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1411. Be stars in open clusters with PTF/iPTF. I.
ID:
ivo://CDS.VizieR/J/AJ/155/91
Title:
Be stars in open clusters with PTF/iPTF. I.
Short Name:
J/AJ/155/91
Date:
21 Oct 2021
Publisher:
CDS
Description:
We conducted a search for Be star candidates in open clusters using H{alpha} imaging photometry of the Palomar Transient Factory Survey to investigate some connections among Be star phenomena, cluster environments, and ages. Stellar members of clusters were identified by spatial distributions, near-infrared magnitudes and colors, and by proper motions. Among 104 open clusters, we identified 96 Be star candidates in 32 clusters; 11 of our candidates have been reported in previous studies. We found that the clusters with age 7.5<log(t(year))=<8.5 tend to have more Be star candidates; there is about a 40% occurrence rate within this age bin. The clusters in this age bin also tend to have a higher Be fraction N(Be)/N(Be+B-type). These results suggest that the environments of young and intermediate clusters are favorable to the formation of Be phenomena. Spatial distribution of Be star candidates with different ages implies that they do not form preferentially in the central regions. Furthermore, we showed that the mid-infrared (MIR) colors of the Be star candidates are similar to known Be stars, which could be caused by free-free emission or bound-free emission. Some Be star candidates might have no circumstellar dust according to their MIR colors. Finally, among 96 Be candidates, we discovered that one Be star candidate FSR 0904-1 exhibits long-term variability on the timescale of ~2000 days with an amplitude of 0.2-0.3 mag, indicating a long timescale of disk evolution.
1412. BEST-II catalog of variables: CoRoT SRc02 field
ID:
ivo://CDS.VizieR/J/AJ/151/110
Title:
BEST-II catalog of variables: CoRoT SRc02 field
Short Name:
J/AJ/151/110
Date:
21 Oct 2021
Publisher:
CDS
Description:
Time-series photometry of the CoRoT field SRc02 was obtained by the Berlin Exoplanet Search Telescope II (BEST II) in 2009. The main aim was to conduct a ground-based follow-up of the CoRoT field in order to detect variable stars with better spatial resolution than what can be achieved with the CoRoT Space Telescope. A total of 1846 variable stars were detected, of which only 30 have been previously known. For nine eclipsing binaries the stellar parameters were determined by modeling their light curves.
1413. BEST-II catalog of variables. III. Puppis field
ID:
ivo://CDS.VizieR/J/AJ/156/204
Title:
BEST-II catalog of variables. III. Puppis field
Short Name:
J/AJ/156/204
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Berlin Exoplanet Search Telescope II (BEST II) is a ground-based, small aperture, wide-angle telescope used to search for stellar light variations in the southern hemisphere. We report the results of a monitoring campaign observing a field in the Puppis constellation in late 2011/early 2012. Light curves were obtained for 130472 stars, out of which we identify 2169 variables, including 1829 newly discovered, 26 previously known, and 314 suspected variable stars. We determine periods and variability class for two previously known, but only suspected to be, variable stars. For eight individual eclipsing binary stars, including the two previously known but unclassified binaries, the system parameters were derived at the epoch of the observation by modeling the light curves. Eventually, in a catalog for all variable stars, we present coordinates, magnitude, and elements of light variations, e.g., epoch, period, amplitude, type, and light curves. This catalog concludes the BEST/BEST II project.
1414. BEST-II catalog of variables. I. Southern fields
ID:
ivo://CDS.VizieR/J/AJ/146/136
Title:
BEST-II catalog of variables. I. Southern fields
Short Name:
J/AJ/146/136
Date:
21 Oct 2021
Publisher:
CDS
Description:
A photometric survey of three southern target fields with BEST II yielded the detection of 2406 previously unknown variable stars and an additional 617 stars with suspected variability. This study presents a catalog including their coordinates, magnitudes, light curves, ephemerides, amplitudes, and type of variability. In addition, the variability of 17 known objects is confirmed, thus validating the results. The catalog contains a number of known and new variables that are of interest for further astrophysical investigations, in order to, e.g., search for additional bodies in eclipsing binary systems, or to test stellar interior models. Altogether, 209070 stars were monitored with BEST II during a total of 128 nights in 2009/2010. The overall variability fraction of 1.2%-1.5% in these target fields is well comparable to similar ground-based photometric surveys. Within the main magnitude range of R{isin}[11, 17], we identify 0.67(3)% of all stars to be eclipsing binaries, which indicates a completeness of about one third for this particular type in comparison to space surveys.
1415. BEST-II periodic variables in CoRoT LRa02 field
ID:
ivo://CDS.VizieR/J/A+A/506/569
Title:
BEST-II periodic variables in CoRoT LRa02 field
Short Name:
J/A+A/506/569
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Berlin Exoplanet Search Telescope II (BEST II) is a small wide field-of-view photometric survey telescope system located at the Observatorio Cerro Armazones, Chile. The high duty cycle combined with excellent observing conditions and millimagnitude photometric precision makes this instrument suitable for ground based support observations for the CoRoT space mission. Photometric data of the CoRoT LRa02 target field collected between November 2008 and March 2009 were analysed for stellar variability. The presented results will help in the future analysis of the CoRoT data, particularly in additional science programs related to variable stars. BEST II observes selected CoRoT target fields ahead of the space mission. The photometric data acquired are searched for stellar variability, periodic variable stars are identified with time series analysis of the obtained stellar light curves. We obtained the light curves of 104335 stars in the CoRoT LRa02 field over 41 nights. Variability was detected in light curves of 3726 stars of which 350 showed a regular period. These stars are, with the exception of 5 previously known variable stars, new discoveries.
1416. BEST-II periodic variables in CoRoT LRa02 field. II.
ID:
ivo://CDS.VizieR/J/AJ/143/140
Title:
BEST-II periodic variables in CoRoT LRa02 field. II.
Short Name:
J/AJ/143/140
Date:
21 Oct 2021
Publisher:
CDS
Description:
The CoRoT (Convection, Rotation and planetary Transit) field LRa02 has been observed with the Berlin Exoplanet Search Telescope II (BEST II) during the southern summer 2007/2008. A first analysis of stellar variability led to the publication of 345 newly discovered variable stars. Now, a deeper analysis of this data set was used to optimize the variability search procedure. Several methods and parameters have been tested in order to improve the selection process compared to the widely used J index for variability ranking. This paper describes an empirical approach to treat systematic trends in photometric data based upon the analysis of variance statistics that can significantly decrease the rate of false detections. Finally, the process of reanalysis and method improvement has virtually doubled the number of variable stars compared to the first analysis by Kabath et al. (Paper I, 2009, Cat. J/A+A/506/569). A supplementary catalog of 272 previously unknown periodic variables plus 52 stars with suspected variability is presented. Improved ephemerides are given for 19 known variables in the field. In addition, the BEST II results are compared with CoRoT data and its automatic variability classification.
1417. BEST periodic variable stars in IR01 field
ID:
ivo://CDS.VizieR/J/AJ/134/1560
Title:
BEST periodic variable stars in IR01 field
Short Name:
J/AJ/134/1560
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report on observations of the COROT IR01 field with the Berlin Exoplanet Search Telescope (BEST). BEST is a small-aperture telescope with a wide field of view (FOV). It is dedicated to searching for variable stars within the target fields of the COROT space mission to aid in minimizing false-alarm rates, and identifying potential targets for additional science. COROT's observational program started in 2007 February, with the "initial run" field (IR01) observed for about 2 months. BEST observed this field for 12 nights spread over 3 months in winter 2006. From the total of 30,426 stars observed in the IR01 field, 3769 were marked as suspected variable stars, and 54 of these showed clear periodicity. From these, 19 periodic stars are within the part of the COROT FOV covered in our data set.
1418. BEST periodic variable stars in LRa1 field
ID:
ivo://CDS.VizieR/J/AJ/136/654
Title:
BEST periodic variable stars in LRa1 field
Short Name:
J/AJ/136/654
Date:
21 Oct 2021
Publisher:
CDS
Description:
In this paper, we report on observations of the CoRoT LRa1 field with the Berlin Exoplanet Search Telescope (BEST). The current paper is part of a series of papers describing the results of our stellar variability survey. The BEST is a small aperture telescope with a wide field of view (FOV). It is dedicated to searching for stellar variability within the target fields of the CoRoT space mission to aid in minimizing false-alarm rates and identify potential targets for additional science. The LRa1 field is CoRoT's second long run field located in the galactic anticenter direction. We observed the LRa1 stellar field on 23 nights between November and March 2005/2006. From 6099 stars marked as variable, 39 were classified as periodic variable stars and 27 of them are within the CoRoT FOV. We also confirmed the variability for four stars listed in the General Catalogue of Variable Stars (GCVS).
1419. BEST periodic variable stars in LRc2 field
ID:
ivo://CDS.VizieR/J/AJ/137/3911
Title:
BEST periodic variable stars in LRc2 field
Short Name:
J/AJ/137/3911
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report on photometric observations of the CoRoT LRc2 field with the new robotic Berlin Exoplanet Search Telescope II (BEST II). The telescope system was installed and commissioned at the Observatorio Cerro Armazones, Chile, in 2007. BEST II is a small aperture telescope with a wide field of view dedicated to the characterization of the stellar variability primarily in CoRoT target fields with high stellar densities. The CoRoT stellar field LRc2 was observed with BEST II up to 20 nights in 2007 July and August. From the acquired data containing about 100,000 stars, 426 new periodic variable stars were identified and 90% of them are located within the CoRoT exoplanetary CCD segments and may be of further interest for CoRoT additional science programs.
1420. BEST variable stars in LRc1 field
ID:
ivo://CDS.VizieR/J/AJ/134/766
Title:
BEST variable stars in LRc1 field
Short Name:
J/AJ/134/766
Date:
21 Oct 2021
Publisher:
CDS
Description:
The COROT space mission will monitor several target fields for up to 150 days to perform asteroseismology and to search for extrasolar planets by photometric transits. Variable stars in the target fields are important objects for additional scientific studies but can also disturb the search for planetary transits. A variability characterization of the target fields prior to COROT observations is therefore important for two reasons: to find interesting variable stars to monitor further and to make an analysis of the impact of the variable stars on detecting extrasolar planet transits with COROT. The Berlin Exoplanet Search Telescope (BEST) is a small wide-angle telescope dedicated to high-precision photometry. It has observed a 9deg^2^ field of view centered at (RA,DE)=(19:00:00.0+00:01:55.2) (J2000.0) over 98 nights to search for variable stars in the surroundings of the first long-run target field (LRc1) of the COROT space mission. In this data set we identified 92 periodic variable stars, 86 of which are new discoveries and 6 of which are known from the General Catalogue of Variable Stars (GCVS). For five of the GCVS stars, variability could not be confirmed. Forty-three of the 92 detected periodic variable stars are identified as eclipsing binaries. We have evaluated the completeness of our survey for eclipsing binaries by comparing it to the expected fraction of eclipsing binaries based on Hipparcos observations. From this evaluation we show that the BEST data set presented here has a completeness of 20%-30% for periods longer than 1 day and is complete relative to Hipparcos for short-period binaries.

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