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

[Abridged] A new scenario --early disc accretion-- has been proposed veryrecently to explain the origin of the multiple population phenomenon inGalactic globular clusters. It envisages the possibility that a fraction oflow- and very low-mass cluster stars may accrete the ejecta of interactingmassive binary (and possibly also fast rotating massive) stars during the fullyconvective, pre-main sequence stage, to reproduce the CN and ONaanticorrelations observed among stars in individual clusters. This scenario isassumed to be able to explain the presence (and properties) of the multiplepopulations in the majority of globular clusters in the Milky Way. Here we haveconsidered the well studied cluster NGC 2808, which displays a triple mainsequence with well defined and separate He abundances. Knowledge of theseabundances allowed us to put strong constraints on the He mass fraction andamount of matter to be accreted by low-mass pre-main sequence stars. We findthat the minimum He mass fraction in the accreted gas has to be $\sim0.44$ toproduce the observed sequences and that at fixed initial mass of the accretingstar, different efficiencies for the accretion are required to produce starsplaced onto the multiple main sequences. This may be explained by differencesin the orbital properties of the progenitors and/or different spatialdistribution of intracluster gas with varying He abundances. Both O-Na and C-Nanticorrelations appear naturally along the main sequences, once consideringthe predicted relationship between He and CNONa abundances in the ejecta of thepolluters. As a consequence of the accretion, we predict no discontinuitybetween the abundance ranges covered by intermediate and blue main sequencestars, but we find a sizeable (several 0.1 dex) discontinuity of the N and Naabundances between objects on the intermediate and red main sequences.

The main sequences of NGC2808: constraints on the early disc accretion scenario