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Register a new userSpectral and photometric analysis of the eclipsing binary epsilon Aurigae prior to and during the 2009-2011 eclipse
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A series of 353 red electronic spectra obtained between 1994 and 2010, and of 171 UBV photometric observations of the 2010 eclipse, were analyzed in an effort to better understand the eclipsing binary eps Aur. The main results follow. (1) We attempted to recover a spectrum of the companion by disentangling the observed spectra of the eps Aur binary failed, but we were able to disentangle the spectrum of telluric lines and obtain a mean spectrum of the F-type primary star. The latter was then compared to a grid of synthetic spectra for a number of plausible values of T(eff) and log(g), but a reasonably good match was not found. However, we conclude that the observed spectrum is that of a low-gravity star. (2) We examined changes in the complex H-alpha line profiles over the past 16 years, with particular emphasis on the 2009-2011 eclipse period, by subtracting a mean out-of-eclipse H-alpha profile (appropriately shifted in radial velocity) from the observed spectra. We find that the dark disk around the unseen companion has an extended atmosphere that manifests itself via blueshifted and redshifted H-alpha shell absorptions seen projected against the F star. Significantly, the H-alpha shell line first appeared three years before first contact of the optical eclipse when the system was not far past maximum separation. (3) Analyses of radial velocities and central intensities of several strong, unblended spectral lines, as well as UBV photometry, demonstrated that these observables showed apparent multiperiodic variability during eclipse. The dominant period of 66.21 was common to all the observables, but with different phase shifts between these variables. This result strongly supports our earlier suggestion that the photometric variability seen during eclipse is intrinsic to the F star, and therefore, the idea of a central brightening due to a hole in the disk should be abandoned.
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We present and analyze epsilon Aurigae data concerning the evolution of the H$alpha$ line on the occasion of the 2009 International observation campaign launched to cover the eclipse of this object. About 250 high resolution spectra of the H$alpha$ line were obtained by amateur covering the three years around eclipse. We visually inspect the dynamical spectrum constructed from the data and analyze the evolution with time of the radial velocity and of EW (Equivalent Width) vs V mag. The spectroscopic data reveal many details which confirm the complexity of the Aurigae system. The object is far from being understood. In particular, according to our measurements, the eclipse duration has been underestimated and key dates were defined. A complete analysis of details revealed by our data would require much time and effort. Observers are encouraged to continue monitoring the H$alpha$ line out of eclipse in the hope that it will provide further important information.
The results of a spectroscopic survey of epsilon Aurigae during eclipse using a network of small telescopes are presented. The spectra have a resolution of 0.35 to 0.65{AA} and cover the period 2008 to 2012 with a typical interval of 4 days during eclipse. This paper specifically covers variations in the K I 7699{AA}, Na D and Mg II 4481{AA} lines. Absorption started increasing in the KI 7699{AA} line 3 months before the eclipse began photometrically and had not returned to pre eclipse levels by the end of the survey March 2012, 7 months after the brightness had returned to normal outside eclipse levels. The contribution of the eclipsing object to the KI 7699{AA} line has been isolated and the data show the excess absorption increasing and decreasing in a series of steps during ingress and egress. This is interpreted as an indication of structure within the eclipsing object. The F star is totally obscured by the eclipsing object at the Na D wavelength during eclipse. The radial velocity of the F star and the mean and maximum radial velocity of the eclipsing material in front of the F star at any given time have been isolated and tracked throughout the eclipse. The quasi-periodic variations seen in the F star RV outside eclipse continued during the eclipse. It is hoped that these results can be used to constrain proposed models of the system and its components.
We report on a total of 106 nights of optical interferometric observations of the $epsilon$ Aurigae system taken during the last 14 years by four beam combiners at three different interferometric facilities. This long sequence of data provides an ideal assessment of the system prior to, during, and after the recent 2009-2011 eclipse. We have reconstructed model-independent images from the 10 in-eclipse epochs which show that a disk-like object is indeed responsible for the eclipse. Using new 3D, time-dependent modeling software, we derive the properties of the F-star (diameter, limb darkening), determine previously unknown orbital elements ($Omega$, $i$), and access the global structures of the optically thick portion of the eclipsing disk using both geometric models and approximations of astrophysically relevant density distributions. These models may be useful in future hydrodynamical modeling of the system. Lastly, we address several outstanding research questions including mid-eclipse brightening, possible shrinking of the F-type primary, and any warps or sub-features within the disk.
We report on observations of the eclipsing binary 2MASS 19090585+4911585 with the 25 cm auxiliary telescope of the University Observatory Jena. We show that a nearby brighter star (2MASS 19090783+4912085) was previously misclassified as the eclipsing binary and find 2MASS 19090585+4911585 to be the true source of variation. We present photometric analysis of VRI light curves. The system is an overcontact binary of W UMa type with an orbital period of (0.288374 +/- 0.000010) d.
The first photometric analysis of V811 Cep was carried out. The first complete light curves of V, R and I bands are given. The analysis was carried out by Wilson-Devinney (W-D) program, and the results show that V811 Cep is a median-contact binary ($f=33.9(pm4.9)%$) with a mass ratio of 0.285. It is a W-subtype contact binary, that is, the component with less mass is hotter than the component with more mass, and the light curves are asymmetric (OConnell effect), which can be explained by the existence of a hot spot on the component with less mass. The orbital inclination is $i=88.3^{circ}$, indicating that it is a totally eclipsing binary, so the parameters obtained are reliable. Through the O-C analyzing, it is found that the orbital period decreases at the rate of $dot{P}=-3.90(pm0.06)times 10^{-7}d cdot yr^{-1}$, which indicates that the mass transfer occurs from the more massive component to the less massive one.
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