Particles photospheric

Cosmochemistry is the study of the chemical compositions of various solar system materials. Chondrites are the most abundant primitive samples. They are essentially sedimentary rocks composed of mechanical mixtures of materials with different origins (chondrules, refractory inclusions, metal, sulfide, matrix), which we will call components. Chondrites formed by the accretion of solid particles within the solar nebula or onto the surfaces of growing planetesimals. They are very old (>4.5 billion years, as measured by radioactive chronometers) and contain some of the earliest formed objects in the solar system. Chondrites have bulk chemical compositions very similar to the solar photosphere, except... 

Brenemann, H. H., Stone, E. C. (1985) Solar coronal and photospheric abundances from solar energetic particle measurements. Astrophys. J., 299, L57-61. 

In the Solar System the bulk elemental composition of the most volatile-rich Cl chondrites resembles closely that of the solar photosphere. Indeed, models that follow the condensation of a solar-composition hot gas reproduce many of the minerals and abundance trends observed in the Solar System. These are also consistent with some of the astronomical observations of dust in protoplanetary disks. Stardust grains also show approximately solar bulk composition in the measurable elements, albeit with some variations (Flynn et al 2006). Some IDPs -mainly the fine-grained, porous, and anhydrous particles - match the solar elemental... 

The relative abundance of chemical elements in cosmic ray sources is in general similar to the solar and to the local galactic abundance but show some significant deviations. The elements that appear underabundant by a factor of about 5 are those elements that are difficult to ionize. The critical ionization potential is approximately 10 eV that corresponds to ionization at an equilibrium temperature 104 K (characteristic e.g. of the solar photosphere). The correlation of abundance with the first ionization potential is also known for solar energetic particles. Thus, it is possible that the outer layers of relatively cool stars serve as injectors of the seed particles required for the subsequent acceleration [17]. For most elements the volatility is correlated with the first ionization potential, so that volatility is also considered as a possible selection factor for the cosmic ray population. Then predominant acceleration and breakup of grains that is natural for the diffusive shock acceleration could explain the situation [18]. 

The sun has the most mass (>99%) of the solar system objects and therefore it is the prime target for studying solar system abundances. Most elements can be measured in the sun s photosphere, but data from the solar chromosphere and corona, solar energetic particles, solar wind, and solar cosmic rays (from solar flares), help to evaluate abundances of elements that have weak absorption lines (because these elements are low in abundance or only have blended absorption lines in the photospheric spectrum). 

Cosmic abundances in the interstellar medium are derived by measuring elemental abundances in stellar photospheres, the atmospheric layer just above the stellar surface. Such measurements indicate the amount of elements available for the formation of molecules and particles. Cosmic dust models indicate that up to 80% of the carbon in the photon-dominated diffuse interstellar medium is incorporated into solid aromatic macromolecules and gaseous polycylic aromatic hydrocarbons (41,30). CO gas and C-based ice species (such as CO, CO2, CH3OH and others) may be responsible for up to -25 % of the carbon in cold dense interstellar regions. 

Outside the star s photosphere is a region called the chromosphere that contains ions, atoms and, in cooler stars, small molecules. These particles absorb some of the light that is emitted from the glowing photosphere. So when researchers analyse the light that reaches the Earth from the star, they observe that certain frequencies are missing - the ones which have been absorbed. 

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