14 Hartfalen

Rutten, Frans H.; Walma, Edmond; Mosterd, Arend

doi:10.1007/978-90-313-9028-1_14

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“…In order to supplement our sample of v sin i and Ca ii measurements, and in order to have an unbiased sample of measurements, we searched the literature for additional v sin i and Ca ii measurements: We found several additional stars with v sin i measurements (see Paper I). But we found only a few measurements of the Ca ii lines for these stars (Stauffer & Hartmann 1986, Rutten 1987, Rutten et al 1989). Instead, we found several measures of the H α EW (Soderblom et al 1991, Hawley et al 1996, Kamper et al 1997, Christian & Mathioudakis 2002, Gizis et al 2002, Pace 2013.…”

Section: The Rac In M3 Dwarfsmentioning

confidence: 61%

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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^∗

Houdebine

Mullan

Bercu

et al. 2017

ApJ

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We study the rotation-activity correlations (RACs) in a sample 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/ sin i 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 R'HK as a function of the Rossby number R0. We find that: (i) For dK4 stars, we confirm R'HK as a function of R0 agrees well with previous results for F-G-K stars. (ii) In dK6, dM2, dM3 and dM4 stars, we find that, at a given R0, the values of R'HK lie 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 TTCC.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.

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Section: The Rac In M3 Dwarfsmentioning

confidence: 61%

“…We also searched the literature for other measurements of the Ca ii EW. We found only a few measurements of the Ca ii EW or flux for our dK6 stars (Marilli et al (1986), Rutten (1987), Duncan et al (1991), Browning et al (2010)). These measures are also listed in Table 2.…”

Section: The Rac In K6 Dwarfsmentioning

confidence: 77%

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^∗

Houdebine

Mullan

Bercu

et al. 2017

ApJ

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14 Hartfalen

Cited by 1 publication

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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^∗

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^∗

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14 Hartfalen

Cited by 1 publication

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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∗

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∗

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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^∗

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^∗