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Chemical abundances of the young inner-disc open cluster NGC 6705 observed by APOGEE: sodium-rich and not α-enhanced.
- Source :
- Monthly Notices of the Royal Astronomical Society; Dec2023, Vol. 526 Issue 2, p2378-2393, 16p
- Publication Year :
- 2023
-
Abstract
- Previous results in the literature have found the young inner-disc open cluster NGC 6705 to be mildly α-enhanced. We examined this possibility via an independent chemical abundance analysis for 11 red-giant members of NGC 6705. The analysis is based on near-infrared APOGEE spectra and relies on LTE calculations using spherical model atmospheres and radiative transfer. We find a mean cluster metallicity of |$\rm [Fe/H] = +0.13 \pm 0.04$| , indicating that NGC 6705 is metal-rich, as may be expected for a young inner-disc cluster. The mean α-element abundance relative to iron is |$\rm \langle [\alpha /Fe]\rangle =-0.03 \pm 0.05$| , which is not at odds with expectations from general Galactic abundance trends. NGC 6705 also provides important probes for studying stellar mixing, given its turn-off mass of M ∼ 3.3 M<subscript>⊙</subscript>. Its red giants have low <superscript>12</superscript>C abundances ([<superscript>12</superscript>C/Fe] = −0.16) and enhanced <superscript>14</superscript>N abundances ([<superscript>14</superscript>N/Fe] = +0.51), which are key signatures of the first dredge-up on the red giant branch. An additional signature of dredge-up was found in the Na abundances, which are enhanced by [Na/Fe] = +0.29, with a very small non-LTE correction. The <superscript>16</superscript>O and Al abundances are found to be near-solar. All of the derived mixing-sensitive abundances are in agreement with stellar models of approximately 3.3 M<subscript>⊙</subscript> evolving along the red giant branch and onto the red clump. As found in young open clusters with similar metallicities, NGC 6705 exhibits a mild excess in the s-process element cerium with |$\rm [Ce/Fe] = +0.13\pm 0.07$|. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00358711
- Volume :
- 526
- Issue :
- 2
- Database :
- Complementary Index
- Journal :
- Monthly Notices of the Royal Astronomical Society
- Publication Type :
- Academic Journal
- Accession number :
- 173152178
- Full Text :
- https://doi.org/10.1093/mnras/stad2896