD3 : Current Developments
- 2017
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Ingår i: Stars. - 9781583819043 ; , s. 518-521
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Konferensbidrag (refereegranskat)abstract
- Today Vienna Atomic Line Database (VALD) is one of main databases of atomic and molecular parameters required for stellar spectra analysis. We present the new features that recently appeared in the VALD3 release, including the effects of isotopic composition and hyperfine splitting. The latest version of VALD contains parameters for several isotopes of Li, Ca, Ti, Cu, Ba, Eu, and hyperfine splitting of 35 isotopes from Li to Eu.
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| 3. |
- Piskunov, Nikolai
(författare)
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Main High-Resolution Near-IR Spectrometer for the VLT
- 2017
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Ingår i: Stars. - 9781583819043 ; , s. 514-517
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Konferensbidrag (refereegranskat)abstract
- We present the ongoing CRISES+ project on the development of a cross dispersed high resolution near-infrared spectrometer for the ESO Very Large Telescope. The presentation highlights the relation between science objectives, technical solutions, and the structure of the project. We also share some of the insights on the implementation and management of the project that are crucial for keeping the tight time-line through efficient interaction between consortium members.
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| 4. |
- Piskunov, Nikolai, et al.
(författare)
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Program Package for the Analysis of High Resolution High Signal-To-Noise Stellar Spectra
- 2017
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Ingår i: Stars. - 9781583819043 ; , s. 509-513
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Konferensbidrag (refereegranskat)abstract
- The program package SME (Spectroscopy Made Easy), designed to perform an analysis of stellar spectra using spectral fitting techniques, was updated due to adding new functions (isotopic and hyperfine splittins) in VALD and including grids of NLTE calculations for energy levels of few chemical elements. SME allows to derive automatically stellar atmospheric parameters: effective temperature, surface gravity, chemical abundances, radial and rotational velocities, turbulent velocities, taking into account all the effects defining spectral line formation. SME package uses the best grids of stellar atmospheres that allows us to perform spectral analysis with the similar accuracy in wide range of stellar parameters and metallicities from dwarfs to giants of BAFGK spectral classes.
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