How far is all the way, and then if it stops, what's stopping it, and what's behind what's stopping it?So, what's the end, you know, is my question to you.'' - This Is Spinal Tap (1984) As was discussed in the introduction, this work is split into two distinct sections, one dealing with carbon-rich evolved stars (chapters 6 & 7) and one dealing with oxygen-rich evolved stars (chapter 8).
How far is all the way, and then if it stops, what's stopping it, and what's behind what's stopping it?So, what's the end, you know, is my question to you.'' - This Is Spinal Tap (1984) As was discussed in the introduction, this work is split into two distinct sections, one dealing with carbon-rich evolved stars (chapters 6 & 7) and one dealing with oxygen-rich evolved stars (chapter 8).Tags: Purdue DissertationCognitive Radio Networks ThesisIt Assignment HelpPaper Collage Ideas For CompetitionStrengths And Weaknesses In Writing PapersNo Essay CollegesHow To Write A Good Thesis For A Research PaperOnline Writing Courses For High School StudentsEssay Report Writing SkillsExplanatory Essay Common Core Rubric
`` Well, I don't really think that the end can be assessed as of itself as being the end because what does the end feel like?
It's like saying when you try to extrapolate the end of the universe, you say, if the universe is indeed infinite, then how - what does that mean?
This error was exposed whilst trying to reconcile meteoritic Si C data with the numerous astronomical observations which had, until now, presented a discrepancy between the type of Si C carbide believed to form around carbon-rich AGB stars and that found in meteorites, also believed to form around such stars.
Meteoritic Si C grains are all of the beta-Si C type, while astronomical observations seemed to be best explained by the presence of alpha-Si C.
The differences and similarities between the various spectra were discussed, and the possible condensation sequence of such minerals in the circumstellar environment around evolved stars was outlined.
The work on carbon-rich stars was split into two section based on the specific dust/molecular species of interest, i.e.dust species formed, grain formation and growth models, radiative transfer models) for such grains.In order to interpret the observed astronomical spectra it is necessary to have a good understanding of the way in which electromagnetic radiation interacts with solids. A simple explanation of how the physical properties of a solid determine its spectrum was discussed in section 4.2, followed by a brief discussion of the special case of very small particles of solids in section 4.3.For instance, the Si C grains found in meteorites are relatively large (up to 26 µm in diameter), whereas the grains expected to cause the 11.3 µm feature are less than about 0.1 µm in size (see section 3.2.2).Isotopic studies of the grains found in meteorites show that even the noble gases trapped in them have signatures of AGB-star formation, and therefore the large grains were also formed in these regions. It was also found that many of the observed 11.3 µm features could be best fit using self-absorbed Si C (i.e., the 11.3 µm Si C feature in both emission an absorption simultaneously), rather than Si C in pure emission.In chapter 2, the basics of stellar evolution and nucleosynthesis were discussed so that the origins of the building blocks of dust grains could be recognized and the evolution of dust type with the evolution of the star could be understood.This chapter also had implications for the meteoritic work discussed in chapter 3.The origin of these bands is believed to be some sort of carbonaceous grain(s) or molecule(s) interacting with ultraviolet light.There have been many suggestions for the origin of these grains/molecules, including the formation around carbon stars.The probability of a grain forming as alpha-Si C and then somehow transforming into beta-Si C is very low, and therefore this discrepancy could not be easily explained.This problem actually arose through a misunderstanding of the optical properties of solids, which lead to the imposition of a matrix-correction factor applied to those spectra taken using a dispersion matrix.