Bibcode
Mashburn, A. L.; Sterling, N. C.; Madonna, S.; Dinerstein, Harriet L.; Roederer, I. U.; Geballe, T. R.
Referencia bibliográfica
The Astrophysical Journal Letters, Volume 831, Issue 1, article id. L3, 7 pp. (2016).
Fecha de publicación:
11
2016
Número de citas
13
Número de citas referidas
11
Descripción
We present near-infrared spectra of 10 planetary nebulae (PNe) in the
Large and Small Magellanic Clouds (LMC and SMC), acquired with the FIRE
and GNIRS spectrometers on the 6.5 m Baade and 8.1 m Gemini South
Telescopes, respectively. We detect Se and/or Kr emission lines in eight
of these objects, the first detections of n-capture elements in
Magellanic Cloud PNe. Our abundance analysis shows large s-process
enrichments of Kr (0.6–1.3 dex) in the six PNe in which it was
detected, and Se is enriched by 0.5–0.9 dex in five objects. We
also estimate upper limits to Rb and Cd abundances in these objects. Our
abundance results for the LMC are consistent with the hypothesis that
PNe with 2–3 M ⊙ progenitors dominate the bright
end of the PN luminosity function in young gas-rich galaxies. We find no
significant correlations between s-process enrichments and other
elemental abundances, central star temperature, or progenitor mass,
though this is likely due to our small sample size. We determine S
abundances from our spectra and find that [S/H] agrees with [Ar/H] to
within 0.2 dex for most objects, but is lower than [O/H] by
0.2–0.4 dex in some PNe, possibly due to O enrichment via third
dredge-up. Our results demonstrate that n-capture elements can be
detected in PNe belonging to nearby galaxies with ground-based
telescopes, allowing s-process enrichments to be studied in PN
populations with well-determined distances.
This paper includes data obtained with the 6.5-m Magellan Telescopes
located at Las Campanas Observatory, Chile, and with the Gemini-South
Telescope at Cerro Pachon, Chile.