CCD, BVRI primary light curves of V1187 Her were taken in 2017 May and 2018 May at the Dark Sky Observatory in North Carolina with the 0.81-m reflector of Appalachian State University. A spectrum was taken earlier at Dominion Astrophysical Observatory (DAO) with the 1.8 m telescope. The spectral type is F(8.5 ± 1)V, resulting in a surface temperature of 6250±125 K (Cox 2000), so solar-type activity is expected. V1187 Her was previously identified as a low-amplitude, short-period, over-contact eclipsing binary (EW) with an orbital period of 0.310726 d. Strikingly, despite its low amplitude (∼0.15 mag), the early light curves show a total eclipse (eclipse duration: 31.5 minutes). This can only occur (in the absence of a strong third light) if the binary is an exceptionally extreme mass ratio binary, perhaps the most extreme known. Eight instances of minimum light were calculated. A 12-year period study reveals a secular period decrease in the orbital period with good confidence. The rate of period change is dP/dt=−1.5×10 −07 d/yr, probably due to magnetic braking. Its Roche Lobe fill-out is found to be a hefty 84% along with a mass ratio of only ∼0.044; indeed, the most extreme known among solar-type (i.e., W UMa) binaries. It has a cool spot region. The secondary component has a temperature of »6680 K, which makes it a W-subtype binary (the less massive component is hotter). The inclination is only ∼67°despite its total eclipses. A q-search was conducted, which showed the 0.044 value was the best fit to the light curves. Additionally, followup observations were taken on 2018 May 4, which confirmed the mass ratio found from the earlier curves.
Abstract. During the past decade, the number known shallow-amplitude, yet totally eclipsing, extreme-mass-ratio binaries has increased from one (AW UMa, which is now in doubt) to about a dozen. Statistics are accumulating that will tell us the nature of these once rare systems. These individual interacting field binaries are believed to be the progenitors of FK Comae-type fast-rotating subgiants, which are similar to the cluster stars called 'variable blue stragglers.' We review our recent observations and new analyses of the individual systems, V409 Hya, GSC 1283 0053 Ori, GSC 2537 520 CVn, using the 2007 Wilson Code and summarize results from our previous observations (V802 Aql, V902 Sgr) and those from the literature (e.g., CK Boo, GR Vir, HV Aqr, UY UMa, EM Pis, CU Tau, TV Mus) to disclose a preliminary picture of the character of this interesting class of binary stars.
Keywords. magnetic fields, binaries: eclipsing, blue stragglersThe full poster (in pdf format) is available at http://www.astro.iag.usp.br/~iaus266/Posters/pSamec.pdf.
AcknowledgementsOur recent CCD observations were taken with the Lowell 0.81 m telescope through our association with NURO (the National Undergraduate Research Observatory) and the SARA (Southeastern Association for Research in Astronomy) 0.9 m telescope. We gratefully acknowledge travel support received through the small research grant program of the American Astronomical Society.
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