HR: 0830h
AN: SP41B-09    [Abstracts]
TI: The Solar Oxygen Abundance, and the Rare Isotopes of C and O, Derived from Infrared Spectra of Carbon Monoxide
AU: * Ayres, T R
EM: ayres@casa.colorado.edu
AF: Center for Astrophysics and Space Astronomy, 389-UCB University of Colorado, Boulder, CO 80309
AU: Plymate, C
EM: plymate@noao.edu
AF: National Solar Observatory, 950 N. Cherry Ave., Tucson, AZ 85726
AU: Keller, C
EM: keller@noao.edu
AF: National Solar Observatory, 950 N. Cherry Ave., Tucson, AZ 85726
AU: Kurucz, R L
EM: kurucz@cfa.harvard.edu
AF: Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138
AB: A detailed abundance analysis is presented for solar oxygen based on the ΔV=1 fundamental (4.6~μm) and ΔV=2 (2.3~μm) first-overtone rovibrational bands of carbon monoxide observed above the Earth's atmosphere at very high spectral resolution and high signal-to-noise by the Shuttle-borne ATMOS Fourier transform spectrometer (FTS). Additional observations to define the reference photospheric thermal structure were taken of the CO fundamental bands in an atmospheric window at 2145~cm^-1 (4.6~μm) using the 1~m FTS of the McMath-Pierce telescope at Kitt Peak and a fast tip/tilt image stabilization system. The latter allowed measurements at the extreme limb where the highly slanted rays probe into the outer layers of the photosphere. High spatial resolution "movies" of weak CO lines at disk center taken under excellent seeing conditions with the Infrared Imaging Spectrometer (IRIS), also on the McMath-Pierce telescope, further constrained thermal and velocity fluctuations in the layers in which the abundance-sensitive CO lines form. This work is meant to complement a series of recent studies which have revised the previously recommended solar oxygen abundance downward by nearly a factor of two; although in fact our conclusions do not support such a revision. The oxygen abundance recovered in the present work is 700±70~ppm (parts per million relative to hydrogen) compared with the proposed downward revision to 460±60~ppm, and the recommended value of 650±100~ppm of a decade ago. In our analysis, a fixed C/O ratio of 0.5, derived in independent work, was assumed; so the associated carbon abundance is 350~ppm. New accurate values for the solar abundance ratios of the rare isotopes of C and O also are reported: ¹²C/¹³C= 70, ¹⁶O/¹⁷O= 400, and ¹⁶O/¹⁸O= 2000. All three ratios are lower than terrestrial or meteoritic values (indicating higher isotopic abundances). We find no evidence in the ATMOS3 spectra for measurable ¹⁴C¹⁶O lines.
DE: 7500 SOLAR PHYSICS, ASTROPHYSICS, AND ASTRONOMY
DE: 7529 Photosphere
SC: Solar Physics Division - AAS [SP]
MN: 2005 Joint Assembly