Journal article Open Access

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

Casey, Brian W.; Mathieu, Robert D.; Vaz, Luiz Paulo R.; Andersen, Johannes; Suntzeff, and Nicholas B.


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{
  "DOI": "10.1086/300270", 
  "abstract": "We analyze new photometric data for the Herbig Be eclipsing binary TY CrA, which securely reveal the secondary eclipse, ~0.03 mag deep in y. From the light-curve solution and our previous spectroscopic data, absolute dimensions of the primary and secondary stars are derived. The masses are found to be M1 = 3.16 \u00b1 0.02 M\u2609 and M2 = 1.64 \u00b1 0.01 M\u2609, the radii are R1 = 1.80 \u00b1 0.10 R\u2609 and R2 = 2.08 \u00b1 0.14 R\u2609, the luminosities are L1 = 67 \u00b1 12 L\u2609 and L2 = 2.4 \u00b1 0.8 L\u2609, and the effective temperatures are T1 = 12,000 \u00b1 500 K and T2 = 4900 \u00b1 400 K. Here the uncertainties represent high-confidence limits, not standard deviations. The secondary star is a pre\u2013main-sequence star located at the base of the Hayashi tracks. As such, it is the least evolved star with a dynamically measured mass. Given higher effective temperatures for the primary (e.g., 12,500 K), the solar-composition 1.64 M\u2609 evolutionary tracks of Swenson et al., Claret, and D'Antona & Mazzitelli are all consistent with the properties of the TY CrA secondary and suggest an age of order 3 Myr. The radius and projected rotational velocity of the secondary star are consistent with synchronous rotation. The primary star is located near the zero-age main sequence, which, for solar compositions, is consistent with an age of 3 Myr. However, the primary star is not well represented by any of the 3.16 M\u2609 evolutionary models, which predict somewhat higher effective temperatures than observed.", 
  "author": [
    {
      "family": "Casey, Brian W."
    }, 
    {
      "family": "Mathieu, Robert D."
    }, 
    {
      "family": "Vaz, Luiz Paulo R."
    }, 
    {
      "family": "Andersen, Johannes"
    }, 
    {
      "family": "Suntzeff, and Nicholas B."
    }
  ], 
  "id": "1059055", 
  "issued": {
    "date-parts": [
      [
        2007, 
        12, 
        18
      ]
    ]
  }, 
  "title": "The Pre-Main-Sequence Eclipsing Binary TY Coronae Australis: Precise Stellar Dimensions and Tests of Evolutionary Models", 
  "type": "article-journal"
}
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