Keck Hires Spectroscopy of Candidate Post T Tauri Stars

Abstract

We use high-signal-to-noise ($\sim$150-450), high resolution ($R\sim 45,000$) Keck HIRES spectroscopy of 13 candidate post T Tauri stars to derive basic physical parameters, lithium abundances and radial velocities. We place our stars in the M${}_v$-T${}_{eff}$ plane for use in determining approximate ages from pre-main sequence isochrones, and confirm these using three relative age indicators in our analysis: Li abundances, chromospheric emission and the kinematic {\it U-V} plane. Using the three age criteria we identify 5 stars (HIP 54529, HIP 62758, HIP 63322, HIP 74045, and HIP 104864) as probable post T Tauri stars with ages between 10 and 100 Myr. We confirm HIP 54529 as an SB2 and HIP 63322 as an SB1 star. We also examine irregular photometric variability of PTTs using the {\it HIPPARCOS} photometry annex. Two of our PTT stars exhibit near-IR excesses compared to Kurucz model flux; while recent work suggests classical T Tauri stars evince similar {\it JHK} excesses presumably indicative of non-photospheric (disk) emission, our results may be illusory artifacts of the chosen {\it I}-band normalization. Near-IR excesses we see in a literature-based sample of PTTs appear to be artifacts of previous spectral type-based $T_{\mathrm{eff}}$ values. Indeed, comparison of the homology of their observed and model photospheric SED's suggests that photometric temperatures are more reliable than temperatures based on spectral standards for the cooler temperature ranges of the stars in this sample. We conclude that our age oriented analysis is a robust means to select samples of nearby, young, isolated post T Tauri stars that otherwise masquerade as normal field stars.

arXiv commentAccepted to AJ, 35 pages, 12 figures

References in corpus (13)

• The Geneva-Copenhagen survey of the Solar neighbourhood: Ages, metallicities, and kinematic properties of 14,000 F and G dwarfs
• Spectroscopic [Fe/H] for 98 extra-solar planet-host stars: Exploring the probability of planet formation
• Catalog of Nearby Exoplanets
• The effective temperature scale of FGK stars. II. Teff : color : [Fe/H] calibrations
• Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 parsecs: The Northern Sample I
• S4N: A Spectroscopic Survey of Stars in the Solar Neighborhood
• Post-T Tauri Stars in the Nearest OB Association
• Lithium in stars with exoplanets
• Velocity distribution of stars in the solar neighbourhood
• On the Ages of Exoplanet Host Stars
• Evidence for J and H-band excess in classical T Tauri stars and the implications for disk structure and estimated ages
• The Lithium-Rotation Correlation in the Pleiades Revisited
• Oxygen from the Lambda 7774 High-Excitation Triplet in Open Cluster Dwarfs: Hyades

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