We have studied the hydrodynamical behavior of the gas expelled by moving Asymptotic Giant Branch Stars interacting with the ISM. Our models follow the wind modulations prescribed by stellar evolution calculations, and we cover a range of expected relative velocities (10 to 100 kms−1), ISM densities (between 0.01 and 1 cm−3), and stellar progenitor masses (1 and 3.5Msun). We have shown how and when bow-shocks, and cometary-like structures form, and in which regime the shells are subject to instabilities. In addition, we have analyzied the results of the simulations in terms of the different kinematical stellar populations expected in the Galaxy.
Possible detection of planar C24 (graphene) in the space.
Nobel-prize winning scientists (2010), Andre Geim and Konstantin Novoselov, synthesized graphene in the laboratory in 2004. Just seven years later, this material of extraordinary strength, thinness and elasticity may have been found in space. The first evidence of the possible existence of C24 - a flat two-dimensional molecule, one atom thick, possibly a "small piece of graphene - in space has been found. To confirm beyond a doubt that what has been detected is actually C24, laboratory spectroscopy would have to be carried out, something which is practically impossible with current laboratory techniques. Because of its high electrical and thermal conductivity, graphene has promising technological applications, such as the manufacture of new materials and advanced electronic devices (computers faster than those with silicon transistors, screens on electronic devices, solar panels, etc.). The properties of graphene (transparency, thinness, possibility of developing materials 200 times stronger than steel from it) have continued to raise expectations of its becoming the material of the future.
In this study, which used NASA's Spitzer telescope, C60 and C70 fullerenes have also been detected in ten planetary nebulae - remnants of stars like the sun, towards the end of their lives - in two galaxies near the Milky Way, the Magellanic Clouds. Also, the first extragalactic detection of the fullerene C70 has been achieved.
The detection of fullerenes and graphenes around old stars as common as our Sun, indicate that these molecules and other allotropic forms of carbon such as nanotubes, nanodiamonds, carbon onions, etc. may be ubiquitous in space and that the basic physical processes needed for life to originate could be more common than we thought, suggesting that life could be created anywhere in the Universe. The most likely explanation for the fullerenes and graphenes generation is that these complex molecules form from the shock-induced decomposition of hydrogenated amorphous carbon grains (HACs), which should be very abundant in the circumstellar shells of these dying stars.
Reference: (2011) The formation of fullerenes: clues from new C60, C70, and (possible) planar C24 detections in Magellanic Cloud Planetary Nebulae, The Astrophysical Journal Letters, 737, L30
We have measured the transitions of two of the most abundant fullerenes, molecules (C60 and C70) in a range of extreme temperatures (from -180 º C to + 250 º C). adsabs.harvard.edu/doi/10.1111/j.1365-2966.2011.18124.x
We have detected large amounts of fullerenes (C60) in three planetary nebulae (PNs) of the Milky Way and one NP of the Small Magellanic Cloud, which is the first extragalactic detection of this molecule (the most complex detected in the space). The results indicate that these complex molecules (with many potential applications in superconducting materials, optical devices, medicines, etc.) are much more common in the universe than previously believed. In addition, we found that these molecules can be form in hydrogen rich enviorement, which contradicts current theories.
In addition, fullerenes have been detected in the two R Coronae Borealis stars less hydrogen-deficient, confirming the results of planetary nebulae. arxiv.org/abs/1009.4357
We have discovered that the origin of some of the radioactive elements found in the most primitive meteorites, whose origin dates back to the time of the formation of the Solar System, could have originated from a star six times the mass of the Sun and undergoing the final stage of its life as it passed through the solar neighbourhood. The disintegration of these isotopes in the interior of the first bodies or protoplanets would be responsible for the internal heating that helped the first minerals to melt and recrystalize in order to form the rocky planets and large asteroids. The abundances of the main radioactive nuclei measured in meteorites would be perfectly consistent with those produced by these types of stars. adsabs.harvard.edu/abs/2009M%26PS...44..627T
We found a possible detection of the simplest PAHs in the Perseus molecular complex (in the line of sight of the star Cernis 52), the naphatalene cation.arxiv.org/abs/0809.0778
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 atlas 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).