Romualda Lazauskaitė - Academia.edu (original) (raw)
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Papers by Romualda Lazauskaitė
2013 balandžio pradžioje LEU Gamtos, matematikos ir technologijų fakulteto laboratorijose svečiav... more 2013 balandžio pradžioje LEU Gamtos, matematikos ir technologijų fakulteto laboratorijose svečiavosi Švenčionių Zigmo Žemaičio gimnazijos dešimtokai. Jie atliko eksperimentinius darbus fi zikos ir chemijos laboratorijose.Lietuvos edukologijos universiteta
VPU doc. dr. A. Ažusieniui įteiktas diplomas, kuris patvirtina , kad Tarptautinė astronomų sąjung... more VPU doc. dr. A. Ažusieniui įteiktas diplomas, kuris patvirtina , kad Tarptautinė astronomų sąjunga asteroidui 2002 FU10 suteikė Ažusienio vardą.Lietuvos edukologijos universiteta
Nuotraukoje : VPU absolventas Lukas Jonaitis.Lietuvos edukologijos universiteta
Apie VPU doc. Algimantą Ažusienį.Lietuvos edukologijos universiteta
Vytauto Didžiojo universitetasŠvietimo akademij
Apie konferenciją, kurią organizavo VPU, Planetariumas ir Lietuvos astronomų sąjunga.Lietuvos edu... more Apie konferenciją, kurią organizavo VPU, Planetariumas ir Lietuvos astronomų sąjunga.Lietuvos edukologijos universiteta
Klubo "Antares" veikloje dalyvauja VPU FTF studentai.Lietuvos edukologijos universiteta
Mokytojų rengimo institutasVilniaus universitetasVytauto Didžiojo universiteta
Open Astronomy, 1998
Synthetic color indices and interstellar reddening-free (J-parameters are calculated for the orig... more Synthetic color indices and interstellar reddening-free (J-parameters are calculated for the original Sloan photometric system using flux distribution functions of real stars and Kurucz model synthetic spectra as radiation sources. Various two-color and interstellar reddening-free Q, Q diagrams are analyzed. Some color indices of the system are good temperature indicators, however, they can be applied only for the unreddened stars or the reddening should be known. Temperatures and gravities of the reddened stars can be determined by using multidimensional space formed by several interstellar reddening-free Q-parameters. The accuracy of photometric classification is very different in various temperature and gravity ranges. When expressed in spectral classes, the classification accuracy in temperatures is from ±1 to ±10 spectral subclasses and in gravities from ±0.1 to ±3.0 dex. The highest accuracy of spectral classes and gravities is for late B, late F, early G and all M subclasses.
The Astronomical Journal, 2020
The open cluster IC 1369, located in Cygnus close to the galactic equator at the 89fdg6 longitude... more The open cluster IC 1369, located in Cygnus close to the galactic equator at the 89fdg6 longitude, and its vicinity are investigated by applying two-dimensional photometric classification of stars down to V = 19 mag measured in the Vilnius seven-color photometric system. Employing the Gaia DR2 coordinates, parallaxes, and proper motions, 143 cluster members are found having cluster membership probabilities ≥0.75. The hottest stars of the evolved main sequence are of spectral class B9. Distances to the cluster, determined by two methods based on the Gaia parallaxes, are 3280 and 3370 pc with an uncertainty of 400–500 pc. Employing the physical HR diagram with the coordinates mathrmlogL/Lodot\\mathrm{log}L/{L}_{\\odot }mathrmlogL/Lodot versus mathrmlogTmathrmeff\\mathrm{log}{T}_{\\mathrm{eff}}mathrmlogTmathrmeff and the Padova isochrones, the cluster age is found to be between 300 and 350 Myr. Among the cluster members we identified six red giants of spectral classes G5–G8 and luminosities II–III, 17 Am stars, one Ap star, and one B5 blue straggler. The extinction shows a steep rise up to ~2.0 mag at 300–700 pc, caused by the extensions of the dust cloud LDN 970 and the Great Cygnus Rift, and up to ~2.5 mag at the edge of the Perseus arm at 3.0 kpc. The extinction is almost constant between 0.9 and 2.5 kpc from the Sun. The average extinction of the cluster members is 2.54 mag. A systematic error of color excesses found in the Argonaut calculator results is discussedMokytojų rengimo institutasVilniaus universiteto astronomijos observatorijaVytauto Didžiojo universiteta
Vilniaus universitetasVytauto Didžiojo universitetasŠvietimo akademij
Mokytojų rengimo institutasVilniaus Gedimino technikos universitetasVilniaus universitetasVytauto... more Mokytojų rengimo institutasVilniaus Gedimino technikos universitetasVilniaus universitetasVytauto Didžiojo universiteta
Rubrika: Vilniaus pedagoginis universitetas.Apie VPU docentą Algimantą Ažusienį.Lietuvos edukolog... more Rubrika: Vilniaus pedagoginis universitetas.Apie VPU docentą Algimantą Ažusienį.Lietuvos edukologijos universiteta
Vilniaus universiteto Teorinės fizikos ir astronomijos institutasVytauto Didžiojo universitetasŠv... more Vilniaus universiteto Teorinės fizikos ir astronomijos institutasVytauto Didžiojo universitetasŠvietimo akademij
Proceedings of the International Astronomical Union, 2009
We derive photometric metallicities for 56 intermediate-age and old star clusters in the Large Ma... more We derive photometric metallicities for 56 intermediate-age and old star clusters in the Large Magellanic Cloud from the slopes of their red-giant branches in near-infrared color–magnitude diagrams (CMDs). The cluster sample covers the LMC bar and disk to a distance of ~2 kpc from the LMC center. The derived cluster metallicity distribution spans a range of [Fe/H] = +0.0 . . . 1.4 and is similar to the metallicity distribution of field stars. We find that the average cluster metallicities in certain fields of the LMC bar and disk may be different, but there seems to be no compelling evidence for a global cluster metallicity gradient in the LMC.
We derive new calibrations that relate the mean J-Ks photometric colors of red giant branch (RGB)... more We derive new calibrations that relate the mean J-Ks photometric colors of red giant branch (RGB) stars at MKs=-5.5 and -5.0 with cluster metallicity. The new calibrations are derived using a sample of intermediate age (1--8 Gyr) clusters in the Large and Small Magellanic Clouds, with the JHKs photometry taken from the SIRIUS photometric survey of the Magellanic Clouds. Cluster metallicities are literature data, obtained either from the high resolution or infrared calcium triplet spectroscopy of individual RGB stars. We find systematic differences between the RGB color vs. metallicity relations derived in this work and those determined by Valenti et al. (2004), the latter ones obtained for a sample of old Galactic globular clusters. In terms of age, this discrepancy corresponds to ˜ 5 Gyr and therefore can be attributed to the age difference between the two cluster samples used in the derivation of the corresponding RGB color vs. metallicity relations.
Mokytojų rengimo institutasVilniaus universitetasVytauto Didžiojo universiteta
Vytauto Didžiojo universitetasŠvietimo akademij
arXiv: Astrophysics, 2002
Energy distributions of synthetic spectra for Kurucz model atmospheres are compared with observed... more Energy distributions of synthetic spectra for Kurucz model atmospheres are compared with observed energy distributions of metal-deficient stars of the blue horizontal-branch (BHB), F-G-K subdwarf (SD) and G-K giant (MDG) types. The best coincidence of the synthetic and observed energy curves is found for BHB stars. The largest differences are found in the ultraviolet wavelengths for subdwarfs and cool MDGs. The influence of errors of effective temperatures, gravities and metallicities is estimated.
2013 balandžio pradžioje LEU Gamtos, matematikos ir technologijų fakulteto laboratorijose svečiav... more 2013 balandžio pradžioje LEU Gamtos, matematikos ir technologijų fakulteto laboratorijose svečiavosi Švenčionių Zigmo Žemaičio gimnazijos dešimtokai. Jie atliko eksperimentinius darbus fi zikos ir chemijos laboratorijose.Lietuvos edukologijos universiteta
VPU doc. dr. A. Ažusieniui įteiktas diplomas, kuris patvirtina , kad Tarptautinė astronomų sąjung... more VPU doc. dr. A. Ažusieniui įteiktas diplomas, kuris patvirtina , kad Tarptautinė astronomų sąjunga asteroidui 2002 FU10 suteikė Ažusienio vardą.Lietuvos edukologijos universiteta
Nuotraukoje : VPU absolventas Lukas Jonaitis.Lietuvos edukologijos universiteta
Apie VPU doc. Algimantą Ažusienį.Lietuvos edukologijos universiteta
Vytauto Didžiojo universitetasŠvietimo akademij
Apie konferenciją, kurią organizavo VPU, Planetariumas ir Lietuvos astronomų sąjunga.Lietuvos edu... more Apie konferenciją, kurią organizavo VPU, Planetariumas ir Lietuvos astronomų sąjunga.Lietuvos edukologijos universiteta
Klubo "Antares" veikloje dalyvauja VPU FTF studentai.Lietuvos edukologijos universiteta
Mokytojų rengimo institutasVilniaus universitetasVytauto Didžiojo universiteta
Open Astronomy, 1998
Synthetic color indices and interstellar reddening-free (J-parameters are calculated for the orig... more Synthetic color indices and interstellar reddening-free (J-parameters are calculated for the original Sloan photometric system using flux distribution functions of real stars and Kurucz model synthetic spectra as radiation sources. Various two-color and interstellar reddening-free Q, Q diagrams are analyzed. Some color indices of the system are good temperature indicators, however, they can be applied only for the unreddened stars or the reddening should be known. Temperatures and gravities of the reddened stars can be determined by using multidimensional space formed by several interstellar reddening-free Q-parameters. The accuracy of photometric classification is very different in various temperature and gravity ranges. When expressed in spectral classes, the classification accuracy in temperatures is from ±1 to ±10 spectral subclasses and in gravities from ±0.1 to ±3.0 dex. The highest accuracy of spectral classes and gravities is for late B, late F, early G and all M subclasses.
The Astronomical Journal, 2020
The open cluster IC 1369, located in Cygnus close to the galactic equator at the 89fdg6 longitude... more The open cluster IC 1369, located in Cygnus close to the galactic equator at the 89fdg6 longitude, and its vicinity are investigated by applying two-dimensional photometric classification of stars down to V = 19 mag measured in the Vilnius seven-color photometric system. Employing the Gaia DR2 coordinates, parallaxes, and proper motions, 143 cluster members are found having cluster membership probabilities ≥0.75. The hottest stars of the evolved main sequence are of spectral class B9. Distances to the cluster, determined by two methods based on the Gaia parallaxes, are 3280 and 3370 pc with an uncertainty of 400–500 pc. Employing the physical HR diagram with the coordinates mathrmlogL/Lodot\\mathrm{log}L/{L}_{\\odot }mathrmlogL/Lodot versus mathrmlogTmathrmeff\\mathrm{log}{T}_{\\mathrm{eff}}mathrmlogTmathrmeff and the Padova isochrones, the cluster age is found to be between 300 and 350 Myr. Among the cluster members we identified six red giants of spectral classes G5–G8 and luminosities II–III, 17 Am stars, one Ap star, and one B5 blue straggler. The extinction shows a steep rise up to ~2.0 mag at 300–700 pc, caused by the extensions of the dust cloud LDN 970 and the Great Cygnus Rift, and up to ~2.5 mag at the edge of the Perseus arm at 3.0 kpc. The extinction is almost constant between 0.9 and 2.5 kpc from the Sun. The average extinction of the cluster members is 2.54 mag. A systematic error of color excesses found in the Argonaut calculator results is discussedMokytojų rengimo institutasVilniaus universiteto astronomijos observatorijaVytauto Didžiojo universiteta
Vilniaus universitetasVytauto Didžiojo universitetasŠvietimo akademij
Mokytojų rengimo institutasVilniaus Gedimino technikos universitetasVilniaus universitetasVytauto... more Mokytojų rengimo institutasVilniaus Gedimino technikos universitetasVilniaus universitetasVytauto Didžiojo universiteta
Rubrika: Vilniaus pedagoginis universitetas.Apie VPU docentą Algimantą Ažusienį.Lietuvos edukolog... more Rubrika: Vilniaus pedagoginis universitetas.Apie VPU docentą Algimantą Ažusienį.Lietuvos edukologijos universiteta
Vilniaus universiteto Teorinės fizikos ir astronomijos institutasVytauto Didžiojo universitetasŠv... more Vilniaus universiteto Teorinės fizikos ir astronomijos institutasVytauto Didžiojo universitetasŠvietimo akademij
Proceedings of the International Astronomical Union, 2009
We derive photometric metallicities for 56 intermediate-age and old star clusters in the Large Ma... more We derive photometric metallicities for 56 intermediate-age and old star clusters in the Large Magellanic Cloud from the slopes of their red-giant branches in near-infrared color–magnitude diagrams (CMDs). The cluster sample covers the LMC bar and disk to a distance of ~2 kpc from the LMC center. The derived cluster metallicity distribution spans a range of [Fe/H] = +0.0 . . . 1.4 and is similar to the metallicity distribution of field stars. We find that the average cluster metallicities in certain fields of the LMC bar and disk may be different, but there seems to be no compelling evidence for a global cluster metallicity gradient in the LMC.
We derive new calibrations that relate the mean J-Ks photometric colors of red giant branch (RGB)... more We derive new calibrations that relate the mean J-Ks photometric colors of red giant branch (RGB) stars at MKs=-5.5 and -5.0 with cluster metallicity. The new calibrations are derived using a sample of intermediate age (1--8 Gyr) clusters in the Large and Small Magellanic Clouds, with the JHKs photometry taken from the SIRIUS photometric survey of the Magellanic Clouds. Cluster metallicities are literature data, obtained either from the high resolution or infrared calcium triplet spectroscopy of individual RGB stars. We find systematic differences between the RGB color vs. metallicity relations derived in this work and those determined by Valenti et al. (2004), the latter ones obtained for a sample of old Galactic globular clusters. In terms of age, this discrepancy corresponds to ˜ 5 Gyr and therefore can be attributed to the age difference between the two cluster samples used in the derivation of the corresponding RGB color vs. metallicity relations.
Mokytojų rengimo institutasVilniaus universitetasVytauto Didžiojo universiteta
Vytauto Didžiojo universitetasŠvietimo akademij
arXiv: Astrophysics, 2002
Energy distributions of synthetic spectra for Kurucz model atmospheres are compared with observed... more Energy distributions of synthetic spectra for Kurucz model atmospheres are compared with observed energy distributions of metal-deficient stars of the blue horizontal-branch (BHB), F-G-K subdwarf (SD) and G-K giant (MDG) types. The best coincidence of the synthetic and observed energy curves is found for BHB stars. The largest differences are found in the ultraviolet wavelengths for subdwarfs and cool MDGs. The influence of errors of effective temperatures, gravities and metallicities is estimated.