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34 results on '"Fagas, M."'

1. Interplay between pulsations and mass loss in the blue supergiant 55 Cygnus = HD 198478

Author

Kraus, M., Haucke, M., Cidale, L. S., Venero, R. O. J., Nickeler, D. H., Nemeth, P., Niemczura, E., Tomic, S., Aret, A., Kubat, J., Kubatova, B., Oksala, M. E., Cure, M., Kaminski, K., Dimitrov, W., Fagas, M., and Polinska, M.

Subjects
Astrophysics - Solar and Stellar Astrophysics
Abstract

Blue supergiant stars are known to display photometric and spectroscopic variability that is suggested to be linked to stellar pulsations. Pulsational activity in massive stars strongly depends on the star's evolutionary stage and is assumed to be connected with mass-loss episodes, the appearance of macroturbulent line broadening, and the formation of clumps in the wind. To investigate a possible interplay between pulsations and mass-loss, we carried out an observational campaign of the supergiant 55 Cyg over a period of five years to search for photospheric activity and cyclic mass-loss variability in the stellar wind. We modeled the H, He I, Si II and Si III lines using the nonlocal thermal equilibrium atmosphere code FASTWIND and derived the photospheric and wind parameters. In addition, we searched for variability in the intensity and radial velocity of photospheric lines and performed a moment analysis of the line profiles to derive frequencies and amplitudes of the variations. The Halpha line varies with time in both intensity and shape, displaying various types of profiles: P Cygni, pure emission, almost complete absence, and double or multiple peaked. The star undergoes episodes of variable mass-loss rates that change by a factor of 1.7-2 on different timescales. We also observe changes in the ionization rate of Si II and determine a multiperiodic oscillation in the He I absorption lines, with periods ranging from a few hours to 22.5 days. We interpret the photospheric line variations in terms of oscillations in p-, g-, and strange modes. We suggest that these pulsations can lead to phases of enhanced mass loss. Furthermore, they can mislead the determination of the stellar rotation. We classify the star as a post-red supergiant, belonging to the group of alpha Cyg variables., Comment: 20 pages, 18 figures, 3 tables, accepted to Astronomy & Astrophysics

Published
2015
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2. Spectroscopic survey of Kepler stars. I. HERMES/Mercator observations of A- and F-type stars

Author

Niemczura, E., Murphy, S. J., Smalley, B., Uytterhoeven, K., Pigulski, A., Lehmann, H., Bowman, D. M., Catanzaro, G., van Aarle, E., Bloemen, S., Briquet, M., De Cat, P., Drobek, D., Eyer, L., Gameiro, J. F. S., Gorlova, N., Kaminski, K., Lampens, P., Marcos-Arenal, P., Papics, P. I., Vandenbussche, B., Van Winckel, H., Steslicki, M., and Fagas, M.

Subjects
Astrophysics - Solar and Stellar Astrophysics
Abstract

The Kepler space mission provided near-continuous and high-precision photometry of about 207,000 stars, which can be used for asteroseismology. However, for successful seismic modelling it is equally important to have accurate stellar physical parameters. Therefore, supplementary ground-based data are needed. We report the results of the analysis of high-resolution spectroscopic data of A- and F-type stars from the Kepler field, which were obtained with the HERMES spectrograph on the Mercator telescope. We determined spectral types, atmospheric parameters and chemical abundances for a sample of 117 stars. Hydrogen Balmer, Fe I, and Fe II lines were used to derive effective temperatures, surface gravities, and microturbulent velocities. We determined chemical abundances and projected rotational velocities using a spectrum synthesis technique. The atmospheric parameters obtained were compared with those from the Kepler Input Catalogue (KIC), confirming that the KIC effective temperatures are underestimated for A stars. Effective temperatures calculated by spectral energy distribution fitting are in good agreement with those determined from the spectral line analysis. The analysed sample comprises stars with approximately solar chemical abundances, as well as chemically peculiar stars of the Am, Ap, and Lambda Boo types. The distribution of the projected rotational velocity, Vsini, is typical for A and F stars and ranges from 8 to about 280 km/s, with a mean of 134 km/s., Comment: Accepted for publication in MNRAS (22 pages, 6 tables)

Published
2015
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3. A search for pulsations in the HgMn star HD 45975 with CoRoT photometry and ground-based spectroscopy

Author

Morel, T., Briquet, M., Auvergne, M., Alecian, G., Ghazaryan, S., Niemczura, E., Fossati, L., Lehmann, H., Hubrig, S., Ulusoy, C., Damerdji, Y., Rainer, M., Poretti, E., Borsa, F., Scardia, M., Schmid, V. S., Van Winckel, H., De Smedt, K., Papics, P. I., Gameiro, J. F., Waelkens, C., Fagas, M., Kaminski, K., Dimitrov, W., Baglin, A., Michel, E., Dumortier, L., Fremat, Y., Hensberge, H., Jorissen, A., and Van Eck, S.

Subjects
Astrophysics - Solar and Stellar Astrophysics
Abstract

The existence of pulsations in HgMn stars is still being debated. To provide the first unambiguous observational detection of pulsations in this class of chemically peculiar objects, the bright star HD 45975 was monitored for nearly two months by the CoRoT satellite. Independent analyses of the light curve provides evidence of monoperiodic variations with a frequency of 0.7572 c/d and a peak-to-peak amplitude of ~2800 ppm. Multisite, ground-based spectroscopic observations overlapping the CoRoT observations show the star to be a long-period, single-lined binary. Furthermore, with the notable exception of mercury, they reveal the same periodicity as in photometry in the line moments of chemical species exhibiting strong overabundances (e.g., Mn and Y). In contrast, lines of other elements do not show significant variations. As found in other HgMn stars, the pattern of variability consists in an absorption bump moving redwards across the line profiles. We argue that the photometric and spectroscopic changes are more consistent with an interpretation in terms of rotational modulation of spots at the stellar surface. In this framework, the existence of pulsations producing photometric variations above the ~50 ppm level is unlikely in HD 45975. This provides strong constraints on the excitation/damping of pulsation modes in this HgMn star., Comment: Accepted for publication in A&A, 14 pages, 15 colour figures (revised version after language editing)

Published
2013
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4. mu Eridani from MOST and from the ground: an orbit, the SPB component's fundamental parameters, and the SPB frequencies

Author

Jerzykiewicz, M., Lehmann, H., Niemczura, E., Molenda-Żakowicz, J., Dymitrov, W., Fagas, M., Guenther, D. B., Hartmann, M., Hrudková, M., Kamiński, K., Moffat, A. F. J., Kuschnig, R., Leto, G., Matthews, J. M., Rowe, J. F., Ruciński, S. M., Sasselov, D., and Weiss, W. W.

Subjects
Astrophysics - Solar and Stellar Astrophysics, J.2
Abstract

MOST time-series photometry of mu Eri, an SB1 eclipsing binary with a rapidly-rotating SPB primary, is reported and analyzed. The analysis yields a number of sinusoidal terms, mainly due to the intrinsic variation of the primary, and the eclipse light-curve. New radial-velocity observations are presented and used to compute parameters of a spectroscopic orbit. Frequency analysis of the radial-velocity residuals from the spectroscopic orbital solution fails to uncover periodic variations with amplitudes greater than 2 km/s. A Rossiter-McLaughlin anomaly is detected from observations covering ingress. From archival photometric indices and the revised Hipparcos parallax we derive the primary's effective temperature, surface gravity, bolometric correction, and the luminosity. An analysis of a high signal-to-noise spectrogram yields the effective temperature and surface gravity in good agreement with the photometric values. From the same spectrogram, we determine the abundance of He, C, N, O, Ne, Mg, Al, Si, P, S, Cl, and Fe. The eclipse light-curve is solved by means of EBOP. For a range of mass of the primary, a value of mean density, very nearly independent of assumed mass, is computed from the parameters of the system. Contrary to a recent report, this value is approximately equal to the mean density obtained from the star's effective temperature and luminosity. Despite limited frequency resolution of the MOST data, we were able to recover the closely-spaced SPB frequency quadruplet discovered from the ground in 2002-2004. The other two SPB terms seen from the ground were also recovered. Moreover, our analysis of the MOST data adds 15 low-amplitude SPB terms with frequencies ranging from 0.109 c/d to 2.786 c/d., Comment: 16 pages, 15 figures, accepted for MNRAS

Published
2013
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5. Asteroids' physical models from combined dense and sparse photometry and scaling of the YORP effect by the observed obliquity distribution

Author

Hanuš, J., Ďurech, J., Brož, M., Marciniak, A., Warner, B. D., Pilcher, F., Stephens, R., Behrend, R., Carry, B., Čapek, D., Antonini, P., Audejean, M., Augustesen, K., Barbotin, E., Baudouin, P., Bayol, A., Bernasconi, L., Borczyk, W., Bosch, J. -G., Brochard, E., Brunetto, L., Casulli, S., Cazenave, A., Charbonnel, S., Christophe, B., Colas, F., Coloma, J., Conjat, M., Cooney, W., Correira, H., Cotrez, V., Coupier, A., Crippa, R., Cristofanelli, M., Dalmas, Ch., Danavaro, C., Demeautis, C., Droege, T., Durkee, R., Esseiva, N., Esteban, M., Fagas, M., Farroni, G., Fauvaud, M., Fauvaud, S., Del Freo, F., Garcia, L., Geier, S., Godon, C., Grangeon, K., Hamanowa, H., Heck, N., Hellmich, S., Higgins, D., Hirsch, R., Husarik, M., Itkonen, T., Jade, O., Kamiński, K., Kankiewicz, P., Klotz, A., Koff, R. A., Kryszczyńska, A., Kwiatkowski, T., Laffont, A., Leroy, A., Lecacheux, J., Leonie, Y., Leyrat, C., Manzini, F., Martin, A., Masi, G., Matter, D., Michałowski, J., Michałowski, M. J., Michałowski, T., Michelet, J., Michelsen, R., Morelle, E., Mottola, S., Naves, R., Nomen, J., Oey, J., Ogloza, W., Oksanen, A., Oszkiewicz, D., Pääkkönen, P., Paiella, M., Pallares, H., Paulo, J., Pavic, M., Payet, B., Polińska, M., Polishook, D., Poncy, R., Revaz, Y., Rinner, C., Rocca, M., Roche, A., Romeuf, D., Roy, R., Saguin, H., Salom, P. A., Sanchez, S., Santacana, G., Santana-Ros, T., Sareyan, J. -P., Sobkowiak, K., Sposetti, S., Starkey, D., Stoss, R., Strajnic, J., Teng, J. -P., Tregon, B., Vagnozzi, A., Velichko, F. P., Waelchli, N., Wagrez, K., and Wücher, H.

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

The larger number of models of asteroid shapes and their rotational states derived by the lightcurve inversion give us better insight into both the nature of individual objects and the whole asteroid population. With a larger statistical sample we can study the physical properties of asteroid populations, such as main-belt asteroids or individual asteroid families, in more detail. Shape models can also be used in combination with other types of observational data (IR, adaptive optics images, stellar occultations), e.g., to determine sizes and thermal properties. We use all available photometric data of asteroids to derive their physical models by the lightcurve inversion method and compare the observed pole latitude distributions of all asteroids with known convex shape models with the simulated pole latitude distributions. We used classical dense photometric lightcurves from several sources and sparse-in-time photometry from the U.S. Naval Observatory in Flagstaff, Catalina Sky Survey, and La Palma surveys (IAU codes 689, 703, 950) in the lightcurve inversion method to determine asteroid convex models and their rotational states. We also extended a simple dynamical model for the spin evolution of asteroids used in our previous paper. We present 119 new asteroid models derived from combined dense and sparse-in-time photometry. We discuss the reliability of asteroid shape models derived only from Catalina Sky Survey data (IAU code 703) and present 20 such models. By using different values for a scaling parameter cYORP (corresponds to the magnitude of the YORP momentum) in the dynamical model for the spin evolution and by comparing synthetics and observed pole-latitude distributions, we were able to constrain the typical values of the cYORP parameter as between 0.05 and 0.6., Comment: Accepted for publication in A&A, January 15, 2013

Published
2013
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6. Four unusual novae observed in Torun: V2362 Cyg, V2467 Cyg, V458 Vul, V2491 Cyg

Author

Ragan, E., Mikolajewski, M., Tomov, T., Dimitrow, W., Fagas, M., Kwiatkowski, T., Schwarzenberg-Czerny, A., Buil, Ch., Swierczynski, E., Brozek, T., Cikala, M., Czart, K., Fidos, A., Frackowiak, S., Galan, C., Karska, A., Klosinska, M., Lewandowski, M., Radomski, T., Rozanski, P., Wiecek, M., Wychudzki, P., Zajczyk, A., and Zielinska, M.

Subjects
Astrophysics - Solar and Stellar Astrophysics
Abstract

We present photometric and spectral observation for four novae: V2362 Cyg, V2467 Cyg, V458 Vul, V2491 Cyg. All objects belongs to the "fast novae" class. For these stars we observed different departures from a typical behavior in the light curve and spectrum., Comment: 4 pages, 4 figures

Published
2010

7. Absolute properties of the main-sequence eclipsing binary FM Leo

Author

Ratajczak, M., Kwiatkowski, T., Schwarzenberg-Czerny, A., Dimitrov, W., Konacki, M., Helminiak, K. G., Bartczak, P., Fagas, M., Kaminski, K., Kankiewicz, P., Borczyk, W., and Rozek, A.

Subjects
Astrophysics - Solar and Stellar Astrophysics
Abstract

First spectroscopic and new photometric observations of the eclipsing binary FM Leo are presented. The main aims were to determine orbital and stellar parameters of two components and their evolutionary stage. First spectroscopic observations of the system were obtained with DDO and PST spectrographs. The results of the orbital solution from radial velocity curves are combined with those derived from the light-curve analysis (ASAS-3 photometry and supplementary observations of eclipses with 1 m and 0.35 m telescopes) to derive orbital and stellar parameters. JKTEBOP, Wilson-Devinney binary modelling codes and a two-dimensional cross-correlation (TODCOR) method were applied for the analysis. We find the masses to be M_1 = 1.318 $\pm$ 0.007 and M_2 = 1.287 $\pm$ 0.007 M_sun, the radii to be R_1 = 1.648 $\pm$ 0.043 and R_2 = 1.511 $\pm$ 0.049 R_sun for primary and secondary stars, respectively. The evolutionary stage of the system is briefly discussed by comparing physical parameters with current stellar evolution models. We find the components are located at the main sequence, with an age of about 3 Gyr., Comment: 5 pages, 4 figures, to appear in MNRAS

Published
2009
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8. V440 Per: the longest period overtone Cepheid

Author

Baranowski, R., Smolec, R., Dimitrov, W., Kwiatkowski, T., Schwarzenberg-Czerny, A., Bartczak, P., Fagas, M., Borczyk, W., Kaminski, K., Moskalik, P., Ratajczak, R., and Rozek, A.

Subjects
Astrophysics - Solar and Stellar Astrophysics, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

V440 Per is a Population I Cepheid with the period of 7.57 day and low amplitude, almost sinusoidal light and radial velocity curves. With no reliable data on the 1st harmonic, its pulsation mode identification remained controversial. We obtained a radial velocity curve of V440 Per with our new high precision and high throughput Poznan Spectroscopic Telescope. Our data reach the accuracy of 130 m/s per individual measurement and yield a secure detection of the 1st harmonic with the amplitude of A_2= 140+/- 15 m/s. The velocity Fourier phase \phi_21 of V440 Per is inconsistent at the 7.25 \sigma level with those of the fundamental mode Cepheids, implying that the star must be an overtone Cepheid, as originally proposed by Kienzle et al.(1999). Thus, V440 Per becomes the longest period Cepheid with the securely established overtone pulsations. We show, that the convective nonlinear pulsation hydrocode can reproduce the Fourier parameters of V440 Per very well. Requirement to match the observed properties of V440 Per constrains free parameters of the dynamical convection model used in the pulsation calculations, in particular the radiative losses parameter., Comment: Submitted to MNRAS

Published
2009
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9. Spectroscopic survey of Kepler stars.(a similar to...) I. HERMES/Mercator observations of A- and F-type stars

Author

Niemczura, E, Murphy, SJ, Smalley, B, Uytterhoeven, K, Pigulski, A, Lehmann, H, Bowman, DM, Catanzaro, G, van Aarle, E, Bloemen, S, Briquet, M, De Cat, P, Drobek, D, Eyer, L, Gameiro, JFS, Gorlova, N, Kaminski, K, Lampens, P, Marcos-Arenal, P, Papics, PI, Vandenbussche, B, Van Winckel, H, Steslicki, M, and Fagas, M

Subjects
abundances [stars], chemically peculiar [stars], general [stars], rotation [stars], Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics::Earth and Planetary Astrophysics, QC, Astrophysics::Galaxy Astrophysics, QB
Abstract

The Kepler space mission provided near-continuous and high-precision photometry of about 207 000 stars, which can be used for asteroseismology. However, for successful seismic modeling it is equally important to have accurate stellar physical parameters. Therefore, supplementary ground-based data are needed. We report the results of the analysis of high-resolution spectroscopic data of A- and F-type stars from the Kepler field, which were obtained with the HERMES spectrograph on the Mercator telescope. We determined spectral types, atmospheric parameters and chemical abundances for a sample of 117 stars. Hydrogen Balmer, Fe i, and Fe ii lines were used to derive effective temperatures, surface gravities, and microturbulent velocities. We determined chemical abundances and projected rotational velocities using a spectrum synthesis technique. The atmospheric parameters obtained were compared with those from the Kepler Input Catalogue (KIC), confirming that the KIC effective temperatures are underestimated for A stars. Effective temperatures calculated by spectral energy distribution fitting are in good agreement with those determined from the spectral line analysis. The analysed sample comprises stars with approximately solar chemical abundances, as well as chemically peculiar stars of the Am, Ap, and λ Boo types. The distribution of the projected rotational velocity, vsin i, is typical for A and F stars and ranges from 8 to about 280 km s−1, with a mean of 134 km s−1. Accepted for publication in MNRAS (22 pages, 6 tables) ispartof: Monthly Notices of the Royal Astronomical Society vol:450 issue:3 pages:2764-2783 status: published

Published
2015

10. Do Slivan states exist in the Flora family?

Author

Kryszczyńska, A., Colas, F., Polińska, M., Hirsch, R., Ivanova, V., Apostolovska, G., Bilkina, B., Velichko, F., Kwiatkowski, T., Kankiewicz, P., Vachier, F., Umlenski, V., Michałowski, T., Marciniak, A., Maury, A., Kamiński, K., Fagas, M., Dimitrov, W., Borczyk, W., Sobkowiak, K., Lecacheux, J., Behrend, R., Klotz, A., Bernasconi, L., Crippa, R., Manzini, F., Poncy, R., Antonini, P., Oszkiewicz, D., Santana-Ros, T., Institut de Mécanique Céleste et de Calcul des Ephémérides (IMCCE), Centre National de la Recherche Scientifique (CNRS)-Université de Lille-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Observatoire de Paris, Université Paris sciences et lettres (PSL), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS]Physics [physics], Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

International audience; Context. Recent studies have uncovered evidence that the statistical properties of asteroids' physical parameters are a fundamental source of information on the physics of their collisions and evolution. The analysis of the spin rates and spin vector distributions helps us to understand the role of various known and new effects. The alignment of spin vectors and the correlation of spin rates are for the first time observed for ten members of the Koronis family. These unexpected non-random orientations of the spin axes and correlations of the spin rates, now known as Slivan states are interpreted in terms of a YORP effect and spin-orbit resonances. Aims. To study non-gravitational-effects, there appears to be a need for new observational campaigns devoted to determining the physical parameters of the asteroid families. Methods. We analysed the photometric observations of the asteroids, which are the most efficient method of studying asteroid physical parameters. Results. We report the results of a ten-year long observational survey of the light variations of objects in the Flora region. We present 544 individual lightcurves of 55 objects obtained at various observing geometries. These lightcurves yield new or refined synodic periods for 32 asteroids and confirm period determinations for 23 objects in our sample. To improve the statistics of the Flora family objects, we add to our dataset 91 objects with reliably determined periods. The distribution of rotation rates for the Flora family is non-Maxwellian at a confidence level of 94% and different from those of the Koronis and the Hungaria families. It seems to be consistent with the long-term influence of the YORP effect, although it is also indicative of a younger age for the Flora family compared to both the Koronis and the Hungaria families. Conclusions. Our new data is a foundation for the spin vector and shape determinations that will be the objectives of the second paper of the series. We search for spin vector and spin periods correlations in order to determine whether Slivan states exist in the Flora family.

Published
2012

11. VizieR Online Data Catalog: Light curves of Flora region asteroids (Kryszczynska+, 2012)

Author

Kryszczynska, A., Colas, F., Polinska, M., Hirsch, R., Ivanova, V., Apostolovska, G., Bilkina, B., Velichko, F. P., Kwiatkowski, T., Kankiewicz, P., Vachier, F., Umlenski, V., Michalowski, T., Marciniak, A., Maury, A., Kaminski, K., Fagas, M., Dimitrov, W., Borczyk, W., Sobkowiak, K., Lecacheux, J., Behrend, R., Klotz, A., Bernasconi, L., Crippa, R., Manzini, F., Poncy, R., Antonini, P., Oszkiewicz, D., Santana-Ros, T., and bibliotheque, la.

Subjects
Photometry: CCD, Minor planets, [PHYS.ASTR] Physics [physics]/Astrophysics [astro-ph], Solar system
Abstract

The files contain asteroid brightness, aspect data and observing information for corresponding date. These files were used for obtaining synodic period rotation. Individual lightcurves within a files are identified with a light curve number, all lightcurves are relative. (2 data files).

Published
2012

12. Interplay between pulsations and mass loss in the blue supergiant 55 Cygnus = HD 198 478

Author

Kraus, M., primary, Haucke, M., additional, Cidale, L. S., additional, Venero, R. O. J., additional, Nickeler, D. H., additional, Németh, P., additional, Niemczura, E., additional, Tomić, S., additional, Aret, A., additional, Kubát, J., additional, Kubátová, B., additional, Oksala, M. E., additional, Curé, M., additional, Kamiński, K., additional, Dimitrov, W., additional, Fagas, M., additional, and Polińska, M., additional

Published
2015
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13. Spectroscopic survey of Kepler stars.★ I. HERMES/Mercator observations of A- and F-type stars

Author

Niemczura, E., primary, Murphy, S. J., additional, Smalley, B., additional, Uytterhoeven, K., additional, Pigulski, A., additional, Lehmann, H., additional, Bowman, D. M., additional, Catanzaro, G., additional, van Aarle, E., additional, Bloemen, S., additional, Briquet, M., additional, De Cat, P., additional, Drobek, D., additional, Eyer, L., additional, Gameiro, J. F. S., additional, Gorlova, N., additional, Kamiński, K., additional, Lampens, P., additional, Marcos-Arenal, P., additional, Pápics, P. I., additional, Vandenbussche, B., additional, Van Winckel, H., additional, Stȩślicki, M., additional, and Fagas, M., additional

Published
2015
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14. V342 Andromedae B is an eccentric-orbit eclipsing binary

Author

Dimitrov, W., primary, Kamiński, K., additional, Lehmann, H., additional, Ligęza, P., additional, Fagas, M., additional, Bagińska, P., additional, Kwiatkowski, T., additional, Bąkowska, K., additional, Kowalczyk, A., additional, Polińska, M., additional, Bartczak, P., additional, Przybyszewska, A., additional, Kruszewski, A., additional, Kurzawa, K., additional, and Schwarzenberg-Czerny, A., additional

Published
2015
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17. A search for pulsations in the HgMn star HD 45975 with CoRoT photometry and ground-based spectroscopy

Author

Morel, T., primary, Briquet, M., additional, Auvergne, M., additional, Alecian, G., additional, Ghazaryan, S., additional, Niemczura, E., additional, Fossati, L., additional, Lehmann, H., additional, Hubrig, S., additional, Ulusoy, C., additional, Damerdji, Y., additional, Rainer, M., additional, Poretti, E., additional, Borsa, F., additional, Scardia, M., additional, Schmid, V. S., additional, Van Winckel, H., additional, De Smedt, K., additional, Pápics, P. I., additional, Gameiro, J. F., additional, Waelkens, C., additional, Fagas, M., additional, Kamiński, K., additional, Dimitrov, W., additional, Baglin, A., additional, Michel, E., additional, Dumortier, L., additional, Frémat, Y., additional, Hensberge, H., additional, Jorissen, A., additional, and Van Eck, S., additional

Published
2013
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18. Global Astrophysical Telescope System – GATS

Author

Polińska, M., primary, Kamiński, K., additional, Dimitrov, W., additional, Fagas, M., additional, Borczyk, W., additional, Kwiatkowski, T., additional, Baranowski, R., additional, Bartczak, P., additional, and Schwarzenberg–Czerny, A., additional

Published
2013
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19. μ Eridani from MOST★ and from the ground: an orbit, the SPB component's fundamental parameters and the SPB frequencies

Author

Jerzykiewicz, M., primary, Lehmann, H., additional, Niemczura, E., additional, Molenda-Żakowicz, J., additional, Dymitrov, W., additional, Fagas, M., additional, Guenther, D. B., additional, Hartmann, M., additional, Hrudková, M., additional, Kamiński, K., additional, Moffat, A. F. J., additional, Kuschnig, R., additional, Leto, G., additional, Matthews, J. M., additional, Rowe, J. F., additional, Ruciński, S. M., additional, Sasselov, D., additional, and Weiss, W. W., additional

Published
2013
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20. Asteroids’ physical models from combined dense and sparse photometry and scaling of the YORP effect by the observed obliquity distribution

Author

Hanuš, J., primary, Ďurech, J., additional, Brož, M., additional, Marciniak, A., additional, Warner, B. D., additional, Pilcher, F., additional, Stephens, R., additional, Behrend, R., additional, Carry, B., additional, Čapek, D., additional, Antonini, P., additional, Audejean, M., additional, Augustesen, K., additional, Barbotin, E., additional, Baudouin, P., additional, Bayol, A., additional, Bernasconi, L., additional, Borczyk, W., additional, Bosch, J.-G., additional, Brochard, E., additional, Brunetto, L., additional, Casulli, S., additional, Cazenave, A., additional, Charbonnel, S., additional, Christophe, B., additional, Colas, F., additional, Coloma, J., additional, Conjat, M., additional, Cooney, W., additional, Correira, H., additional, Cotrez, V., additional, Coupier, A., additional, Crippa, R., additional, Cristofanelli, M., additional, Dalmas, Ch., additional, Danavaro, C., additional, Demeautis, C., additional, Droege, T., additional, Durkee, R., additional, Esseiva, N., additional, Esteban, M., additional, Fagas, M., additional, Farroni, G., additional, Fauvaud, M., additional, Fauvaud, S., additional, Del Freo, F., additional, Garcia, L., additional, Geier, S., additional, Godon, C., additional, Grangeon, K., additional, Hamanowa, H., additional, Heck, N., additional, Hellmich, S., additional, Higgins, D., additional, Hirsch, R., additional, Husarik, M., additional, Itkonen, T., additional, Jade, O., additional, Kamiński, K., additional, Kankiewicz, P., additional, Klotz, A., additional, Koff, R. A., additional, Kryszczyńska, A., additional, Kwiatkowski, T., additional, Laffont, A., additional, Leroy, A., additional, Lecacheux, J., additional, Leonie, Y., additional, Leyrat, C., additional, Manzini, F., additional, Martin, A., additional, Masi, G., additional, Matter, D., additional, Michałowski, J., additional, Michałowski, M. J., additional, Michałowski, T., additional, Michelet, J., additional, Michelsen, R., additional, Morelle, E., additional, Mottola, S., additional, Naves, R., additional, Nomen, J., additional, Oey, J., additional, Ogłoza, W., additional, Oksanen, A., additional, Oszkiewicz, D., additional, Pääkkönen, P., additional, Paiella, M., additional, Pallares, H., additional, Paulo, J., additional, Pavic, M., additional, Payet, B., additional, Polińska, M., additional, Polishook, D., additional, Poncy, R., additional, Revaz, Y., additional, Rinner, C., additional, Rocca, M., additional, Roche, A., additional, Romeuf, D., additional, Roy, R., additional, Saguin, H., additional, Salom, P. A., additional, Sanchez, S., additional, Santacana, G., additional, Santana-Ros, T., additional, Sareyan, J.-P., additional, Sobkowiak, K., additional, Sposetti, S., additional, Starkey, D., additional, Stoss, R., additional, Strajnic, J., additional, Teng, J.-P., additional, Trégon, B., additional, Vagnozzi, A., additional, Velichko, F. P., additional, Waelchli, N., additional, Wagrez, K., additional, and Wücher, H., additional

Published
2013
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21. Photometry and models of selected main belt asteroids

Author

Marciniak, A., primary, Bartczak, P., additional, Santana-Ros, T., additional, Michałowski, T., additional, Antonini, P., additional, Behrend, R., additional, Bembrick, C., additional, Bernasconi, L., additional, Borczyk, W., additional, Colas, F., additional, Coloma, J., additional, Crippa, R., additional, Esseiva, N., additional, Fagas, M., additional, Fauvaud, M., additional, Fauvaud, S., additional, Ferreira, D. D. M., additional, Hein Bertelsen, R. P., additional, Higgins, D., additional, Hirsch, R., additional, Kajava, J. J. E., additional, Kamiński, K., additional, Kryszczyńska, A., additional, Kwiatkowski, T., additional, Manzini, F., additional, Michałowski, J., additional, Michałowski, M. J., additional, Paschke, A., additional, Polińska, M., additional, Poncy, R., additional, Roy, R., additional, Santacana, G., additional, Sobkowiak, K., additional, Stasik, M., additional, Starczewski, S., additional, Velichko, F., additional, Wucher, H., additional, and Zafar, T., additional

Published
2012
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22. Photometry and models of selected main belt asteroids

Author

Marciniak, A., primary, Michałowski, T., additional, Polińska, M., additional, Bartczak, P., additional, Hirsch, R., additional, Sobkowiak, K., additional, Kamiński, K., additional, Fagas, M., additional, Behrend, R., additional, Bernasconi, L., additional, Bosch, J.-G., additional, Brunetto, L., additional, Choisay, F., additional, Coloma, J., additional, Conjat, M., additional, Farroni, G., additional, Manzini, F., additional, Pallares, H., additional, Roy, R., additional, Kwiatkowski, T., additional, Kryszczyńska, A., additional, Rudawska, R., additional, Starczewski, S., additional, Michałowski, J., additional, and Ludick, P., additional

Published
2011
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23. Absolute properties of the main-sequence eclipsing binary FM Leo

Author

Ratajczak, M., primary, Kwiatkowski, T., additional, Schwarzenberg-Czerny, A., additional, Dimitrov, W., additional, Konacki, M., additional, Hełminiak, K. G., additional, Bartczak, P., additional, Fagas, M., additional, Kamiński, K., additional, Kankiewicz, P., additional, Borczyk, W., additional, and Rożek, A., additional

Published
2010
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24. V440 Per: the longest-period overtone Cepheid

Author

Baranowski, R., primary, Smolec, R., additional, Dimitrov, W., additional, Kwiatkowski, T., additional, Schwarzenberg-Czerny, A., additional, Bartczak, P., additional, Fagas, M., additional, Borczyk, W., additional, Kamiński, K., additional, Moskalik, P., additional, Ratajczak, R., additional, and Rożek, A., additional

Published
2009
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25. ASTEROSEISMOLOGY OF HYBRID PULSATORS MADE POSSIBLE: SIMULTANEOUS MOST SPACE PHOTOMETRY AND GROUND-BASED SPECTROSCOPY OF γ PEG

Author

Handler, G., primary, Matthews, J. M., additional, Eaton, J. A., additional, Daszyńska-Daszkiewicz, J., additional, Kuschnig, R., additional, Lehmann, H., additional, Rodríguez, E., additional, Pamyatnykh, A. A., additional, Zdravkov, T., additional, Lenz, P., additional, Costa, V., additional, Díaz-Fraile, D., additional, Sota, A., additional, Kwiatkowski, T., additional, Schwarzenberg-Czerny, A., additional, Borczyk, W., additional, Dimitrov, W., additional, Fagas, M., additional, Kamiński, K., additional, Rożek, A., additional, van Wyk, F., additional, Pollard, K. R., additional, Kilmartin, P. M., additional, Weiss, W. W., additional, Guenther, D. B., additional, Moffat, A. F. J., additional, Rucinski, S. M., additional, Sasselov, D. D., additional, and Walker, G. A. H., additional

Published
2009
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26. New binary asteroid 809 Lundia

Author

Kryszczyńska, A., primary, Colas, F., additional, Descamps, P., additional, Bartczak, P., additional, Polińska, M., additional, Kwiatkowski, T., additional, Lecacheux, J., additional, Hirsch, R., additional, Fagas, M., additional, Kamiński, K., additional, Michałowski, T., additional, and Marciniak, A., additional

Published
2009
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27. Photometry and models of selected main belt asteroids. VI. 160 Una, 747 Winchester, and 849 Ara

Author

Marciniak, A., primary, Michałowski, T., additional, Hirsch, R., additional, Polińska, M., additional, Kamiński, K., additional, Kwiatkowski, T., additional, Kryszczyńska, A., additional, Behrend, R., additional, Bernasconi, L., additional, Michałowski, J., additional, Starczewski, S., additional, Fagas, M., additional, and Sobkowiak, K., additional

Published
2009
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28. Photometry and models of selected main belt asteroids

Author

Marciniak, A., primary, Michałowski, T., additional, Kaasalainen, M., additional, Kryszczyńska, A., additional, Kwiatkowski, T., additional, Hirsch, R., additional, Kamiński, K., additional, Fagas, M., additional, Polińska, M., additional, Velichko, F. P., additional, Michałowski, M. J., additional, Snodgrass, C., additional, Behrend, R., additional, and Bernasconi, L., additional

Published
2007
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29. Physical models of ten asteroids from an observers' collaboration network

Author

Ďurech, J., primary, Kaasalainen, M., additional, Marciniak, A., additional, Allen, W. H., additional, Behrend, R., additional, Bembrick, C., additional, Bennett, T., additional, Bernasconi, L., additional, Berthier, J., additional, Bolt, G., additional, Boroumand, S., additional, Crespo da Silva, L., additional, Crippa, R., additional, Crow, M., additional, Durkee, R., additional, Dymock, R., additional, Fagas, M., additional, Fauerbach, M., additional, Fauvaud, S., additional, Frey, M., additional, Gonçalves, R., additional, Hirsch, R., additional, Jardine, D., additional, Kamiński, K., additional, Koff, R., additional, Kwiatkowski, T., additional, López, A., additional, Manzini, F., additional, Michałowski, T., additional, Pacheco, R., additional, Pan, M., additional, Pilcher, F., additional, Poncy, R., additional, Pray, D., additional, Pych, W., additional, Roy, R., additional, Santacana, G., additional, Slivan, S., additional, Sposetti, S., additional, Stephens, R., additional, Warner, B., additional, and Wolf, M., additional

Published
2007
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30. Interplay between pulsations and mass loss in the blue supergiant 55 Cygnus = HD198 478.

Author

Kraus, M., Haucke, M., Cidale, L. S., Venero, R. O. J., Nickeler, D. H., Németh, P., Niemczura, E., Tomić, S., Aret, A., Kubát, J., Kubátová, B., Oksala, M. E., Curé, M., Kamiński, K., Dimitrov, W., Fagas, M., and Polińska, M.

Subjects
STELLAR oscillations, MASS loss (Astrophysics), SUPERGIANT stars, SOLAR granulation, RADIAL velocity of stars, STELLAR radiation, STELLAR spectra
Abstract

Context. Blue supergiant stars are known to display photometric and spectroscopic variability that is suggested to be linked to stellar pulsations. Pulsational activity in massive stars strongly depends on the star's evolutionary stage and is assumed to be connected with mass-loss episodes, the appearance of macroturbulent line broadening, and the formation of clumps in the wind. Aims. To investigate a possible interplay between pulsations and mass-loss, we carried out an observational campaign of the supergiant 55 Cyg over a period of five years to search for photospheric activity and cyclic mass-loss variability in the stellar wind. Methods. We modeled the H, He i, Si ii, and Si iii lines using the nonlocal thermal equilibrium atmosphere code FASTWIND and derived the photospheric and wind parameters. In addition, we searched for variability in the intensity and radial velocity of photospheric lines and performed a moment analysis of the line profiles to derive frequencies and amplitudes of the variations. Results. The Hα line varies with time in both intensity and shape, displaying various types of profiles: P Cygni, pure emission, almost complete absence, and double or multiple peaked. The star undergoes episodes of variable mass-loss rates that change by a factor of 1.7-2 on different timescales. We also observe changes in the ionization rate of Si ii and determine a multiperiodic oscillation in the He i absorption lines, with periods ranging from a few hours to 22.5 days. Conclusions. We interpret the photospheric line variations in terms of oscillations in p-, g-, and strange modes. We suggest that these pulsations can lead to phases of enhanced mass loss. Furthermore, they can mislead the determination of the stellar rotation. We classify the star as a post-red supergiant, belonging to the group of α Cyg variables. [ABSTRACT FROM AUTHOR]

Published
2015
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31. Photometry and models of selected main belt asteroids

Author

Marciniak, A., Michałowski, T., Kaasalainen, M., Kryszczyńska, A., Kwiatkowski, T., Hirsch, R., Kamiński, K., Fagas, M., Polińska, M., Velichko, F. P., Michałowski, M. J., Snodgrass, C., Behrend, R., Bernasconi, L., Marciniak, A., Michałowski, T., Kaasalainen, M., Kryszczyńska, A., Kwiatkowski, T., Hirsch, R., Kamiński, K., Fagas, M., Polińska, M., Velichko, F. P., Michałowski, M. J., Snodgrass, C., Behrend, R., and Bernasconi, L.

Abstract

We present photometric observations of three asteroids: 73 Klytia, 377 Campania, and 378 Holmia, together with their spin and shape models. The models were constructed with the lightcurve inversion method, using all available lightcurves of these objects. In the case of Campania, the long persisting doubts about its rotational period have been resolved. Various authors state periods between 8.48 and 16 h, while the period we determined is $11.664401 \pm 0.000010$h.

Published
2008
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32. New binary asteroid 809 Lundia

Author

Kryszczy?ska, A., Colas, F., Descamps, P., Bartczak, P., Poli?ska, M., Kwiatkowski, T., Lecacheux, J., Hirsch, R., Fagas, M., Kami?ski, K., Micha?owski, T., and Marciniak, A.

Abstract

CCD photometry of 809 Lundia obtained between September?2005 and January?2006 at Borowiec and Pic du Midi Observatories demonstrates that this object is a synchronous binary system with an orbital period of 15.418?? 0.001?h. In this paper, we present the results of photometric observations of Lundia from two oppositions in 2005/2006 and?2007, as well as the first modelling of the system. For simplicity we assumed a fluid-like nature for each component with a modified Roche model and a triaxial ellipsoid shape in kinematic models. Our models provided similar results. Poles of the orbit in ecliptic coordinates are ? = 119 ? 2?, ? = 28 ? 4??(modified Roche) or ? = 120 ? 5?, ? = 18 ? 12?? (kinematic). Triaxial ellipsoid shape solutions and a separation between components of 15.8?km are given after taking an equivalent diameter of 9.1?km from H?= 11.8?mag and assuming an albedo of?0.4. The orbital period of the Lundia system obtained from modelling is the same as from the lightcurve analysis i.e., 15.418?? 0.001?h. The bulk density of both components is?1.64 or 1.71?? 0.01?g/cm3. The double system of Lundia probably originates from the fission process of a single body that could have been spun up by the YORP?effect. The predicted lightcurves for future oppositions are also presented.

Published
2009

33. New spectroscopy of multiple stars RR Lyncis and HT Virginis

Author

Bensch, K., Dimitrov, W., Zywucka, N., Fagas, M., Krzysztof Kamiński, Przybyszewska, A., Maliczak, M., Kurzawa, K., Kruszewski, A., Kowalczyk, T., Borczyk, W., Bakowska, K., Bartczak, P., Kwiatkowski, T., and Schwarzenberg-Czerny, A.

Subjects
Astrophysics::Instrumentation and Methods for Astrophysics, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics
Abstract

In this paper we present radial velocity measurements as a result of new spectroscopic observations of RR Lyncis and HT Virginis. Both systems are worth to be the objects of a long-term monitoring. The observations made during a long period of time reveal the apsidal motion and the movements around the center of mass of the systems. Long-term measurements enable us to measure the light-time effect in the eclipsing binaries as well. Data were collected using the Poznan Spectroscopic Telescope (PST1) at Borowiec station (Baranowski et al. 2009) covering a range of wavelength 4280-7500 Å. The telescope is equipped with an echelle spectrograph thermally stabilized to 0.1oC. The data were calibrated with ThAr (Thorium-Argon) lamp. Data reduction was performed with IRAF

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