Pub Date : 2017-09-27DOI: 10.32023/0001-5237/67.3.1
M. Rozyczka, I. B. Thompson, W. Pych, W. Narloch, R. Poleski, A. Schwarzenberg-Czerny
The field of the globular cluster M22 (NGC 6656) was monitored between 2000 and 2008 in a search for variable stars. $BV$ light curves were obtained for 359 periodic, likely periodic, and long-term variables, 238 of which are new detections. Thirty nine newly detected variables, and 63 previously known ones are members or likely members of the cluster, including 20 SX Phe, 10 RRab and 16 RRc-type pulsators, one BL Her-type pulsator, 21 contact binaries, and 9 detached or semi-detached eclipsing binaries. The most interesting among the identified objects are V112 - a bright multimode SX Phe pulsator, V125 - a $beta$ Lyr-type binary on the blue horizontal branch, V129 - a blue/yellow straggler with a W UMa-like light curve, located halfway between the extreme horizontal branch and red giant branch, and V134 - an extreme horizontal branch object with $P=2.33$ d and a nearly sinusoidal light curve; all four of them are proper motion (PM) members of the cluster. Among nonmembers, a $P=2.83$ d detached eclipsing binary hosting a $delta$ Sct-type pulsator was found, and a peculiar $P=0.93$ d binary with ellipsoidal modulation and narrow minimum in the middle of one of the descending shoulders of the sinusoid. We also collected substantial new data for previously known variables; in particular we revise the statistics of the occurrence of the Blazhko effect in RR Lyr-type variables of M22.
{"title":"The Clusters AgeS Experiment (CASE). Variable stars in the field of the globular cluster NGC 6362","authors":"M. Rozyczka, I. B. Thompson, W. Pych, W. Narloch, R. Poleski, A. Schwarzenberg-Czerny","doi":"10.32023/0001-5237/67.3.1","DOIUrl":"https://doi.org/10.32023/0001-5237/67.3.1","url":null,"abstract":"The field of the globular cluster M22 (NGC 6656) was monitored between 2000 and 2008 in a search for variable stars. $BV$ light curves were obtained for 359 periodic, likely periodic, and long-term variables, 238 of which are new detections. Thirty nine newly detected variables, and 63 previously known ones are members or likely members of the cluster, including 20 SX Phe, 10 RRab and 16 RRc-type pulsators, one BL Her-type pulsator, 21 contact binaries, and 9 detached or semi-detached eclipsing binaries. The most interesting among the identified objects are V112 - a bright multimode SX Phe pulsator, V125 - a $beta$ Lyr-type binary on the blue horizontal branch, V129 - a blue/yellow straggler with a W UMa-like light curve, located halfway between the extreme horizontal branch and red giant branch, and V134 - an extreme horizontal branch object with $P=2.33$ d and a nearly sinusoidal light curve; all four of them are proper motion (PM) members of the cluster. Among nonmembers, a $P=2.83$ d detached eclipsing binary hosting a $delta$ Sct-type pulsator was found, and a peculiar $P=0.93$ d binary with ellipsoidal modulation and narrow minimum in the middle of one of the descending shoulders of the sinusoid. We also collected substantial new data for previously known variables; in particular we revise the statistics of the occurrence of the Blazhko effect in RR Lyr-type variables of M22.","PeriodicalId":44887,"journal":{"name":"Acta Astronomica","volume":"66 1","pages":"203"},"PeriodicalIF":2.2,"publicationDate":"2017-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47785374","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-09-01DOI: 10.32023/0001-5237/67.3.4
M. Wolf, P. Zasche, H. Kučáková, K. Honkova, J. Juryšek, M. Mašek, R. Uhlář, M. Urbanik
{"title":"The Triple Eccentric Systems V974 Cyg, RU Mon, and V456 Oph","authors":"M. Wolf, P. Zasche, H. Kučáková, K. Honkova, J. Juryšek, M. Mašek, R. Uhlář, M. Urbanik","doi":"10.32023/0001-5237/67.3.4","DOIUrl":"https://doi.org/10.32023/0001-5237/67.3.4","url":null,"abstract":"","PeriodicalId":44887,"journal":{"name":"Acta Astronomica","volume":"67 1","pages":"257-271"},"PeriodicalIF":2.2,"publicationDate":"2017-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45920285","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-09-01DOI: 10.32023/0001-5237/67.3.3
P. Zasche, M. Wolf, J. Vraštil, P. Fatka, A. Galád, K. Hornoch, Zdeněk Janák, J. Janík, Eva Kortusová, P. Kurfürst, P. Kušnirák, E. Paunzen, L. Řezba, V. Votruba, M. Zejda, P. Zieliński
The eclipsing system OGLE-SMC-ECL-0277 was found to exhibit unusual photometric variability. Beside its eclipsing nature additional variations with the periodicity of about 1500 d are also seen. Variations of the eclipse depth during the time span of the observational data (mainly taken from the OGLE survey, partly our new ones) are the most pronounced. The complex behavior of all these changes makes this system absolutely unique, no such variability was ever detected and studied in other systems before. Hence, are there some new phenomena, new physics or an unknown effects playing a role? We tried to understand these variations using four different hypotheses (i.e. inclination change, spot evolution, and/or pulsation of one or both components) and comparing their results we discussed which of them is the most likely. Neither of the presented hypotheses is able to describe in detail the behavior of OGLE-SMC-ECL-0277. We also discuss a possibility that the variable can be a member of the so-called double periodic variables group.
{"title":"The Strange Case of OGLE-SMC-ECL-0277","authors":"P. Zasche, M. Wolf, J. Vraštil, P. Fatka, A. Galád, K. Hornoch, Zdeněk Janák, J. Janík, Eva Kortusová, P. Kurfürst, P. Kušnirák, E. Paunzen, L. Řezba, V. Votruba, M. Zejda, P. Zieliński","doi":"10.32023/0001-5237/67.3.3","DOIUrl":"https://doi.org/10.32023/0001-5237/67.3.3","url":null,"abstract":"The eclipsing system OGLE-SMC-ECL-0277 was found to exhibit unusual photometric variability. Beside its eclipsing nature additional variations with the periodicity of about 1500 d are also seen. Variations of the eclipse depth during the time span of the observational data (mainly taken from the OGLE survey, partly our new ones) are the most pronounced. The complex behavior of all these changes makes this system absolutely unique, no such variability was ever detected and studied in other systems before. Hence, are there some new phenomena, new physics or an unknown effects playing a role? We tried to understand these variations using four different hypotheses (i.e. inclination change, spot evolution, and/or pulsation of one or both components) and comparing their results we discussed which of them is the most likely. Neither of the presented hypotheses is able to describe in detail the behavior of OGLE-SMC-ECL-0277. We also discuss a possibility that the variable can be a member of the so-called double periodic variables group.","PeriodicalId":44887,"journal":{"name":"Acta Astronomica","volume":"67 1","pages":"243-255"},"PeriodicalIF":2.2,"publicationDate":"2017-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43848520","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Methode des moindres carres appliquee a la reduction des cliches astrometriques","authors":"H. Debehogne, E. V. Hemelrijck","doi":"10.18758/A_149","DOIUrl":"https://doi.org/10.18758/A_149","url":null,"abstract":"","PeriodicalId":44887,"journal":{"name":"Acta Astronomica","volume":"1 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2017-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48631554","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-06-01DOI: 10.32023/0001-5237/67.2.6
Z. Stuchlík, J. Schee, E. Šrámková, G. Török
We study properties of Keplerian disks and their high-frequency quasi-periodic oscillations (HF QPOs) in the field of quark stars with dimensionless spin a breaking the black-hole spin limit of a = 1 up to a approximate to 1.3. Using the external geometry of the superspinning quark stars approximated by the Kerr geometry, we show that the Keplerian disks have to touch the surface of such quark stars and their accretion efficiency eta approximate to 18% significantly exceeds the efficiency related to the Schwarzschild black holes. Using the geodesic oscillation models, we test possible existence of the superspinning quark stars in atoll sources demonstrating the twin HF QPOs with resonant frequency ratios 3:2, 4:3, 5:4. For explanation of the twin HF QPOs we consider the standard relativistic precession model and its modifications, the tidal distortion model, the resonance epicyclic and the warped disk model. In a given model, we assume occurrence of the twin oscillatory modes at a common resonant dimensionless radius x = r/M determined by the frequency ratio and the quark star spin a. The theoretical limit R > 3M on the quark star surface radius puts strong restrictions on the relations between the resonant radii x and the quark star spin a. These restrictions imply that all the considered geodesic oscillation models can be excluded, except for one variant of the relativistic precession model, or alternatively the tidal distortion and warped disk models, that allow for appearance of the twin HF QPOs with frequency ratio 3 : 2 at radii slightly above the theoretical limit on the radius of the quark star surface, but exclude the smaller frequency ratios (4:3, 5:4).
{"title":"Superspinning Quark Stars Limited by Twin High-FrequencyQuasiperiodic Oscillations","authors":"Z. Stuchlík, J. Schee, E. Šrámková, G. Török","doi":"10.32023/0001-5237/67.2.6","DOIUrl":"https://doi.org/10.32023/0001-5237/67.2.6","url":null,"abstract":"We study properties of Keplerian disks and their high-frequency\u0000quasi-periodic oscillations (HF QPOs) in the field of quark\u0000stars with dimensionless spin a breaking the black-hole spin\u0000limit of a = 1 up to a approximate to 1.3. Using the external\u0000geometry of the superspinning quark stars approximated by the\u0000Kerr geometry, we show that the Keplerian disks have to touch\u0000the surface of such quark stars and their accretion efficiency\u0000eta approximate to 18% significantly exceeds the efficiency\u0000related to the Schwarzschild black holes. Using the geodesic\u0000oscillation models, we test possible existence of the\u0000superspinning quark stars in atoll sources demonstrating the\u0000twin HF QPOs with resonant frequency ratios 3:2, 4:3, 5:4. For\u0000explanation of the twin HF QPOs we consider the standard\u0000relativistic precession model and its modifications, the tidal\u0000distortion model, the resonance epicyclic and the warped disk\u0000model. In a given model, we assume occurrence of the twin\u0000oscillatory modes at a common resonant dimensionless radius x =\u0000r/M determined by the frequency ratio and the quark star spin\u0000a. The theoretical limit R > 3M on the quark star surface\u0000radius puts strong restrictions on the relations between the\u0000resonant radii x and the quark star spin a. These restrictions\u0000imply that all the considered geodesic oscillation models can\u0000be excluded, except for one variant of the relativistic\u0000precession model, or alternatively the tidal distortion and\u0000warped disk models, that allow for appearance of the twin HF\u0000QPOs with frequency ratio 3 : 2 at radii slightly above the\u0000theoretical limit on the radius of the quark star surface, but\u0000exclude the smaller frequency ratios (4:3, 5:4).","PeriodicalId":44887,"journal":{"name":"Acta Astronomica","volume":"67 1","pages":"181-201"},"PeriodicalIF":2.2,"publicationDate":"2017-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44570875","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-06-01DOI: 10.32023/0001-5237/67.2.5
A. Majczyna, J. Madej, A. Różańska, M. Należyty
{"title":"Accuracy of Mass and Radius Determination for Neutron Stars in X-ray Bursters from Simulated LOFT Spectra","authors":"A. Majczyna, J. Madej, A. Różańska, M. Należyty","doi":"10.32023/0001-5237/67.2.5","DOIUrl":"https://doi.org/10.32023/0001-5237/67.2.5","url":null,"abstract":"","PeriodicalId":44887,"journal":{"name":"Acta Astronomica","volume":"67 1","pages":"171-180"},"PeriodicalIF":2.2,"publicationDate":"2017-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45853260","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-03-01DOI: 10.32023/0001-5237/67.1.5
J. Krełowski, G. Galazutdinov, A. Bondar, L. Byeong-Cheol
{"title":"Constant Intensities of Diffuse Interstellar Bands in the Spectrum of AE Aur","authors":"J. Krełowski, G. Galazutdinov, A. Bondar, L. Byeong-Cheol","doi":"10.32023/0001-5237/67.1.5","DOIUrl":"https://doi.org/10.32023/0001-5237/67.1.5","url":null,"abstract":"","PeriodicalId":44887,"journal":{"name":"Acta Astronomica","volume":"67 1","pages":"71"},"PeriodicalIF":2.2,"publicationDate":"2017-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47501017","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1995-01-01DOI: 10.1007/3-540-59157-5_201
R. Napiwotzki
{"title":"White dwarfs in old planetary nebulae","authors":"R. Napiwotzki","doi":"10.1007/3-540-59157-5_201","DOIUrl":"https://doi.org/10.1007/3-540-59157-5_201","url":null,"abstract":"","PeriodicalId":44887,"journal":{"name":"Acta Astronomica","volume":"443 1","pages":"176-185"},"PeriodicalIF":2.2,"publicationDate":"1995-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"51601226","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1987-01-01DOI: 10.1016/0273-1177(88)90427-9
A. Gicger
{"title":"Statistical analysis of dwarf nova outbursts","authors":"A. Gicger","doi":"10.1016/0273-1177(88)90427-9","DOIUrl":"https://doi.org/10.1016/0273-1177(88)90427-9","url":null,"abstract":"","PeriodicalId":44887,"journal":{"name":"Acta Astronomica","volume":"37 1","pages":"29-39"},"PeriodicalIF":2.2,"publicationDate":"1987-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0273-1177(88)90427-9","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"53550679","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1986-01-01DOI: 10.1007/978-94-009-4714-6_33
M. Muciek, P. North, F. Rufener, J. Gertner
{"title":"A Photometric Investigation of the Magnetic Star 53 Cameloprdalis","authors":"M. Muciek, P. North, F. Rufener, J. Gertner","doi":"10.1007/978-94-009-4714-6_33","DOIUrl":"https://doi.org/10.1007/978-94-009-4714-6_33","url":null,"abstract":"","PeriodicalId":44887,"journal":{"name":"Acta Astronomica","volume":"90 1","pages":"199-199"},"PeriodicalIF":2.2,"publicationDate":"1986-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"51542375","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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