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arXiv · 1908.10952

Masses and Implications for Ages of Low-Mass Pre-Main Sequence Stars in Taurus and Ophiuchus

M. Simon·S. Guilloteau·Tracy L. Beck·E. Chappilon·E. Di Folco A. Dutrey·Gregory A. Feiden·N. Grosso·L. Prato·Gail. H. Schaefer
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Abstract

The accuracy of masses of pre-main sequence (PMS) stars derived from their locations on the Hertzsprung-Russell Diagram (HRD) can be tested by comparison with accurate and precise masses determined independently. We present 29 single stars in the Taurus star-forming region (SFR) and 3 in the Ophiuchus SFR with masses measured dynamically to a precision of at least $10 \%$. Our results include 9 updated mass determinations and 3 that have not had their dynamical masses published before. This list of stars with fundamental, dynamical masses, M$_{dyn}$, is drawn from a larger list of 39 targets in the Taurus SFR and 6 in the Ophiuchus SFR. Placing the stars with accurate and precise dynamical masses on HRDs that do not include internal magnetic fields underestimates the mass compared to M$_{dyn}$ by about $30 \%$. Placing them on an HRD that does include magnetic fields yields mass estimates in much better agreement with M$_{dyn}$, with an average difference between M$_{dyn}$ and the estimated track mass of $0.01\pm0.02$~\msun. The ages of the stars, 3--10 MY on tracks that include magnetic fields, is older than the 1--3 MY indicated by the non-magnetic models. The older ages of T Tauri stars predicted by the magnetic models increase the time available for evolution of their disks and formation of the giant gas exoplanets. The agreement between our M$_{dyn}$ values and the masses on the magnetic field tracks provides indirect support for these older ages.

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M. Simon, S. Guilloteau, Tracy L. Beck, E. Chappilon, E. Di Folco A. Dutrey, Gregory A. Feiden, N. Grosso, L. Prato, Gail. H. Schaefer. 2019-08-28. Masses and Implications for Ages of Low-Mass Pre-Main Sequence Stars in Taurus and Ophiuchus. https://doi.org/10.3847/1538-4357/ab3e3b

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