The Lyman-alpha line in various solar features. I - Observations

Fontenla, J. M.; Reichmann, E. J.; Tandberg-Hanssen, E.

doi:10.1086/166392

Cited by 56 publications

(66 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…There is no doubt that most of the Ly-α and Ly-β emissions come from the chromosphere and lower TR (Fontenla et al 1988). Network is the location where magnetic flux converges, and from which magnetic funnels (which might be related to solar wind, or just be the legs of trans-network loops) originate (Peter 2001).…”

Section: The Self-reversal Of the Profilesmentioning

confidence: 99%

“…And thus its resonance lines, especially the Lyman-alpha (Ly-α) and Lyman-beta (Ly-β) lines, play an important role in the overall radiative energy transport of the Sun (Fontenla et al 1988).…”

Section: Introductionmentioning

confidence: 99%

“…It is so dominant that ≈75% of the integrated radiance from 800 Å to 1500 Å in the quiet Sun come from this single line . Energy losses through the Ly-α emission are the most important radiative losses in the lower transition region, where the approximate temperature ranges from 8000 K to 30 000 K (Fontenla et al 1988). Also, the spectral irradiance at the center of the solar Ly-α line profile is the main excitation source responsible for the atomic hydrogen resonant scattering in cool cometary and planetary material, and thus is required in modelling the Ly-α emissions occurring in cool interplanetary environments .…”

Section: Introductionmentioning

confidence: 99%

“…Basri et al (1979) used high-resolution Ly-α spectra obtained by the HRTS (High Resolution Telescope and Spectrograph) instrument on rocket flight to investigate the network contrast and center-to-limb variation in the line profiles. Later, Ly-α profiles with both high spectral and spatial resolutions were obtained by the UVSP instrument onboard SMM (Solar Maximum Mission, e.g., Fontenla et al 1988). The early studies on the Ly-α and Ly-β line profiles revealed clearly that the Lyman lines are highly variable not only in time, but also in space.…”

Section: Introductionmentioning

confidence: 99%

“…Observations have shown that the self-reversals are almost absent in sunspot regions (Fontenla et al 1988;Curdt et al 2001;Tian et al 2009). In contrast, the lower Lyman line profiles observed in the plage region are obviously reversed, a phenomenon also found in the normal quiet Sun (Tian et al 2009).…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Hydrogen Lyman-α and Lyman-β spectral radiance profiles in the quiet Sun

Curdt

Marsch

Schühle

2009

A&A

View full text Add to dashboard Cite

Aims. We extend earlier work by studying the line profiles of the hydrogen Lyman-α and Lyman-β lines in the quiet Sun. They were obtained quasi-simultaneously in a raster scan with a size of about 150 × 120 near disk center. Methods. The self-reversal depths of the Ly-α and Ly-β profiles. we are quantified by measuring the maximum spectral radiances of the two horns and the minimum spectral radiance of the central reversal. The information on the asymmetries of the Ly-α and Ly-β profiles is obtained through calculating the 1st and 3rd-order moments of the line profiles. By comparing maps of self-reversal depths and the moments with radiance images of the Lyman lines, photospheric magnetograms, and Dopplergrams of two other optically thin lines, we studied the spatial distribution of the Ly-α and Ly-β profiles with different self-reversal depths, and investigated the relationship between profile asymmetries and flows in the solar atmosphere. Results. We find that the emissions of the Lyman lines tend to be more strongly absorbed in the internetwork, as compared to those in the network region. Almost all of the Ly-α profiles are self-reversed, while about 17% of the Ly-β profiles are not reversed. The ratio of Ly-α and Ly-β intensities seems to be independent of the magnetic field strength. Most Ly-α profiles are stronger in the blue horn, whereas most Ly-β profiles are stronger in the red horn. However, the opposite asymmetries of Ly-α and Ly-β are not correlated pixelto-pixel. We also confirm that when larger transition-region downflows are present, the Ly-α and Ly-β profiles are more enhanced in the blue and red horns, respectively. The first-order moment of Ly-β, which reflects the combined effects of the profile asymmetry and motion of the emitting material, strongly correlates with the Doppler shifts of the Si iii and O vi lines, while this correlation is much weaker for Ly-α. Our analysis shows that both Ly-α and Ly-β might be more redshifted if stronger transition-region downflows are present. We also find that the observed average Ly-β profile is redshifted with respect to its rest position.

show abstract

Section: The Self-reversal Of the Profilesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%