Ministerio de Economía y Competitividad Gobierno de Canarias Universidad de La Laguna CSIC Centro de Excelencia Severo Ochoa

Astrophysics Research Projects

Physic of Stars, Planetary Systems and the Interstellar Medium

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Chemical Composition of Ionized Nebulae (P/308614)


César Esteban López, Simone Madonna

  IAC Collaborators: Miguel Cerviño Saavedra

A.R. López-Sánchez (AAO, Australia); F. Bresolin (IfA, Hawai, EEUU); C. Morisset, L. Carigi, M. Peimbert, M. Peña, G. Delgado-Inglada (IA-UNAM, México); M. Rodríguez, G. Domínguez-Guzmán (INAOE, México); X. Fang (University of Hong Kong); N.C. Sterling (University of West Georgia, EEUU); R. Wesson (UCL, UK); H. Monteiro (U. Itajubá, Brasil), H. Boffin (ESO, Alemania); S. Akras. D. R. Gonçalves (Obs. Valongo, Brasil)


This project is devoted to study the structure, dynamics, physical conditions and chemical evolution of Galactic and extragalactic ionized nebulae through detailed analysis and modelization of their spectra.


 We have used deep spectra from a sample of HII regions in the Galactic anticenter obtained with OSIRIS@GTC - supplemented with high quality data from the literature - to obtain the O abundance gradient in the outer parts of the galaxy (up to 17 kpc) from direct measurement of the electronic temperature and collisional excitation lines. We found that the slope of the O gradient remains the same as in the inner part of the disk, dismissing the possibility of a flattening of the gradient in the outer Galactic disc as suggested by previous works. The results of this work were highlighted in a press release from the IAC.

Deep observations in the near IR have allowed our group to detect for the first time several lines of neutron-capture elements in planetary nebulae. In particular, using the near-IR spectrograph FIRE@6.5m Magellan telescope, the [Se III] 1.0992 μm and [Kr VI] 1.2330 μm lines have been detected for the first time in several planetary nebulae. Additionally, making use of observations in the science verification phase of the near-IR spectrograph EMIR, we have detected new n-capture emission lines in several planetary nebulae. The detection of these lines has boosted updated atomic data calculations for abundance determinations using these lines.


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