AN OPTICAL SPECTROSCOPIC STUDY OF T TAURI STARS. I. PHOTOSPHERIC PROPERTIES

By G. Herczeg, L. Hillenbrand. 2014

202 citations recorded by the source corpus.

Estimates of the mass and age of young stars from their location in the H-R diagram are limited by not only the typical observational uncertainties that apply to field stars, but also by large systematic uncertainties related to circumstellar phenomena. In this paper, we analyze flux-calibrated optical spectra to measure accurate spectral types and extinctions of 281 nearby T Tauri stars (TTSs). The primary advances in this paper are (1) the incorporation of a simplistic accretion continuum in optical spectral type and extinction measurements calculated over the full optical wavelength range and (2) the uniform analysis of a large sample of stars, many of which are well known and can serve as benchmarks. Comparisons between the non-accreting TTS photospheric templates and stellar photosphere models are used to derive conversions from spectral type to temperature. Differences between spectral types can be subtle and difficult to discern, especially when accounting for accretion and extinction. The spectral types measured here are mostly consistent with spectral types measured over the past decade. However, our new spectral types are one to two subclasses later than literature spectral types for the original members of the TW Hya Association (TWA) and are discrepant with literature values for some well-known members of the Taurus Molecular Cloud. Our extinction measurements are consistent with other optical extinction measurements but are typically 1 mag lower than near-IR measurements, likely the result of methodological differences and the presence of near-IR excesses in most CTTSs. As an illustration of the impact of accretion, spectral type, and extinction uncertainties on the H-R diagrams of young clusters, we find that the resulting luminosity spread of stars in the TWA is 15%–30%. The luminosity spread in the TWA and previously measured for binary stars in Taurus suggests that for a majority of stars, protostellar accretion rates are not large enough to significantly alter the subsequent evolution.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/1d486aa3c7caecf8515d4e409158346d0a139210

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In Astronomy and Astrophysics

1. A. Mann
2. E. Gaidos
3. A. Kraus
4. D. Charbonneau
5. Michael J. Ireland
6. G. Herczeg
7. E. Newton
8. J. Irwin

Citations in the corpus

• ExoMol line lists – XVIII. The high-temperature spectrum of VO (2016, background): “The more complex T Tauri atmosphere models have also incorporated VO absorption bands (Herczeg & Hillenbrand 2014).”
• Gaps and Rings in an ALMA Survey of Disks in the Taurus Star-forming Region (2018, methodology): “Stellar effective temperatures and stellar luminosities are adopted from Herczeg & Hillenbrand (2014) and then updated for individual Gaia DR2 distances (Gaia Collaboration et al. 2018) for the full sample.”
• X-Shooter study of accretion in Chamaeleon I (2015, background): “This approach is thought to lead to more reliable estimates for the stellar mass and radius, which are necessary ingredients when estimating Ṁacc and ages (Manara et al. 2013b; Herczeg & Hillenbrand 2014, hereafter HH14).”
• ZODIACAL EXOPLANETS IN TIME (ZEIT). III. A SHORT-PERIOD PLANET ORBITING A PRE-MAIN-SEQUENCE STAR IN THE UPPER SCORPIUS OB ASSOCIATION (2016, methodology): “We compared our optical spectrum of K2-33 to a grid of 270 unreddened optical spectra of young stars from Herczeg & Hillenbrand (2014).”