Matteo Cantiello edited Abstract.tex  over 10 years ago

Commit id: 1bd420d77e0e3db71decec0d1866411a14160701

deletions | additions      

       

Stars are born rotating. Observations of during the  main sequencestars  reveal that the majority of objects with mass above $\sim 1.5\mso$ are spinning fairly rapidly. From the zero age main sequence to the final compact remnant, calculations including mechanisms for the transport of angular momentum can make predictions about the evolution of the internal angular momentum distribution. Thanks to asteroseismology and in particular to the KEPLER satellite it is now possible to test these predictions. This is because predictions, since  the splitting of mixed modes allows to measure the core rotation of in  red giants(RGB)  and clump stars. Here we calculate state-of-the-art stellar evolution models of rotating low-mass stars in the mass range $1.5-3.0 \mso$ from their zero age main sequence to the cooling white dwarf stage. These models include transport of angular momentum due to rotational mixing anddynamo generated  magnetic fields in radiative zones. zones (generated by the Spruit-Tayler dynamo).  These models fail to predict the asteroseismic observations of stars on the RGB and during core He burning. In particular the rate of spin-down burning, implying that some extra angular momentum process must be operating  on the early RGB deduced from ensemble asteroseisomology can not be reproduced, implying that stronger torques between core and envelope operate in low-mass stars climbing the RGB. of low mass stars.  %To test such predictions, rotational periods can be observed, providing a direct constraint of the surface rotation rate. %Moreover the efficiency of internal transport mechanisms can sometimes be inferred by using indirect proxies, for example %the change in the surface abundances of certain isotopes. This is because the same instabilities and/or circulations %believed to be responsible for the angular momentum transport can also displace chemicals in the radial direction. %Recently it has also become possible to directly probe the rotation profile of stars other than the Sun. This is thanks %to asteroseismology: using the splitting of mixed modes it is possible to measure the degree of differential rotation %between core and envelope. Here we calculate state-of-the-art stellar evolution models of rotating low-mass stars in the %mass range $1.5-3.0 \mso$ from their zero age main sequence to the cooling white dwarf stage. These models include %transport of angular momentum due to rotational mixing and magnetic fields in radiative zones (generated by the Spruit-%Tayler dynamo). We show how the predictions of these calculations compare to the available observational constraints, %with a particular emphasis on the asteroseismic information coming from KEPLER observations of red giant stars.