- ID:
- ivo://CDS.VizieR/J/AJ/150/27
- Title:
- New catalog of variable stars in M37 field
- Short Name:
- J/AJ/150/27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a comprehensive re-analysis of stellar photometric variability in the field of the open cluster M37 following the application of a new photometry and de-trending method to the MMT/Megacam image archive. This new analysis allows a rare opportunity to explore photometric variability over a broad range of timescales, from minutes to a month. The intent of this work is to examine the entire sample of more than 30000 objects for periodic, aperiodic, and sporadic behaviors in their light curves. We show a modified version of the fast {chi}^2^ periodogram algorithm (F{chi}^2^) and change-point analysis as tools for detecting and assessing the significance of periodic and non-periodic variations. The benefits of our new photometry and analysis methods are evident. A total of 2306 stars exhibit convincing variations that are induced by flares, pulsations, eclipses, starspots, and unknown causes in some cases. This represents a 60% increase in the number of variables known in this field. Moreover, 30 of the previously identified variables are found to be false positives resulting from time-dependent systematic effects. The new catalog includes 61 eclipsing binary systems, 92 multiperiodic variable stars, 132 aperiodic variables, and 436 flare stars, as well as several hundreds of rotating variables. Based on extended and improved catalog of variables, we investigate the basic properties (e.g., period, amplitude, type) of all variables. The catalog can be accessed through the web interface (http://stardb.yonsei.ac.kr/).
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/619/A85
- Title:
- 54 new eccentric galactic eclipsing binaries
- Short Name:
- J/A+A/619/A85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of the apsidal motion and light curve parameters of 54 never-before-studied galactic Algol-type binaries. This is the first analysis of such a large sample of eccentric eclipsing binaries in our Galaxy, and has enabled us to identify several systems that are worthy of further study. Bringing together data from various databases and surveys, supplemented with new observations, we have been able to trace the long-term evolution of the eccentric orbit over durations extending back up to several decades. Our present study explores a rather different sample of stars to those presented in the previously published catalogue of eccentric eclipsing binaries, sampling to fainter magnitudes, covering later spectral types, sensitive to different orbital periods with more than 50% of our systems having periods longer than six days. The typical apsidal motion in the sample is rather slow (mostly of order of centuries long), although in some cases this is less than 50yr. All of the systems, except one, have eccentricities less than 0.5, with an average value of 0.23. Several of the stars also show evidence for additional period variability. In particular we can identify three systems in the sample, HD 44093, V611 Pup, and HD 313631, which likely represent relativistic apsidal rotators.
- ID:
- ivo://CDS.VizieR/J/other/IBVS/5586
- Title:
- New elements for 80 eclipsing binaries V.
- Short Name:
- J/other/IBVS/558
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This research presents new elements for 80 eclipsing binaries found with the help of the ASAS-3 (Cat. <II/264>), Hipparcos (Cat. <I/239>) and NSVS (2004AJ....127.2436W) databases.
- ID:
- ivo://CDS.VizieR/J/ApJ/684/635
- Title:
- New low-mass eclipsing binary from SDSS-II
- Short Name:
- J/ApJ/684/635
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present observations of a new low-mass, double-lined eclipsing binary system discovered using repeat observations of the celestial equator from the Sloan Digital Sky Survey II. Using near-infrared photometry and optical spectroscopy we have measured the properties of this short-period [P=0.407037(14)days] system and its two components. We find the following parameters for the two components: M_1_=0.272+/-0.020M_{sun}_, R_1_=0.268+/-0.010R_{sun}_, M_2_=0.240+/-0.022M_{sun}_, R_2_=0.248+/-0.0090R_{sun}_, T_1_=3320+/-130K, and T_2_=3300+/-130K. The masses and radii of the two components of this system agree well with theoretical expectations based on models of low-mass stars, within the admittedly large errors.
- ID:
- ivo://CDS.VizieR/J/AJ/153/36
- Title:
- New minima timings and RVs for 3 eclipsing binaries
- Short Name:
- J/AJ/153/36
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Eclipsing binaries remain crucial objects for our understanding of the universe. In particular, those that are components of multiple systems can help us solve the problem of the formation of these systems. Analysis of the radial velocities together with the light curve produced for the first time precise physical parameters of the components of the multiple systems V773 Cas, QS Aql, and BR Ind. Their visual orbits were also analyzed, which resulted in slightly improved orbital elements. What is typical for all these systems is that their most dominant source is the third distant component. The system V773 Cas consists of two similar G1-2V stars revolving in a circular orbit and a more distant component of the A3V type. Additionally, the improved value of parallax was calculated to be 17.6 mas. Analysis of QS Aql resulted in the following: the inner eclipsing pair is composed of B6V and F1V stars, and the third component is of about the B6 spectral type. The outer orbit has high eccentricity of about 0.95, and observations near its upcoming periastron passage between the years 2038 and 2040 are of high importance. Also, the parallax of the system was derived to be about 2.89 mas, moving the star much closer to the Sun than originally assumed. The system BR Ind was found to be a quadruple star consisting of two eclipsing K dwarfs orbiting each other with a period of 1.786 days; the distant component is a single-lined spectroscopic binary with an orbital period of about 6 days. Both pairs are moving around each other on their 148 year orbit.
- ID:
- ivo://CDS.VizieR/J/AJ/153/137
- Title:
- New NSVS 14256825 eclipse times
- Short Name:
- J/AJ/153/137
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The cyclic behavior of (O-C) residuals of eclipse timings in the sdB+M eclipsing binary NSVS 14256825 was previously attributed to one or two Jovian-type circumbinary planets. We report 83 new eclipse timings that not only fill in the gaps in those already published but also extend the time span of the (O-C) diagram by three years. Based on the archival and our new data spanning over more than 17 years, we re-examined the up-to-date system (O-C). The data revealed a systematic, quasi-sinusoidal variation deviating from an older linear ephemeris by about 100 s. It also exhibits a maximum in the (O-C) near JD 2456400 that was previously unknown. We consider two most credible explanations of the (O-C) variability: the light propagation time due to the presence of an invisible companion in a distant circumbinary orbit, and magnetic cycles reshaping one of the binary components, known as the Applegate or Lanza-Rodono effect. We found that the latter mechanism is unlikely due to the insufficient energy budget of the M-dwarf secondary. In the framework of the third-body hypothesis, we obtained meaningful constraints on the Keplerian parameters of a putative companion and its mass. Our best-fitting model indicates that the observed quasi-periodic (O-C) variability can be explained by the presence of a brown dwarf with the minimal mass of 15 Jupiter masses rather than a planet, orbiting the binary in a moderately elliptical orbit (e~0.175) with a period of ~10 years. Our analysis rules out the two-planet model proposed earlier.
- ID:
- ivo://CDS.VizieR/J/MNRAS/376/573
- Title:
- New times of minima of VZ CVn
- Short Name:
- J/MNRAS/376/573
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new photometric two-colour observations of the double-lined close binary star VZ CVn. Combining two data sets obtained in 1971-72 and in 2006, the physical parameters of both components were derived. After removing the light variations due to the eclipses and proximity effects, a periodic variation in the more massive component with a dominant period of 1.06876d could be detected in the first photometric data set. In accordance with its position on the Hertzsprung-Russell diagram and both its pulsation period and pulsation constant of 0.62d, the primary component of VZ CVn should be an excellent {gamma} Doradus candidate. The less massive secondary component seems to have smaller radius with respect to its mass. Both components appear to have lower luminosities with respect to their masses; hence, their radiative properties seem to be different. The evolutionary status of the components is also discussed.
- ID:
- ivo://CDS.VizieR/J/PASP/131/G5001
- Title:
- New variable stars and eclipsing binaries
- Short Name:
- J/PASP/131/G5001
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Evryscope is a telescope array designed to open a new parameter space in optical astronomy, detecting short-timescale events across extremely large sky areas simultaneously. The system consists of a 780 MPix 22-camera array with an 8150 sq. deg. field of view, 13'' per pixel sampling, and the ability to detect objects down to m_g'_~=16 in each 2-minute dark-sky exposure. The Evryscope, covering 18400 sq. deg. with hours of high-cadence exposure time each night, is designed to find the rare events that require all-sky monitoring, including transiting exoplanets around exotic stars like white dwarfs and hot subdwarfs, stellar activity of all types within our galaxy, nearby supernovae, and other transient events such as gamma-ray bursts and gravitational-wave electromagnetic counterparts. The system averages 5000 images per night with ~300000 sources per image, and to date has taken over 3.0M images, totaling 250 TB of raw data. The resulting light curve database has light curves for 9.3M targets, averaging 32600 epochs per target through 2018. This paper summarizes the hardware and performance of the Evryscope, including the lessons learned during telescope design, electronics design, a procedure for the precision polar alignment of mounts for Evryscope-like systems, robotic control and operations, and safety and performance-optimization systems. We measure the on-sky performance of the Evryscope, discuss its data analysis pipelines, and present some example variable star and eclipsing binary discoveries from the telescope. We also discuss new discoveries of very rare objects including two hot subdwarf eclipsing binaries with late M-dwarf secondaries (HW Vir systems), two white dwarf/hot subdwarf short-period binaries, and four hot subdwarf reflection binaries. We conclude with the status of our transit surveys, M-dwarf flare survey, and transient detection.
- ID:
- ivo://CDS.VizieR/J/A+A/519/A12
- Title:
- 1318 new variable stars in Galactic plane
- Short Name:
- J/A+A/519/A12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have conducted a deep photometric survey of a 0.5deg*0.5deg area of the Galactic Plane using the WFI instrument on the 2.2-m ESO telescope on La Silla, Chile. The dataset comprises a total of 267 R-band images, 204 from a 16 day observation run in 2005, supplemented by 63 images from a six week period in 2002. Our reduction employed the new numerical kernel difference image analysis method as implemented in the pySIS3 code and resulted in more than 500000 lightcurves of stars down to a magnitude limit of R~24.5. A search for variable stars resulted in the detection of 1318 variables of different types. 1011 of these are eclipsing or contact binary stars. A number of the contact binaries have low mass-ratios and several of the detached binaries appear to have low-mass components. Three candidate contact binaries have periods at the known cut off including two with periods lower than any previously published. Also identified are 3 possible pre-main sequence detached eclipsing binaries.
- ID:
- ivo://CDS.VizieR/J/MNRAS/482/3058
- Title:
- New variable stars towards Galactic Bulge
- Short Name:
- J/MNRAS/482/3058
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the detection of 3714 variable stars towards the Galactic bulge, including 2521 previously uncatalogued variables, using time-series photometry extracted from data obtained with the VIMOS imager at the Very Large Telescope. Observations of the Sagittarius Window Eclipsing Extrasolar Planet Search (SWEEPS) field in the Galactic Bulge were taken over 2yr between March and October at a cadence of ~4d, enabling the detection of variables with periods up to ~100d. Many of these were already known, but we detected a significant number of new variables, including 11 Cepheids, a further 88 potential Cepheid candidates, and many contact binaries. Here we publish the catalogue of the new variables, containing coordinates, mean magnitudes as well as periods and classification; full light curves for these variables are also made available electronically.
