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

Journal Article · Mon Feb 01 04:00:00 EST 1982 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/159639· OSTI ID:5202060

Vial, J C

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), Journal Name: Astrophys. J.; (United States) Vol. 253:1; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640104* -- Astrophysics & Cosmology-- Solar Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CALCIUM IONS
CHARGED PARTICLES
DATA PROCESSING
ELEMENTS
FUNCTIONS
HYDROGEN
IONS
LYMAN LINES
MAGNESIUM IONS
NONMETALS
OPACITY
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
PROCESSING
SOLAR ACTIVITY
SOLAR PROMINENCES
SPECTRA
SPECTRAL FUNCTIONS
ULTRAVIOLET SPECTRA