Optically thick lines in a quiescent prominece: Profiles of Ly. cap alpha. , Ly. beta. (H I), k and h (Mg II) and K and H (Ca II) lines with the OSO 8 LPSP instrument
A full set of observations of the resonance lines of Mg II, Ca II, H I (and O VI) and the Ly..beta..(H I) line has been obtained with the LPSP instrument on OSO 8. The observing modes (images, profiles) and the procedures of analysis are described, and special attention is paid to the intensity calibrations. Typical line profile parameters (widths,intensities) are summarized in Table 1. The Ca II lines have a low opacity: in the K line center it varies from 1.4 to 3.2. Nonthermal velocities range from 5 to 9 km s/sup -1/, and line shifts are small but reach 8 km s/sup -1/ at the edges. Intensities are lower than the incident chromospheric intensities multiplied by the dilution factor. The ratio of K/sub 3/ and H/sub 3/ intensities (K/sub 3//H/sub 3/) is approx.1.4. The Mg II lines are measured in the whole prominence only. Departures from Gaussian profiles may result from the integration of many elements with different velocities along the line of sight and also from line saturation. However, we observe an intensity ratio k/h of approx.1.6, higher than the K/H ratio (as it is in the chromosphere). This result can be understood if the source function of resonance lines of Mg II and Ca II is dominated by the incident radiation, but the important width of Mg II lines, as compared to Ca II lines, is not explained. The full profiles of Ly..cap alpha.. and Ly..beta.. (H I) lines are observed for the first time in a quiescent prominence. Both are reversed, with a separation of 0.35-0.40 A for Ly..cap alpha.. and 0.33 A for Ly..beta... Intensities are about equal to the incident chromospheric intensities multiplied by the dilution factor. Opacities are very high, and the radiation transfer is dominated by the scattering of chromospheric Ly..cap alpha.. and Ly..beta.. photons. The Ly..cap alpha../Ly..beta.. ratio is lower than the chromospheric one. The ratio of ly..cap alpha.. to Ca K intensities does not vary very much. Both features indicate that the ionizing Lyman continuum penetrates fully in the prominence.
- Research Organization:
- Laboratoire de Physique Stellaire et Planetaire
- OSTI ID:
- 5202060
- Journal Information:
- Astrophys. J.; (United States), Vol. 253:1
- Country of Publication:
- United States
- Language:
- English
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GENERAL PHYSICS
SOLAR PROMINENCES
ULTRAVIOLET SPECTRA
CALCIUM IONS
DATA PROCESSING
HYDROGEN
LYMAN LINES
MAGNESIUM IONS
OPACITY
SPECTRAL FUNCTIONS
CHARGED PARTICLES
ELEMENTS
FUNCTIONS
IONS
NONMETALS
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
PROCESSING
SOLAR ACTIVITY
SPECTRA
640104* - Astrophysics & Cosmology- Solar Phenomena