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Sökning: WFRF:(Hebb Leslie)

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  • Chew, Yilen Gomez Maqueo, et al. (författare)
  • Luminosity Discrepancy in the Equal-Mass, Pre-Main-Sequence Eclipsing Binary Par 1802 : Non-Coevality or Tidal Heating?
  • 2012
  • Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 745:1, s. 58-
  • Tidskriftsartikel (refereegranskat)abstract
    • Parenago 1802, a member of the similar to 1 Myr Orion Nebula Cluster, is a double-lined, detached eclipsing binary in a 4.674 day orbit, with equal-mass components (M-2/M-1 = 0.985 +/- 0.029). Here we present extensive VI(C)JHK(S) light curves (LCs) spanning similar to 15 yr, as well as a Keck/High Resolution Echelle Spectrometer (HIRES) optical spectrum. The LCs evince a third light source that is variable with a period of 0.73 days, and is also manifested in the high-resolution spectrum, strongly indicating the presence of a third star in the system, probably a rapidly rotating Classical T Tauri star. We incorporate this third light into our radial velocity and LC modeling of the eclipsing pair, measuring accurate masses (M-1 = 0.391 +/- 0.032 and M-2 = 0.385 +/- 0.032 M-circle dot), radii (R-1 = 1.73 +/- 0.02 and R-2 = 1.62 +/- 0.02 R-circle dot), and temperature ratio (T-eff,T-1/T-eff,T-2 = 1.0924 +/- 0.0017). Thus, the radii of the eclipsing stars differ by 6.9% +/- 0.8%, the temperatures differ by 9.2% +/- 0.2%, and consequently the luminosities differ by 62% +/- 3%, despite having masses equal to within 3%. This could be indicative of an age difference of similar to 3 x 10(5) yr between the two eclipsing stars, perhaps a vestige of the binary formation history. We find that the eclipsing pair is in an orbit that has not yet fully circularized, e = 0.0166 +/- 0.003. In addition, we measure the rotation rate of the eclipsing stars to be 4.629 +/- 0.006 days; they rotate slightly faster than their 4.674 day orbit. The non-zero eccentricity and super-synchronous rotation suggest that the eclipsing pair should be tidally interacting, so we calculate the tidal history of the system according to different tidal evolution theories. We find that tidal heating effects can explain the observed luminosity difference of the eclipsing pair, providing an alternative to the previously suggested age difference.
  • Rich, Evan A., et al. (författare)
  • The fundamental stellar parameters of FGK stars in the SEEDS survey Norman, OK 73071, USA
  • 2017
  • Ingår i: Monthly notices of the Royal Astronomical Society. - 0035-8711 .- 1365-2966. ; 472:2, s. 1736-1752
  • Tidskriftsartikel (refereegranskat)abstract
    • Large exoplanet surveys have successfully detected thousands of exoplanets to-date. Utilizing these detections and non-detections to constrain our understanding of the formation and evolution of planetary systems also requires a detailed understanding of the basic properties of their host stars. We have determined the basic stellar properties of F, K and G stars in the Strategic Exploration of Exoplanets and Disks with Subaru (SEEDS) survey from Echelle spectra taken at the Apache Point Observatory's 3.5m telescope. Using ROBOSPECT to extract line equivalent widths and TemperatureGravity microtrubulentVelocity ITerations to calculate the fundamental parameters, we have computed T-eff, log(g), v(t), [Fe/H], chromospheric activity and the age for our sample. Our methodology was calibrated against previously published results for a portion of our sample. The distribution of [Fe/H] in our sample is consistent with that typical of the Solar neighbourhood. Additionally, we find the ages of most of our sample are < 500 Myr, but note that we cannot determine robust ages from significantly older stars via chromospheric activity age indicators. The futuremeta-analysis of the frequency ofwide stellar and sub-stellar companions imaged via the SEEDS survey will utilize our results to constrain the occurrence of detected comoving companions with the properties of their host stars.
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