ABYSS III: Observing accretion activity in young stars through empirical veiling measurements

TL;DR

This paper investigates accretion activity in young stars by empirically measuring veiling across different wavelengths, revealing how veiling correlates with stellar properties and supporting accretion shock models.

Contribution

It introduces a method to measure veiling in CTTSs using SDSS-V spectra and analyzes its dependence on stellar parameters, advancing understanding of stellar accretion processes.

Findings

Veiling varies with wavelength, temperature, and age.

Empirical measurements support existing accretion shock models.

Veiling is confirmed as a key diagnostic for stellar accretion.

Abstract

Stellar accretion plays an important role in the early stages of stellar evolution, particularly in Classical T Tauri Stars (CTTSs). Accretion of a CTTS can be related to different physical parameters such as effective temperature (T$_{\text{eff}}$), age, abundance of hydrogen, etc. We can infer how accretion works by examining it across different wavelength regions. Accretion can be traced using veiling, a parameter that measures how excess emission from accretion affects the photospheric spectrum of CTTS. In this study, we selected a sample of CTTSs, Weak-line T Tauri Stars (WTTSs), and field stars, observed as a part of the SDSS-V Milky Way Mapper using the BOSS spectrograph. We measured veiling for CTTSs through comparing them to theoretical spectra. Next, we assessed the effect of veiling on different stellar properties, including wavelength, H$\alpha$ emission, effective temperature, and age. We investigated how veiling changes with these parameters and what the physical reasons behind the changes can be. Finally, we evaluated how our findings align with existing accretion shock models. This study highlights veiling as a critical diagnostic tool for understanding accretion in young stars.