HD 174884: a strongly eccentric, short-period early-type binary system discovered by CoRoT

Maceroni, C.; Montalbán, J.; Michel, E.; Harmanec, P.; Prša, Andrej; Briquet, Maryline; Niemczura, E.; Morel, Thierry; Ladjal, D.; Auvergne, M.; Baglin, A.; Baudin, F.; Catala, C.; Samadi, R.; Aerts, C.

doi:10.1051/0004-6361/200913311

Cited by 78 publications

(92 citation statements)

References 38 publications

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“…(10) The ratios T 2 /T 1 of our targets fall in the range 0.8-1.0 with one exception, KIC 6220470, which value is 0.56 (Figure 14, middle). Opposite discrepancy has been found for HD 174884 (Maceroni et al 2009), which components are with equal temperatures irrespective of the negligible secondary eclipse. (11) The values q st of the mass ratios, obtained by the empirical relation temperature-mass of MS stars (Table 4), differed from those determined by our phoebe models q ≡ q PH (Figure 14, right).…”

Section: Discussionmentioning

confidence: 85%

Light Curve Solutions of Ten Eccentric Kepler Binaries, Three of them with Tidally Induced Humps

Kjurkchieva

Vasileva

2015

Publ. Astron. Soc. Aust.

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We carried out light curve solutions of ten detached eclipsing eccentric binaries observed by Kepler. The formal errors of the derived parameters from the light curve solutions are below 1%. Our results give indications that the components of the eccentric binaries (especially those with mass ratios below 0.5) do not follow precisely the empirical relations between the stellar parameters derived from the study of circular-orbit binaries. We found the following peculiarities of the targets: (a) the components of KIC 9474969 have almost the same temperatures while their radii and masses differ by a factor around 2.5; (b) KIC 6949550 reveals semi-regular light variations with an amplitude of 0.004 and a period around 7 d which are modulated by long-term variations; (c) KIC 6220470, KIC 11071207, and KIC 9474969 exhibit tidally induced 'hump' around the periastron. These are the targets with the biggest relative radii of our sample. We derived the dependence of the hump amplitude on the relative stellar radii, eccentricity, and mass ratio of eccentric binary consisting of MS stars.

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Section: Discussionmentioning

confidence: 85%

Light Curve Solutions of Ten Eccentric Kepler Binaries, Three of them with Tidally Induced Humps

Kjurkchieva

Vasileva

2015

Publ. Astron. Soc. Aust.

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“…There is an additional difficulty in finding low-q binaries, which is the low brightness ratio of the binary components. The identification of the faint lines of the secondary or the shallow secondary eclipse is then challenging and requires high SNR data (for an extreme case of eclipse depths see Maceroni et al 2009). Considering that, any new object with q < ∼ 0.85 is valuable.…”

Section: Discussionmentioning

confidence: 99%

Orbital and physical parameters of eclipsing binaries from the All-Sky Automated Survey catalogue

Hełminiak

Konacki

Złoczewski

et al. 2011

A&A

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Aims. We present the results of our spectroscopic and photometric analysis of two newly discovered low-mass detached eclipsing binaries found in the All-Sky Automated Survey (ASAS) catalogue: ASAS J093814-0104.4 and ASAS J212954-5620.1. Methods. Using the Grating Instrument for Radiation Analysis with a Fibre-Fed Echelle (GIRAFFE) on the 1.9-m Radcliffe telescope at the South African Astronomical Observatory (SAAO) and the University College London Echelle Spectrograph (UCLES) on the 3.9-m Anglo-Australian Telescope, we obtained high-resolution spectra of both objects and derived their radial velocities (RVs) at various orbital phases. The RVs of both objects were measured with the two-dimensional cross-correlation technique (TODCOR) using synthetic template spectra as references. We also obtained V and I band photometry using the 1.0-m Elizabeth telescope at SAAO and the 0.4-m Panchromatic Robotic Optical Monitoring and Polarimetry Telescopes (PROMPT) located at the Cerro Tololo Inter-American Observatory (CTIO). The orbital and physical parameters of the systems were derived with PHOEBE and JKTEBOP codes. We compared our results with several sets of widely-used isochrones. Results. Our multi-epoch photometric observations demonstrate that both objects show significant out-of-eclipse modulations, which vary in time. We believe that this effect is caused by stellar spots, which evolve on time scales of tens of days. For this reason, we constructed our models on the basis of photometric observations spanning short time scales (less than a month). Our modeling indicates that (1) ASAS J093814-0104.04 is a main sequence active system with nearly-twin components with masses of M 1 = 0.771 ± 0.033 M , M 2 = 0.768 ± 0.021 M and radii of R 1 = 0.772 ± 0.012 R and R 2 = 0.769 ± 0.013 R . (2) ASAS J212954-5620.1 is a main sequence active binary with component masses of M 1 = 0.833 ± 0.017 M , M 2 = 0.703 ± 0.013 M and radii of R 1 = 0.845 ± 0.012 R and R 2 = 0.718 ± 0.017 R . Conclusions. Both systems seem to confirm the well-known characteristic of active low-mass stars, for which the observed radii are larger and the temperatures lower than predicted by evolutionary models. Other parameters agree within errors with the models of main sequence stars. The time-varying spot configuration may imply a variable level of activity, which may manifest itself in small changes of the measured radii.

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“…Full Tables 2-4 are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/583/A122 of surface differential rotation (Lanza et al 2014), and the detection of eclipsing binary systems (e.g., Maceroni et al 2009;Slawson et al 2011;Maciel et al 2011). The aforementioned science cases represent only a few of the major topics among the many aspects of time-domain, high-precision photometry.…”

Section: Introductionmentioning

confidence: 99%

The variability behaviour of CoRoT M-giant stars

Lopes

Neves

Leão

et al. 2015

A&A

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Context. For six years the Convection, Rotation, and planetary Transits (CoRoT) space mission has been acquiring photometric data from more than 100 000 point sources towards and directly opposite the inner and outer regions of the Galaxy. The high temporal resolution of the CoRoT data, combined with the wide time span of the observations, enabled the study of short-and long-time variations in unprecedented detail. Aims. The aim of this work is to study the variability and evolutionary behaviour of M-giant stars using CoRot data. Methods. From the initial sample of 2534 stars classified as M giants in the CoRoT databases, we selected 1428 targets that exhibit well defined variability, by visual inspection. Then, we defined three catalogues: C1 -stars with T eff < 4200 K and LCs displaying semi-sinusoidal signatures; C2 -rotating variable candidates with T eff > 4200 K; C3 -long-period variable candidates (with LCs showing a variability period up to the total time span of the observations). The variability period and amplitude of C1 stars were computed using Lomb-Scargle and harmonic fit methods. Finally, we used C1 and C3 stars to study the variability behaviour of M-giant stars. Results. The trends found in the V − I vs. J − K colour-colour diagram are in agreement with standard empirical calibrations for M giants. The sources located towards the inner regions of the Galaxy are distributed throughout the diagram, while the majority of the stars towards the outer regions of the Galaxy are spread between the calibrations of M giants and the predicted position for carbon stars. The stars classified as supergiants follow a different sequence from the one found for giant stars. We also performed a Kolmogorov-Smirnov (KS) test of the period and amplitude of stars towards the inner and outer regions of the Galaxy. We obtained a low probability that the two samples came from the same parent distribution. The observed behaviour of the period-amplitude and period-effective temperature (T eff ) diagrams are, in general, in agreement with those found for Kepler sources and ground based photometry, with pulsation being the dominant cause responsible for the observed modulation. We also conclude that short-time variations on M-giant stars do not exist or are very rare, and the few cases we found are possibly related to biases or background stars.

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HD 174884: a strongly eccentric, short-period early-type binary system discovered by CoRoT

Cited by 78 publications

References 38 publications

Light Curve Solutions of Ten Eccentric Kepler Binaries, Three of them with Tidally Induced Humps

Light Curve Solutions of Ten Eccentric Kepler Binaries, Three of them with Tidally Induced Humps

Orbital and physical parameters of eclipsing binaries from the All-Sky Automated Survey catalogue

The variability behaviour of CoRoT M-giant stars

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