- ID:
- ivo://CDS.VizieR/J/A+A/544/A53
- Title:
- Long-term photometry and spectroscopy of EE Cep
- Short Name:
- J/A+A/544/A53
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- EE Cep is an unusual long-period (5.6yr) eclipsing binary discovered during the mid-twentieth century. It undergoes almost-grey eclipses that vary in terms of both depth and duration at different epochs. The system consists of a Be type star and a dark dusty disk around an invisible companion. EE Cep together with the widely studied epsilon Aur are the only two known cases of long-period eclipsing binaries with a dark, dusty disk component responsible for periodic obscurations. Two observational campaigns were carried out during the eclipses of EE Cep in 2003 and 2008/9 to verify whether the eclipsing body in the system is indeed a dark disk and to understand the observed changes in the depths and durations of the eclipses. Multicolour photometric data and spectroscopic observations performed at both low and high resolutions were collected with several dozen instruments located in Europe and North America. We numerically modelled the variations in brightness and colour during the eclipses. We tested models with different disk structure, taking into consideration the inhomogeneous surface brightness of the Be star. We considered the possibility of disk precession. The complete set of observational data collected during the last three eclipses are made available to the astronomical community. The 2003 and 2008/9 eclipses of EE Cep were very shallow. The latter is the shallowest among all observed. The very high quality photometric data illustrate in detail the colour evolution during the eclipses for the first time. Two blue maxima in the colour indices were detected during these two eclipses, one before and one after the photometric minimum. The first (stronger) blue maximum is simultaneous with a "bump" that is very clear in all the UBV(RI)C light curves. A temporary increase in the I-band brightness at the orbital phase ~0.2 was observed after each of the last three eclipses. Variations in the spectral line profiles seem to be recurrent during each cycle. The NaI lines always show at least three absorption components during the eclipse minimum and strong absorption is superimposed on the H{alpha} emission. These observations confirm that the eclipsing object in EE Cep system is indeed a dark, dusty disk around a low luminosity object. The primary appears to be a rapidly rotating Be star that is strongly darkened at the equator and brightened at the poles. Some of the conclusions of this work require verification in future studies: (i) a complex, possibly multi-ring structure of the disk in EE Cep; (ii) our explanation of the "bump" observed during the last two eclipses in terms of the different times of obscuration of the hot polar regions of the Be star by the disk; and (iii) our suggested period of the disk precession (~11-12Porb) and predicted depth of about 2m for the forthcoming eclipse in 2014.
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Search Results
- ID:
- ivo://CDS.VizieR/J/other/JAD/18.5
- Title:
- Long-term photometry of 11 RS CVn stars
- Short Name:
- J/other/JAD/18.5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- I present BVRI photometry of short-period (P<1d) eclipsing RS CVn binary star systems collected between 1988 and 2009 at Mount Laguna Observatory. Most of the data are for ER Vul and WY Cnc, with light curves nearly every year during that time period. I also present light curves for at least several years for XY UMa, BH Vir, CG Cyg, RT And, and UV Psc. I have fewer light curves for SV Cam, UV Leo, 1E1919+0427, and GSC 2038-0293. In addition to the eclipsing short-period systems, I also include UBVRI data for two longer period non-eclipsing RS CVn binary systems: UZ Lib and DM UMa, as well as two active chromosphere single stars: FK Com and HD 199178.
- ID:
- ivo://CDS.VizieR/J/A+A/281/811
- Title:
- Long-term variations in V471 Tau
- Short Name:
- J/A+A/281/811
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (no description available)
- ID:
- ivo://CDS.VizieR/J/AJ/123/3460
- Title:
- Low-amplitude variables in NGC 6791
- Short Name:
- J/AJ/123/3460
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have undertaken a long-term project, the Planets in Stellar Clusters Extensive Search (PISCES), to search for transiting planets in open clusters. As our first target, we have chosen NGC 6791, a very old, populous, metal-rich cluster. We present the results of a test observing run at the F.L. Whipple Observatory's 1.2 m telescope, from 2001 July 6 to August 1. Our primary goal is to demonstrate the feasibility of obtaining the accuracy required for planetary-transit detection using image subtraction photometry on data collected with a 1 m class telescope. We present a catalog of 62 variable stars, 47 of them newly discovered, most with low-amplitude variability. Among those there are several BY Draconis type variables. We have also observed outbursts in the cataclysmic variables B7 and B8.
- ID:
- ivo://CDS.VizieR/J/AJ/141/78
- Title:
- Low-mass eclipsing binaries in KIC
- Short Name:
- J/AJ/141/78
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We identify 231 objects in the newly released Cycle 0 data set from the Kepler Mission as double-eclipse, detached eclipsing binary systems with Teff<5500K and orbital periods shorter than ~32 days. We model each light curve using the JKTEBOP code with a genetic algorithm to obtain precise values for each system. We identify 95 new systems with both components below 1.0M_{sun}_ and eclipses of at least 0.1mag, suitable for ground-based follow-up. Of these, 14 have periods less than 1.0-day, 52 have periods between 1.0 and 10.0-days, and 29 have periods greater than 10.0-days. This new sample of main-sequence, low-mass, double-eclipse, detached eclipsing binary candidates more than doubles the number of previously known systems and extends the sample into the completely heretofore unexplored P>10.0-day period regime.
- ID:
- ivo://CDS.VizieR/J/A+AS/110/329
- Title:
- LTE model atmospheres coeff.
- Short Name:
- J/A+AS/110/329
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Linear, quadratic and square root limb-darkening coefficients have been computed by means of least squares fits to model atmospheres by Kurucz (1991) with the main purpose of facilitating the analysis of light curves of eclipsing binaries. Results are compared with previously published values using the same of different models and various fitting procedures.
- ID:
- ivo://CDS.VizieR/J/other/NewA/51.59
- Title:
- LY And photometric followup
- Short Name:
- J/other/NewA/51.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a low-dispersion spectrum and two sets of CCD photometric light curves of the eclipsing binary LY And for the first time. The spectrum of LY And was classified as G2. We derived an updated ephemeris based on all previously available and our newly acquired minimum light times. Our analyses of LY And light curve minimum times reveals that the differences between calculated and observed minimum times for LY And can be represented by an upward parabolic curve, which means its orbital period is increasing with a rate of 1.88 (+/-0.13)x10^-7^days/year. This increase in orbital period may be interpreted as mass transfer from the primary component to the secondary component, with a rate of dM1/dt=-4.54x10^-8^M_{sun}_/year. By analyzing our CCD photometric light curves obtained in 2015, we obtained its photometric solution with the Wilson-Devinney program. This photometric solution also fits very well our light curves obtained in 2014. Our photometric solution shows that LY And is a contact eclipsing binary and its contact factor is f=(17.8+/-1.9)%. Furthermore, both our spectroscopic and photometric data show no obvious chromospheric activity of LY And.
- ID:
- ivo://CDS.VizieR/J/AJ/134/1963
- Title:
- MACHO r,b light curves of MC eclipsing binaries
- Short Name:
- J/AJ/134/1963
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new sample of 4634 eclipsing binary stars in the Large Magellanic Cloud (LMC), expanding on a previous sample of 611 objects and a new sample of 1509 eclipsing binary stars in the Small Magellanic Cloud (SMC), that were identified in the light-curve database of the MACHO project. We perform a cross-correlation with the OGLE-II LMC sample, finding 1236 matches. A cross correlation with the OGLE-II SMC sample finds 698 matches. We then compare the LMC subsamples corresponding to the center and periphery of the LMC and find only minor differences between the two populations. These samples are sufficiently large and complete that statistical studies of the binary star populations are possible.
349. MACHO Variables V.
- ID:
- ivo://CDS.VizieR/J/AJ/114/326
- Title:
- MACHO Variables V.
- Short Name:
- J/AJ/114/326
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the characteristics of 611 eclipsing binary stars in the Large Magellanic Cloud found by using the MACHO Project photometry database. The sample is magnitude limited, and extends down the main sequence to about spectral type A0. Many evolved binaries are also included. Each eclipsing binary is classified according to the traditional scheme of the General Catalogue of Variable Stars (EA and EB), and also according to a new decimal classification scheme defined in this paper. The new scheme is sensitive to the two major sources of variance in eclipsing binary star light curves -- the sum of radii, and the surface-brightness ratio, and allow greater precision in characterizing the light curves. Examples of each type of light curve and their variations are given. Sixty-four of the eclipsing binaries have eccentric, rather than circular, orbits. The ephemeris and principal photometric characteristics of each eclipsing binary are listed in a table. Photometric orbits based on the Nelson-Davis-Etzel model have been fitted to all light curves. These data will be useful for planning future observations of these binaries. Plots of all data and fitted orbits and a table of the fitted orbital parameters are available on the AAS CD-ROM series, Vol. 9, 1997. These data are also available at the MACHO home page (http://wwwmacho.mcmaster.ca/). (c) 1997 American Astronomical Society.
- ID:
- ivo://CDS.VizieR/J/AJ/115/1894
- Title:
- M31A eclipsing binaries and Cepheids
- Short Name:
- J/AJ/115/1894
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have undertaken a long-term project, DIRECT, to obtain the direct distances to two important galaxies in the cosmological distance ladder, M31 and M33, using detached eclipsing binaries (DEBs) and Cepheids. While rare and difficult to detect, DEBs provide us with the potential to determine these distances with an accuracy better than 5%. The extensive photometry obtained in order to detect DEBs provides us with good light curves for the Cepheid variables. These are essential to the parallel project to derive direct Baade-Wesselink distances to Cepheids in M31 and M33. For both Cepheids and eclipsing binaries, the distance estimates will be free of any intermediate steps. As a first step in the DIRECT project, between 1996 September and 1997 January we obtained 36 full nights on the Michigan-Dartmouth-MIT Observatory 1.3m telescope and 45 full/partial nights on the F. L. Whipple Observatory 1.2m telescope to search for DEBs and new Cepheids in the M31 and M33 galaxies. In this paper, second in a series, we present the catalog of variable stars, most of them newly detected, found in the field M31A [({alpha},{delta})=(11.34{deg}, 41.73{deg}), J2000.0]. We have found 75 variable stars: 15 eclipsing binaries, 43 Cepheids, and 17 other periodic, possible long-period or nonperiodic variables. The catalog of variables, as well as their photometry and finding charts, is available via anonymous ftp and the World Wide Web. The CCD frames are available upon request.
