Spectral and photometric analysis of the eclipsing binaryϵ Aurigae prior to and during the 2009–2011 eclipse

A high angular and spectral resolution view into the hidden companion ofεAurigae

“…), exhibit variations on time scales of 50-200 d. The doubling of the Hα absorption has been observed by Chadima et al (2011) who -thanks to systematic spectral observations -were able to demonstrate that the atmosphere of the disk starts to be projected against the F primary a full 3 years before the beginning of the photometric eclipse. Chadima et al (2011) subtracted the average, disentangled, outof-eclipse Hα profile (properly shifted in velocity) from the individual Hα profiles recorded during the recent eclipse and obtained profiles with two Hα absorptions, comparably strong and symmetrically blue-and red-shifted near the mid-eclipse. They argued that these additional absorptions come from the parts of the atmosphere of the dark rotating disk around the secondary, projected against the F primary.…”

“…There is rich evidence that the disk has an extended semi-transparent atmosphere, which is optically thick only in certain spectral lines. It is most pronounced in the hydrogen lines of the Balmer series (Kuiper et al 1937;Chadima et al 2011) but a disk atmosphere is also observed in some optically thin metallic lines, very clearly, for instance, in the K I 769.9 nm line (Lambert & Sawyer 1986;Leadbeater & Stencel 2010). The K I line, virtually missing in the out-of-eclipse spectrum of ε Aur, becomes very strong and double during the eclipse.…”

“…The K I line, virtually missing in the out-of-eclipse spectrum of ε Aur, becomes very strong and double during the eclipse. The absorption line profiles of the F primary (Struve 1956) as well as the Hα profile (Cha et al 1994;Chadima et al 2011) and the brightness of the object (Hopkins & Stencel 2004;Chadima et al 2011;Hopkins & Stencel, in prep. ), exhibit variations on time scales of 50-200 d. The doubling of the Hα absorption has been observed by Chadima et al (2011) who -thanks to systematic spectral observations -were able to demonstrate that the atmosphere of the disk starts to be projected against the F primary a full 3 years before the beginning of the photometric eclipse.…”

“…The absorption line profiles of the F primary (Struve 1956) as well as the Hα profile (Cha et al 1994;Chadima et al 2011) and the brightness of the object (Hopkins & Stencel 2004;Chadima et al 2011;Hopkins & Stencel, in prep. ), exhibit variations on time scales of 50-200 d. The doubling of the Hα absorption has been observed by Chadima et al (2011) who -thanks to systematic spectral observations -were able to demonstrate that the atmosphere of the disk starts to be projected against the F primary a full 3 years before the beginning of the photometric eclipse. Chadima et al (2011) subtracted the average, disentangled, outof-eclipse Hα profile (properly shifted in velocity) from the individual Hα profiles recorded during the recent eclipse and obtained profiles with two Hα absorptions, comparably strong and symmetrically blue-and red-shifted near the mid-eclipse.…”

“…Analysis of published, out-of-eclipse photometry from 1842 to 2006 Kim (2008) concluded that the F star is a multiperiodic pulsator with two dominant periods of 67 and 123 d. Chadima et al (2011) claimed multiperiodicity based on data from the 2009-2011 eclipse, consistenly finding a period of 66.21 d in the UBV photometry, central intensities and residual radial velocities of the red Si II and Fe II lines. The ∼0.1 mag variations are seen both out of eclipse and during the primary eclipse.…”