Physics of Planetary Nebulae (P15/86)

External Collaborators

A. García-Hernandez Univ. de Texas, Austin, EEUU
P. García-Lario     ESAC - ESA, Madrid
G. García-Segura    UNAM, Ensenada, México
L. Stanghellini     NOAO, Tucson, EEUU
E. Villaver         STScI, Baltimore, EEUU

Introduction

Low- and intermediate-mass ( M < 8 solar masses, M) stars constitute the majority of the stars in the Universe. Many of these stars end their lives with a phase of strong mass loss and experience thermal pulses on the Asymptotic Giant Branch (AGB), being one of the main contributors to the interstellar medium enrichment. We investigate the transition phase between the last thermal pulses on the AGB and the formation of Planetary Nebulae (PNe). In particular, we focus on the C and O isotopic 12C/13C, 17O/16O, and 18O/16O ratios to pose observational constraints on the current AGB nucleosynthesis theoretical models as well as to study their relation with the presence of Li and neutron-rich elements in AGB stars. During these thermal pulses, the AGB can lose up to 10-4 M per year and forms complex organic molecules; we aim to investigate whether these molecules are fullerenes. We also study the hydrodynamic processes that give rise to different morphologies and also the complex structure detected in the molecular hydrogen in PNe. Finally, we study PNs in the Magellanic Clouds with the aim of deriving an [OIII] luminosity function that could be used as a standard candle for deriving extragalactic distances

Milestones

We have found that intermediate-mass (4 to 8 solar masses) AGB stars in our Galaxy that are rubidium-rich owing to overproduction of the long-lived radioactive isotope 87Rb, as predicted theoretically 40 years ago. This represents a direct observational evidence that the 22Ne(alpha,n)25Mg reaction must be the dominant neutron source in these stars. These stars then challenge our understanding of the late stages of the evolution of intermediate-mass stars and would promote a highly variable Rb/Sr environment in the early solar nebula. Garcia-Hernandez, D.A., Garcia-Lario, P., Plez, B., D'Antona, F., Manchado, A., & Trigo-Rodriguez, J.~M. 2006, Science, ArXiv Astrophysics e-prints, arXiv:astro-ph/0611319

We have built an spectroscopic altas of 103 post-AGB stars. "A spectroscopic atlas of post-AGB stars and planetary nebulae selected from the IRAS Point Source Catalogue", O. Suarez, P. Garca-Lario, A. Manchado, M. Manteiga, A. Ulla, and S.R. Pottasch, 2006, A&A, 458, 173

We have built a catalog of Northern Galactic Planetary, "The IAC Morphological Catalog of Northern Galactic Planetary Nebulae". The catalog is composed of 607 images of 243 Northern planetary nebulae larger than 4 arcsec. The images have been obtained through narrow-band filters centered on nebular emission lines ([O III] 5007 Å, H-alpha 6563 Å, and [N II] 6584 Å).

Supervised Theses

"La formación de nebulosas planetarias a través de los datos IRAS", Pedro Garcia Lario 1992

"Spatially Resolved Study of Chemical Abundances in Planetary Nebulae", Martin Guerrero Roncel 1995

"The cicumstellar evolution from the AGB to the planetary nebula phase", Eva Villaver Sobrino 2001
hydrodynamical simulation on the formation of AGBs
hydrodynamical simulations on the formation of PNs
hydrodynamical simulation on the interaction with the ISM (caption)

"Star forming rate in 0.5 < z< 1 galaxies: a scientific case for the multi-slit NIR spectrograph LIRIS", Carlos Dominguez Tagle 2003

"Study of the transition phase between AGB stars and PNe", Anibal Garcia Hernandez 2005

A. Manchado.
Copyright IAC, 2006.