Odesa Astronomical Publications

Постійне посилання зібрання

https://dspace.onu.edu.ua/handle/123456789/13200
ISSN 1810-4215
eISSN 2786-5215

Журнал «Одеські астрономічні публікації» публікує наукові статі з питань астрономії, астрофізики, космічних досліджень, а також матеріали конференцій, які організовуються й проводяться за участю НДІ «Астрономічна обсерваторія» Одеського національного університету імені І. І. Мечникова.

Повні тексти видання доступні на сайті Наукової бібліотеки ОНУ імені І. І. Мечникова за посиланням:
https://lib.onu.edu.ua/ukrayinska-odessa-astronomical-publications/

Сайт видання: http://oap.onu.edu.ua/

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Перегляд Odesa Astronomical Publications за Автор "Berdnikov, L. N."

Зараз показуємо 1 - 5 з 5
  • Ескіз
    Документ
    CHEMICAL COMPOSITION AND ATMOSPHERE PARAMETERS OF THE DOUBLE-MODE CEPHEID U TRA
    (Astroprint, 2013) Usenko, I. A.; Kniazev, A. Yu.; Berdnikov, L. N.; Kravtsov, V. V.
    Four high-resolution spectra of the doble-mode Cepheid U TrA have been obtained during its pulsational period. For the first time, we obtained accurate atmosphere parameters and the chemical abundance of a number of elements, in particular of sodium, magnesium, and aluminium. We estimated the mean Teff = 6085 29 K, log g = 2.00 0.15, and Vt = 3.90 0.25 kms -1 . A deficit of carbon ([C=H] = –0.35 0.23 dex), overabundance of both sodium ([Na=H] = +0.15 0.25 dex) and aluminium ([Al=H] = +0.30 0.32 dex) are typical for Cepheids passing through the first dredge-up phase. The abundance of iron ([Fe=H] = +0.01 0.15 dex) is very close to the solar one. Moreover, we find that -elements, those of Fe-group, as well as ”light”- and ”heavy”-, s- and rprocess elements, all of them have abundances close to solar values, too, excepting maybe several elements with slight enhance or deficit.
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    Документ
    FUNDAMENTAL PARAMETERS AND CHEMICAL COMPOSITION OF CEPHEID X SGR.
    (Astroprint, 2012) Usenko, I. A.; Kniazev, A. Yu.; Berdnikov, L. N.; Kravtsov, V. V.
    Five high-resolutioned spectra of unusual Cepheid X Sgr have been obtained during its pulsational period. For the first time we obtain accurate fundamental parameters and abundances of chemical elements, in particular of sodium, magnesium and aluminium. We estimate the mean Teff = 6143 30 K; log g = 2.00; Vt = 4.35 kms -1 . The estimated effective temperature and surface gravity are relatively high compared to the typical values characteristic of Cepheids with pulsational period around 7 days. A deficit of carbon ([C/H] = -0.26 0.04 dex), overabundances of sodium ([Na/H] =+0.31 0.04 dex) and aluminium ([Al/H] = +0.21 0.08 dex) are typical for Cepheids passing through the first dredge-up phase. However, an obvious overabundance of magnesium([Mg/H] = +0.19 0.04 dex) is unusual. The abundance of iron ([Fe/H] = -0.02 0.01 dex) is very close to the solar one. Abundances of α - elements, (those of Fe-group, as well as ”light ” and ”heavy”, s- and r-process elements) are comparable to the solar values, except for several elements showing slight over- or underabundances.
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    MULTIPHASE SPECTROSCOPIC OBSERVATIONS OF THE LONG-PERIOD CEPHEIDS l CARINAE
    (Astroprint, 2013) Usenko, I. A.; Kravtsov, V. V.; Kovtyukh, Valery V.; Berdnikov, L. N.; Kniazev, A. Yu.; Chini, R.; Fokin, A. B.
    Thirty three spectra (one spectrum for the each of 33 observational nights) have been performed to cover all pulsational period of the 35.5-days Cepheid l Car. Due to these data we have obtained for the first time the detailed curves of effective temperature, gravity and turbulent velocity. Curves of gravity and turbulent velocity show complicated changes, connceted probably with dynamics of extensive Cepheid’s atmosphere. The mean atmosphere parameters of l Car are: Teff = 4984 15 K; log g = 1.13; Vt = 6.67 km s−1. Having a solar metallicity [Fe/H] = +0.02 dex, this Cepheid demonstrate sudden results for the ”key” elements abundances of yellow supergiants evolution, – all they are close to the solar ones. In this case l Car resembles to SV Vul, – Cepheid with 45-days pulsational period and nearly like spectral type. It is possible that l Car is an object crossing the Cepheids instability strip for the first time. The content of other elements is close to solar one too.
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    Документ
    SPECTROSCOPIC INVESTIGATIONS OF CEPHEIDS IN CARINA
    (Astroprint, 2010-07) Usenko, I. A.; Berdnikov, L. N.; Kravtsov, V. V.; Kniazev, A. Yu.; Chini, R.; Hoffmeister, V. H.; Stahl, O.; Drass, H.
    Spectroscopic investigations of seven southern CepheidsWWCar, SX Car, UZ Car, UY Car, GX Car, HW Car and YZ Car have been performed. It was founded out six objects have metallicities, close to solar one and their CNO-, odd elements and Mg content indicate that these objects are on the stage after the first dredge-up. CepheidWWCar is an unusual objects because it has noticeable overabundance of [C/H] = +0.3 dex, [N/H] = +0.95 dex, whereas sodium in deficient ([Na/H] = -0.46 dex), and magnesium content is the largest ([Mg/H] = -0.12 dex) in comparison with other objects from this list having close pulsation periods.
  • Ескіз
    Документ
    Spectroscopical study of faint Southern Cepheids with Southern African Large Telescope (SALT). First results.
    (Одеський національний університет імені І. І. Мечникова, 2017) Usenko, I. A.; Kniazev, A. Yu.; Kovtyukh, Valery V.; Belik, S. I.; Berdnikov, L. N.
    First Cepheids observations using echelle-spectrograph HRS fed by Southern African Large Telescope (SALT) were realized during 2016. All spectra have been obtained in the medium resoltion mode (R 31000–41000) wth high S/N ratio near 50–220. All data were processed using package developed by authors based on the standard system of astronomical data reduction MIDAS. Using new echelle data we found the atmosphere parameters and chemical composition for 30 faint Cepheids of southern hemisphere, where for the most of theses stars these results we obtained for the first time. 28 stars are Cepheids after the first-dredge up stage, while ASAS 075842-25336.1 and ASAS 1131714-6605.0 having remarkable Li I 6707.8 ˚A absorption line and anomalous CNO and Na content could be consider as first crossing of the Cepheids instability strip.