Reduction and analysis of large-scale variable star data sets  Page description

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Details of project

  
Identifier
38437
Type K
Principal investigator Kovács, Géza
Title in Hungarian Nagymennyiségű változócsillagászati észlelések feldolgozása és analízise
Title in English Reduction and analysis of large-scale variable star data sets
Panel Physics 1
Department or equivalent Konkoly Thege Miklós Astronomical Institute (Research Centre for Astronomy and Earth Sciences)
Participants Bakos, Gáspár
Kolláth, Zoltán
Starting date 2002-01-01
Closing date 2005-12-31
Funding (in million HUF) 10.750
FTE (full time equivalent) 0.00
state closed project





 

Final report

  
Results in Hungarian
A kovetkezo harom fo temakort vizsgaltuk: (a) periodikus tranzit detektalas es extraszolaris bolygok vizsgalata a HATNet es a WHAT automata tavcsovek eszlelesei alapjan; (b) a MACHO adatbazis RR Lyrae csillagainak periodus analizise; (c) pulzalo valtozocsillagok elmeleti es empirikus vizsgalata. A kovetkezo eredmenyeket kaptuk. Tema (a): kis aperturaju, teljesen automatizalt tavcsovek alkalmasak nehany millimagnitudo pontossagu eszlelesekre es forro Jupiterek (HJ-k) detektalasara; a BLS algoritmusunk hatasos eszkoz periodikus tranzitok kereseseben; az adatfeldolgozas miatt fellepu szisztematikak kiszuresenek hatekony eszkoze a TFA algoritmusunk; a HD 189733 HJ rendszer valojaban egy harmas rendszer, K fo- es M masod-komponensekkel, valamint a fokomponens korul keringo bolygoval. Tema (b): az LMC-ben talalhato alapmodusu RR Lyrae csillagok 12%-a mutat Blashko jelenseget. Ez az ertek szignifikansan magasabb, mint az ujabb analizisunk alapjan az elso felhangu csillagokra kapott gyakorisag, amely a rendelkezesre allo adatok felhasznalasaval 7.5%-nak adodott. Tema (c): nincs ellentmondas az RR Lyrae es a Cepheida valtozok alapjan a Baade-Wesselink modszer segitsegevel szamitott tavolsagok kozott. Az LMC tavolsagara konzisztens ertekeket kaptunk; tobb irregularis valtozo fenygorbejenek analizalasa alapjan tovabbi megerositest kaptunk ezen csillagok kaotikus pulzaciojara.
Results in English
We have investigated the following three major topics: (a) periodic transit detection and extrasolar planetary studies based on large-scale photometric databases of the HATNet and WHAT automated telescopes; (b) frequency analysis of RR Lyrae stars in the MACHO database; (c) theoretical and empirical stellar pulsation studies. We obtained the following results. Topic (a): small aperture fully automated telescopes are able to gather few millimag precision photometric data and detect transits caused by hot Jupiters; our BLS algorithm is very efficient in searching for periodic transits; the effects of systematics due to errors in the data acquisition can be successfully filtered by our TFA algorithm; the hot Jupiter system HD 189733 is a triple system with a K primary and M secondary and the planet orbiting the primary. Topic (b): the incidence rate of the Blazhko stars pulsating in the fundamental mode is 12% in the LMC. This is significantly higher than that of the first overtone Blazhko stars (which is 7.5%, according to our new analysis of all available data. Topic (c): there is no contradiction between the distances derived by Baade-Wesselink analyses of RR Lyrae and Cepheid variables and they both yield consistent distances for the LMC; by analyzing the archival data of several irregular variables, we got further support for the presence of chaotic pulsations in these stars.
Full text http://real.mtak.hu/592/
Decision
Yes





 

List of publications

  
Kovacs, G.: Nonradial Pulsations in Classical Pulsators (invited paper), ASP Conf. Proc. , 259, 396-403, 2002
Kovacs, G.: Globular Cluster Distances and Physical Properties From Double- and Fundamental Mode Variables, ASP Conf. Proc., 265, 163-176, 2002
Kovacs, G, Zucker, S., Mazeh, T.: A box-fitting algorithm in the search for periodic transits, Astronomy and Astrophysics, 391, 369-377, 2002
Bakos, G. Á., Lázár, J., Papp, I., Sári, P., Green, E. M.: System Description and First Light Curves of the Hungarian Automated Telescope, an Autonomous Observatory for Variability Search, The Publications of the Astronomical Society of the Pacific, 114, 974-987, 2002
Alcock, C.; Alves, D. R.; Becker, A.; Bennett, D.; Cook, K. H.; Drake, A.; Freeman, K.; Geha, M.; Griest, K.; Kovács, G.; and coauthors: The MACHO Project Large Magellanic Cloud Variable Star Inventory. XI. Frequency Analysis of the Fundamental-Mode RR Lyrae Stars, The Astrophysical Journal, Volume 598, Issue 1, pp. 597-609, 2003
Kovács, Géza: Consistent distances from Baade-Wesselink analyses of Cepheids and RR Lyraes, Monthly Notice of the Royal Astronomical Society, Volume 342, Issue 4, pp. L58-L62., 2003
Bakos, G.; Noyes, R. W.; Kovács, G.; Stanek, K. Z.; Sasselov, D. D.; Domsa, I.: Wide-Field Millimagnitude Photometry with the HAT: A Tool for Extrasolar Planet Detection, The Publications of the Astronomical Society of the Pacific, Volume 116, Issue 817, pp. 266-277., 2004
Szabó, R.; Kolláth, Z.; Buchler, J. R.: Automated nonlinear stellar pulsation calculations: Applications to RR Lyrae stars. The slope of the fundamental blue edge and the first RRd model survey, Astronomy and Astrophysics, v.425, p.627-639, 2004
Buchler, J. Robert; Kolláth, Zoltán; Cadmus, Robert R., Jr.: Evidence for Low-dimensional Chaos in Semiregular Variable Stars, The Astrophysical Journal, Volume 613, Issue 1, pp. 532-547., 2004
Buchler, J. R.; Kolláth, Z.; Beaulieu, J.-P.: Magellanic Cloud Cepheids: Pulsational and evolutionary modelling vs. observations, Astronomy and Astrophysics, v.423, p.643-650, 2004
Kovács, Géza; Bakos, Gáspár; Noyes, Robert W.: A trend filtering algorithm for wide-field variability surveys, Monthly Notices of the Royal Astronomical Society, Volume 356, Issue 2, pp. 557-567., 2005
Kovacs, G.: Iron abundances derived from RR~Lyrae light curves and low-dispersion spectroscopy, Astronomy and Astrophysics, 438, 227-238, 2005
Kovács, G., Bakos, G.: Testing the Rate of False Planetary Transits due to Binary Star Blending, ''A Decade of Extrasolar Planets around Normal Stars'', May 2-5, 2005, STScI, to appear, astro-ph/0508081, 2006
Kovács, G.: Metallicity effects on distances based on double-mode Cepheids, Memorie della Societa' Astronomica Italiana, Vol. 76/4, p. ??, astro-ph/0511524, 2006
Shporer, A., Mazeh, T., Moran, A., Bakos, G., Kovacs, G. and Mashal, E.: The WHAT Project, ''Tenth anniversary of 51 Peg-b: Status of and prospects for hot Jupiter studies'', ed. L. Arnold et al., to appear, astro-ph/0510766, 2006
Nagy, A. and Kovacs, G.: On the incidence rate of first overtone Blazhko stars in the Large Magellanic Cloud, Astronomy and Astrophysics, ???, ???-???, accepted, 2006
Bakos, G. A., Pal, A., Latham, D. W., Noyes, R. W. and Stefanik, R. P.: A stellar companion in the HD 189733 System with known transiting extrasolar planet, ApJ (Letters), ???, ???, accepted, astro-ph/0602136, 2006




 

Events of the project

  
2012-01-04 06:36:06
Kutatóhely váltás
A kutatás helye megváltozott. Korábbi kutatóhely: (MTA Csillagászati és Földtudományi Kutatóközpont), Új kutatóhely: Konkoly Thege Miklós Csillagászati Intézet (MTA Csillagászati és Földtudományi Kutatóközpont).



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