scholarly journals Erratum: Photometric and radial-velocity time-series of RR Lyrae stars in M3: analysis of single-mode variables

2018 ◽  
Vol 481 (2) ◽  
pp. 2778-2778
Author(s):  
J Jurcsik ◽  
P Smitola ◽  
G Hajdu ◽  
Á Sódor ◽  
J Nuspl ◽  
...  
Keyword(s):  
Time Series ◽  
Radial Velocity ◽  
Single Mode ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Lyrae Stars

scholarly journals Photometric and radial-velocity time series of RR Lyrae stars in M3: analysis of single-mode variables

2017 ◽  
Vol 468 (2) ◽  
pp. 1317-1337 ◽  
Author(s):  
J. Jurcsik ◽  
P. Smitola ◽  
G. Hajdu ◽  
Á. Sódor ◽  
J. Nuspl ◽  
...  
Keyword(s):  
Time Series ◽  
Radial Velocity ◽  
Single Mode ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Lyrae Stars

scholarly journals The Virgo Stellar Stream: Extended sample

2009 ◽  
Vol 5 (S262) ◽  
pp. 131-134 ◽  
Author(s):  
S. Duffau ◽  
A. K. Vivas ◽  
R. Zinn ◽  
R. A. Méndez ◽  
M. T. Ruiz
Keyword(s):  
Radial Velocity ◽  
Spectroscopic Study ◽  
The Sun ◽  
Rr Lyrae Stars ◽  
Survey Team ◽  
Rr Lyrae ◽  
Abundance Estimates ◽  
Metal Abundance ◽  
Lyrae Stars

AbstractWe have completed a spectroscopic study of the “12.4 hr clump”, the second largest substructure in the Quasar Equatorial Survey Team (QUEST) catalog. First discovered as an over-density of RR Lyrae stars (Vivas et al. 2001, ApJL 554 33), the region containing the “12.4 hr clump” has generated much interest (Newberg et al. (2002), Martinez-Delgado et al. (2007), Juric et al. (2008), amongst many others). Our first spectroscopic study of this clump revealed the presence of a sharp peak in the radial velocity histogram for the candidate stars (Duffau et al. 2006). The combination of this result and metal abundance estimates for the sample was then interpreted as a signature of the presence of a stellar stream within the clump. This sub-structure was named the “Virgo Stellar Stream” (VSS), given its location in the direction of the Virgo Constellation, at approximately 20 kpc from the Sun. Several other groups have studied this region and have suggested that the over-density containing the VSS could extend to larger areas of the sky (outside QUEST's observing range). We present the complete spectroscopic follow up of the clump candidates present in QUEST and the composite of the studies we performed along the same l.o.s., including data at brighter magnitudes (Vivas et al. 2008). Our study confirmed the nature of the VSS, revealed its likely extent within the QUEST survey and defined a number of its relevant properties.

[ITAL]BVI[/ITAL] Time-Series Data of the Galactic Globular Cluster NGC 3201. I. RR Lyrae Stars

2002 ◽  
Vol 124 (3) ◽  
pp. 1528-1554 ◽  
Author(s):  
A. M. Piersimoni ◽  
G. Bono ◽  
V. Ripepi
Keyword(s):  
Time Series ◽  
Globular Cluster ◽  
Time Series Data ◽  
Series Data ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Lyrae Stars

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

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.

scholarly journals A DECam view of the diffuse dwarf galaxy Crater II – Variable stars

2019 ◽  
Vol 492 (1) ◽  
pp. 1061-1077 ◽  
Author(s):  
A Katherina Vivas ◽  
Alistair R Walker ◽  
Clara E Martínez-Vázquez ◽  
Matteo Monelli ◽  
Giuseppe Bono ◽  
...  
Keyword(s):  
Time Series ◽  
Dwarf Galaxy ◽  
Position Angle ◽  
Variable Stars ◽  
Distance Modulus ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
The Galaxy ◽  
Binary Evolution ◽  
Lyrae Stars

ABSTRACT Time series observations of a single dithered field centred on the diffuse dwarf satellite galaxy Crater II were obtained with the Dark Energy Camera (DECam) at the 4m Blanco Telescope at Cerro Tololo Inter-American Observatory, Chile, uniformly covering up to two half-light radii. Analysis of the g and i time series results in the identification and characterization of 130 periodic variable stars, including 98 RR Lyrae stars, 7 anomalous Cepheids, and 1 SX Phoenicis star belonging to the Crater II population, and 24 foreground variables of different types. Using the large number of ab-type RR Lyrae stars present in the galaxy, we obtained a distance modulus to Crater II of (m − M)0 = 20.333 ± 0.004 (stat) ±0.07 (sys). The distribution of the RR Lyrae stars suggests an elliptical shape for Crater II, with an ellipticity of 0.24 and a position angle of 153°. From the RR Lyrae stars, we infer a small metallicity dispersion for the old population of Crater II of only 0.17 dex. There are hints that the most metal-poor stars in that narrow distribution have a wider distribution across the galaxy, while the slightly more metal-rich part of the population is more centrally concentrated. Given the features in the colour–magnitude diagram of Crater II, the anomalous Cepheids in this galaxy must have formed through a binary evolution channel of an old population.

scholarly journals Gaia Data Release 2

2019 ◽  
Vol 625 ◽  
pp. A97 ◽  
Author(s):  
L. Rimoldini ◽  
B. Holl ◽  
M. Audard ◽  
N. Mowlavi ◽  
K. Nienartowicz ◽  
...  
Keyword(s):  
Time Series ◽  
High Amplitude ◽  
Rr Lyrae Stars ◽  
Long Period ◽  
Rr Lyrae ◽  
Multi Stage ◽  
Long Period Variables ◽  
Data Release ◽  
Lyrae Stars

Context. More than half a million of the 1.69 billion sources in Gaia Data Release 2 (DR2) are published with photometric time series that exhibit light variations during the 22 months of observation. Aims. An all-sky classification of common high-amplitude pulsators (Cepheids, long-period variables, δ Scuti/SX Phoenicis, and RR Lyrae stars) is provided for stars with brightness variations greater than 0.1 mag in G band. Methods. A semi-supervised classification approach was employed, firstly training multi-stage random forest classifiers with sources of known types in the literature, followed by a preliminary classification of the Gaia data and a second training phase that included a selection of the first classification results to improve the representation of some classes, before the improved classifiers were applied to the Gaia data. Dedicated validation classifiers were used to reduce the level of contamination in the published results. A relevant fraction of objects were not yet sufficiently sampled for reliable Fourier series decomposition, consequently classifiers were based on features derived from statistics of photometric time series in the G, GBP, and GRP bands, as well as from some astrometric parameters. Results. The published classification results include 195 780 RR Lyrae stars, 150 757 long-period variables, 8550 Cepheids, and 8882 δ Scuti/SX Phoenicis stars. All of these results represent candidates whose completeness and contamination are described as a function of variability type and classification reliability. Results are expressed in terms of class labels and classification scores, which are available in the vari_classifier_result table of the Gaia archive.

scholarly journals NGC 1261: A TIME-SERIES VI STUDY OF ITS VARIABLE STARS

2019 ◽  
Vol 55 (2) ◽  
pp. 337-350 ◽  
Author(s):  
A. Arellano Ferro ◽  
I. H. Bustos Fierro ◽  
J. H. Calderón ◽  
J. A. Ahumada
Keyword(s):  
Time Series ◽  
Variable Stars ◽  
Individual Values ◽  
Ccd Photometry ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Cluster Distance ◽  
The Mean ◽  
Lyrae Stars ◽  
Gaia Dr2

Time-series VI CCD photometry of the globular cluster NGC 1261 is employed to study its variable star population. A membership analysis of most variables based on Gaia DR2 proper motions and colours was performed prior to the estimation of the mean cluster distance and metallicity. The light curves of the member RR Lyrae were Fourier decomposed to calculate their individual values of distance, [Fe/H], radius and mass. The I band P-L for RR Lyrae stars was also employed. Our best estimates of the metallicity and distance of this Oo I cluster are [Fe/H]ZW =−1.42 ± 0.05 dex and d = 17.2 ± 0.4 kpc. No mixture of fundamental and first overtone RR Lyrae stars in the either-or or bimodal region is seen in this cluster, as it seems to be the rule for Oo I clusters with a red horizontal branch. A multi-approach search in a region of about 10' × 10' around the cluster revealed no new variable stars within the limitations of our CCD photometry.

scholarly journals Review of Observational Data on RR Lyrae Stars

1971 ◽  
Vol 2 ◽  
pp. 781-787
Author(s):  
G. van Herk
Keyword(s):  
Radial Velocity ◽  
Observational Data ◽  
Proper Motion ◽  
Point Of View ◽  
Proper Motions ◽  
Physical Point ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Complete Set ◽  
Lyrae Stars

The data on which my work on the secular parallaxes of RR Lyrae stars is based (Bull. Astron. Inst. Neth.18) were in many respects so incomplete that I have tried to interest astronomers to get a more complete set of data. The number of stars for which I had a proper motion was only 168, and for which a radial velocity was known, was 180, with an overlap of only 138 stars. The accuracy of the proper motions was certainly unsatisfactory for 43% of the total. The greatest trouble in dealing with such insufficient numbers arises when one wants to subdivide the material into groups which are homogeneous from a physical point of view. Many subdivisions, in making up my paper, were not tried at all, simply because the material was inadequate.In recent years plenty of work has been done by various investigators, of which I will at this point only mention the work on proper motions done at the Leander McCormick Observatory, and the great number of radial velocities determined by Dr. Clube and his associates. I do not, however, believe we are yet in a position to consider the whole subject as finished. Discussions about space motions, as given by Professor Oort in the book Stellar Structures, Volume V, will, at this time, be hardly improved upon. I still feel we should increase the number of stars substantially in order to get a better statistical discussion possible. This means we have to go to fainter stars. Plenty of these stars will be found on the plates which have served to make the Charts of the Carte du Ciel, which means we have at least one old position available for proper motions. At Leiden we are now engaged in the determination or redetermination of the proper motions of 430 RR Lyrae stars.

scholarly journals Gaia Data Release 2

2018 ◽  
Vol 618 ◽  
pp. A30 ◽  
Author(s):  
B. Holl ◽  
M. Audard ◽  
K. Nienartowicz ◽  
G. Jevardat de Fombelle ◽  
O. Marchal ◽  
...  
Keyword(s):  
Time Series ◽  
Variable Stars ◽  
Great Promise ◽  
Published Data ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Short Timescale ◽  
Classical Statistics ◽  
Data Release ◽  
Lyrae Stars

Context. The Gaia Data Release 2 (DR2) contains more than half a million sources that are identified as variable stars. Aims. We summarise the processing and results of the identification of variable source candidates of RR Lyrae stars, Cepheids, long-period variables (LPVs), rotation modulation (BY Dra-type) stars, δ Scuti and SX Phoenicis stars, and short-timescale variables. In this release we aim to provide useful but not necessarily complete samples of candidates. Methods. The processed Gaia data consist of the G, GBP, and GRP photometry during the first 22 months of operations as well as positions and parallaxes. Various methods from classical statistics, data mining, and time-series analysis were applied and tailored to the specific properties of Gaia data, as were various visualisation tools to interpret the data. Results. The DR2 variability release contains 228 904 RR Lyrae stars, 11 438 Cepheids, 151 761 LPVs, 147 535 stars with rotation modulation, 8882 δ Scuti and SX Phoenicis stars, and 3018 short-timescale variables. These results are distributed over a classification and various Specific Object Studies tables in the Gaia archive, along with the three-band time series and associated statistics for the underlying 550 737 unique sources. We estimate that about half of them are newly identified variables. The variability type completeness varies strongly as a function of sky position as a result of the non-uniform sky coverage and intermediate calibration level of these data. The probabilistic and automated nature of this work implies certain completeness and contamination rates that are quantified so that users can anticipate their effects. Thismeans that even well-known variable sources can be missed or misidentified in the published data. Conclusions. The DR2 variability release only represents a small subset of the processed data. Future releases will include more variable sources and data products; however, DR2 shows the (already) very high quality of the data and great promise for variability studies.

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