SIMBAD references

2017ApJ...837...96H - Astrophys. J., 837, 96-96 (2017/March-1)

The rotation-activity correlations in K and M dwarfs. II. New constraints on the dynamo mechanisms in late-K and M dwarfs before and at the transition to complete convection.


Abstract (from CDS):

We study the rotation-activity correlations (RACs) in a sample of stars from spectral type dK4 to dM4. We study RACs using chromospheric data and coronal data. We study the Ca II line surface fluxes-P/sini RACs. We fit the RACs with linear homoscedastic and heteroscedastic regression models. We find that these RACs differ substantially from one spectral sub-type to another. For dM3 and dM4 stars, we find that the RACs cannot be described by a simple model, but instead that there may exist two distinct RAC behaviors for the low-activity and the high-activity stellar sub-samples, respectively. Although these results are preliminary and will need confirmation, the data suggest that these distinct RACs may be associated with different dynamo regimes. We also study RHK^′^ as a function of the Rossby number R0. We find (i) for dK4 stars, RHK^′^ as a function of R0 agrees well with previous results for F-G-K stars and (ii) in dK6, dM2, dM3, and dM4 stars, at a given R0, the values of RHK^′^ lie at a factor of 3, 10, 20, and 90, respectively, below the F-G-K RAC. Our results suggest a significant decrease in the efficiency of the dynamo mechanism(s) as regards chromospheric heating before and at dM3, i.e., before and at the transition to complete convection. We also show that the ratio of coronal heating to chromospheric heating LX/LHK increases by a factor of 100 between dK4 and dM4 stars.

Abstract Copyright: © 2017. The American Astronomical Society. All rights reserved.

Journal keyword(s): stars: activity - stars: chromospheres - stars: coronae - stars: late-type - stars: low-mass - stars: magnetic field - stars: magnetic field

VizieR on-line data: <Available at CDS (J/ApJ/837/96): table2.dat table3.dat table4.dat table5.dat table6.dat table7.dat table8.dat>

Simbad objects: 453

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