Red Giant Data Analysis

Both Caltech and Non-Caltech students will be considered

Project Title:

Project Description and Background Information:

The goal of the project will be to study circumstellar matter around red giant stars and planetary nebulae. When stars like the Sun get old, they become cooler and redder, increase their sizes and energy output tremendously, and eject prodigious amounts of matter (forming a circumstellar cloud) - they are called red giant stars. Most of the carbon and particulate matter (crucial building blocks for solar systems like ours) in the universe is manufactured and dispersed by red giant stars. A planetary nebula is formed when the red giant has ejected all of its outer layers, exposing a very hot core (six or more times hotter than the Sun). The ultraviolet radiation from this core bathes the surrounding cloud of ejected matter, ionising the gas and making it glow. The mass ejection process is poorly understood. Nor do we understand how planetary nebulae acquire their strikingly beautiful shapes and symmetries, since the red giant stars and the gas/dust clouds which surround them are mostly round. The circumstellar clouds around red giant stars are rich in molecules like carbon monoxide which emits radiation at specific wavelengths in the millimeter-wave range. Planetary nebulae emit radiation in the visible. By using a variety of observational techniques to detect these radiations, we can probe the structure and kinematics of the ejected matter, and thus investigate the physical mechanisms responsible for the mass ejections and their symmetries. My observations include imaging with the Hubble Space Telescope, and spectroscopy using ground-based telescopes.

The project will involve computer analysis and modeling of the imaging and/or spectroscopic data. Inital data reduction of the data is carried out using in-house analysis programs, which run on our Unix workstations. The images, together with the spectroscopic data, can be used to derive the 3-dimensional structure of, and physical conditions in, the circumstellar clouds. The most important quantities one needs to derive are, for example, the desities, temperatures, and expansion velocity of the gas in the circumstellar cloud: these tell us how much matter has been ejected (up to 0.5 solar masses) and over what period of time (~10,000 years). Some of these can be derived directly, others require building numerical models. The SURF student will work with me on carrying out specific tasks in the data reduction/modeling of selected objects and, depending on how far the work has progressed, on the preparation of a conference and/or journal paper reporting the results.

Literature references or articles that may provide more information on the project:

Mass Loss From Red Giants, Astrophysics and Space Science Library, Vol 117: Proceedings of a conference held at UCLA, eds. M. Morris and B. Zuckerman (published by D. Reidel)

The student should glance through the review articles, with special emphasis on the following - by Iben, pg 1; Wannier, pg 65, Morris, pg 129, Omont, pg 269, and Cohen, pg 291

Requirements (skills, specific coursework, academic major, year in school, etc.):

The student should be majoring in physics or astronomy, and should have programming skills in Fortran or C. He or she should have done basic courses in, or have knowledge of, Molecular and Atomic Physics, Electricity and Magnetism, Quantum Mechanics, and Thermodynamics. Strong computational skills can compensate for some deficiencies in the course work requirements above. He/she should be a Junior.

Research Sponsor Name: Raghvendra Sahai
E-Mail: sahai@lb6.jpl.nasa.gov
Division: JPL -Division 32
Telephone: (818) 394-0452
Address: M/C 183-900

For further information, contact Dr. Sahai

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