Lithium Abundances From Optical High-Resolution Spectroscopy of Weak-Line T Tauri Stars

Xing, L. F.

doi:10.1088/0004-637x/723/2/1542

Cited by 22 publications

(14 citation statements)

References 47 publications

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“…Henry et al (1996 measure a high level of Ca H and K emission, but Hα is strongly in absorption . The latter paper and Torres et al (2006) also measure Li i equivalent widths of 0.35 and 0.2 Å, respectively, compatible with those measured by Xing (2010) in weak-line TTauri stars with similar spectral type and rotation period. We wonder whether Soderbloms remark that the star is somewhat enigmatic because its position is well-above the main-sequence (while the Hα absorption excludes it is a classical T Tauri type star), might be due to a luminosity estimate not taking into account the binary nature of the object.…”

Section: Example 3: Cyclic Variabilitysupporting

confidence: 80%

Detectability of micro-variables in the ASAS database

David

Hensberge

Nitschelm

2013

A&A

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Aims. We exploit nine years of photometry in the ASAS V-band catalogue to develop a method to select in an objective way the best quality data and detect low-amplitude variables. We concentrate on bright stars (V < 10) and avoid open cluster stellar densities. Methods. We use the (probable) members of the Sco-Cen associations as a test sample of bright stars that includes periodic early-type photometric variables as well as young late-type stars with cyclic or irregular variability patterns. We select grade-A observations with consistent photometry in all apertures, amounting to 88 ± 4 per cent of all grade-A data in most cases, and use the aperture with lowest dispersion of magnitudes (excluding one percent of data to avoid sparse surviving outliers) to search for periodicities, cycles and long-term trends. The well-known alias problems, due to the once-per-night observing cadence in the ASAS project, can often be alleviated for the bright stars by use of the Hipparcos satellite photometry. Results. Micro-variables with a range of variability as low as 0.01-0.02 mag for periodic variables (V magnitudes 7-10) and 0.04 mag for irregular long-term variables are detected. In total 37 light variables are identified: 14 were previously unknown, and another 12 were listed as suspected variables. The light variability in the young associations in Sco-Cen is briefly discussed. Conclusions. The ASAS database contains much more information on photometric variables than retrieved commonly.

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Section: Example 3: Cyclic Variabilitysupporting

confidence: 80%

Detectability of micro-variables in the ASAS database

David

Hensberge

Nitschelm

2013

A&A

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“…Surface lithium is destroyed when the base of the CZ is deep enough so that the temperature is higher than ∼2.5 × 10 6 K (Swenson & Faulkner 1992;D'Antona & Mazzitelli 1994;Ventura et al 1998). Pre-MS lithium depletion has been observed in young clusters and T Tauri stars in many previous studies Garcia Lopez et al 1994;Xing 2010;King et al 2000;Sestito et al 2003). When the star evolves to the MS stage, the base of the CZ is not hot enough for lithiumburning.…”

Section: Introductionmentioning

confidence: 90%

Lithium Abundance as a Predictor of Mass and Age in Solar-Analog Stars

Chen

et al. 2012

ApJ

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In order to estimate the mass and age of stars, we construct a grid of stellar models for eight solar-analog stars including diffusion and rotation-induced mixing for the given ranges of stellar mass, metallicity, and rotational rate. By combining stellar models with observational data including lithium abundance, we obtain more accurate estimations of mass and age for solar-analog stars. The results indicate that stars HIP 56948, HIP 73815, and HIP 78399 are three possible solar twins. Furthermore, we find that lithium depletion due to extra-mixing in solar analogs strongly depends on mass, metallicity, and rotational history. Therefore, lithium abundance can be used as a good constraint in stellar modeling.

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“…Favata et al (1997) and Cenarro et al (2007) determined [4570, 3.50, 0.16] using the Strömgren photometry of Morale et al (1996) and the calibration relation of Alonso et al (1996). Xing (2010) gives T eff = 4908 K and log g = 4.45 dex, computed from the (B − V) colour and calibrations of Casagrande et al (2006). Biazzo et al (2012) give [5100, 4.2, 0.05], based on highresolution spectroscopic observations.…”

Section: Remarkable Starsmentioning

confidence: 99%

New atmospheric parameters and spectral interpolator for the MILES cool stars

Sharma

Prugniel

Singh

2015

A&A

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Context. The full spectrum fitting of stellar spectra against a library of empirical spectra is a well-established approach to measure the atmospheric parameters of FGK stars with a high internal consistency. Extending it towards cooler stars still remains a challenge. Aims. We address this question by improving the interpolator of the Medium-resolution INT Library of Empirical Spectra (MILES) library in the low effective temperature regime (T eff < 4800 K), and we refine the determination of the parameters of the cool MILES stars. Methods. We use the ULySS package to determine the atmospheric parameters (T eff , log g and [Fe/H]), and measure the biases of the results with respect to our updated compilation of parameters calibrated against theoretical spectra. After correcting some systematic effects, we compute a new interpolator that we finally use to redetermine the atmospheric parameters homogeneously and assess the biases. Results. Based on an updated literature compilation, we determine T eff in a more accurate and unbiased manner compared to those determined with the original interpolator. The validity range is extended downwards to about T eff = 2900 K compared to 3500 K previously. The mean residual biases on T eff , log g, and [Fe/H], with respect to the literature compilation for the coolest stars (T eff ≤ 3800 K) computed using the new interpolator, are −15 K, −0.02 dex, and 0.02 dex respectively. The corresponding estimations of the external precision are 63 K, 0.23 dex, and 0.15 dex respectively. For the stars with T eff in the range 3800−4200 K, the determinations of T eff and [Fe/H] have been slightly improved. At higher temperatures, the new interpolator is comparable to the original one. The new version of the interpolator is publicly available.

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Lithium Abundances From Optical High-Resolution Spectroscopy of Weak-Line T Tauri Stars

Cited by 22 publications

References 47 publications

Detectability of micro-variables in the ASAS database

Detectability of micro-variables in the ASAS database

Lithium Abundance as a Predictor of Mass and Age in Solar-Analog Stars

New atmospheric parameters and spectral interpolator for the MILES cool stars

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