![]() ![]() (''thick disc'') stars and low- (''thin disc'') stars. Introduction The first dredge up mixing episode in a star occurs during the evolution from the main sequence through the subgiant branch to the tip of the. Substantial separation in birth ratios between high. The table shows the lifetimes of stars as a. Depending on the mass of the star, its lifetime can range from a few million years for the most massive to trillions of years for the least massive, which is considerably longer than the current age of the universe. In the MaNGA integral field survey of nearby galaxies. Stellar evolution is the process by which a star changes over the course of time. The stellar N/O trend agrees well with Dopita et al.'sĬalibration of gas phase log(N/O) with metallicity, and with gas phase trends For the younger populations, N/Fe FDU is much smaller than N/Fe ini, but with increasing age it comes progressively closer to its initial value. and supernova) are compared to observed CEMP-no abundances through the 2D abundance diagram C/N vs. Leaves trends of log(N/O) and log(C/N) with metallicity, as expected based on The values of N/Fe FDU are lower than N/Fe ini, and display a clear trend with age, despite the fact that N/Fe ini is the same at all ages. Applying mixing corrections to the APOGEEĪbundances removes the observed age-dependence of log(N/O) and log(C/N), but it In stars with increasing mass, the convective envelope during the RGB dredges up increasing amounts of CNO-processed material from regions where H. Mixing processes fail, predicting trends with surface gravity or evolutionary Because the reaction 14 N(p, ) 15 O is much slower than other reactions in the CNO cycle, the abundance of 14 N is drastically increased in regions of CNO burning, primarily at the expense of 12 C. Plausible uncertainties in the birth abundances. Models with standard mixing can reproduce the observed trends to within , we test theoretical stellar models that predict this mixing, thenĪpply these models to derive birth C, N, and O abundances for these stars. Using a sample of $\simĥ100$ stars with elemental abundances from APOGEE and asteroseismic masses from Material mixed into the stars' convective envelopes. Download a PDF of the paper titled CNO dredge-up in a sample of APOGEE/Kepler red giants: Tests of stellar models and Galactic evolutionary trends of N/O and C/N, by Fiorenzo Vincenzo and 10 other authors Download PDF Abstract: Surface abundances of C, N, and O in red giants are affected by processed ![]()
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