The Predicted Properties of Helium-Enriched Globular Cluster Progenitors at High Redshift. (arXiv:2005.06488v2 [astro-ph.SR] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Nataf_D/0/1/0/all/0/1">David M. Nataf</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Horiuchi_S/0/1/0/all/0/1">Shunsaku Horiuchi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Costa_G/0/1/0/all/0/1">Guglielmo Costa</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wyse_R/0/1/0/all/0/1">Rosemary F. G. Wyse</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ting_Y/0/1/0/all/0/1">Yuan-Sen Ting</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Crocker_R/0/1/0/all/0/1">Roland Crocker</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Federrath_C/0/1/0/all/0/1">Christoph Federrath</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Chen_Y/0/1/0/all/0/1">Yang Chen</a>

Globular cluster progenitors may have been detected by textit{HST}, and are
predicted to be observable with textit{JWST} and ground-based extremely-large
telescopes with adaptive optics. This has the potential to elucidate the issue
of globular cluster formation and the origins of significantly helium-enriched
subpopulations, a problem in Galactic astronomy with no satisfactory
theoretical solution. Given this context, we use model stellar tracks and
isochrones to investigate the predicted observational properties of
helium-enriched stellar populations in globular cluster progenitors. We find
that, relative to helium-normal populations, helium-enriched
(${Delta}Y=+0.12$) stellar populations similar to those inferred in the most
massive globular clusters, are expected, modulo some rapid fluctuations in the
first $sim$30 Myr, to be brighter and redder in the rest frame. At fixed age,
stellar mass, and metallicity, a helium-enriched population is predicted to
converge to being $sim$0.40 mag brighter at $lambda approx 2.0, {mu}m$,
and to be 0.30 mag redder in the textit{JWST}-NIRCam colour $(F070W-F200W)$,
and to actually be fainter for $lambda lesssim 0.50 , {mu}m$. Separately,
we find that the time-integrated shift in ionizing radiation is a negligible
$sim 5%$, though we show that the Lyman-$alpha$ escape fraction could end up
higher for helium-enriched stars.

Globular cluster progenitors may have been detected by textit{HST}, and are
predicted to be observable with textit{JWST} and ground-based extremely-large
telescopes with adaptive optics. This has the potential to elucidate the issue
of globular cluster formation and the origins of significantly helium-enriched
subpopulations, a problem in Galactic astronomy with no satisfactory
theoretical solution. Given this context, we use model stellar tracks and
isochrones to investigate the predicted observational properties of
helium-enriched stellar populations in globular cluster progenitors. We find
that, relative to helium-normal populations, helium-enriched
(${Delta}Y=+0.12$) stellar populations similar to those inferred in the most
massive globular clusters, are expected, modulo some rapid fluctuations in the
first $sim$30 Myr, to be brighter and redder in the rest frame. At fixed age,
stellar mass, and metallicity, a helium-enriched population is predicted to
converge to being $sim$0.40 mag brighter at $lambda approx 2.0, {mu}m$,
and to be 0.30 mag redder in the textit{JWST}-NIRCam colour $(F070W-F200W)$,
and to actually be fainter for $lambda lesssim 0.50 , {mu}m$. Separately,
we find that the time-integrated shift in ionizing radiation is a negligible
$sim 5%$, though we show that the Lyman-$alpha$ escape fraction could end up
higher for helium-enriched stars.

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