Conveners
Dust and presolar grains
- Maria Lugaro (Konkoly Observatory)
Dust and presolar grains
- Maria Lugaro (Konkoly Observatory)
Dust and presolar grains
- There are no conveners in this block
Presolar grains are microscopic dust grains that formed in the gas outflows or explosions of ancient stars that died before the formation of the solar system. The majority (~90% in number) of presolar SiC grains, including Types mainstream (MS), Y, and Z, came from low-mass C-rich asymptotic giant branch (AGB) stars, which is supported by the ubiquitous presence of SiC dust observed in the...
The Chicago Instrument for Laser Ionization (CHILI), a microbeam laser resonance ionization mass spectrometer, has measured the isotopic compositions of Fe, Ni, Sr, Zr, Mo, Ru, and Ba in presolar SiC and graphite grains, revealing much about $\textit{s}$-process nucleosynthesis in AGB stars. In CHILI, atoms are removed from samples by sputtering with Ga$^+$ ions or ablating with a 351 nm...
We have measured Mo, Ru, and Ba isotopes in 49 presolar SiC and 11 high-density graphite grains from the Murchison meteorite with the Chicago Instrument for Laser Ionization (CHILI), a microbeam laser resonance ionization mass spectrometer. Each of these elements has seven stable isotopes, which allow study of s-, r-, and p-process products. Correlated nucleosynthetic effects observed...
Stellar grains are solid samples of stars that were trapped in the interior of primitive meteorites. Lewis et al. first identified stellar grains in 1987. The complex origins of stellar grains have been the topic of research since then. One of the important markers of their origin is a short-lived radioactive nucleus, the $^{26}$Al (t$_{1/2}$=0.717 Myr). The strength of the conclusions drawn...
Most of the stars in the Universe will end their evolution by losing their envelope during the thermally pulsing asymptotic giant branch (TP-AGB) phase, enriching the interstellar medium of galaxies with heavy elements, partially condensed into dust grains formed in their extended envelopes. Among these stars, carbon-rich TP-AGB stars (C-stars) are particularly relevant for the chemical...
Spherically symmetric AGB outflows are the exception rather than the rule: both small-scale asymmetries (e.g., clumps) and large-scale asymmetries (e.g., spirals and disks) are widely observed. Binary interaction, either with a stellar or a planetary companion, has been proposed as the driving mechanism behind the large-scale asymmetries.
Recently, we found a stellar companion can strongly...
Asymptotic giant branch stars are major sources for carbon dust in galaxies. The analysis of these objects in the Large Magellanic Clouds unearthed a group of stars, called "Extremely Red Objects" (EROs). The analysis of EROs spectral energy distribution suggests the presence of large quantities of dust in their surroundings, which demands gas densities in the outflow significantly higher than...
The asymptotic giant branch (AGB) phase modelling is made uncertain by the poor knowledge of some physical mechanisms that play a crucial role on the internal structure and the late evolution of low- and intermediate-mass stars. On the contrary, the post-AGB phase is only marginally affected by the uncertainties mentioned and spectra can be more easily analyzed to derive the chemical...
Metal oxides are promising candidates as a primary dust condensate in the atmospheres of oxygen-rich evolved stars. Typically, Al2O3 and TiO2 are considered as they represent the most prominent case studies. However, also mixed metal oxides, containing more than one metal, represent realistic alternatives to Al2O3 and TiO2 as a first solid in the rich gas mixture of
stellar atmospheres....
Primitive Solar System materials contain small amounts of presolar grains that formed in the winds of evolved stars and in the ejecta of stellar explosions [1]. These grains exhibit large isotopic abundance anomalies, the fingerprints of nucleosynthetic and mixing processes in their parent stars, and of Galactic chemical evolution (GCE). Silicates are the most abundant type of presolar grains...
Sakurai's Object (V4334 Sgr) is a low mass post-AGB star that has been forming dust in an eruptive event since 1996. We have been analysing 6-14 μm Spitzer spectra obtained at 6 epochs between 2005 April and 2008 October to determine temporal changes in the dust features. An initially rapid mid-infrared flux decrease stalled after 2008 April 21. Optically thin emission due to nanometre-sized...
After decades of failures and misunderstandings, scientists have solved a cosmic riddle — what happens to the tons of dust particles that hit the Earth every day but seldom if ever get discovered in the places that humans know best, like buildings and parking lots, sidewalks and park benches. The answer? Nothing. Look harder. The tiny flecks are everywhere, all over the roof. The morphology of...
In a large-scale nucleosynthesis parameter study, we have extended the initial ideas of Hoffman et al. [1], who showed that light p-nuclei can be produced in the neutrino-driven winds of core-collapse supernovae (cc-SNe). Our project began about a decay ago, based on the r-process model of Farouqi et al. [2], where we found that in the low-entropy (S) charged-particle component of moderately...
