SIMBAD references

2012ApJ...760....9A - Astrophys. J., 760, 9 (2012/November-3)

Mass loss in pre-main-sequence stars via coronal mass ejections and implications for angular momentum loss.


Abstract (from CDS):

We develop an empirical model to estimate mass-loss rates via coronal mass ejections (CMEs) for solar-type pre-main-sequence (PMS) stars. Our method estimates the CME mass-loss rate from the observed energies of PMS X-ray flares, using our empirically determined relationship between solar X-ray flare energy and CME mass: log (MCME[g]) = 0.63xlog (Eflare[erg]) - 2.57. Using masses determined for the largest flaring magnetic structures observed on PMS stars, we suggest that this solar-calibrated relationship may hold over 10 orders of magnitude in flare energy and 7 orders of magnitude in CME mass. The total CME mass-loss rate we calculate for typical solar-type PMS stars is in the range 10–12-10–9 M/yr. We then use these CME mass-loss rate estimates to infer the attendant angular momentum loss leading up to the main sequence. Assuming that the CME outflow rate for a typical ∼1 M T Tauri star is <10–10 M/yr, the resulting spin-down torque is too small during the first ∼1 Myr to counteract the stellar spin-up due to contraction and accretion. However, if the CME mass-loss rate is ≳ 10–10 M/yr, as permitted by our calculations, then the CME spin-down torque may influence the stellar spin evolution after an age of a few Myr.

Abstract Copyright:

Journal keyword(s): stars: activity - stars: evolution - stars: mass-loss - stars: pre-main sequence - stars: solar-type

Simbad objects: 7

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