Population III

Abstract. We have studied the effects of an hypothetical initial generation made only of very massive stars (M > 100M , pair-creation SNe) on the chemical and photometric evolution of spheroidal systems. We found that the effects of Population III stars on the chemical enrichment is negligible if only one or two generations of such stars occurred, whereas they produce quite different results from the standard models if they continuously formed for a period not shorter than 0.1 Gyr. In this case, the results produced are at variance with the main observational constraints of ellipticals such as the average [< a/Fe > ] ratio in stars and the color-magnitude diagram. 

Therefore, from the chemical and photometric point of view there is no need to invoke the existence of Population III stars in spheroids. 

Quality of evidence I, randomized clinical trial data II, data from clinical trials that are not randomized or were conducted in other populations III, expert opinion. 

Of a special astronomical interest is the absorption due to pairs of H2 molecules which is an important opacity source in the atmospheres of various types of cool stars, such as late stars, low-mass stars, brown dwarfs, certain white dwarfs, population III stars, etc., and in the atmospheres of the outer planets. In short absorption of infrared or visible radiation by molecular complexes is important in dense, essentially neutral atmospheres composed of non-polar gases such as hydrogen. For a treatment of such atmospheres, the absorption of pairs like H-He, H2-He, H2-H2, etc., must be known. Furthermore, it has been pointed out that for technical applications, for example in gas-core nuclear rockets, a knowledge of induced spectra is required for estimates of heat transfer [307, 308]. The transport properties of gases at high temperatures depend on collisional induction. Collision-induced absorption may be an important loss mechanism in gas lasers. Non-linear interactions of a supermolecular nature become important at high laser powers, especially at high gas densities. 

Collision-induced absorption spectra are also of considerable interest for studies of the atmospheres of late stars [241, 307, 112] certain white dwarfs [366, 300, 239, 240] low-mass stars, brown dwarfs, certain cool white dwarfs [240] and the hypothetical population III stars [306, 372],... 

The supermassive stars thought to populate the early universe are known as population III stars and may be the progenitors for population II stars, the old red stars found in galaxies today, which are rich in heavy elements. [For more information, see Linda Rowan, Old metals, new stars, Science 290(5489) 13 (October 6, 2000).]... 

Vasek, F. C., Outcrossing in Natural Populations. III. The Deer Creek... 

Is there zero metallicity gas (or stars for that matter) in galaxies Pre-enrichment by an initial stellar Population III also provides a solution to the G-dwarf problem and to the origin of metals seen in Lya forest clouds. What is the composition of the huge gas reservoirs in the outer parts of spirals and irregulars ... 

Initial conditions- One can assume that all the initial gas out of which the galaxy will form is already present when the star formation process starts or that the gas is slowly accumulated in time. Then one can assume that the initial chemical composition of this gas is primordial (no metals) or that some pre-enrichment has already taken place (e.g. Population III stars). As we will see in the following, different assumptions are required for different galaxies. 

Fundamental to the existence of a carbon chemistry then is the synthesis and dispersal of carbon by stars. Recent cosmological simulations indicate that the formation of the first stars (so called population III or zero metallicity stars) may have occurred as early as 200 million years after the big bang (8). These very... 

The cycle of birth and death of stars that is initiated by population III stars constantly increases the abundance of heavy elements in the interstellar medium, a crucial prerequisite for terrestrial (rocky) planet formation and subsequently for the origin of life (75). Metals dispersed in the interstellar gas or incorporated into micron-sized dust particles and molecules like CO and water, have the ability to cool the interstellar gas much more efficiently than molecular hydrogen does for population III stars. These elements and molecules are also excited through atomic and molecular collisions and their return to lower lying energy levels releases energy via far-infrared and sub-millimeter radiation below... 

Although, strictly speaking, not an alternative cosmology, the notion of Population III stars assumes increasing importance in the resolution of anomalies associated with nucleogenesis, dark matter and 3K backgroimd radiation in standard cosmology. The subject is reviewed by Carr et al. (1984), with many references. 

Population III stars correspond to the missing supergiants, high up the main sequence, mentioned by Hoyle (1955). The comment that stars above the main-sequence limit of a cluster... 

If Population III remnants are to provide the missing mass, one may need to give up the conventional cosmological nucleosynthesis picture anyway [.as.] the dark matter problem cannot be solved by black holes or low-mass stars of nonprimordial origin unless one modifies the conventional nucleosynthesis scenario". 

Lansman RA, Shade RO, Shapira JF, Avise JC (1981) The use of restriction endonucleases to measure mitochondrial DNA sequence relatedness in natural populations. III. techniques and potential applications. J Mol Evol 17 214-226... 

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