scholarly journals Variable stars in the field of intermediate-age open cluster NGC 559

2020 ◽  
Vol 499 (1) ◽  
pp. 618-630
Author(s):  
Y C Joshi ◽  
Ancy A John ◽  
J Maurya ◽  
A Panchal ◽  
Brijesh Kumar ◽  
...  
Keyword(s):  
Binary Stars ◽  
Binary Systems ◽  
Open Cluster ◽  
Variable Stars ◽  
Photometric Variability ◽  
Eclipsing Binary ◽  
V Band ◽  
Target Field ◽  
Periodicity Analysis ◽  
Short Period

ABSTRACT This work presents the first long-term photometric variability survey of the intermediate-age open cluster NGC 559. Time series V-band photometric observations on 40 nights taken over more than 3 yr with three different telescopes are analysed to search for variable stars in the cluster. We investigate the data for the periodicity analysis and reveal 70 variable stars including 67 periodic variables in the target field, all of them are newly discovered. The membership analysis of the periodic variables reveals that 30 of them belong to the cluster and remaining 37 are identified as field variables. Out of the 67 periodic variables, 48 are short-period (P < 1 d) variables and 19 are long-period (P > 1 d) variables. The variable stars have periodicity between 3 h to 41 d and their brightness ranges from V  = 10.9 to 19.3 mag. The periodic variables belonging to the cluster are then classified into different variability types on the basis of observational properties such as shape of the light curves, periods, amplitudes, as well as their positions in the Hertzsprung–Russell (H–R) diagram. As a result, we identify 1 Algol type eclipsing binary, 1 possible blue straggler star, 3 slowly pulsating B type stars, 5 rotational variables, 11 non-pulsating variables, 2 FKCOM variables, and remaining 7 are characterized as miscellaneous variables. We also identify three eclipsing binary stars (EBs) belonging to the field star population. The phoebe package is used to analyse the light curve of all four EBs in order to determine the parameters of the binary systems such as masses, temperatures, and radii.

scholarly journals Photometric, kinematic, and variability study in the young open cluster NGC 1960

2020 ◽  
Vol 492 (3) ◽  
pp. 3602-3621 ◽  
Author(s):  
Y C Joshi ◽  
J Maurya ◽  
A A John ◽  
A Panchal ◽  
S Joshi ◽  
...  
Keyword(s):  
Open Cluster ◽  
Mass Range ◽  
Mass Function ◽  
Variable Stars ◽  
B Stars ◽  
V Band ◽  
Short Period ◽  
Young Open Cluster ◽  
Mass Segregation ◽  
Variability Study

ABSTRACT We present a comprehensive photometric analysis of a young open cluster NGC 1960 (= M36) along with the long-term variability study of this cluster. Based on the kinematic data of Gaia DR2, the membership probabilities of 3871 stars are ascertained in the cluster field among which 262 stars are found to be cluster members. Considering the kinematic and trigonometric measurements of the cluster members, we estimate a mean cluster parallax of 0.86 ± 0.05 mas and mean proper motions of μRA = −0.143 ± 0.008 mas yr−1 and μDec. = −3.395 ± 0.008 mas yr−1. We obtain basic parameters of the cluster such as E(B − V) = 0.24 ± 0.02 mag, log(Age/yr) = 7.44 ± 0.02, and d = 1.17 ± 0.06 kpc. The mass function slope in the cluster for the stars in the mass range of 0.72–7.32 M⊙ is found to be γ = −1.26 ± 0.19. We find that mass segregation is still taking place in the cluster which is yet to be dynamically relaxed. This work also presents first high-precision variability survey in the central 13 arcmin × 13 arcmin region of the cluster. The V-band photometric data accumulated on 43 nights over a period of more than 3 yr reveals 76 variable stars among which 72 are periodic variables. Among them, 59 are short period (P < 1 d) and 13 are long period (P > 1 d). The variable stars have V magnitudes ranging between 9.1 to 19.4 mag and periods between 41 min and 10.74 d. On the basis of their locations in the H–R diagram, periods, and characteristic light curves, 20 periodic variables belong to the cluster are classified as 2 δ-Scuti, 3 γ-Dor, 2 slowly pulsating B stars, 5 rotational variables, 2 non-pulsating B stars, and 6 as miscellaneous variables.

scholarly journals "FOUR CANDIDATE BINARY STARS WITH STRONG REFLECTION EFFECT FROM THE ZWICKY TRANSIENT FACILITY"

2020 ◽  
pp. 1-8
Author(s):  
K. Bernhard ◽  
S. Hümmerich
Keyword(s):  
Binary Stars ◽  
Binary Systems ◽  
Variable Star ◽  
Spectroscopic Studies ◽  
Variable Stars ◽  
Reflection Effect ◽  
Strong Reflection ◽  
Short Period

We present five stars from the ZTF Catalogue of Periodic Variable Stars whose properties are fully compatible with variable stars of GCVS-type R, that is, short-period binary systems with light variations dominated by strong reflection effect. If verified by spectroscopic studies, our results show that the variability amplitude limit of 1.0 mag (V) currently listed in the International Variable Star Index can be exceeded and may be in need of revision.

scholarly journals ASAS census of twins

2020 ◽  
Vol 496 (3) ◽  
pp. 2605-2612
Author(s):  
Volkan Bakış ◽  
Zeki Eker ◽  
Oğuzhan Sarı ◽  
Gökhan Yücel ◽  
Eda Sonbaş
Keyword(s):  
Spectral Type ◽  
Binary Stars ◽  
Binary Systems ◽  
Eclipsing Binaries ◽  
Physical Parameters ◽  
Eclipsing Binary ◽  
Type Distribution ◽  
Eclipsing Binary Stars ◽  
Detached Binaries

ABSTRACT Twin binaries were identified among the eclipsing binaries with δ > –30° listed in the All Sky Automated Survey (ASAS) catalogue. In addition to the known twin binaries in the literature, 68 new systems have been identified and photometric and spectroscopic observations were done. Colour, spectral type, temperature, ratio of radii and masses of the components have been derived and are presented. Including 12 twin binary systems that exist in both ASAS and the catalogue of absolute parameters of detached eclipsing binary stars, a total of 80 twin detached binary systems have been statistically studied. A comparison of the spectral type distribution of the twins with those of detached eclipsing binary stars in the ASAS database shows that the spectral type distribution of twins is similar to that of detached systems. This result has been interpreted as indicating that there is no special formation mechanism for twins compared to normal detached binaries. As a result of our case study for HD 154010, a twin binary, we present the precise physical parameters of the system.

scholarly journals Discovery of β Cep pulsations in the eclipsing binary V453 Cygni

2020 ◽  
Vol 497 (1) ◽  
pp. L19-L23 ◽  
Author(s):  
John Southworth ◽  
D M Bowman ◽  
A Tkachenko ◽  
K Pavlovski
Keyword(s):  
Physical Properties ◽  
Satellite Data ◽  
Binary Stars ◽  
Mass Measurement ◽  
Physical Processes ◽  
Primary Star ◽  
Eclipsing Binary ◽  
Period Orbit ◽  
Orbital Frequency ◽  
Short Period

ABSTRACT V453 Cyg is an eclipsing binary containing 14 and 11 $\, {\rm M}_\odot$ stars in an eccentric short-period orbit. We have discovered β Cep-type pulsations in this system using Transiting Exoplanet Survey Satellite data. We identify seven significant pulsation frequencies, between 2.37 and 10.51 d−1, in the primary star. These include six frequencies that are separated by yet significantly offset from harmonics of the orbital frequency, indicating they are tidally perturbed modes. We have determined the physical properties of the system to high precision: V453 Cyg A is the first β Cep pulsator with a precise mass measurement. The system is a vital tracer of the physical processes that govern the evolution of massive single and binary stars.

scholarly journals Discovery and characterisation of long-period eclipsing binary stars from Kepler K2 campaigns 1, 2, and 3

2018 ◽  
Vol 616 ◽  
pp. A38 ◽  
Author(s):  
P. F. L. Maxted ◽  
R. J. Hutcheon
Keyword(s):  
Binary Stars ◽  
Binary Systems ◽  
Binary Star ◽  
Eclipsing Binaries ◽  
Star Model ◽  
Eclipsing Binary ◽  
Giant Stars ◽  
Long Period ◽  
Eclipsing Binary Stars

Context. The Kepler K2 mission now makes it possible to find and study a wider variety of eclipsing binary stars than has been possible to-date, particularly long-period systems with narrow eclipses. Aims. Our aim is to characterise eclipsing binary stars observed by the Kepler K2 mission with orbital periods longer than P ≈ 5.5 days. Methods. The ellc binary star model has been used to determine the geometry of eclipsing binary systems in Kepler K2 campaigns 1, 2 and 3. The nature of the stars in each binary is estimated by comparison to stellar evolution tracks in the effective temperature – mean stellar density plane. Results. 43 eclipsing binary systems have been identified and 40 of these are characterised in some detail. The majority of these systems are found to be late-type dwarf and sub-giant stars with masses in the range 0.6–1.4 solar masses. We identify two eclipsing binaries containing red giant stars, including one bright system with total eclipses that is ideal for detailed follow-up observations. The bright B3V-type star HD 142883 is found to be an eclipsing binary in a triple star system. We observe a series of frequencies at large multiples of the orbital frequency in BW Aqr that we tentatively identify as tidally induced pulsations in this well-studied eccentric binary system. We find that the faint eclipsing binary EPIC 201160323 shows rapid apsidal motion. Rotational modulation signals are observed in 13 eclipsing systems, the majority of which are found to rotate non-synchronously with their orbits. Conclusions. The K2 mission is a rich source of data that can be used to find long period eclipsing binary stars. These data combined with follow-up observations can be used to precisely measure the masses and radii of stars for which such fundamental data are currently lacking, e.g., sub-giant stars and slowly-rotating low-mass stars.

scholarly journals High Temperature Structure in Cool Binary Stars

1996 ◽  
Vol 152 ◽  
pp. 141-145
Author(s):  
A.K. Dupree ◽  
N.S. Brickhouse ◽  
G.J. Hanson
Keyword(s):  
High Temperature ◽  
Binary Stars ◽  
Binary Systems ◽  
Emission Measure ◽  
Temperature Structure ◽  
Differential Emission Measure ◽  
Absolute Size ◽  
Hot Plasma ◽  
Short Period ◽  
Different Temperatures

Strong high temperature emission lines in the EUVE spectra of binary stars containing cool components (Alpha Aur [Capella], 44ι Boo, Lambda And, and VY Ari) provide the basis to define reliably the differential emission measure of hot plasma. The emission measure distributions for the short-period (P ≤ 13 d) binary systems show a high temperature enhancement over a relatively narrow temperature region similar to that originally found in Capella (Dupree et al. 1993). The emission measure distributions of rapidly rotating single stars 31 Com and AB Dor also contain a local enhancement of the emission measure although at different temperatures and width from Capella, suggesting that the enhancement in these objects may be characteristic of rapid rotation of a stellar corona. This feature might be identified with a (polar) active region, although its density and absolute size are unknown; in the binaries Capella and VY Ari, the feature is narrow and it may arise from an interaction region between the components.

scholarly journals Starspot Activity on Short-period RS CVn Stars

1991 ◽  
Vol 130 ◽  
pp. 370-372
Author(s):  
Michael Zeilik
Keyword(s):  
Binary Stars ◽  
Binary Systems ◽  
Magnetic Activity ◽  
Close Binary ◽  
Tidal Interactions ◽  
Rs Cvn Stars ◽  
Short Period ◽  
Basic Physics ◽  
Synchronous Rotation ◽  
Orbital Periods

We have yet to understand the magnetic activity cycles of cool close binary systems of sunlike stars. Mutual tidal interactions, as well as magnetic ones, may result from a regime of dynamo models not yet tested, because these have been developed for single stars. To arrive at the basic physics, though, requires that we first examine the phenomenology of magnetic activity for binary systems. In particular, we would like to discover if such activity has a clearly-defined cycle, such as the sun exibits.Among the proxy indicators of magnetic activity are the Ca II H and K lines. Strassmeier et al. (1988) used the strength of these lines as the primary criterion for the inclusion of systems in The Catalog of Chromospherically Binary Stars. Of the RS CVn stars in the catalog, 12 have orbital periods of one day or shorter; 9 are eclipsing systems. As part of a decade-long program, we have focussed our observations and models on eight of the short-period group (Hall, 1976): XY UMa, UV Psc, SV Cam, RT And, CG Cyg, ER Vul, BH Vir, and WY Cnc. These close systems are tidally-locked in synchronous rotation and tidally-distorted into Roche lobe configurations.

scholarly journals The Amateur and Eclipsing Binary Stars

1988 ◽  
Vol 98 ◽  
pp. 35-39 ◽  
Author(s):  
Frank Bradshaw Wood
Keyword(s):  
Binary Stars ◽  
Variable Stars ◽  
Eclipsing Binary ◽  
Astronomical Observations ◽  
Minimum Light ◽  
Eclipsing Binary Stars ◽  
Made In

Probably no other branch of science has benefited as much from the work of dedicated amateurs as has the science of Astronomy. While some amateurs have made many useful types of astronomical observations– comets, meteors, occultations, etc. – perhaps none has been as extensive and as useful as those made in the field of variable stars. There are not nearly enough professional astronomers to keep under proper observation the increasingly large number of known variables. While all kinds of them are well worth continuous study, this paper will call attention to the importance of eclipsing variables and in particular the systematic and continuing observation of their times of minimum light.

Variable Star Identification in the BATC Field of M67

2005 ◽  
Vol 277-279 ◽  
pp. 869-875
Author(s):  
Hwihyun Kim ◽  
Yong Ik Byun
Keyword(s):  
Binary Systems ◽  
Main Sequence ◽  
Variable Star ◽  
Open Cluster ◽  
Open Clusters ◽  
Eclipsing Binaries ◽  
Photometric Variability ◽  
Phase Dispersion ◽  
Star Identification

We present the result of photometric variability investigation for stars in the field of M67. The old open cluster M67, one of the most studied open clusters, shows the sign of significant main-sequence binary population in its color-magnitude diagrams. Identification of eclipsing binaries and follow-up studies will enable us to study the nature of binary population in most direct manner. We used approximately 350 images from the BATC (Beijing-Arizona-Taipei-Connecticut) data archive to examine variability within one square degree field centered on M67. A total of 18 stars were classified to be real variables. Our new discoveries include seven eclipsing binary systems of which two are likely to be W UMa systems. All of these variables were found using the phase dispersion minimization (PDM) method developed by Shin and Byun[11].

scholarly journals Spot evolution in the eclipsing binary CoRoT 105895502

2019 ◽  
Vol 623 ◽  
pp. A107 ◽  
Author(s):  
S. Czesla ◽  
S. Terzenbach ◽  
R. Wichmann ◽  
J. H. M. M. Schmitt
Keyword(s):  
Light Curve ◽  
Binary Systems ◽  
Temporal Behavior ◽  
Mass Ratio ◽  
Late Type ◽  
Stellar Rotation ◽  
Orbital Inclination ◽  
Eclipsing Binary ◽  
Short Period ◽  
Curve Modeling

Stellar activity is ubiquitous in late-type stars. The special geometry of eclipsing binary systems is particularly advantageous to study the stellar surfaces and activity. We present a detailed study of the 145 d CoRoT light curve of the short-period (2.17 d) eclipsing binary CoRoT 105895502. By means of light-curve modeling with Nightfall, we determine the orbital period, effective temperature, Roche-lobe filling factors, mass ratio, and orbital inclination of CoRoT 105895502 and analyze the temporal behavior of starspots in the system. Our analysis shows one comparably short-lived (≈40 d) starspot, remaining quasi-stationary in the binary frame, and one starspot showing prograde motion at a rate of 2.3° day−1, whose lifetime exceeds the duration of the observation. In the CoRoT band, starspots account for as much as 0.6% of the quadrature flux of CoRoT 105895502, however we cannot attribute the spots to individual binary components with certainty. Our findings can be explained by differential rotation, asynchronous stellar rotation, or systematic spot evolution.

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