Wyniki wyszukiwania - BazTech

1

The OGLE Collection of Variable Stars. Over 15 000 δ Scuti Stars in the Large Magellanic Cloud

Soszyński I., Pietrukowicz P., Udalski A., Skowron J., Szymański M. K., Poleski R., Skowron D. M., Kozłowski S., Mróz P., Iwanek P., Wrona M., Ulaczyk K., Rybicki K., Gromadzki M., Mróz M.

Acta Astronomica

|

2023

|

Vol. 73, No. 2

105--126

EN

We present the OGLE collection of δ Scuti stars in the Large Magellanic Cloud and in its foreground. Our dataset encompasses a total of 15 256 objects, constituting the largest sample of extragalactic δ Sct stars published so far. In the case of 12 δ Sct pulsators, we detected additional eclipsing or ellipsoidal variations in their light curves. These are the first known candidates for binary systems containing δ Sct components beyond the Milky Way. We provide observational parameters for all variables, including pulsation periods, mean magnitudes, amplitudes, and Fourier coefficients, as well as long-term light curves in the I- and V-bands collected during the fourth phase of the OGLE project. We construct the period-luminosity (PL) diagram, in which fundamental-mode and first-overtone δ Sct stars form two nearly parallel ridges. The latter ridge is an extension of the PL relation obeyed by first-overtone classical Cepheids. The slopes of the PL relations for δ Sct variables are steeper than those for classical Cepheids, indicating that the continuous PL relation for first-overtone δ Sct variables and Cepheids is non-linear, exhibiting a break at a period of approximately 0.5 d. We also report the enhancement of the OGLE collection of Cepheids and RR Lyr stars with newly identified and reclassified objects, including pulsators contained in the recently published Gaia DR3 catalog of variable stars. As a by-product, we estimate the contamination rate in the Gaia DR3 catalogs of Cepheids and RR Lyr variables.

2

The OGLE Collection of Variable Stars. Over 2600 δ Scuti Stars in the Small Magellanic Cloud

Soszyński I., Udalski A., Skowron J., Pietrukowicz P., Szymański M. K., Poleski R., Skowron D. M., Kozłowski S., Mróz P., Iwanek P., Wrona M., Ulaczyk K., Rybicki K., Gromadzki M.

Acta Astronomica

|

2022

|

Vol. 72, No. 4

245--256

EN

We present the first-ever collection of δ Scuti stars found over the entire area of the Small Magellanic Cloud (SMC). The sample consists of 2810 variables of which over 2600 objects belong to the SMC while the remaining stars are most likely members of the Milky Way's halo. The sample has been divided into 2733 single mode and 77 multimode pulsators. We provide observational parameters (pulsation periods, mean magnitudes, amplitudes, Fourier coefficients) of all δ Sct stars and the long-term I- and V-band time-series photometric measurements collected during the fourth phase of the Optical Gravitational Lensing Experiment (OGLE-IV).

3

Final Release of the OGLE Collection of Cepheids and RR Lyrae Stars in the Magellanic System. The Outer Regions

Soszyński I., Udalski A., Szymański M. K., Pietrukowicz P., Skowron J., Skowron D. M., Poleski R., Kozłowski S., Mróz P., Ulaczyk K., Rybicki K., Iwanek P., Wrona M.

Acta Astronomica

|

2019

|

Vol. 69, No. 2

87--99

EN

We present the final release of the OGLE collection of classical pulsators (Cepheids and RR Lyr stars) in the Large and Small Magellanic Clouds. The sky coverage has been increased from 670 to 765 square degrees compared to the previous edition of our collection. We also add some Cepheids and RR Lyr stars found by the Gaia team and reclassify three Cepheids. Ultimately, our collection consists of 9650 classical Cepheids, 343 type II Cepheids, 278 anomalous Cepheids, and 47 828 RR Lyr stars inside and toward the Magellanic System.

4

Three-Dimensional Distributions of Type II Cepheids and Anomalous Cepheids in the Magellanic Clouds. Do these Stars Belong to the Old, Young or Intermediate-Age Population?

Iwanek P., Soszyński I., Skowron D., Skowron J., Mróz P., Kozłowski S., Udalski A., Szymański M. K., Pietrukowicz P., Poleski R., Jacyszyn-Dobrzeniecka A.

Acta Astronomica

|

2018

|

Vol. 68, No. 3

213--236

EN

The nature of type II Cepheids and anomalous Cepheids is still not well known and their evolutionary channels leave many unanswered questions. We use complete collection of classical pulsating stars in the Magellanic Clouds discovered by the OGLE project, to compare their spatial distributions, which are one of the characteristic features directly related to the star formation history. In this analysis we use 9649 classical Cepheids, 262 anomalous Cepheids, 338 type II Cepheids and 46 443 RR Lyr stars from both Magellanic Clouds. We compute three-dimensional Kolmogorov-Smirnov tests for every possible pair of type II and anomalous Cepheids with classical Cepheids, and RR Lyr stars. We confirm that BL Her stars are as old as RR Lyr variable stars - their spatial distributions are similar, and they create a vast halo around both galaxies. We discover that spatial distribution of W Vir stars has attributes characteristic for both young and old stellar populations. Hence, it seems that these similarities are related to the concentration of these stars in the center of the Large Magellanic Cloud, and the lack of a vast halo. This leads to the conclusion that W Vir variables could be a mixture of old and intermediate-age stars. Our analysis of the three-dimensional distributions of anomalous Cepheids shows that they differ significantly from classical Cepheids. Statistical tests of anomalous Cepheids distributions with RR Lyr distributions do not give unambiguous results. We consider that these two distributions can be similar through the vast halos they create. This similarity would confirm anomalous Cepheids evolution scenario that assumes coalescence of a binary system.

5

The OGLE Collection of Variable Stars. Type II Cepheids in the Magellanic System

Soszyński I., Udalski A., Szymański M. K., Wyrzykowski Ł., Ulaczyk K., Poleski R., Pietrukowicz P., Kozłowski S., Skowron D., Skowron J., Mróz P., Rybicki K., Iwanek P.

Acta Astronomica

|

2018

|

Vol. 68, No. 2

89--109

EN

We present a nearly complete collection of type II Cepheids in the Magellanic System. The sample consists of 338 objects: 285 and 53 variables in the Large and Small Magellanic Clouds, respectively. Based on the pulsation periods and light-curve morphology, we classified 118 of our type II Cepheids as BL Her, 120 as W Vir, 34 as peculiar W Vir, and 66 as RV Tau stars. For all objects, we publish time-series {\it VI} photometry obtained during the OGLE-IV survey, from 2010 to the end of 2017. We present the most interesting individual objects in our collection: 16 type II Cepheids showing additional eclipsing or ellipsoidal variability, two RV Tau variables more than 2.5 mag fainter than other stars of this type in the LMC, an RVb star that drastically decreased the amplitude of the long-period modulation, type II Cepheids exhibiting significant amplitude and period changes, and an RV Tau star which undergoes interchanges of deep and shallow minima. We show that peculiar W Vir stars have markedly different spatial distribution than other subclasses of type II Cepheids, which indicates different evolutionary histories of these objects.

6

OGLE-ing the Magellanic System: Three-Dimensional Structure of the Clouds and the Bridge using RR Lyrae Stars

Jacyszyn-Dobrzeniecka A. M., Skowron D. M., Mróz P., Soszyński I., Udalski A., Pietrukowicz P., Skowron J., Poleski R., Kozłowski S., Wyrzykowski Ł., Pawlak M., Szymański M. K., Ulaczyk K.

Acta Astronomica

|

2017

|

Vol. 67, No. 1

1--35

EN

We present a three-dimensional analysis of a sample of 22 859 type ab RR Lyr stars in the Magellanic System from the OGLE-IV Collection of RR Lyr stars. The distance to each object was calculated based on its photometric metallicity and a theoretical relation between color, absolute magnitude and metallicity. The LMC RR Lyr distribution is very regular and does not show any substructures. We demonstrate that the bar found in previous studies may be an overdensity caused by blending and crowding effects. The halo is asymmetrical with a higher stellar density in its north-eastern area, which is also located closer to us. Triaxial ellipsoids were fitted to surfaces of a constant number density. Ellipsoids farther from the LMC center are less elongated and slightly rotated toward the SMC. The inclination and position angle change significantly with the $a$ axis size. The median axis ratio is 1:1.23:1.45. The RR Lyr distribution in the SMC has a very regular, ellipsoidal shape and does not show any substructures or asymmetries. All triaxial ellipsoids fitted to surfaces of a constant number density have virtually the same shape (axis ratio) and are elongated along the line-of-sight. The median axis ratio is 1:1.10:2.13. The inclination angle is very small and thus the position angle is not well defined. We present the distribution of RR Lyr stars in the Magellanic Bridge area, showing that the Magellanic Clouds' halos overlap. A comparison of the distributions of RR Lyr stars and Classical Cepheids shows that the former are significantly more spread and distributed regularly, while the latter are very clumped and form several distinct substructures.

7

Concluding Henrietta Leavitt's Work on Classical Cepheids in the Magellanic System and Other Updates of the OGLE Collection of Variable Stars

Soszyński I., Udalski A., Szymański M. K., Wyrzykowski Ł., Ulaczyk K., Poleski R., Pietrukowicz P., Kozłowski S., Skowron D. M., Skowron J., Mróz P., Pawlak M.

Acta Astronomica

|

2017

|

Vol. 67, No. 2

103--113

EN

More than a century ago, Henrietta Leavitt discovered the first Cepheids in the Magellanic Clouds together with the famous period-luminosity relationship revealed by these stars, which soon after revolutionized our view of the Universe. Over the years, the number of known Cepheids in these galaxies has steadily increased with the breakthrough in the last two decades thanks to the new generation of large-scale long-term sky variability surveys. Here we present the final upgrade of the OGLE Collection of Cepheids in the Magellanic System which already contained the vast majority of known Cepheids. The updated collection now comprises 9649 classical and 262 anomalous Cepheids. Type-II Cepheids will be updated shortly. Thanks to high completeness of the OGLE survey the sample of classical Cepheids includes virtually all stars of this type in the Magellanic Clouds. Thus, the OGLE survey concludes the work started by Henrietta Leavitt. Additionally, the OGLE sample of RR Lyr stars in the Magellanic System has been updated. It now counts 46 443 variables. A collection of seven anomalous Cepheids in the halo of our Galaxy detected in front of the Magellanic Clouds is also presented. OGLE photometric data are available to the astronomical community from the OGLE Internet Archive. The time-series photometry of all pulsating stars in the OGLE Collection has been supplemented with new observations.

8

The OGLE Collection of Variable Stars. Over 45 000 RR~Lyrae Stars in the Magellanic System

Soszyński I., Udalski A., Szymański M. K., Wyrzykowski Ł., Ulaczyk K., Poleski R., Pietrukowicz P., Kozłowski S., Skowron D. M., Skowron J., Mróz P., Pawlak M.

Acta Astronomica

|

2016

|

Vol. 66, No. 2

131--147

EN

We present the largest collection of RR Lyrae stars in the Magellanic System and in its foreground. The sample consists of 45 451 RR Lyr stars, of which 39 082 were detected toward the Large Magellanic Cloud and 6369 toward the Small Magellanic Cloud. We provide long-term time-series photometric measurements collected during the fourth phase of the Optical Gravitational Lensing Experiment (OGLE-IV). We discuss several potential astrophysical applications of our collection: investigation of the structure of the Magellanic Clouds and the Galactic halo, studies of the globular clusters in the Magellanic System, analysis of double-mode RR Lyr stars, and search for RR Lyr stars in eclipsing binary systems.

9

The OGLE Collection of Variable Stars. Eclipsing Binaries in the Magellanic System

Pawlak M., Soszyński I., Udalski A., Szymański M. K., Wyrzykowski Ł., Ulaczyk K., Poleski R., Pietrukowicz P., Kozłowski S., Skowron D. M., Skowron J., Mróz P., Hamanowicz A.

Acta Astronomica

|

2016

|

Vol. 66, No. 4

421--432

EN

We present the collection of eclipsing binaries in the Large and Small Magellanic Clouds, based on the OGLE survey. It contains 48 605 systems, 40 204 belonging to the LMC and 8401 to the SMC. Out of the total number of presented here binaries, 16 374 are the new discoveries. We present the time-series photometry obtained for the selected objects during the fourth phase of the OGLE project. The catalog has been created using a two step machine learning procedure based on the Random Forest algorithm

10

OGLE-ing the Magellanic System: Three-Dimensional Structure of the Clouds and the Bridge Using Classical Cepheids

Jacyszyn-Dobrzeniecka A. M., Skowron D. M., Mróz P., Skowron J., Soszyński I., Udalski A., Pietrukowicz P., Kozłowski S., Wyrzykowski Ł., Poleski R., Pawlak M., Szymański M. K., Ulaczyk K.

Acta Astronomica

|

2016

|

Vol. 66, No. 2

149--196

EN

We analyzed a sample of 9418 fundamental-mode and first-overtone classical Cepheids from the OGLE-IV Collection of Classical Cepheids. The distance to each Cepheid was calculated using the period-luminosity relation for the Wesenheit magnitude, fitted to our data. The classical Cepheids in the LMC are situated mainly in the bar and in the northern arm. The eastern part of the LMC is closer to us and the plane fit to the whole LMC sample yields the inclination i=24.°2 ±0.°7 and position angle P.A.=151.°4±1.°7. We redefined the LMC bar by extending it in the western direction and found no offset from the plane of the LMC contrary to previous studies. On the other hand, we found that the northern arm is offset from a plane by about -0.5 kpc, which was not observed before. The age distribution of the LMC Cepheids shows one maximum at about 100 Myr. We demonstrate that the SMC has a non-planar structure and can be described as an extended ellipsoid. We identified two large ellipsoidal off-axis structures in the SMC. The northern one is located closer to us and is younger, while the south-western is farther and older. The age distribution of the SMC Cepheids is bimodal with one maximum at 110 Myr, and another one at 220 Myr. Younger stars are located in the closer part of this galaxy while older ones are more distant. We classified nine Cepheids from our sample as Magellanic Bridge objects. These Cepheids show a large spread in three-dimensions although five of them form a connection between the Clouds. The closest one is closer than any of the LMC Cepheids, while the farthest one - farther than any SMC Cepheid. All but one Cepheids in the Magellanic Bridge are younger than 300 Myr. The oldest one can be associated with the SMC Wing.

11

OGLE-ing the Magellanic System: Photometric Metallicity from Fundamental Mode RR Lyrae Stars

Skowron D. M., Soszyński I., Udalski A., Szymański M. K., Pietrukowicz P., Skowron J., Poleski J., Wyrzykowski Ł., Ulaczyk K., Kozłowski S., Mróz P., Pawlak M.

Acta Astronomica

|

2016

|

Vol. 66, No. 3

269--292

EN

In an era of extensive photometric observations, the catalogs of RR Lyr type variable stars number tens of thousands of objects. The relation between the iron abundance [Fe/H] and the Fourier parameters of the stars light curve allows us to investigate mean metallicities and metallicity gradients in various stellar environments, independently of time-consuming spectroscopic observations. In this paper we use almost 6500 V- and I-band light curves of fundamental mode RR Lyr stars from the OGLE-IV survey to provide a relation between the V- and I-band phase parameter ϕ31 used to estimate [Fe/H]. The relation depends on metallicity, which limits its applicability. We apply this relation to metallicity formulae developed for the Johnson V- and the Kepler Kp-band to obtain the relation between [Fe/H] and ϕ31 for the I-band photometry. Last, we apply the new relation of Nemec to the OGLE-IV fundamental mode RR Lyr stars data and construct a metallicity map of the Magellanic Clouds. Median [Fe/H] is -1.39±0.44 dex for the LMC and -1.77±0.48 dex for the SMC, on the Jurcsik metallicity scale. We also find a metallicity gradient within the LMC with a slope of -0.029±0.002 dex/kpc in the inner 5 kpc and -0.030±0.003 dex/kpc beyond 8 kpc, and no gradient in-between (-0.019±0.002 dex/kpc integrally). We do not observe a metallicity gradient in the SMC, although we show that the metal-rich RRab stars are more concentrated toward the SMC center than the metal-poor.

12

OGLE Collection of Star Clusters. New Objects in the Outskirts of the Large Magellanic Cloud

Sitek M., Szymański M. K., Skowron D. M., Udalski A., Kostrzewa-Rutkowska Z., Skowron J., Karczmarek P., Cieślar M., Wyrzykowski Ł., Kozłowski S., Pietrukowicz P., Soszyński I., Mróz P., Pawlak M., Poleski R., Ulaczyk K.

Acta Astronomica

|

2016

|

Vol. 66, No. 3

255--267

EN

The Magellanic System (MS), consisting of the Large Magellanic Cloud (LMC), the Small Magellanic Cloud (SMC) and the Magellanic Bridge (MBR), contains diverse sample of star clusters. Their spatial distribution, ages and chemical abundances may provide important information about the history of formation of the whole System. We use deep photometric maps derived from the images collected during the fourth phase of the Optical Gravitational Lensing Experiment (OGLE-IV) to construct the most complete catalog of star clusters in the Large Magellanic Cloud using the homogeneous photometric data. In this paper we present the collection of star clusters found in the area of about 225 square degrees in the outer regions of the LMC. Our sample contains 679 visually identified star cluster candidates, 226 of which were not listed in any of the previously published catalogs. The new clusters are mainly young small open clusters or clusters similar to associations.

13

Gaia and Variable Stars

Udalski A., Soszyński I., Skowron D. M., Skowron J., Pietrukowicz P., Mróz P., Poleski R., Szymański M. K., Kozłowski S., Wyrzykowski Ł., Ulaczyk K., Pawlak M.

Acta Astronomica

|

2016

|

Vol. 66, No. 4

433--453

EN

We present a comparison of the Gaia DR1 samples of pulsating variable stars - Cepheids and RR Lyr type - with the OGLE Collection of Variable Stars aiming at the characterization of the Gaia mission performance in the stellar variability domain. Out of 575 Cepheids and 2322 RR Lyr candidates from the Gaia DR1 samples located in the OGLE footprint in the sky, 559 Cepheids and 2302 RR Lyr stars are genuine pulsators of these types. The number of misclassified stars is low indicating reliable performance of the Gaia data pipeline. The completeness of the Gaia DR1 samples of Cepheids and RR Lyr stars is at the level of 60-75% as compared to the OGLE Collection dataset. This level of completeness is moderate and may limit the applicability of the Gaia data in many projects.

14

The OGLE Collection of Variable Stars. Classical Cepheids in the Magellanic System

Soszyński I., Udalski A., Szymański M. K., Skowron D., Pietrzyński G., Poleski R., Pietrukowicz P., Skowron J., Mróz P., Kozłowski S., Wyrzykowski Ł., Ulaczyk K., Pawlak M.

Acta Astronomica

|

2015

|

Vol. 65, No. 4

297--312

EN

We present here a nearly complete census of classical Cepheids in the Magellanic System. The sample extends the set of Cepheids published in the past by the Optical Gravitational Lensing Experiment (OGLE) to the outer regions of the Large (LMC) and Small Magellanic Cloud (SMC). The entire collection consists of 9535 Cepheids of which 4620 belong to the LMC and 4915 are members of the SMC. We provide the I- and V-band time-series photometry of the published Cepheids, their finding charts, and basic observational parameters. Based on this unique OGLE sample of Cepheids we present updated period-luminosity relations for fundamental, first, and second mode of pulsations in the I- and V-bands and for the WI extinction-free Wesenheit index. We also show the distribution of classical Cepheids in the Magellanic System. The OGLE collection contains several classical Cepheids in the Magellanic Bridge - the region of interaction between the Magellanic Clouds. The discovery of classical Cepheids and their estimated ages confirm the presence of young stellar population between these galaxies.

15

The OGLE Collection of Variable Stars. Anomalous Cepheids in the Magellanic Clouds

Soszyński I., Udalski A., Szymański M. K., Pietrzyński G., Wyrzykowski Ł., Ulaczyk K., Poleski R., Pietrukowicz P., Kozłowski S., Skowron J., Skowron D., Mróz P., Pawlak M.

Acta Astronomica

|

2015

|

Vol. 65, No. 3

233--250

EN

We present a collection of 250 anomalous Cepheids (ACs) discovered in the OGLE-IV fields toward the Large (LMC) and Small Magellanic Cloud (SMC). The LMC sample is an extension of the OGLE-III Catalog of ACs published in 2008, while the SMC sample contains the first known bona fide ACs in this galaxy. The total sample is composed of 141 ACs in the LMC and 109 ACs in the SMC. All these stars pulsate in single modes: fundamental (174 objects) or first overtone (76 objects). Additionally, we report the discovery of four ACs located in the foreground of the Magellanic Clouds. These are the first unambiguously identified fundamental-mode ACs known in the Galactic field. We demonstrate that the coefficients φ21 and φ31 determined by the Fourier light curve decomposition are useful discriminators between classical Cepheids and ACs, at least in the LMC and in the field of the Milky Way. In the SMC, the light curve shapes and mean magnitudes of short-period classical Cepheids make them similar to ACs, which is a source of difficulties in the discrimination of both classes of pulsators. The presence of unidentified ACs in the catalogs of classical Cepheids may be partly responsible for the observed non-linearity of the period--luminosity relation observed for short-period Cepheids in the SMC. We compare spatial distributions of ACs, classical Cepheids and RR Lyr stars. We show that the distribution of ACs resembles that of old stars (RR Lyr variables), although in the LMC there are visible structures typical for young population (classical Cepheids): the bar and spiral arms. This may suggest that ACs are a mixture of relatively young stars and mergers of very old stars.

16

OGLE-IV: Fourth Phase of the Optical Gravitational Lensing Experiment

Udalski A., Szymański M. K., Szymański G.

Acta Astronomica

|

2015

|

Vol. 65, No. 1

1--38

EN

We present both the technical overview and main science drivers of the fourth phase of the Optical Gravitational Lensing Experiment (hereafter OGLE-IV). OGLE-IV is currently one of the largest sky variability surveys worldwide, targeting the densest stellar regions of the sky. The survey covers over 3000 square degrees in the sky and monitors regularly over a billion sources. The main targets include the inner Galactic Bulge and the Magellanic System. Their photometry spans the range of 12

17

Multi-Mode and Non-Standard Classical Cepheids in the Magellanic System

Soszyński I., Udalski A., Szymański M. K., Poleski R., Pietrukowicz P., Kozłowski S., Mróz P., Wyrzykowski Ł., Skowron D., Skowron J., Pietrzyński G., Ulaczyk K., Pawlak M.

Acta Astronomica

|

2015

|

Vol. 65, No. 4

329--339

EN

We present a sample of the most interesting classical Cepheids selected from the OGLE collection of classical Cepheids in the Magellanic System. The main selection criterion for this sample was the presence of non-standard, unique pulsational properties. The sample contains the first known double-mode Cepheid pulsating in the second- and third-overtone modes and a large number of objects with non-radial modes excited. We also found Cepheids revealing Blazhko-like light curve modulation, objects ceasing pulsations or showing atypical shapes of their light curves. Additionally, the status of several triple mode classical Cepheids is updated based on OGLE-IV photometry extending the time baseline to 15 years.

18

Eclipsing Binaries with Classical Cepheid Component in the Magellanic System

Udalski A., Soszyński I., Szymański M. K., Pietrzyński G., Poleski R., Pietrukowicz P., Kozłowski S., Mróz P., Skowron D., Skowron J., Wyrzykowski Ł., Ulaczyk K., Pawlak M.

Acta Astronomica

|

2015

|

Vol. 65, No. 4

341--350

EN

We present a census of eclipsing binary systems with classical Cepheid as a component. All such systems known were found in the OGLE collection of classical Cepheids in the Magellanic System. We extend the list of potential candidates adding four new objects found in the OGLE-IV photometric data. One of the new Cepheids in the eclipsing system, OGLE-SMC-CEP-3235, revealed only one eclipse during 15 years of the OGLE photometric monitoring. However, it additionally shows very well pronounced light-time effect indicating that the binarity is real and the system is physically bound. We also search for the light-time effect in other known eclipsing Cepheids and we clearly detect it in OGLE-LMC-CEP-1812. We discuss application of this tool for the search for Cepheids in non-eclipsing binary systems.

19

An X-Shooter View of the Symbiotic Star [JD2002] 11

Hajduk M., Gromadzki M., Mikołajewska J., Miszalski B., Soszyński I.

Acta Astronomica

|

2015

|

Vol. 65, No. 2

139--149

EN

We aimed to verify the nature and derive the basic parameters of the symbiotic star candidate [JD2002] 11. For this purpose, we obtained and analyzed an X-Shooter spectrum of [JD2002] 11. We also used optical and infrared photometry available for the object. Emission-line diagnostic ratios are characteristic of a dusty type symbiotic star and reveal a two-component nebula (low- and high-density). The spectral energy distribution is well fitted with a two-component black body spectrum with the respective temperatures of 1150 K and 600 K. The total luminosity of 3000 L⊙ is consistent with the expected luminosity of a typical Mira star, embedded in an optically thick dust shell. We conclude that [JD2002] 11 is the ninth symbiotic star in total and only the second dusty type symbiotic star discovered in the Small Magellanic Cloud.

20

Variable Stars from the OGLE-III Shallow Survey in the Large Magellanic Cloud

Ulaczyk K., Szymański M. K., Udalski A., Kubiak M., Pietrzyński G., Soszyński I., Wyrzykowski Ł., Poleski R., Gieren W., Walker A. R., Garcia-Varel A.

Acta Astronomica

|

2013

|

Vol. 63, No. 2

159--179

EN

We describe variable stars found in the data collected during the OGLE-III Shallow Survey covering the I-band magnitude range from 9.7 mag to 14.5 mag. The main result is the extension of period-luminosity relations for Cepheids up to 134 days. We also detected 82 binary systems and 110 long-period variables not present in the main OGLE catalogs. Additionally 558 objects were selected as candidates for miscellaneous variables.