Abstract
Abstract Magnetic fields and mass accretion processes create dark and bright spots on the surface of young stars. These spots manifest as surface thermal inhomogeneities, which alter the global temperature measured on the stars. To understand the effects and implications of these starspots, we conducted a large iSHELL high-resolution infrared spectroscopic survey of T Tauri stars in Taurus-Auriga and Ophiuchus star-forming regions. From the K-band spectra, we measured stellar temperatures and magnetic field strengths using a magnetic radiative transfer code. We compared our infrared-derived parameters against literature optical temperatures and found (a) a systematic temperature difference between optical and infrared observations, and (b) a positive correlation between the magnetic field strengths and the temperature differences. The discrepant temperature measurements imply significant differences in the inferred stellar masses from stellar evolutionary models. To discern which temperature better predicts the mass of the star, we compared our model-derived masses against dynamical masses measured from Atacama Large Millimeter/submillimeter Array and the Plateau de Bure Interferometer for a subsample of our sources. From this comparison we conclude that, in the range of stellar masses from 0.3 to 1.3 M ⊙, neither infrared nor optical temperatures perfectly reproduce the stellar dynamical masses. But, on average, infrared temperatures produce more precise and accurate stellar masses than optical ones.
Highlights
Corresponding author: Christian Flores vection, producing localized dark regions (Berdyugina 2005). there has been substantial research on the photometric effects of spots in stars, spectroscopic signatures have often been neglected, in part because spectroscopic monitoring of stars is observationally expensive and because most evolved stars host weak magnetic fields
The parameter values are reported as the median of the Markov Chain Monte Carlo (MCMC) distributions while the uncertainty in the stellar parameters are reported as 3σ values
The natural question is does the optical or infrared temperature better correspond with the mass of the star? To address this, we focus on a sub-sample of our young stars that have dynamical masses derived from CO and CN observations obtained with the Atacama Large Millimeter/submillimeter Array (ALMA) and the Plateau de Bure Interferometer (PdBI) (Schaefer et al 2009; Guilloteau et al 2014; Simon et al 2019)
Summary
Corresponding author: Christian Flores vection, producing localized dark regions (Berdyugina 2005). there has been substantial research on the photometric effects of spots in stars, spectroscopic signatures have often been neglected, in part because spectroscopic monitoring of stars is observationally expensive and because most evolved stars host weak magnetic fields. In a study of low-mass stars with ages from less than one Myr to over a Gyr old, Vidotto et al (2014) found that the average magnetic field strength derived from polarimetry in young stars is thousands of times stronger than the magnetic field value of main-sequence stars. This field difference means that the size and/or temperature contrast of cold spots on young stars, could be considerably larger than what is observed on their more evolved counterparts. Understanding and correcting for this effect is of paramount importance as direct mass measurements of young stars are often hard and expensive to obtain and, most of the time, impossible (Guilloteau et al 2014; Simon et al 2017, 2019; Braun et al 2021)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
