An Empirical Criterion to Classify T Tauri Stars and Substellar Analogs Using Low-Resolution Optical Spectroscopy

2003

157 citations recorded by the source corpus.

We have compiled and studied photometric and spectroscopic data published in the literature of several star-forming regions and young open clusters (Orion, Taurus, IC 348, Sco-Cen complex, Chamaeleon I, TW Hydrae association, σ Orionis cluster, IC 2391, α Persei cluster, and the Pleiades). Our goal was to seek the definition of a simple empirical criterion to classify stars or brown dwarfs that are accreting matter from a disk on the sole basis of low-resolution optical spectroscopic data. We show that, using Hα equivalent widths and spectral types, we can statistically classify very young stars and brown dwarfs as classical T Tauri stars and substellar analogs. As a boundary between accreting and nonaccreting objects, we use the saturation limit of chromospheric activity at log [L(Hα)/L(bol)] = -3.3 (determined in the open clusters). We discuss the uncertainties in the classification scheme due to the occurrence of flares. We have used this spectroscopic empirical criterion to classify objects found in the literature, and we compute the fraction of accreting objects in several star-forming regions. The fraction of accreting objects appears to decrease from about 50% to about 5% from 1 to 10 Myr for both stars and brown dwarfs.

Subfields: Astronomy and Astrophysics, Spectroscopy

View Paper: https://www.semanticscholar.org/paper/aa630ba0c6192774705263f1b16596beb8d58bad

Citations in the corpus

• Timescale of mass accretion in pre-main-sequence stars (2009, unknown): “Barrado y Navascués & Martín (2003) have defined an empirical criterion based on the saturation limit of the chromospheric activity.”
• The star formation history and accretion-disc fraction among the K-type members of the Scorpius–Centaurus OB association (2016, unknown): “These stars are also plotted against Hα equivalent width (EW(Hα)) in Figure 13, demonstrating that accreting stars identified with the Barrado y Navascués & Martín (2003) EW(Hα) criteria also typically exhibit a W1 band excess due to the presence of a warm cir- MNRAS 000, 1–32 (2015) cumstellar gas…”