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

We analyse pre-Main Sequence evolutionary tracks for low mass stars withmasses $m \le 1.4 \msol$ based on the Baraffe et al. (1998) input physics. Wealso extend the recent Chabrier et al. (2000) evolutionary models based ondusty atmosphere to young brown dwarfs down to one mass of Jupiter. We analysecurrent theoretical uncertainties due to molecular line lists, convection andinitial conditions. Simple tests on initial conditions show the highuncertainties of models at ages $\simle$ 1 Myr. We find a significantsensitivity of atmosphere profiles to the treatment of convection at lowgravity and $\te < 4000$ K, whereas it vanishes as gravity increases. Thiseffect adds another source of uncertainty on evolutionary tracks at very earlyphases. We show that at low surface gravity ($\log g \simle 3.5$,) the commonpicture of vertical Hayashi lines with constant $\te$ is oversimplified. Theeffect of a variation of initial deuterium abundance is studied. We compare ourmodels with evolutionary tracks available in the literature and discuss themain differences. We finally analyse to which extent current observations ofyoung systems provide a good test for pre-Main Sequence tracks.Comment: 12 pages, Latex file, uses aa.cls, accepted for publication in A&

Evolutionary models for low-mass stars and brown dwarfs: Uncertainties and limits at very young ages