Dennis edited WH_YIS_THIS_PARA_WIDER__.tex  almost 9 years ago

Commit id: 00b4a9d120a393f5f78d273d39688370a911156a

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with suppressed modes (filled circles), we can deduce a lower limit to the field  strength in the core from the underlying contours.   For stars without suppressed modes (open circles), we can only derive an  upper limit to the field at the hydrogen-burning shell; above or below the shell the field could potentially be larger. [TO ADDRESS THE SAME COMMENT FROM VICTOR AND DANIEL WE COULD SAY SOMETHING LIKE (JIM/MATTEO PLEASE EDIT IF YOU LIKE) Hence, one can therefore expect normal and dipole-suppressed stars fall in the same region of Fig. 4 even if their magnetic field strength is only slightly different. However, we do conclude(OR would expect) that the dipole-suppressed stars on average exhibit stronger fields than their normal star counter parts.]  Considering first the low-mass stars ($< 1.1$\msol), we see from Figure 4 that magnetic fields above $10 $\approx 10  \, {\rm kG}$ are not present at the hydrogen-burning shell when the stars are near the red giant luminosity bump (\numax\ $\sim50 $\aprox 50  \, \mu{\rm Hz}$). Assuming magnetic flux conservation from the main-sequence phase, this suggests that magnetic fields above $1 $\approx 1  \, {\rm kG}$ do not exist within the cores of Sun-like stars. stars (Fuller et al. 2015).  This does not rule out strong horizontal fields near the radiative-convective boundary because these fields are outside the core and cannot cause mode suppression when the star evolves into a red giant. %For stars with suppressed modes we derive the lower limit of how  %strong the field in the core [at least] needs to be for suppression to  %be observed.  Turning to higher masses, we see that for a given \numax\, stars above 1.4\msol 1.4\msol\  require increasingly strong magnetic fields to suppress their dipole modes. From Figure 4, there is no clear upper limit to the field strengths attainable in red giant cores, given that suppressed stars are common even when field strengths $ B> 1 \, {\rm MG}$ are required for suppression. However, the hint of a decline in the occurrence of dipole-suppressed stars above 2\msol\ seen in Fig. 3 suggests there may be a mass above which dynamo-generated magnetic fields can no longer cause oscillation mode suppression in intermediate-mass stars. %Such a cutoff might be caused by the different core structure of stars more massive than 2\msol, which evolve through the red giant phase much faster than stars of lower mass.   [THIS PARA SEEMS TO BE REPEATING WHAT WAS SAID 4 AND 5 PARAs AGO]  The high occurrence rate of dipole mode suppression shows demonstrates  that core-dynamo-generated fields can remain through the red giant phase, more than $10^8 \, {\rm yr}$ after the dynamo shuts off at the end of hydrogen-core burning. The occurrence rate of these long-lived core fields is much larger than the occurrence rate of strong fields observed at the surfaces of magnetic A stars, which may have been generated by a pre-hydrogen-core burning dynamo during star formation (e.g., \citealt{Moss_2004}). We conclude that fields generated during hydrogen-core burning are able to settle into stable equilibrium configurations much more commonly (greater than $60\%$ of the time) than fields generated during star formation (less than $10\%$ of the time). %JIM/MATTEO: HERE MORE STUFF RELATED TO THAT INCLUDING FIG 4b OF NUMBER OF NORMAL/SUPPRESSED   %STARS IN EACH B_c BIN...TAKE IT AWAY!!!