Preliminary Results of a Search for Variable Stars in the Globular Cluster M 13

AbstractWe present preliminary results of the variability survey in the field of the globular cluster NGC 4833. We observed all 34 variable stars known in the cluster. In addition, we have found two new SX Phoenicis stars, one new RR Lyrae star, twelve new eclipsing systems mostly of the W Ursae Majoris type, nine new variable red giants, and ten new field-stars showing irregular variations. Properties of RR Lyrae stars indicate that NGC 4833 is an Oosterhoff's type II globular cluster.

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STRucture and Evolution of the GAlaxy (STREGA): The case of Pal 3

Proceedings of the International Astronomical Union ◽

10.1017/s1743921319006549 ◽

2019 ◽

Vol 14 (S351) ◽

pp. 478-481

Author(s):

M. I. Moretti ◽

I. Musella ◽

M. Marconi ◽

V. Ripepi ◽

R. Molinaro

Keyword(s):

Time Series ◽

Globular Cluster ◽

Variable Stars ◽

Rr Lyrae Stars ◽

North East ◽

The North ◽

Rr Lyrae ◽

The Galaxy ◽

Lyrae Stars ◽

Candidate Variable

AbstractIn the context of the STRucture and Evolution of the GAlaxy survey, we describe the preliminary results obtained for the fields around the globular cluster Pal 3 (about 2.75 square degrees), by exploiting the obtained g, r, i time series photometry. The final aim is to use variable stars as tools to verify and study the presence of streams around Pal 3. We found 20 candidate variable stars of which 7 RR Lyrae stars possibly belonging to Pal 3, also at large distance from the center. The distribution of the candidate RR Lyrae seems to confirm a preferential distribution in the north-east direction, confirming previous results in literature.

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Optical and Near-infrared Pulsation Properties of RR Lyrae and Population II Cepheid Variables in the Messier 15 Globular Cluster

The Astrophysical Journal ◽

10.3847/1538-4357/ac214d ◽

2021 ◽

Vol 922 (1) ◽

pp. 20

Author(s):

Anupam Bhardwaj ◽

Marina Rejkuba ◽

G. C. Sloan ◽

Marcella Marconi ◽

Soung-Chul Yang

Keyword(s):

Globular Cluster ◽

Near Infrared ◽

Variable Stars ◽

Log P ◽

Distance Modulus ◽

Distance Measurements ◽

Rr Lyrae Stars ◽

Rr Lyrae ◽

Cepheid Variables ◽

Lyrae Stars

Abstract Messier 15 (NGC 7078) is an old and metal-poor post core-collapse globular cluster that hosts a rich population of variable stars. We report new optical (gi) and near-infrared (NIR, JK s ) multi-epoch observations for 129 RR Lyrae, 4 Population II Cepheids (3 BL Herculis, 1 W Virginis), and 1 anomalous Cepheid variable candidate in M15 obtained using the MegaCam and the WIRCam instruments on the 3.6 m Canada–France–Hawaii Telescope. Multi-band data are used to improve the periods and classification of variable stars, and determine accurate mean magnitudes and pulsational amplitudes from the light curves fitted with optical and NIR templates. We derive optical and NIR period–luminosity relations for RR Lyrae stars which are best constrained in the K s band, m K s = − 2.333 ( 0.054 ) log P + 13.948 ( 0.015 ) with a scatter of only 0.037 mag. Theoretical and empirical calibrations of RR Lyrae period–luminosity–metallicity relations are used to derive a true distance modulus to M15: 15.196 ± 0.026 (statistical) ± 0.039 (systematic) mag. Our precise distance moduli based on RR Lyrae stars and Population II Cepheid variables are mutually consistent and agree with recent distance measurements in the literature based on Gaia parallaxes and other independent methods.

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CCD Photometry of RR Lyrae Stars in NGC 6388 and M15

International Astronomical Union Colloquium ◽

10.1017/s0252921100117786 ◽

1993 ◽

Vol 139 ◽

pp. 338-338

Author(s):

N.A. Silbermann ◽

H.A. Smith ◽

M. Bolte

Keyword(s):

Globular Clusters ◽

Variable Stars ◽

Ccd Photometry ◽

Rr Lyrae Stars ◽

Preliminary Results ◽

Rr Lyrae ◽

Lyrae Stars

AbstractWe present preliminary results of a program of CCD photometry of RR Lyrae variable stars in the globular clusters NGC 6388 and M15.

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A Survey of Magellanic Cloud Clusters for RR Lyrae Stars

Symposium - International Astronomical Union ◽

10.1017/s0074180900039838 ◽

1984 ◽

Vol 108 ◽

pp. 37-38

Author(s):

J. A. Graham ◽

J. M. Nemec

Keyword(s):

Variable Stars ◽

Magellanic Cloud ◽

Magellanic Clouds ◽

The Other ◽

Rr Lyrae Stars ◽

Preliminary Results ◽

Rr Lyrae ◽

Other Hand ◽

Cloud Clusters ◽

Lyrae Stars

Preliminary results are presented of a search for RR Lyrae variable stars in old clusters in the Magellanic Clouds. RR Lyraes have been found in NGC 1786 and NGC 2210. With the exceptions of NGC 339 (SMC) and NGC 2019 and Hodge 11 (LMC), all clusters classified as type VII by Searle, Wilkinson and Bagnuolo (1980) contain RR Lyrae variables. On the other hand, none have yet been found in clusters of type VI.

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The Variable Stars in NGC 6723

International Astronomical Union Colloquium ◽

10.1017/s0252921100033492 ◽

1973 ◽

Vol 21 ◽

pp. 178-179

Author(s):

John Menzies

Keyword(s):

Southern Hemisphere ◽

Globular Cluster ◽

Variable Stars ◽

Horizontal Branch ◽

Rr Lyrae Stars ◽

Rr Lyrae ◽

Horizontal Branch Stars ◽

Magnitude Diagram ◽

The Mean ◽

Lyrae Stars

Abstract*.A study has been made of the variables in the Southern Hemisphere globular cluster NGC 6723, which is suspected of being relatively metal-rich on the basis of its colour-magnitude diagram and of its integrated spectral type of G3. Seven new RR Lyrae stars and two bright red, probably semiregular, variables have been found and the suspected variable of Fourcade and Laborde has been confirmed. The complement of RR Lyrae stars is now 27, consisting of 4 c-type and 23 ab-type variables, the mean periods being Pc = 0.d292 and Pab = 0.d537. On the basis of the two-colour diagram of the horizontal branch stars the cluster is considered to be virtually un-reddened. Applying Christy’s models to the data from this study we find the following parameters for the variables: Mv= 1.m10, mass = 0.42 M⊙, and Y=0.4.

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Variable Stars in the Sculptor Dwarf Galaxy

International Astronomical Union Colloquium ◽

10.1017/s025292110011783x ◽

1993 ◽

Vol 139 ◽

pp. 358-358

Author(s):

C. G. Goldsmith

Keyword(s):

Dwarf Galaxies ◽

Dwarf Galaxy ◽

Variable Stars ◽

University Of Washington ◽

Rr Lyrae Stars ◽

Preliminary Results ◽

Rr Lyrae ◽

The Mean ◽

Lyrae Stars ◽

Plate Collection

This project was initiated in 1985 by James Nemec (University of Washington) and Nicholas Suntzeff (C.T.I.O.). The goal was to study the system of ∼600 variable stars in the Sculptor dwarf galaxy. In 1987 the author became the recipient of the plate collection, which formed the basis for his Ph.D. dissertation. In this paper preliminary results are presented. Briefly, 612 stars were studied, of which 432 are van Agt (1978) stars and 180 are newly discovered variable stars. A total of 381 stars are confirmed variables. Most of these are RR Lyraes, but many anomalous Cepheids and some candidate eclipsing variables were also found. Several candidate double-mode RR Lyrae stars were also identified. The mean period of the ab-type RR Lyrae stars is 0.60±0.08 day, and the mean period of the c-type stars is 0.35±0.03 day, not unlike the mean periods of other nearby dwarf galaxies.

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General Properties of the Two Groups of Globular Clusters and Their Variable Stars

Symposium - International Astronomical Union ◽

10.1017/s0074180900010743 ◽

1975 ◽

Vol 67 ◽

pp. 541-543

Author(s):

A. V. Mironov ◽

N. N. Samus'

Keyword(s):

Chemical Composition ◽

Globular Clusters ◽

Variable Stars ◽

Rr Lyrae Stars ◽

General Properties ◽

Rr Lyrae ◽

Lyrae Stars

The dependences of the numbers of variable stars in globular clusters on the chemical composition are studied. For given metallicity the numbers of RR Lyrae stars reduced to some definite total number of stars in the cluster are different for the two groups of globular clusters introduced by Mironov.

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The Milky Way Revealed by Variable Stars. I. Sample Selection of RR Lyrae Stars and Evidence for Merger History

The Astrophysical Journal Supplement Series ◽

10.3847/1538-4365/ac347f ◽

2022 ◽

Vol 258 (1) ◽

pp. 20

Author(s):

Iminhaji Ablimit ◽

Gang Zhao ◽

Uy. Teklimakan ◽

Jian-Rong Shi ◽

Kunduz Abdusalam

Keyword(s):

Milky Way ◽

Sample Selection ◽

Variable Stars ◽

Rr Lyrae Stars ◽

Rr Lyrae ◽

Sky Survey ◽

Spectroscopic Information ◽

History Of ◽

Dual Origin ◽

Lyrae Stars

Abstract In order to study the Milky Way, RR Lyrae (RRL) variable stars identified by Gaia, ASAS-SN, and ZTF sky survey projects have been analyzed as tracers in this work. Photometric and spectroscopic information of 3417 RRLs including proper motions, radial velocity, and metallcity are obtained from observational data of Gaia, LAMOST, GALAH, APOGEE, and RAVE. Precise distances of RRLs with typical uncertainties less than 3% are derived by using a recent comprehensive period–luminosity–metallicity relation. Our results from kinematical and chemical analysis provide important clues for the assembly history of the Milky Way, especially for the Gaia–Sausage ancient merger. The kinematical and chemical trends found in this work are consistent with those of recent simulations that indicated that the Gaia–Sausage merger had a dual origin in the Galactic thick disk and halo. As recent similar works have found, the halo RRL sample in this work contains a subset of radially biased orbits besides a more isotropic component. This higher orbital anisotropy component amounts to β ≃ 0.8, and it contributes between 42% and 83% of the halo RRLs at 4 < R( kpc) < 20.

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Professional/Amateur Cooperation in the Study of Variable Stars as Illustrated by the Fourth Edition of the GCVS

International Astronomical Union Colloquium ◽

10.1017/s0252921100092800 ◽

1988 ◽

Vol 98 ◽

pp. 188-189

Author(s):

M.S. Frolov

Keyword(s):

Classical Group ◽

Cataclysmic Variables ◽

Variable Stars ◽

Eclipsing Binaries ◽

Fourth Edition ◽

Rr Lyrae Stars ◽

Rr Lyrae ◽

Long Time ◽

Hand Involvement ◽

Lyrae Stars

Let us divide variable stars into two main groups: the first “classical” group, includes objects known for a long time, such as Cepheids, RR-Lyrae stars, Miras, cataclysmic variables, eclipsing binaries, etc. The second group includes micropulsating variables of δ Scuti and β Cephei types, magnetic variables, rotating variables of BY Draconis type, etc.Historically, the contribution of amateurs in investigating the first group was very significant, and it continues to increase. On the other hand, involvement in studying the second group of stars was practically equal to zero some years ago, but today one can see the beginnings of an expansion of amateur work on this second group of variables – among brighter objects, of course. One reason is the beginning of cooperation between amateurs and professional astronomers having powerful instruments.

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