The Effects of Starspots on Spectroscopic Mass Estimates of Low-mass Young Stars

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 ALMA and PdBI for a sub-sample of our sources. From this comparison we conclude that, in the range of stellar masses from 0.3 to 1.3 ${\mathrm{M}}_{\odot }$, 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.

Accepted for publication in ApJ. The manuscript has 20 pages, 11 Figures (+2 figure sets in the online version of ApJ), and 2 Tables

References in corpus (14)

• A grid of MARCS model atmospheres for late-type stars I. Methods and general properties
• New evolutionary models for pre-main sequence and main sequence low-mass stars down to the hydrogen-burning limit
• An Optical Spectroscopic Study of T Tauri Stars. I. Photospheric Properties
• Stellar magnetism: empirical trends with age and rotation
• The Magnetic Fields of Classical T Tauri Stars
• Placing the spotted T Tauri star LkCa 4 on an HR diagram
• The masses of young stars: CN as a probe of dynamical masses
• Hyperfine Splitting in the VALD Database of Spectral-line Parameters
• Dynamical Masses of Low Mass Stars in the Taurus and Ophiuchus Star Forming Regions
• Spots, plages, and flares on lambda Andromedae and II Pegasi
• Dynamical stellar masses of pre-main sequence stars in Lupus and Taurus obtained with ALMA surveys in comparison with stellar evolutionary models
• Magnetic fields of intermediate mass T Tauri stars
• The Mean Magnetic Field Strength of CI Tau
• Is T Tauri North a 'Classical' T Tauri star?

Cited by in corpus (12)

• The ALMA view of MP Mus (PDS 66): a protoplanetary disk with no visible gaps down to 4 au scales
• Detectability of Rotational Modulation in Kepler Sun-like Stars as a Function of Age
• Stable accretion and episodic outflows in the young transition disk system GM Aurigae
• Empirical Determination of the Lithium 6707.856 Å Wavelength in Young Stars
• Estimating the Convective Turnover Time
• Correlating Changes in Spot Filling Factors with Stellar Rotation: The Case of LkCa 4
• Orbital parameters and activity of ZZ Tau -- a low mass young binary with circumbinary disc
• LAMOST medium-resolution observations of the Pleiades
• V892 Tau: A tidally perturbed circumbinary disc in a triple stellar system
• Star-Crossed Lovers DI Tau A and B: Orbit Characterization and Physical Properties Determination
• Using Gravity as an Age Indicator for Young Stars
• The Variation of Circumstellar Parameters through Early Stellar Evolution