Absolute dimensions and masses of the remarkable spotted dM4e eclipsing binary flare star CM Draconis

Lacy, Claud H.

doi:10.1086/155698

Cited by 123 publications

(135 citation statements)

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“…The inflated radii of components of late-type binaries are their main characteristic and are observed for many years (see Fig. 1 in Lacy 1977). Recently, some successful efforts of an explanation involving the influence of rotationally driven magnetic activity on the effectiveness of convection and mixing have been made and seem to have strong support in the recent burst in the number of discovered and characterized low-mass eclipsing binaries.…”

Section: X-ray Emissionmentioning

confidence: 95%

“…Since the discovery of the first eclipsing late-type systems -YY Gem (Kron 1952;Bopp 1974), CM Dra (Lacy 1977) or CU Cnc (Delfosse et al 1999) -and the first comparisons of their observed properties with the evolutionary models (e.g. Lacy 1977), it became clear that the stellar evolution theory, despite being very successful in many fields, fails to reproduce the observed parameters of late-type stars, especially radii and temperatures.…”

Section: Introductionmentioning

confidence: 99%

“…Lacy 1977), it became clear that the stellar evolution theory, despite being very successful in many fields, fails to reproduce the observed parameters of late-type stars, especially radii and temperatures. An increasing number of recently discovered systems (see Torres et al 2010, for a recent review) confirms these discrepancies at least for systems on the main sequence.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: X-ray Emissionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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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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“…1. Since the writing of DDK00, a clear trend of increasing O−C values has become apparent, which is also apparent from the extension into the past through the inclusion of the values from Lacy (1977), which weren't included in DDK00's analysis. The linear ephemerides of DDK00, therefore, no longer provides the best description of the observed O−C values.…”

Section: The Observed Minimum Timesmentioning

confidence: 99%

“…The notion that a component of CM Dra may be magnetically active cannot be completely discarded, since several large flare events have been reported in the literature (Lacy 1977;Kim et al 1997;Deeg et al 1998). In Applegate's model, the angular momentum of the entire system remains constant, but the distribution of angular momentum between the components' mutual orbit and the active star's internal rotation varies.…”

Section: Applegate's Mechanismmentioning

confidence: 99%

Extrasolar planet detection by binary stellar eclipse timing: evidence for a third body around CM Draconis

Deeg

Ocaña

Kozhevnikov

et al. 2008

A&A

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Aims. Our objective is to elucidate the physical process that causes the observed observed-minus-calculated (O-C) behavior in the M4.5/M4.5 binary CM Dra and to test for any evidence of a third body around the CM Dra system. Methods. New eclipse minimum timings of CM Dra were obtained between the years 2000 and 2007. The O-C times of the system are fitted against several functions, representing different physical origins of the timing variations.Results. Using our observational data in conjunction with published timings going back to 1977, a clear non-linearity in O-C times is apparent. An analysis using model-selection statistics gives about equal weight to a parabolic and to a sinusoidal fitting function. Attraction from a third body, either at large distance in a quasi-constant constellation across the years of observations or from a body on a shorter orbit generating periodicities in O−C times is the most likely source of the observed O−C times. The white dwarf GJ 630.1B, a proper motion companion of CM Dra, can however be rejected as the responsible third body. Also, no further evidence of the shortperiodic planet candidate described by Deeg et al. (2000, A&A, 358, L5) is found, whereas other mechanisms, such as period changes from stellar winds or Applegate's mechanism can be rejected. Conclusions. A third body, being either a few-Jupiter-mass object with a period of 18.5 ± 4.5 years or an object in the mass range of 1.5 M jup to 0.1 M with periods of hundreds to thousands of years is the most likely origin of the observed minimum timing behavior.

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Fundamental properties of lower main‐sequence stars

Torres

2013

Astron Nachr

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The field of exoplanet research has revitalized interest in M dwarfs, which have become favorite targets of Doppler and transit surveys. Accurate measurements of their basic properties such as masses, radii, and effective temperatures have revealed significant disagreements with predictions from stellar evolution theory in the sense that stars are larger and cooler than expected. These anomalies are believed to be due to high levels of activity in these stars. The evidence for the radius discrepancies has grown over the years as more and more determinations have become available; however, fewer of these studies include accurate determinations of the temperatures. The ubiquitous mass-radius diagrams featured in many new discovery papers are becoming more confusing due to increased scatter, which may be due in part to larger than realized systematic errors affecting many of the published measurements. A discussion of these and other issues is given here from an observer's perspective, along with a summary of theoretical efforts to explain the radius and temperature anomalies.

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Absolute dimensions and masses of the remarkable spotted dM4e eclipsing binary flare star CM Draconis

Cited by 123 publications

References 0 publications

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

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

Extrasolar planet detection by binary stellar eclipse timing: evidence for a third body around CM Draconis

Fundamental properties of lower main‐sequence stars

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