The Presence of Two Distinct Red Giant Branches in the Globular Cluster NGC 1851 - Astrophysics > Astrophysics of GalaxiesReportar como inadecuado




The Presence of Two Distinct Red Giant Branches in the Globular Cluster NGC 1851 - Astrophysics > Astrophysics of Galaxies - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online.

Abstract: There is a growing body of evidence for the presence of multiple stellarpopulations in some globular clusters, including NGC 1851. For most of thesepeculiar globular clusters, however, the evidence for the multiple redgiant-branches RGBs having different heavy elemental abundances as observedin Omega Centauri is hitherto lacking, although spreads in some lighterelements are reported. It is therefore not clear whether they also share thesuggested dwarf galaxy origin of Omega Cen or not. Here we show from the CTIO4m UVI photometry of the globular cluster NGC 1851 that its RGB is clearlysplit into two in the U - I color. The two distinct RGB populations are alsoclearly separated in the abundance of heavy elements as traced by Calcium,suggesting that the type II supernovae enrichment is also responsible, inaddition to the pollutions of lighter elements by intermediate mass asymptoticgiant branch stars or fast-rotating massive stars. The RGB split, however, isnot shown in the V - I color, as indicated by previous observations. Ourstellar population models show that this and the presence of bimodalhorizontal-branch distribution in NGC 1851 can be naturally reproduced if themetal-rich second generation stars are also enhanced in helium.



Autor: Sang-Il Han, Young-Wook Lee, Seok-Joo Joo, Sangmo Tony Sohn, Suk-Jin Yoon, Hak-Sub Kim, Jae-Woo Lee

Fuente: https://arxiv.org/



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