Wyniki wyszukiwania - Biblioteka Nauki

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The Optical Gravitational Lensing Experiment. Planetary and Low-Luminosity Object Transits in the Carina Fields of the Galactic Disk

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Udalski A. , Szewczyk O. , Żebruń K. , Pietrzyński G. , Szymański M. , Kubiak M. , Soszyński I. , Wyrzykowski Ł.

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2002

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tom Vol. 52, No. 4

317--359

EN

We present results of the second "planetary and low-luminosity object transit" campaign conducted by the OGLE-III survey. Three fields (35'×35' each) located in the Carina regions of the Galactic disk (l≈290°) were monitored continuously in February-May 2002. About 1150 epochs were collected for each field. The search for low depth transits was conducted on about 103 000 stars with photometry better than 15 mmag. In total, we discovered 62 objects with shallow depth (≤0.08 mag) flat-bottomed transits. For each of these objects several individual transits were detected and photometric elements were determined. Also lower limits on radii of the primary and companion were calculated. The 2002 OGLE sample of stars with transiting companions contains considerably more objects that may be Jupiter-sized (R<1.6 RJup) compared to our 2001 sample. There is a group of planetary candidates with the orbital periods close to or shorter than one day. If confirmed as planets, they would be the shortest period extrasolar planetary systems. In general, the transiting objects may be extrasolar planets, brown dwarfs, or M-type dwarfs. One should be, however, aware that in some cases unresolved blends of regular eclipsing stars can mimic transits. Future spectral analysis and eventual determination of the amplitude of radial velocity should allow final classification. High resolution spectroscopic follow-up observations are, therefore, strongly encouraged. All photometric data are available to the astronomical community from the OGLE Internet archive.

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

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Udalski A. , Żebruń K. , Szymański M. , Kubiak M. , Soszyński I. , Szewczyk O. , Wyrzykowski Ł. , Pietrzyński G.

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tom Vol. 52, No. 2

115--128

EN

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<1.6 RJup). OGLE-TR-56 is a particularly interesting case. Its transit has only 13 mmag depth, short duration and a period of 1.21190 days. Model fit indicates that the companion may be Saturn-sized if the passage were central. Spectroscopic follow-up observations are encouraged for final classification of the transiting objects as planets, brown dwarfs or late M-type dwarf stars. We also provide the most recent ephemerides of other most promising planetary transits: OGLE-TR-10 and OGLE-TR-40 based on observations collected in June 2002. All photometric data are available to the astronomical community from the OGLE Internet archive.

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Mt. Suhora Survey - Searching for Pulsating M Dwarfs. I

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Baran A. S. , Winiarski M. , Krzesiński J. , Fox-Machado L. , Kawaler S. D. , Dróżdż M. , Faltenbacher A. , Thompson M. A. , Reed M. D.

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tom Vol. 61, No. 1

37--58

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We present the first results of our M dwarf survey in search for stellar pulsation in low mass main sequence stars. Theoretical calculations predict that ε mechanism might drive a fundamental radial mode in these stars and therefore pulsations could be observed photometrically. Although M dwarfs are known for their flare and spot activity they have not yet been the subject of dedicated time-series surveys for pulsation. In this work we include the light curves and amplitude spectra of 46 M dwarfs, which have been observed during the first two years of our survey. We did not detect any pulsations yet. As a by-product of our search, we describe the light curves of some flare M dwarfs. The survey will last for two more years and during that period more than a hundred of M0-M4 type main sequence stars will be observed.

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High Proper Motion Objects toward the Inner Milky Way: Characterization of Newly Identified Nearby Stars from the VISTA Variables in the Vía Láctea Survey

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Gromadzki M. , Kurtev R. , Beamán J. C. , Tekola A. , Ramphul R. , Ivanov V. D. , Minniti D. , Folkes S. L. , Vaisanen P. , Kniazev A. Y. , Borissova J. , Parsons S. G. , Villanueva V.

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tom Vol. 66, No. 3

293--306

EN

The census of the Solar neighborhood is still incomplete, as demonstrated by recent discoveries of many objects within 5-10 pc from the Sun. The area around the mid-plane and bulge of the Milky Way presents the most difficulties in searches for such nearby objects, and is therefore deficient in the known population. This is largely due to high stellar densities encountered. Spectroscopic, photometric and kinematic characterization of these objects allows better understanding of the local mass function, the binary fraction, and provides new interesting targets for more detailed studies. We report the spectroscopic follow-up and characterization of twelve bright high proper motion objects, identified from the VISTA Variables in Vía Láctea survey (VVV). We used the 1.9-m telescope of the South African Astronomical Observatory (SAAO) for low-resolution optical spectroscopy and spectral classification, and the MPG/ESP 2.2-m telescope Fiber-fed Extended Range Optical Spectrograph (FEROS) high-resolution optical spectroscopy to obtain the radial and space velocities for three of them. Six of our objects have co-moving companions. We derived optical spectral types and photometric distances, and classified all of them as K and M dwarfs within 27-264 pc from the Sun. Finally, we found that one of the sources, VVV J141421.23-602326.1 (a co-moving companion of VVV J141420.55-602337.1), appears to be a rare massive white dwarf located close to the ZZ Cet instability strip in the CMD and CC diagrams. Many of the objects in our list are interesting targets for exoplanet searches.