Neutron-capture Elements in Planetary Nebulae: First Detections of Near-infrared [Te iii] and [Br v] Emission Lines
Dinerstein, Harriet L.
Sterling, N. C.
Kaplan, Kyle F.
Rubio-Díez, Maria del Mar
AffiliationUniv Arizona, Dept Astron
nuclear reactions, nucleosynthesis, abundances
planetary nebulae: individual (IC 418, NGC 7027)
stars: AGB and post-AGB
MetadataShow full item record
PublisherIOP PUBLISHING LTD
CitationSimone Madonna et al 2018 ApJL 861 L8
JournalASTROPHYSICAL JOURNAL LETTERS
Rights© 2018. The American Astronomical Society. All rights reserved.
Collection InformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at email@example.com.
AbstractWe have identified two new near-infrared (NIR) emission lines in the spectra of planetary nebulae arising from heavy elements produced by neutron-capture reactions: [Te III] 2.1019 mu m and [Br V] 1.6429 mu m. [Te III] was detected in both NGC 7027 and IC 418, while [Br V] was seen in NGC 7027. The observations were obtained with the medium-resolution spectrograph Espectrografo Multiobjeto Infra-Rojo (EMIR) on the 10.4 m Gran Telescopio Canarias at La Palma, and with the high-resolution Immersion GRating INfrared Spectrometer (IGRINS) on the 2.7 m Harlan J. Smith telescope at McDonald Observatory. New calculations of atomic data for these ions, specifically A-values and collision strengths, are presented and used to derive ionic abundances of Te2+ and Br4+. We also derive ionic abundances of other neutron-capture elements detected in the NIR spectra, and estimate total elemental abundances of Se, Br, Kr, Rb, and Te after correcting for unobserved ions. Comparison of our derived enrichments to theoretical predictions from asymptotic giant branch (AGB) evolutionary models shows reasonable agreement for solar metallicity progenitor stars of similar to 2-4Me circle dot. The spectrally isolated [Br V] 1.6429 mu m line has advantages for determining nebular Br abundances over optical [Br III] emission lines that can be blended with other features. Finally, measurements of Te are of special interest because this element lies beyond the first peak of the s-process, and thus provides new leverage on the abundance pattern of trans-iron species produced by AGB stars.
VersionFinal published version
SponsorsSpanish Ministerio de Economia y Competividad [AYA2015-65205-P, AYA2017-83383-P]; NSF [AST-1412928, AST-1715332, AST-1229522]; Severo Ochoa excellence program [SEV-2015-0548]; University of Texas at Austin; Korean GMT Project of KASI