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1
Content available remote The Cluster AgeS Experiment (CASE). Variable Stars in the Field of the Globular Cluster M10
Rozyczka M., Narloch W., Schwarzenberg-Czerny A., Thompson I. B., Poleski R., Pych W.
Acta Astronomica
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2018
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Vol. 68, No. 3
237--258
EN
The field of the globular cluster M10 (NGC 6254) was monitored between 1998 and 2015 in a search for variable stars. V-band light curves were derived for 40 variables or likely variables, most of which are new detections. Proper motions obtained within the CASE project indicate that 18 newly detected variables and 14 previously known ones are members or likely members of the cluster, including one RRc-type, three type II Cepheids, and 14 SX Phe-type pulsators, one contact binary, and six semi-regular red giants. As a by-product of the search we discovered a candidate binary comprised of main sequence stars with the record-short orbital period of 0.042 d. We also confirmed the photometric variability of the red straggler M10-VLA1 hinted at by Shishkovsky, who discovered this object spectroscopically. In Appendix 1 we show that CASE proper motion measurements are in a good agreement with those retrieved from the Gaia archive, while Appendix 2 presents evidence for low frequency γ Dor-type oscillations in SX Phe stars belonging to M10.
2
Content available remote The Cluster AgeS Experiment (CASE). Detecting Aperiodic Photometric Variability with the Friends of Friends Algorithm
Rozyczka M., Narloch W., Pietrukowicz P., Thompson I. B., Pych W., Poleski R.
Acta Astronomica
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2018
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Vol. 68, No. 1
63--78
EN
We adapt the friends of friends algorithm to the analysis of light curves, and show that it can be succesfully applied to searches for transient phenomena in large photometric databases. As a test case we search OGLE-III light curves for known dwarf novae. A single combination of control parameters allows us to narrow the search to 1% of the data while reaching a ≈90% detection efficiency. A search involving ≈2% of the data and three combinations of control parameters can be significantly more effective - in our case a 100% efficiency is reached. The method can also quite efficiently detect semi-regular variability. In particular, 28 new semi-regular variables have been found in the field of the globular cluster M22, which was examined earlier with the help of periodicity-searching algorithms.
3
Content available remote The Cluster AgeS Experiment (CASE). Variable Stars in the Field of the Globular Cluster M22
Rozyczka M., Thompson I. B., Pych W., Narloch W., Poleski R., Schwarzenberg-Czerny A.
Acta Astronomica
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2017
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Vol. 67, No. 3
203--224
EN
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. 39 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 β 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 members of the cluster. Among nonmembers, a P=2.83 d detached eclipsing binary hosting a δ 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.
4
Content available remote The Clusters AgeS Experiment (CASE). Variable stars in the field of the globular cluster NGC 362
Rozyczka M., Thompson I. B., Narloch W., Pych W., Schwarzenberg-Czerny A.
Acta Astronomica
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2016
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Vol. 66, No. 3
307--332
EN
The field of the globular cluster NGC 362 was monitored between 1997 and 2015 in a search for variable stars. BV light curves were obtained for 151 periodic or likely periodic variable stars, over a hundred of which are new detections. Twelve newly detected variable stars are proper-motion members of the cluster: two SX Phe and two RR Lyr pulsators, one contact binary, three detached or semi-detached eclipsing binaries, and four spotted variable stars. The most interesting objects among these are the binary blue straggler V20 with an asymmetric light curve, and the 8.1 d semidetached binary V24 located on the red giant branch of NGC 362, which is a Chandra X-ray source. We also provide substantial new data for 24 previously known variable stars.
5
Content available remote The Clusters AgeS Experiment (CASE). Variable Stars in the Field of the Globular Cluster NGC~3201
Kaluzny J., Rozyczka M., Thompson I. B., Narloch W., Mazur B., Pych W., Schwarzenberg-Czerny A.
Acta Astronomica
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2016
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Vol. 66, No. 1
31--53
EN
The field of the globular cluster NGC 3201 was monitored between 1998 and 2009 in a search for variable stars. BV light curves were obtained for 152 periodic or likely periodic variables, fifty-seven of which are new detections. Thirty-seven newly detected variables are proper motion members of the cluster. Among them we found seven detached or semi-detached eclipsing binaries, four contact binaries, and eight SX Phe pulsators. Four of the eclipsing binaries are located in the turnoff region, one on the lower main sequence and the remaining two slightly above the subgiant branch. Two contact systems are blue stragglers, and another two reside in the turnoff region. In the blue straggler region a total of 266 objects were found, of which 140 are proper motion (PM) members of NGC 3201, and another nineteen are field stars. Seventy-eight of the remaining objects for which we do not have PM data are located within the half-light radius from the center of the cluster, and most of them are likely genuine blue stragglers. Four variable objects in our field of view were found to coincide with X-ray sources: three chromospherically active stars and a quasar at a redshift z≈0.5.
6
Content available remote The Clusters AgeS Experiment (CASE). Variable Stars in the Field of the Globular Cluster M12
Kaluzny J., Thompson I. B., Narloch W., Pych W., Rozyczka M.
Acta Astronomica
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2015
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Vol. 65, No. 3
267--282
EN
The field of the globular cluster M12 (NGC 6218) was monitored between 1995 and 2009 in a search for variable stars. BV light curves were obtained for thirty-six periodic or likely periodic variable stars. Thirty-four of these are new detections. Among the latter we identified twenty proper-motion members of the cluster: six detached or semi-detached eclipsing binaries, five contact binaries, five SX Phe pulsators, and three yellow stragglers. Two of the eclipsing binaries are located in the turnoff region, one on the lower main sequence and the remaining three among the blue stragglers. Two contact systems are blue stragglers, and the remaining three reside in the turnoff region. In the blue straggler region a total of 103 objects were found, of which 42 are proper motion members of M12, and another four are field stars. 55 of the remaining objects are located within two core radii from the center of the cluster, and as such they are likely genuine blue stragglers. We also report the discoveries of a radial color gradient of M12, and the shortest period among contact systems in globular clusters in general.
7
Content available remote The Clusters AgeS Experiment (CASE). Variable Stars in the Field of the Globular Cluster NGC 6362
Kaluzny J., Thompson I. B., Rozyczka M., Pych W., Narloch W.
Acta Astronomica
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2014
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Vol. 64, No. 4
309--322
EN
The field of the globular cluster NGC 6362 was monitored between 1995 and 2009 in a search for variable stars. BV light curves were obtained for 69 periodic variable stars including 34 known RR Lyr stars, 10 known objects of other types and 25 newly detected variable stars. Among the latter we identified 18 proper-motion members of the cluster: seven detached eclipsing binaries (DEBs), six SX Phe stars, two W UMa binaries, two spotted red giants, and a very interesting eclipsing binary composed of two red giants - the first example of such a system found in a globular cluster. Five of the DEBs are located at the turnoff region, and the remaining two are redward of the lower main sequence. Eighty-four objects from the central 9×9 arcmin2 of the cluster were found in the region of cluster blue stragglers. Of these 70 are proper motion (PM) members of NGC 6362 (including all SX Phe and two W UMa stars), and five are field stars. The remaining nine objects lacking PM information are located at the very core of the cluster, and as such they are likely genuine blue stragglers.
8
Content available remote The Clusters AgeS Experiment (CASE). Analysis of the Detached Eclipsing Binary V15 in the Metal-Rich Open Cluster NGC 6253
Rozyczka M., Kaluzny J., Thompson I. B., Dotter A., Pych W., Narloch W.
Acta Astronomica
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2014
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Vol. 64, No. 3
233--246
EN
We present the first detailed analysis of the detached eclipsing binary V15 in the super-metal rich open cluster NGC 6253. We obtain the following absolute parameters: Mp=1.303±0.006 MSun, Rp=1.71±0.03 RSun, Lp=2.98±0.10 LSun for the primary, and Ms=1.225±0.006 MSun, Rs=1.44±0.02 RSun, Ls=2.13±0.06 LSun for the secondary. Based on Dartmouth isochrones, the age of NGC 6253 is estimated to be 3.80-4.25 Gyr from the mass-radius diagram and 3.9-4.6 Gyr from color-magnitude diagram fitting. Both of these estimates are significantly higher than those reported so far. The derived apparent distance modulus of 11.65 mag agrees well with the range of 10.9-12.2 mag derived by other authors; however our estimated reddening (0.113 mag) is lower than the lowest published value (0.15 mag). We confirm earlier observations that model atmospheres are not accurate enough to account for the whole CMD of the cluster, with the largest discrepancies appearing on the subgiant and giant branches. Although age estimation from the mass-radius diagram is a relatively safe, distance- and reddening-independent procedure, our results should be verified by photometric and spectroscopic observations of additional detached eclipsing binaries which we have discovered, at least two of which are proper-motion members of NGC 6253.
9
Content available Mikromorfologia glin lodowcowych jako narzędzie w rekonstrukcji procesów subglacjalnych
Narloch W., Piotrowski J. A.
Przegląd Geologiczny
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2013
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Vol. 61, nr 5
294--303
EN
Micromorphology has become an important tool in investigations of glacial tills. Structure and texture of tills studied in thin sections can be used to decipher the origin of tills, in particular their depositional and deformational history, but also to shed light on the nature of subglacial erosion, transport and deposition processes in general. In combination with laboratory experiments on till shearing under controlled conditions, micromorphology yields useful, quantitative data on till rheology that helps understanding the processes of ice movement over soft, deformable beds.This paper is a review of micromorphology applications to the study of subglacial tills as reported in the leading modern literature and presentation of a case study from Obórki site in north-central Poland that illustrates the potential of this method in the context of the last Scandinavian Ice Sheet.
10
Content available Zróżnicowanie facjalne glin jako wskaźnik fluktuacji ciśnienia wód subglacjalnych na kontakcie lodu i podłoża podczas zlodowacenia wisły w północnej części Pojezierza Dobrzyńskiego
Narloch W., Wojciechowska J. M., Osowicka A., Wysota W., Piotrowski J. A., Sobiech M.
Landform Analysis
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2013
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Vol. 25
125--133
PL
Badaniom sedymentologicznym poddano gliny lodowcowe fazy poznańskiej zlodowacenia wisły na dwóch stanowiskach terenowych (Przeszkoda i Obórki), zlokalizowanych w północnej części Pojezierza Dobrzyńskiego. Podczas ostatniego zlodowacenia obszar ten był pokryty lobem lodowcowym Wisły, którego rozwój był najprawdopodobniej determinowany przez wiślany strumień lodowy. W rekonstrukcji procesów formowania glin oraz mechanizmów ruchu lodu została zastosowana kompleksowa analiza glin, w tym: cech sedymentacyjnych, uziarnienia, składu petrograficznego, orientacji dłuższej osi głazików oraz analiza mikromorfologiczna. Analizowane gliny są masywne i warstwowane. Badania sugerują występowanie złożonych i czasowo zmiennych warunków pod lobem Wisły, prawdopodobnie spowodowanych przez fluktuacje ciśnienia wód subglacjalnych. Ruch lodu był wynikiem kombinacji deformacji podłoża i poślizgu bazalnego.
EN
Sedimentological analyses were performed on glacial till of the Weichselian glaciation in two field sites (Przeszkoda and Obórki) which are located in northern part of the Dobrzyń Lakeland. During the last glaciation this area was covered by the Vistula ice lobe which development has been determined by the Vistula Ice Stream. A multi-proxy approach including a study of sedimentary features, grain size, petrographic composition, till fabric and till micromorphology was used in reconstruction of till formation and ice movement mechanisms. Analysed tills are massive and stratified. We suggest existing of complex and temporally variable conditions under the Vistula ice lobe, probably caused by subglacial water fluctuations. Ice movement was caused by a combination of bed deformation and basal sliding.
11
Content available remote The Clusters AgeS Experiment (CASE): Variable Stars in the Globular Cluster 47 Tucanae
Kaluzny J., Rozyczka M., Pych W., Krzeminski W., Zloczewski K., Narloch W., Thompson I. B.
Acta Astronomica
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2013
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Vol. 63, No. 3
309--322
EN
Based on over 5400 BV images of 47 Tuc collected between 1998 and 2010 we obtained light curves of 65 variables, 19 of which are newly detected objects. New variables are located mostly just outside the core in a region poorly studied by earlier surveys of the cluster. Among them there are four detached eclipsing binaries and five likely optical counterparts of X-ray sources. Two detached systems are promising targets for follow-up observations. We briefly discuss properties of the most interesting new variables.
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