Frontiers of Astronomy with the World's Largest Radio Telescope

Äîêóìåíò âçÿò èç êýøà ïîèñêîâîé ìàøèíû. Àäðåñ îðèãèíàëüíîãî äîêóìåíòà : http://www.naic.edu/~astro/frontiers/abstract/abstract.shtml
Äàòà èçìåíåíèÿ: Unknown
Äàòà èíäåêñèðîâàíèÿ: Sat Dec 22 17:36:34 2007
Êîäèðîâêà: IBM-866
Ïîèñêîâûå ñëîâà: iss

Abstracts

Name:Bennett Link
Institution:Montana State University
Title:Neutron Star Structure and Equation of State
Abstact:
An outstanding fundamental question in physics concerns the properties of matter near and above nuclear density. Matter at supra-nuclear densities, while inaccessible in the laboratory, exists in abundance in the nearly 2000 neutron stars detected so far by radio surveys. I will describe how the interpretation of precision timing data of pulsars has advanced our understanding of the state and dynamics of the neutron star interior. I will conclude with discussion of what we hope to learn from future observations and theoretical efforts.

Name:Hector Arce
Institution:AMNH
Title:Studying Complex and Pre-biotic Molecules in the ISM using the Arecibo Observatory
Abstact:
The study of complex molecules in the interstellar medium (ISM) is important for understanding the physical and chemical processes in the ISM as well as the origins of life. To date, over 140 molecules have been identified in space. Many of these are quite complex, including small sugars and other organic molecules containing as many as 8 to 13 atoms (e.g., Hollis et al. 2000; Remijan et al. 2006). The detection of many complex molecules shows that they can easily form in molecular clouds, even before stars and planets fully form. Some of the complex molecules found in the ISM are large pre-biotic organic molecules, thought to be important to life. It is therefore a possibility that chemical processes in the interstellar medium provided the essential material that allowed the emergence of life. A thorough chemical inventory is needed to establish if there is any connection between life on Earth and the ISM. Detection and identification of complex molecules in different environments (i.e., cold dark clouds, PDRs, diffuse clouds, warm star forming regions, etc.) provide critical information for better understanding the possible formation (and destruction) pathways of these molecules, as well as for constraining chemical models. During the different stages of star formation, from starless core to the pre-main sequence star stage, different physical processes affect the environment thereby leaving a particular chemical imprint on the gaseous surroundings. Hence, information on the chemical composition of the interstellar gas can be used to study the physical and chemical evolution of clouds and the star formation process (e.g., van Dishoeck et al. 1995). Arecibo Observatory, with its unmatched collecting area, is an excellent instrument for the study of the chemistry of the interstellar medium. While millimeter observations have been important in the study of complex molecules in the warm (T > 100 K) molecular gas, radio observations are important for studying the cold gas where complex molecules only show low-energy transitions with frequencies of less than about 12 GHz. Studies using single dish observations are crucial for mapping any possible extended emission òÀÓòÀÓwhich is very likely to be present for low-energy transitions of molecules in the cold extended gas (Hollis 2005). Moreover, in certain cases radio observations of warm and hot molecular gas at low frequencies are needed (in addition to millimeter wavelength observations) in order to study the excitation conditions and the column density of the gas, as well as for confirming the detection of previously undetected molecules. With considerably better sensitivity and a beam size at least three times smaller than any other single dish telescope at the same wavelength, the Arecibo Observatory can provide observations unmatched by any other facility in the world.