The Ohio State University. Department of Astronomy Honors Theses; Abstract: Omega Centauri hereafter Omega Centhe largest globular cluster in the Galaxy, is an important environment for studying nucleosynthesis because of its significant abundance variations and evidence of multiple stellar generations.
Bring fact-checked results to the top of your browser search. The techniques of astronomy Astronomical observations involve a sequence of stages, each of which may impose constraints on the type of information attainable. Radiant energy is collected with telescopes and brought to a focus on a detector, which is calibrated so that its sensitivity and spectral response are known.
Accurate pointing and timing are required to permit the correlation of observations made with different instrument systems working in different wavelength intervals and located at places far apart. The radiation must be spectrally analyzed so that the processes responsible for radiation emission can be identified.
Since that time, telescopes have become central to astronomy. Having apertures much larger than the pupil of the human eyetelescopes permit the study of faint and distant objects.
In addition, sufficient radiant energy can be collected in short time intervals to permit rapid fluctuations in intensity to be detected. Further, with more energy collected, a spectrum can be greatly dispersed and examined in much greater detail.
Keck II is on the left and Keck I on the right. Keck Observatory Optical telescopes are either refractors or reflectors that use lenses or mirrorsrespectively, for their main light-collecting elements objectives.
Refractors are effectively limited to apertures of about cm approximately 40 inches or less because of problems inherent in the use of large glass lenses.
These distort under their own weight and can be supported only around the perimeter; an appreciable amount of light is lost due to absorption in the glass. Large-aperture refractors are very long and require large and expensive domes. The largest modern telescopes are all reflectors, the very largest composed of many segmented components and having overall diameters of about 10 metres 33 feet.
Reflectors are not subject to the chromatic problems of refractors, can be better supported mechanically, and can be housed in smaller domes because they are more compact than the long-tube refractors. The angular resolving power or resolution of a telescope is the smallest angle between close objects that can be seen clearly to be separate.
Resolution is limited by the wave nature of light. Sophisticated computing programs can allow much-improved resolution, and the performance of telescopes on Earth can be improved through the use of adaptive optics, in which the surface of the mirror is adjusted rapidly to compensate for atmospheric turbulence that would otherwise distort the image.
In addition, image data from several telescopes focused on the same object can be merged optically and through computer processing to produce images having angular resolutions much greater than that from any single component.
The atmosphere does not transmit radiation of all wavelengths equally well.
Longer infrared wavelengths are strongly absorbed by atmospheric water vapour and carbon dioxide. Atmospheric effects can be reduced by careful site selection and by carrying out observations at high altitudes. Most major optical observatories are located on high mountainswell away from cities and their reflected lights.
Infrared telescopes have been located atop Mauna Kea in Hawaii, in the Atacama Desert in Chile, and in the Canary Islandswhere atmospheric humidity is very low.
Airborne telescopes designed mainly for infrared observations—such as on the Stratospheric Observatory for Infrared Astronomy SOFIAa jet aircraft fitted with astronomical instruments—operate at an altitude of about 12 km 40, feet with flight durations limited to a few hours.
Telescopes for infraredX-rayand gamma-ray observations have been carried to altitudes of more than 30 kmfeet by balloons. Higher altitudes can be attained during short-duration rocket flights for ultraviolet observations.
Telescopes for all wavelengths from infrared to gamma rays have been carried by robotic spacecraft observatories such as the Hubble Space Telescope and the Wilkinson Microwave Anisotropy Probewhile cosmic rays have been studied from space by the Advanced Composition Explorer.
National Radio Astronomy Observatory Angular resolution better than one milliarcsecond has been achieved at radio wavelengths by the use of several radio telescopes in an array. In such an arrangement, the effective aperture then becomes the greatest distance between component telescopes.
In another technique, called very long baseline interferometry VLBIsimultaneous observations are made with radio telescopes thousands of kilometres apart; this technique requires very precise timing.
Hajor Earth is a moving platform for astronomical observations. Use of radiation detectors Although the human eye remains an important astronomical tool, detectors capable of greater sensitivity and more rapid response are needed to observe at visible wavelengths and, especially, to extend observations beyond that region of the electromagnetic spectrum.Isotopes Lecture 2: Cosmic Abundances, Nucleosynthesis and Element Origins 5 Stellar Death Like people, it's often hard to say when stars begin to .
Journal: Cosmic Abundances as Records of Stellar Evolution and Nucleosynthesis in honor of David L. Lambert, ASP Conference Series, Vol.
, Proceedings of a symposium held June, in Austin, Texas. Edited by Thomas G. Barnes III and Frank N. Bash.
San Francisco: Astronomical Society of the Pacific, , p Nucleosynthesis is a gradual, still ongoing process: Big Bang. Star. Formation. Life of a Piecing together the fossil record of chemical evolution s-process stellar burning. Type Ia Novae r-process. CS with SDSS data on stellar dynamics, abundances in Milky Way Mock SEGUE Obs.
stages of stellar evolution (e.g., dwarf stars). Their variability in stars themselves but rather reflects galactic chemical evolution. Nucleosynthesis in previous generations of stars led to heavy the elements and avoid the term ‘cosmic abundances.’.
This has decreased the metal content in the solar convection zone by almost a factor of two compared with the widely used compilation by Anders & Grevesse (). While resolving a number of long-standings problems, the new 3D-based element abundances also pose serious challenges, most notably for helioseismology.
Dec 19, · Stellar nucleosynthesis is the process by which the natural abundances of the chemical elements within stars change due to nuclear fusion reactions in the cores and their overlying mantles. Stars are said to evolve (age) with changes in the abundances of the elements within. Cosmic Abundances as Records of Stellar Evolution and Nucleosynthesis in Honor of David L Article · January with 25 Reads Cite this publication. based telescopes of the abundances of these elements have led to entirely new insights into the origin of the cosmic rays. Element Genesis We now know that nucleosynthesis, the genesis of the chemical elements and their isotopes, took.
Abstract The abundances of the rare light elements, Li, Be, and B, provide clues about stellar structure and evolution, about Galactic evolution and about their nucleosynthesis.