The Pre–Main-Sequence Eclipsing Binary TY Coronae Australis: Precise Stellar Dimensions and Tests of Evolutionary Models

Casey, B. W.; Vaz, L. P. R.; Andersen, J.; Suntzeff, Nicholas B.

doi:10.1086/300270

Cited by 87 publications

(132 citation statements)

References 31 publications

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“…Typically, the 3σ-error at low Straižys et al (1996); (4) Knude & Hog (1998); (5) Casey et al (1998); (6) Kun (1998); (7) column densities is 0.5−1.5 mag. The extinction measurements "saturate" at about A V = 25 mag.…”

Section: Extinction Mapping Methodsmentioning

confidence: 99%

Probing the evolution of molecular cloud structure

Kainulainen

Beuther

Henning

et al. 2009

A&A

421

600

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Context. Probability distribution of densities is a fundamental measure of molecular cloud structure, containing information on how the material arranges itself in molecular clouds. Aims. We derive the probability density functions (PDFs) of column density for a complete sample of prominent molecular cloud complexes closer than d < ∼ 200 pc. For comparison, additional complexes at d ≈ 250−700 pc are included in the study. Methods. We derive near-infrared dust extinction maps for 23 molecular cloud complexes, using the nicest colour excess mapping technique and data from the 2MASS archive. The extinction maps are then used to examine the column density PDFs in the clouds. Results. The column density PDFs of most molecular clouds are well-fitted by log-normal functions at low column densities (0.5 mag < A V < ∼ 3−5 mag, or −0.5 < ln A V /A V < ∼ 1). But at higher column densities prominent power-law-like wings are common. In particular, we identify a trend among the PDFs: active star-forming clouds always have prominent non-log-normal wings. In contrast, clouds without active star formation resemble log-normals over the whole observed column density range or show only low excess of higher column densities. This trend is also reflected in the cumulative forms of the PDFs, showing that the fraction of high column density material is significantly larger in star-forming clouds. These observations agree with an evolutionary trend where turbulent motions are the main cloud-shaping mechanism for quiescent clouds, but the density enhancements induced by them quickly become dominated by gravity (and other mechanisms), which is in turn strongly reflected by the shape of the column density PDFs. The dominant role of the turbulence is restricted to the very early stages of molecular cloud evolution, comparable to the onset of active star formation in the clouds.

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Section: Extinction Mapping Methodsmentioning

confidence: 99%

Probing the evolution of molecular cloud structure

Kainulainen

Beuther

Henning

et al. 2009

A&A

421

600

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“…In order to analyse our light and radial-velocity curves of U Oph simultaneously, we have extensively improved our version of the WD model (Wilson & Devinney 1971;Wilson 1979Wilson , 1993, previously modified as described by Vaz et al 1995 andCasey et al 1998) so as to treat systems with significant apsidal motion (Vieira 2003) and/or light-time effects during the observing period.…”

Section: Light-curve Solutionsmentioning

confidence: 99%

Absolute dimensions of eclipsing binaries

Vaz¹,

Andersen

Claret³

2007

A&A

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Context. Precise stellar masses and radii provide unique information on stellar evolution. In a Galactic context, they may also provide information on the evolution of the Solar neighbourhood. Aims. We aim to determine absolute dimensions for the mid B-type eclipsing binary U Ophiuchi and compare the inferred ages and chemical compositions to those of other binary stars with masses near 5 M . Methods. We determine masses, radii, log g, log T eff , and luminosities for the stars in U Oph from new radial velocities and uvby light curves. By improving the Wilson-Devinney code, we also derive precise apsidal-motion and light-time orbits of this triple system, using 353 times of minimum over 120 years. Finally, we compare the data for U Oph and three similar systems with the predictions of stellar models. Results. The stars in U Oph have masses of 5.27 ± 0.09 M and 4.74 ± 0.07 M , radii of 3.48 ± 0.02 R and 3.11 ± 0.03 R ; we argue that systematic errors are negligible. The apsidal motion period is exceptionally short, U ∼ 21 yr, while the light-time orbit has P 3 ∼ 38.4 yr. The precise log g values for DI Her, U Oph, V760 Sco, and MU Cas, all within 10% of 5 M , place them successively from the ZAMS to the TAMS, at ages of 5−100 × 10 6 yr. Current stellar evolution models fit both stars in each system very well if the (otherwise unconstrained) metal abundance Z is adjusted in each case. Conclusions. More accurate data and/or binary systems with larger mass ratios are needed to actually test stellar models near 5 M . The different Z values found for these young, nearby systems suggest that disk stars form with a range of metal abundances even today, but more data are needed to confirm this result.

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“…There are only six known low-mass pre-main sequence eclipsing binaries with M < 1.5 M : RXJ 0529.4+0041A (Covino et al 2000(Covino et al , 2004, V1174 Ori (Stassun et al 2004), 2MASS J05352184-20130546085 (Stassun et al 2006(Stassun et al , 2007, JW 380 (Irwin et al 2007), Par 1802 Stassun et al 2008), and ASAS J052821+0338.5 (Stempels et al 2008). In addition, EK Cep (Popper 1987), TY CrA (Casey et al 1998), and RS Cha (Alecian et al 2005(Alecian et al , 2007 are known to be higher mass eclipsing systems with at least one PMS component.…”

Section: Introductionmentioning

confidence: 99%

MML 53: a new low-mass, pre-main sequence eclipsing binary in the Upper Centaurus-Lupus region discovered by SuperWASP

Hebb¹,

Stempels²,

Aigrain³

et al. 2010

A&A

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We announce the discovery of a new low-mass, pre-main sequence eclipsing binary, MML 53. Previous observations of MML 53 found it to be a pre-main sequence spectroscopic multiple associated with the 15-22 Myr Upper Centaurus-Lupus cluster. We identify the object as an eclipsing binary for the first time through the analysis of multiple seasons of time series photometry from the SuperWASP transiting planet survey. Re-analysis of a single archive spectrum shows MML 53 to be a spatially unresolved triple system of young stars which all exhibit significant lithium absorption. Two of the components comprise an eclipsing binary with period, P = 2.097891(6) ± 0.000005 and mass ratio, q ∼ 0.8. Here, we present the analysis of the discovery data.

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The Pre–Main-Sequence Eclipsing Binary TY Coronae Australis: Precise Stellar Dimensions and Tests of Evolutionary Models

Cited by 87 publications

References 31 publications

Probing the evolution of molecular cloud structure

Probing the evolution of molecular cloud structure

Absolute dimensions of eclipsing binaries

MML 53: a new low-mass, pre-main sequence eclipsing binary in the Upper Centaurus-Lupus region discovered by SuperWASP

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