English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Recent theoretical work has shown that the pre-main-sequence (PMS) evolutionof stars is much more complex than previously envisioned. Instead of thetraditional steady, one-dimensional solution, accretion may be episodic and notnecessarily symmetrical, thereby affecting the energy deposited inside the starand its interior structure. Given this new framework, we want to understandwhat controls the evolution of accreting stars. We use the MESA stellarevolution code with various sets of conditions. In particular, we account forthe (unknown) efficiency of accretion in burying gravitational energy into theprotostar through a parameter, $\xi$, and we vary the amount of deuteriumpresent. We confirm the findings of previous works that the evolution changessignificantly with the amount of energy that is lost during accretion. We findthat deuterium burning also regulates the PMS evolution. In the low-entropyaccretion scenario, the evolutionary tracks in the H-R diagram aresignificantly different from the classical tracks and are sensitive to thedeuterium content. A comparison of theoretical evolutionary tracks andobservations allows us to exclude some cold accretion models ($\xi\sim 0$) withlow deuterium abundances. We confirm that the luminosity spread seen inclusters can be explained by models with a somewhat inefficient injection ofaccretion heat. The resulting evolutionary tracks then become sensitive to theaccretion heat efficiency, initial core entropy, and deuterium content. In thiscontext, we predict that clusters with a higher D/H ratio should have lessscatter in luminosity than clusters with a smaller D/H. Future work on thisissue should include radiation-hydrodynamic simulations to determine theefficiency of accretion heating and further observations to investigate thedeuterium content in star-forming regions. (abbrev.)

Revisiting the pre-main-sequence evolution of stars I. Importance of accretion efficiency and deuterium abundance