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165 results on '"Szewczyk, O."'

151. The Optical Gravitational Lensing Experiment. Search for Planetary and Low-Luminosity Object Transits in the Galactic Disk. Results of 2001 Campaign - Supplement

Author

Pietrzynski, G., Wyrzykowski, L., Szewczyk, O., Soszynski, I., Kubiak, M., Szymanski, M., Zebrun, K., and Udalski, A.

Subjects
Astrophysics (astro-ph), FOS: Physical sciences, Astrophysics
Abstract

The photometric data collected during 2001 season OGLE-III planetary/low luminosity object transit campaign were reanalyzed with the new transit search technique -- the BLS method by Kovacs, Zucker and Mazeh. In addition to all presented in our original paper transits, additional 13 objects with transiting low-luminosity companions were discovered. We present here a supplement to our original catalog -- the photometric data, light curves and finding charts of all 13 new objects. The model fits to the transit light curves indicate that a few new objects may be Jupiter-sized (R, 7 pages, Latex. Appendix in 'jpg' format. Full resolution pages of Appendix and photometric data presented in the paper are available from the OGLE Internet archive: http://www.astrouw.edu.pl/~ogle or its US mirror http://bulge.princeton.edu/~ogle

152. The Optical Gravitational Lensing Experiment. Variable baseline microlensing events in the Galactic bulge

Author

Wyrzykowski, L., Udalski, A., Mao, S., Kubiak, M., Szymanski, M. K., Pietrzynski, G., Soszynski, I., and Szewczyk, O.

Subjects
Astrophysics (astro-ph), FOS: Physical sciences, Astrophysics
Abstract

We present the first systematic search for microlensing events with variability in their baselines using data from the third phase of the Optical Gravitational Lensing Experiment (OGLE-III). A total of 137 candidates (88 new) was discovered toward the Galactic bulge. Among these, 21 have periodic oscillations in their baselines, 111 are irregular variables and 5 are potential long period detached eclipsing binaries. This is about 10% of the total number of constant baseline events. They are hence quite common and can be regarded as a new type of exotic events, which allow the determination of extra parameters of the events. We show that microlensing of variable stars may allow us to break the degeneracy between the blending parameter and magnification. We note that in some cases variability hidden in the baseline due to strong blending may be revealed in highly magnified events and resemble other exotic microlensing behavior, including planetary deviation. A new system (VEWS) for detecting ongoing variable baseline microlensing events is presented., Comment: The paper with high quality figures is available from http://www.astrouw.edu.pl/~wyrzykow/varbaseevents.ps.gz

153. The optical gravitational lensing experiment. The OGLE-III catalog of variable stars. VI. Delta scuti stars in the large magellanic cloud

Author

Poleski, R., Soszyński, I., Udalski, A., Szymański, M. K., Kubiak, M., Pietrzyński, G., Wyrzykowski, Ł., Szewczyk, O., and Krzysztof Ulaczyk

Subjects
Astrophysics - Solar and Stellar Astrophysics, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Solar and Stellar Astrophysics, FOS: Physical sciences, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics::Galaxy Astrophysics, Solar and Stellar Astrophysics (astro-ph.SR)
Abstract

The sixth part of the OGLE-III catalog of Variable Stars presents \delta Sct pulsators in the Large Magellanic Cloud. Altogether 2786 variable stars were found and amongst them 92 are multi-mode objects, including 67 stars pulsating in the fundamental mode and the first overtone (F/1O), nine double-mode pulsators with various combinations of the first three overtones excited (1O/2O, 2O/3O and 1O/3O pulsators), and two triple mode (F/1O/2O) \delta Sct stars. In total 1490 of stars are marked as uncertain, due to scattered photometry and small amplitudes. For single-mode objects it was not possible to unambiguously identify pulsation mode, however we suggest the most of the single-mode variable stars pulsate in the first overtone., Comment: 16 pages, 7 figures

154. Binary lenses in OGLE III EWS database. Season 2005

Author

Skowron, J., Jaroszyński, M., Udalski, A., Kubiak, M., Szymański, M. K., Pietrzyński, G., Soszyński, I., Szewczyk, O., Wyrzykowski, Ł., and Krzysztof Ulaczyk

Subjects
Astrophysics (astro-ph), FOS: Physical sciences, Astrophysics
Abstract

We present nine new binary lens candidates from OGLE-III Early Warning System database for the season of 2005. We have also found four events interpreted as single mass lensing of double sources. The candidates have been selected by visual light curves inspection. Examining the models of binary lenses in our previous studies (10 caustic crossing events of OGLE-II seasons 1997--1999 and 34 binary lens events of OGLE-III seasons 2002--2004, including one planetary event), in this work and in three publications concerning planetary events of season 2005, we find four cases of extreme mass ratio binaries (q, Comment: 19 pages, 45 figures

155. The Optical Gravitational Lensing Experiment. The OGLE-III Catalog of Variable Stars. V. R Coronae Borealis Stars in the Large Magellanic Cloud

Author

Soszyński, I., Udalski, A., Szymański, M. K., Kubiak, M., Pietrzyński, G., Wyrzykowski, Ł., Szewczyk, O., Krzysztof Ulaczyk, and Poleski, R.

Subjects
Astrophysics - Solar and Stellar Astrophysics, FOS: Physical sciences, Solar and Stellar Astrophysics (astro-ph.SR)
Abstract

The fifth part of the OGLE-III Catalog of Variable Stars presents 23 R CrB (RCB) stars in the Large Magellanic Cloud (LMC). 17 of these objects have been spectroscopically confirmed by previous studies, while 6 stars are new candidates for RCB variables. We publish the VI multi-epoch OGLE photometry for all objects. We use the sample of carbon-rich long-period variables released in the previous part of this catalog to select objects with severe drops in luminosity, i.e. with the DY-Per-like light curves. DY Per stars are often related to R CrB variables. We detect at least 600 candidates for DY Per stars, mostly among dust enshrouded giants. We notice that our candidate DY Per stars form a continuity with other carbon-rich long-period variables, so it seems that DY Per stars do not constitute a separate group of variable stars., Comment: 13 pages, 5 color figures

156. Variability-selected QSO candidates in OGLE-II Galactic bulge fields

Author

Sumi, T., Wozniak, P. R., Eyer, L., Dobrzycki, A., Udalski, A., Szymanski, M. K., Kubiak, M., Pietrzynski, G., Soszynski, I., Zebrun, K., Szewczyk, O., Wyrzykowski, L., Sumi, T., Wozniak, P. R., Eyer, L., Dobrzycki, A., Udalski, A., Szymanski, M. K., Kubiak, M., Pietrzynski, G., Soszynski, I., Zebrun, K., Szewczyk, O., and Wyrzykowski, L.

Abstract

We present 97 QSO candidates in 48 Galactic bulge fields of the Optical Gravitational Lensing Experiment II (OGLE-II) covering ∼11 deg2, which are selected via their variability. We extend light curves of variable objects which were detected in a 3-yr baseline in the OGLE-II variable star catalogue to fourth year. We search for objects that are faint (16 < I0 < 18.5) and slowly variable over 4 yr in this catalogue by using the variogram/structure function. Finding the QSOs in such stellar-crowded and high extinction fields is challenging, but should be useful for the astrometric reference frame. Spectroscopic follow-up observations are required to confirm these QSO candidates. Follow-up observations are being prepared for four of these fields (BUL_SC1, 2, 32 and 45). Follow-up observations for other fields are strongly encouraged. The complete list and light curves of all 97 candidates are available in electronic format at

160. OGLE-2003-BLG-262: Finite-Source Effects from a Point-Mass Lens.

Author

Yoo, Jaiyul, DePoy, D. L., Gal-Yam, A., Gaudi, B. S., Gould, A., Han, C., Lipkin, Y., Maoz, D., Ofek, E. O., Park, B. -G, Pogge, R. W., Collaboration, The μFUN, Udalski, A., Soszyński, I., Wyrzykowski, Ł, Kubiak, M., Szymański, M., Pietrzyński, G., Szewczyk, O., and Żebruń, K.

Published
2004
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162. Limb-darkening measurements for a cool red giant in microlensing event OGLE 2004-BLG-482⋆

Author

Zub, M., Cassan, A., Heyrovský, D., Fouqué, P., Stempels, H. C., Albrow, M. D., Beaulieu, J.-P., Brillant, S., Christie, G. W., Kains, N., Kozłowski, S., Kubas, D., Wambsganss, J., Batista, V., Bennett, D. P., Cook, K., Coutures, C., Dieters, S., Dominik, M., Dominis Prester, D., Donatowicz, J., Greenhill, J., Horne, K., Jørgensen, U. G., Kane, S. R., Marquette, J.-B., Martin, R., Menzies, J., Pollard, K. R., Sahu, K. C., Vinter, C., Williams, A., Gould, A., DePoy, D. L., Gal-Yam, A., Gaudi, B. S., Han, C., Lipkin, Y., Maoz, D., Ofek, E. O., Park, B.-G., Pogge, R. W., McCormick, J., Udalski, A., Szymański, M. K., Kubiak, M., Pietrzyński, G., Soszyński, I., Szewczyk, O., and Wyrzykowski, Ł.

Abstract

Aims.We present a detailed analysis of OGLE 2004-BLG-482, a relatively high-magnification single-lens microlensing event that exhibits clear extended-source effects. These events are relatively rare, but they potentially contain unique information on the stellar atmosphere properties of their source star, as shown in this study.

Published
2011
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163. OGLE 2008–BLG–290: an accurate measurement of the limb darkening of a galactic bulge K Giant spatially resolved by microlensing

Author

Fouqué, P., Heyrovský, D., Dong, S., Gould, A., Udalski, A., Albrow, M. D., Batista, V., Beaulieu, J.-P., Bennett, D. P., Bond, I. A., Bramich, D. M., Calchi Novati, S., Cassan, A., Coutures, C., Dieters, S., Dominik, M., Dominis Prester, D., Greenhill, J., Horne, K., Jørgensen, U. G., Kozłowski, S., Kubas, D., Lee, C.-H., Marquette, J.-B., Mathiasen, M., Menzies, J., Monard, L. A. G., Nishiyama, S., Papadakis, I., Street, R., Sumi, T., Williams, A., Yee, J. C., Brillant, S., Caldwell, J. A. R., Cole, A., Cook, K. H., Donatowicz, J., Kains, N., Kane, S. R., Martin, R., Pollard, K. R., Sahu, K. C., Tsapras, Y., Wambsganss, J., DePoy, D. L., Gaudi, B. S., Han, C., Lee, C.-U., Park, B.-G., Kubiak, M., Szymański, M. K., Pietrzyński, G., Soszyński, I., Szewczyk, O., Ulaczyk, K., Abe, F., Fukui, A., Furusawa, K., Gilmore, A. C., Hearnshaw, J. B., Itow, Y., Kamiya, K., Kilmartin, P. M., Korpela, A. V., Lin, W., Ling, C. H., Masuda, K., Matsubara, Y., Miyake, N., Muraki, Y., Nagaya, M., Ohnishi, K., Okumura, T., Perrott, Y., Rattenbury, N. J., Saito, To., Sako, T., Sato, S., Skuljan, L., Sullivan, D., Sweatman, W., Tristram, P. J., Allan, A., Bode, M. F., Burgdorf, M. J., Clay, N., Fraser, S. N., Hawkins, E., Kerins, E., Lister, T. A., Mottram, C. J., Saunders, E. S., Snodgrass, C., Steele, I. A., Anguita, T., Bozza, V., Harpsøe, K., Hinse, T. C., Hundertmark, M., Kjærgaard, P., Liebig, C., Mancini, L., Masi, G., Rahvar, S., Ricci, D., Scarpetta, G., Southworth, J., Surdej, J., Thöne, C. C., Riffeser, A., and Seitz, S.

Abstract

Context. Not only is gravitational microlensing a successful tool for discovering distant exoplanets, but it also enables characterization of the lens and source stars involved in the lensing event.Aims. In high-magnification events, the lens caustic may cross over the source disk, which allows determination of the angular size of the source and measurement of its limb darkening.Methods. When such extended-source effects appear close to maximum magnification, the resulting light curve differs from the characteristic Paczyński point-source curve. The exact shape of the light curve close to the peak depends on the limb darkening of the source. Dense photometric coverage permits measurement of the respective limb-darkening coefficients.Results. In the case of the microlensing event OGLE 2008-BLG-290, the K giant source star reached a peak magnification at about 100. Thirteen different telescopes have covered this event in eight different photometric bands. Subsequent light-curve analysis yielded measurements of linear limb-darkening coefficients of the source in six photometric bands. The best-measured coefficients lead to an estimate of the source effective temperature of about 4700$^{+100}_{-200}$K. However, the photometric estimate from colour-magnitude diagrams favours a cooler temperature of 4200 ±100 K.Conclusions. Because the limb-darkening measurements, at least in the CTIO/SMARTS2 $V_\mathrm{s}$- and $I_\mathrm{s}$-bands, are among the most accurate obtained, the above disagreement needs to be understood. A solution is proposed, which may apply to previous events where such a discrepancy also appeared.

Published
2010

164. Molecular design, synthesis and anticancer activity of new thiopyrano[2,3-d]thiazoles based on 5-hydroxy-1,4-naphthoquinone (juglone).

Author

Ivasechko I, Lozynskyi A, Senkiv J, Roszczenko P, Kozak Y, Finiuk N, Klyuchivska O, Kashchak N, Manko N, Maslyak Z, Lesyk D, Karkhut A, Polovkovych S, Czarnomysy R, Szewczyk O, Kozytskiy A, Karpenko O, Khyluk D, Gzella A, Bielawski K, Bielawska A, Dzubak P, Gurska S, Hajduch M, Stoika R, and Lesyk R

Subjects
Humans, Animals, Mice, Thiazoles chemistry, Doxorubicin pharmacology, Drug Screening Assays, Antitumor, Molecular Structure, Molecular Docking Simulation, Structure-Activity Relationship, Cell Proliferation, Cell Line, Tumor, Antineoplastic Agents chemistry, Naphthoquinones pharmacology
Abstract

A series of 11-substituted 9-hydroxy-3,5,10,11-tetrahydro-2H-benzo[6,7]thiochromeno[2,3-d][1,3]thiazole-2,5,10-triones 3.1-3.13 were synthesized via hetero-Diels-Alder reaction of 5-ene-4-thioxo-2-thiazolidinones and 5-hydroxy-1,4-naphthoquinone (juglone). The structure of newly synthesized compounds was established by means of spectral data and a single-crystal X-ray diffraction analysis. The synthesized compounds were tested on a panel of cell lines representing different types of cancer as well as normal and pseudonormal cells and peripheral human blood lymphocytes. Compound 3.10 was found to be the most active derivative, exhibiting a cytotoxic effect similar to doxorubicin's one (IC 50 ranged from 0.6 to 5.98 μM), but less toxic to normal and pseudonormal cells. All synthesized compounds were able to interact with DNA, although their anticancer activity did not correlate with the potency of interaction with DNA. The status of p53 in colorectal cancer cells correlated with the activity of the synthesized derivatives 3.1, 3.7, and 3.10. Compound 3.10 did not have an acute toxic effect on the body of С57BL/6 mice, unlike the well-known anticancer drug doxorubicin, which was used as a positive control. The injection of 3.10 (20 mg/kg) to mice had no effect on the counts of leukocytes, erythrocytes, platelets and hemoglobin level in their blood, in contrast to doxorubicin, which caused anemia and leukopenia, indicating bio-tolerance of 3.10in vivo., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier Masson SAS.. All rights reserved.)

Published
2023
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165. All-normal dispersion supercontinuum vs frequency-shifted solitons pumped at 1560 nm as seed sources for thulium-doped fiber amplifiers.

Author

Szewczyk O, Tarnowski K, Głuszek A, Szulc D, Stefańska K, Mergo P, and Soboń G

Abstract

We present a direct comparison between two types of femtosecond 2 µm sources used for seeding of an ultrafast thulium-doped fiber amplifier based on all-normal dispersion supercontinuum and soliton self-frequency shift. Both nonlinear effects were generated in microstructured silica fibers, pumped with low-power femtosecond pulses at 1.56 µm originating from an erbium-doped fiber laser. We performed a full characterization of both nonlinear processes, including their shot-to-shot stability, phase coherence, and relative intensity noise. The results revealed that the solitons show comparable performance to supercontinuum in terms of relative intensity noise and shot-to-shot stability, despite the anomalous dispersion regime. Both sources can be successfully used as seeds for Tm-doped fiber amplifiers as an alternative to Tm-doped oscillators. The results show that the sign of chromatic dispersion of the fiber is not crucial for obtaining a stable, high-quality, and low-noise spectral conversion process when pumped with sub-50 fs laser pulses.

Published
2021
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