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New Photometric and Spectroscopic Observations of the Eclipsing Binary V2080 Cygni

Dimitrov W., Kamiński K., Bąkowska K., Kamińska M. K., Tokarek J., Pawłowski M., Boneva D., Bartczak P., Kwiatkowski T., Schwarzenberg-Czerny A.

Acta Astronomica

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2022

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Vol. 72, No. 1

55--67

EN

We present new spectroscopic and photometric measurements of the eclipsing binary V2080 Cyg. It is a detached system with similar components and an orbital period of 4.9 d. We collected spectroscopic data with two instruments, 1.88 m DDO telescope equipped with Cassegrain spectrograph and 0.5 m PST1 connected to a fiber-fed echell\'e spectrograph. We collected 127 measurements for each component, which significantly increase the number of available radial velocity measurements for the V2080 Cyg system. Obtained masses of the eclipsing components are M1=1.189± 0.007 and M2=1.138±0.007 M☉. We also collected a multicolor photometry. The three-band light curves obtained together with the radial velocity data enabled us to calculate the model of the system. New estimations of the orbital inclination and radii of the components were computed. We obtained as well new times of minima. The O-C diagrams indicate variation, which requires more recent data to be confirmed. The possible existence of a third body could cause a light-time effect in the system. In addition, we analyze the Gaia mission results. V2080 Cyg A has three visual companions. However, according to Gaia parallaxes and proper motions, they cannot be dynamically connected with the eclipsing binary and therefore are background stars.

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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.

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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.

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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.

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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.

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Planets in Stellar Clusters Extensive Search. V. Search for Planets and Identification of 18 new Variable Stars in the Old Open Cluster NGC 188

Mochejska B. J., Stanek K. Z., Sasselov D. D., Szentgyorgyi A. H., Cooper R. L., Hickox R. C., Hradecky V., Marrone D., P., Winn J. N., Schwarzenberg-Czerny A.

Acta Astronomica

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2008

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Vol. 58, No. 3

263--278

EN

We have undertaken a long-term project, Planets in Stellar Clusters Extensive Search (PISCES), to search for transiting planets in open clusters. In this paper we present the results for NGC 188, an old, rather populous cluster. We have monitored the cluster for more than 87 hours, spread over 45 nights. We have not detected any good transiting planet candidates. We have discovered 18 new variable stars in the cluster, bringing the total number of identified variables to 28, and present for them high precision light curves, spanning 15 months.

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Curious Variables Experiment (CURVE). Three Periodicities of BF Ara

Olech A., Rutkowski A., Schwarzenberg-Czerny A.

Acta Astronomica

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2007

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Vol. 57, No. 4

331--345

EN

We report CCD photometry of the dwarf nova BF Ara in quiescence carried out throughout fifteen consecutive nights. Light curve in this interval is dominated by a large amplitude (≈0.8 mag), two period modulations. Higher amplitude signal has a period of 0.082159(4) days, which was increasing at the rate of P/Psh=3.8(3)×10-5. Weaker and stable second signal has a period of 0.084176(21) days. Because the superhump period of BF Ara is equal to 0.08797(1) days, the first modulation is interpreted as quiescent negative superhump arising from retrograde precession of titled accretion disk and the latter one as the orbital period of the binary. The respective period excess and defect are ε=4.51%±0.03% and ε-=-2.44%±0.02%. Thus BF Ara is yet another in-the-gap nova with mass ratio of q≈0.21.

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Cluster AgeS Experiment (CASE): Dwarf Novae and a Probable Microlensing Event in the Globular Cluster M22

Pietrukowicz P., Kaluzny J., Thompson I. B., Jaroszyński M., Schwarzenberg-Czerny A., Krzeminski W., Pych W.

Acta Astronomica

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2005

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Vol. 55, No. 3

261--274

EN

We report the identification of a new cataclysmic variable (denoted as CV2) and a probable microlensing event in the field of the globular cluster M22. Two outbursts were observed for CV2. During one of them superhumps with Psh=0.08875 d were present in the light curve. CV2 has an X-ray counterpart detected by XMM-Newton. A very likely microlensing event at a radius of 2.'3 from the cluster center was detected. It had an amplitude of Δ V=0.75 mag and a characteristic time of 15.9 days. Based on model considerations we show that the most likely configuration has the source in the Galactic bulge with the lens in the cluster. Two outbursts were observed for the already known dwarf nova CV1.

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Curious Variables Experiment (CURVE). Superhump Period Change Pattern in KS UMa and Other Dwarf Novae

Olech A., Schwarzenberg-Czerny A., Kędzierski P., Złoczewski K., Mularczyk K., Wiśniewski M.

Acta Astronomica

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2003

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Vol. 56, No. 2

175--194

EN

We report extensive photometry of the dwarf nova KS UMa throughout its 2003 superoutburst till quiescence. During the superoutburst the star displayed clear superhumps with a mean period of Psh=0.070092(23) days. In the middle stage of superoutburst the period was increasing with a rate of P/P=(21±12)×10-5 and later was decreasing with a rate of P/P=-(21±8)×10-5. At the end of superoutburst and during first dozen days of quiescence the star was showing late superhumps with a mean period of Plate=0.06926(2) days. This phenomenon was observed even 30 days after beginning of the superoutburst. In quiescence the star shows quasi-periodic modulations with amplitude reaching 0.5 mag. The most common structure observed during this stage was sinusoidal wave characterized by a period of about 0.1 days. Comparing KS UMa to other SU UMa stars we conclude that this group of dwarf novae shows decreasing superhump periods at the beginning and the end of superoutburst but increasing period in the middle phase.