Fourier transform spectrometer observations of solar carbon monoxide. I. The fundamental and first overtone bands in the quiet sun

Journal Article · Fri May 01 04:00:00 EDT 1981 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/158888· OSTI ID:6338445

Ayers, T R; Testerman, L

We describe measurements of the 2200 cm/sup -1/ fundamental (..delta..V = 1) and 4300 cm/sup -1/ first overtone (..delta..V = 2) vibration-rotation band systems of solar carbon monoxide. Our observations were obtained with the Fourier Transform Spectrometer of the McMath telescope at Kitt Peak. The overtone measurements were taken at the East, North, and West heliocentric limbs (..mu.. = 0.2) and at disk center. Spectrum ratio techniques were used to eliminate terrestrial absorption effects in the East/West and North/Center pairs. Observations of the strong fundamental bands were obtained at disk center and near the North limb. We confirm the surprisingly low core brightness temperatures of the strongest CO..delta..V = 1 lines near the limb reported previously by Noyes and Hall. Based on numerical spectrum simulations, we find that the fundemental band core brightness temperatures are incompatible with the cool photosphere of the Vernazza et al. reference model, as well as with the presence of a chromospheric temperature inversion at the tau/sub 5000tsA/ = 10/sup -3.5/ level. Instead, the ..delta..V = 1 lines seem to require a comparitively hot outer photosphere, but with monotonically declining temperatures in the atmospheric layers where homogeneous models would place a chromospheric temperature inversion. We have examined the possibility that thermal inhomogeneities might be responsible for the unusual behavior of the ..delta..V = 1 CO lines. We find that the class of horizontally sinusoidal thermal perturbations proposed by Keil and Canfield have little effect on deriving a mean model and are not likely responsible for the ''chromosphereless'' behavior of the CO fundamental features. However, the somewhat discordant behavior of the ..delta..V = 1 lines at disk center compared with the North limb (..mu.. = 0.2) seems to favor a limb shadowing effect, whereby the cooler components of a structured atmosphere are more heavily weighted than the hotter components for limb lines of sight. The lack

• Research Organization: Joint Institute for Laboratory Astrophysics, University of Colorado and National Bureau of Standards
• OSTI ID: 6338445
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 245:3; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640104* -- Astrophysics & Cosmology-- Solar Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ABUNDANCE
ATMOSPHERES
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CHALCOGENIDES
CHEMICAL COMPOSITION
CHROMOSPHERE
DATA ANALYSIS
ENERGY LEVELS
EXCITED STATES
FUNCTIONAL MODELS
INFRARED SPECTRA
MATHEMATICAL MODELS
OXIDES
OXYGEN COMPOUNDS
PHOTOSPHERE
ROTATIONAL STATES
SIMULATION
SOLAR ATMOSPHERE
SPECTRA
STAR MODELS
VIBRATIONAL STATES