A high angular and spectral resolution view into the hidden companion of<i>ε</i>Aurigae

Mourard, D.; Harmanec, P.; Stencel, R. E.; Berio, P.; Chesneau, O.; Clausse, J. M.; Ligi, R.; Nardetto, N.; Perraut, K.; Stee, Philippe; Tallon–Bosc, I.; McAlister, Harold A.; Brummelaar, T. ten; Ridgway, S. T.; Sturmann, J.; Sturmann, L.; Turner, N.; Farrington, C.; Goldfinger, P. J.

doi:10.1051/0004-6361/201219218

Cited by 17 publications

(10 citation statements)

References 28 publications

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“…The interferometric (uniform-disk) diameter of the F0-supergiant, 2.10±0.04 mas (λ1.6 μm; Kloppenborg et al 2010) and 2.10±0.02 mas (λ660 nm; Mourard et al 2012), suggests a stellar radius of between 140-340 R if at distances between 625-1500 pc, respectively. Our new effective temperature of 7395±70 K constrains the plausible range for its luminosity to log L/ log L = 4.7-5.5 (M V = -7. m 0 to -8. m 9).…”

Section: Discussion and Summarymentioning

confidence: 96%

“…The recent eclipse took place in [2009][2010][2011], and a suite of modern instrumentation was pointed to this star for the first time. Most notably, interferometric imaging with the CHARA array resolved the opaque dusty disk in front of the F0 star during eclipse (Kloppenborg et al 2010;Mourard et al 2012). Too numerous is the literature on Aur to be cited here but we refer the reader to the recent summaries by Stefanik et al (2010), Stencel et al (2011), Chadima et al (2011), Harmanec et al (2013), and the many citations therein.…”

Section: Introductionmentioning

confidence: 99%

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Time‐series high‐resolution spectroscopy and photometry of ε Aurigae from 2006–2013: Another brick in the wall

et al. 2014

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We present continuous and time-resolved R = 55 000 opticaléchelle spectroscopy of Aurigae from [2006][2007][2008][2009][2010][2011][2012][2013] We conclude that Hα is contaminated by changes in the circumstellar environment while the Hβ and V I photometry stems predominantly from the non radial pulsations of the F0 supergiant. We isolate the disk-rotation profile from 61 absorption lines and found that low disk eccentricity generally relates to low disk rotational velocity (but not always) while high disk eccentricity always relates to high velocity. There is also the general trend that the disk-absorption in spectral lines with higher excitation potential comes from disk regions with higher eccentricity and thus also with higher rotational velocity. The dependency on transition probability is more complex and shows a bi-modal trend. The outskirts of the disk is distributed asymmetrically around the disk and appears to have been built up mostly in a tail along the orbit behind the secondary. Our data show that this tail continues to eclipse the F0 Iab primary star even two years after the end of the photometric eclipse. High-resolution spectra were also taken of the other, bona-fide, visual-binary components of Aur (ADS 3605BCDE). Only the C-component, a K3-4-giant, appears at the same distance than Aur but its radial velocity is in disagreement with a bound orbit. The other components are a nearby (≈ 7 pc) cool DA white dwarf, a G8 dwarf, and a B9 supergiant, and not related to Aur. The cool white dwarf shows strong DIB lines that suggest the existence of a debris disk around this star.

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Section: Discussion and Summarymentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

Time‐series high‐resolution spectroscopy and photometry of ε Aurigae from 2006–2013: Another brick in the wall

et al. 2014

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“…The material in the disk seems to be over abundant in 13 C and rare-earth elements which may be the result of accretion and/or mass transfer during the AGB and post-AGB stage of the primary (see Griffin & Stencel 2012;Stencel 2013). Mourard et al (2012) by Parthasarathy & Pottasch (1986). High-mass model of F0Ia star cannot explain the over abundance of s-process elements.…”

Section: Low-mass Model For ǫmentioning

confidence: 99%

A study of K i 7699 Å and related shell lines during the recent eclipse of ϵ Aurigae

Muthumariappan

Parthasarathy

Leadbeater³

et al. 2014

Monthly Notices of the Royal Astronomical Society

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“…Even though we recorded data with telescope triplets, we cannot retrieve closure phases on our targets since the signal-to-noise ratio on this observable is strongly limited by the saturation limit of the VEGA photon-counting detectors (see Fig. 4 in Mourard et al 2012).…”

Section: Data Processingmentioning

confidence: 99%

Benchmarking the fundamental parameters of Ap stars with optical long-baseline interferometric measurements

Perraut

Cunha

Romanovskaya

et al. 2020

A&A

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Context. The variety of physical processes at play in chemically peculiar stars makes it difficult to determine their fundamental parameters. In particular, for the magnetic ones, called Ap stars, the strong magnetic fields and the induced spotted stellar surfaces may lead to biased effective temperatures when these values are derived through spectro-photometry. Aims. We propose to benefit from the exquisite angular resolution provided by long-baseline interferometry in the visible to determine the accurate angular diameters of a number of Ap stars, and thus estimate their radii by a method that is as independent as possible of atmospheric models. Methods. We used the visible spectrograph VEGA at the CHARA interferometric array to complete the sample of Ap stars currently observable with this technique. We estimated the angular diameter and radius of six new targets. We estimated their bolometric flux based solely on observational spectroscopic and photometric data to derive nearly model-independent luminosities and effective temperatures. Results. We extend to 14 the number of Ap stars for which interferometric angular diameters have been measured. The fundamental parameters we derived for the complete Ap sample are compared with those obtained through a self-consistent spectroscopic analysis. Based on a model fitting approach of high-resolution spectra and spectro-photometric observations over a wide wavelength range, this method takes into account the anomalous chemical composition of the atmospheres and the inhomogeneous vertical distribution for different chemical elements. Regarding both the radii and the effective temperatures, the derived values from our interferometric observations and from self-consistent modelling are consistent within better than 2σ for nine targets out of ten. We thus benchmark nine Ap stars for effective temperatures ranging from 7200 and 9100 K, and luminosities ranging between 7 L⊙ and 86 L⊙. Conclusions. These results will be key for the future derivation of accurate radii and other fundamental parameters of fainter peculiar stars for which both the sensitivity and the angular resolution of the current interferometers are not sufficient. Within the context of the observations of Ap stars with the Transiting Exoplanet Survey Satellite (TESS), these interferometric measurements are crucial for testing the mechanism of pulsation excitation at work in these peculiar stars. In particular, our interferometric measurements provide accurate locations in the Hertzsprung-Russell diagram for hot Ap stars among which pulsations may be searched for with TESS, putting to test the blue edge of the theoretical instability strip. These accurate locations could be used to derive masses and ages of these stars through a specific grid of models, and to test correlations between the properties of these peculiar stars and their evolutionary state.

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

Cited by 17 publications

References 28 publications

Time‐series high‐resolution spectroscopy and photometry of ε Aurigae from 2006–2013: Another brick in the wall

Time‐series high‐resolution spectroscopy and photometry of ε Aurigae from 2006–2013: Another brick in the wall

A study of K i 7699 Å and related shell lines during the recent eclipse of ϵ Aurigae

Benchmarking the fundamental parameters of Ap stars with optical long-baseline interferometric measurements

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