A survey of extended matter around chromospherically active binary systems

Abstract

We present an analysis of colour excess (CE) observations for 13 chromospherically active binary systems, together with 27 inactive reference stars of similar spectral types and luminosity classes of the components of these 13 binaries. We used the observations which were made by Johnson-Cousins ${BVR}_{c}\mathrm{I}_{c}$ , 2MASS, and WISE photometric systems. Our new photometric ${BVR}_{c}\mathrm{I}_{c}$ observations were obtained by means of 1 m telescope at TÜBİTAK National Observatory and 40 cm telescope at Ankara University Kreiken Observatory. To check the existence of extended matter around an active binary component(s) of these 13 binary systems, we examined the CE values at around primary/secondary minima and outside eclipses. The comparison of these CEs, obtained relative to those of reference stars of the same ${(B-V)_\circ}$ colours, especially during primary minima with those of secondary minima and outside eclipses, showed that these systems have greater excess radiation in primary minima than in both secondary minima and outside eclipses. We observed that the colour excesses, in general, most likely arise from the extended matter around the cooler component of a binary system. The comparison of CE values also showed that the extended matter of some of these systems was most likely covered or affected both of their components. Since no observational data were obtained during primary minimum of RW UMa, by excluding this binary system, an examination of the locations of cool and active components of the remaining 12 systems of this study on Hertzsprung-Russell diagram, together with corresponding evolutionary tracks, showed that most of the active binary systems have an extended matter not only caused from stellar activity but also more likely caused from evolutionary processes.

New Spectral Analysis Results Within the Scope of Extended Matter Research in the Ar Lacertae Active Binary System

“…In addition, photometric data, from Karakuş & Ekmekçi (2020), of AR Lac in the Johnson-Cousins BV R c I c and medium WISE bands were used to make a comparison with our spectroscopic results. In all these bands, the photometric light curves of AR Lac were also constructed and evaluated using the photometric colour excess measurements of Karakuş & Ekmekçi (2020). Some details about these photometric observational data are presented below in § 2.3.…”

“…By taking advantage of the geometric configuration of the components of an active and total eclipsing binary system, the presence of an excess radiation of the active component can easily be detected during the primary minimum, at which the occultation of the hotter component by the cooler and active one occurs (e.g. Hall & Ramsey 1994;Karakuş & Ekmekçi 2020). This configuration, during the primary minimum of a total eclipsing and active binary system, could also give an advantage to search for the interaction between the activity/spots phenomena and the extended/circumstellar matter which may exist in the system.…”

“…Recently, research on the extended/circumstellar matter in CABs was presented by Karakuş & Ekmekçi (2020). Based on their photometric CCD data of 13 CABs, including AR Lac, and together with the 2MASS and WISE data, they found that AR Lac had some fluctuations in colour excess (CE) values around primary minimum.…”

“…They concluded that the main source of excess radiation in AR Lac is stellar activity. This stellar activity is expected to contribute to the formation of extended/circumstellar matter in AR Lac, but significant evidence on how much it contributes could not be presented by Karakuş & Ekmekçi (2020), based solely on their results of photometric CE measurements.…”

“…In this study, the spectra of AR Lac taken during the observing period 2013-2016 at different orbital phases by using the Coudé Echelle and TFOSC (Faint Object Spectrograph and Camera) instruments were analysed to investigate and to reveal the relationship between its stellar activity and a possible extended/circumstellar matter of the system. In addition, together with the results of this spectral analysis of the AR Lac system, an evaluation was made by including the results given by Karakuş & Ekmekçi (2020) based on their photometric CCD, 2MASS and WISE data taken during minima and outside eclipses. Within the scope of this evaluation, the B, V , R c , I c , and W1, W2, W3, W4 of WISE band light curves of AR Lac were also taken into consideration.…”