New identifications of disk emission lines in the Ca ii H and K line wings

Engvold, O.; Halvorsen, Henrik

doi:10.1007/bf00152907

Cited by 6 publications

(4 citation statements)

References 7 publications

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“…We may comment that no cycle variation is seen in the strength of the very weak rare earth emission lines of Ce II 3967.043 and Nd II 3934.798 found in the wings of H and K, see Fig. 1 (Engvold & Halvorsen 1973). Time series analysis shows the relative intensity of Ce II is (0.005±0.0006)+0.00016y, and Nd II is (0.1±0.003)−(6.8e-06)y, where y=year−1900.…”

Section: Results For Chromospheric Linesmentioning

confidence: 91%

Sun‐as‐a‐Star Spectrum Variations 1974–2006

Livingston

Wallace

White³

et al. 2007

ApJ

141

152

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We have observed selected Fraunhofer lines, both integrated over the Full Disk and for a small circular region near the center of the solar disk, on 1215 days for the past 30 years. Full Disk results: Chromosphere: Ca II K 3933Å nicely tracks the 11 year magnetic cycle based on sunspot number with a peak amplitude in central intensity of ∼37%. The wavelength of the mid-line core absorption feature, called K3, referenced to nearby photospheric Fe, displays an activity cycle variation with an amplitude of 3 mÅ. The separation of the K2 red and blue emission features has increased during the 1976-2006 period of our program. Other chromospheric lines such as He I 10830Å, Ca II 8542Å, Hα , and the CN 3883Å bandhead track Ca II K intensity with lower relative amplitudes. Low photosphere: Temperature sensitive CI 5380Å appears constant in intensity to 0.2%. High photosphere: The cores of strong Fe I lines, Na D1 and D2, and the Mg I b lines, present a puzzling signal perhaps indicating a role for the 22 y Hale cycle. Solar minimum around 1985 was clearly seen, but the following minimum in 1996 was missing. This anomalous behavior, which is not seen in comparison atmospheric O 2 , requires further observations and theoretical inquiry. Center Disk results: Both Ca II K and C I 5380Å intensities are constant, indicating that the basal quiet atmosphere is unaffected by cycle magnetism within our observational error. A lower limit to the Ca II K central intensity atmosphere is 0.040. This possibly represents conditions as they were during the Maunder Minimum. Converted to the Mt Wilson S-index (H+K index) the Sun Center Disk is at the lower activity limit for solar-type stars. The Wavelength of Ca II K3 varies with the cycle by 6 mÅ, a factor of 2X over the full disk value. This may indicate the predominance of radial motions at Center Disk. This is not an effect of motions in plages since they are absent at Center Disk. This 11 y variation in the center of chromospheric lines could complicate the radial velocity detection of planets around solar-type stars. An appendix provides instructions for URL access to both the raw and reduced data.

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Section: Results For Chromospheric Linesmentioning

confidence: 91%

Sun‐as‐a‐Star Spectrum Variations 1974–2006

Livingston

Wallace

White³

et al. 2007

ApJ

141

152

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“…The spectral line seen in emission between Ca ii H and Hǫ up to a height of nearly 2 Mm should pertain to singly ionized iron (cf. Engvold and Halvorsen 1973;Lites 1974;Rutten and Stencel 1980;Watanabe and Steenbock 1986;Schmidt and Fisher 2013). Figure 13 shows the FWHM of the laterally averaged profiles for He i at 1083 nm, Ca ii H and Hǫ.…”

Section: (Pseudo-)slit-spectrograph Datamentioning

confidence: 99%

Spectroscopy at the Solar Limb: II. Are Spicules Heated to Coronal Temperatures?

Beck

Rezaei

Puschmann³

et al. 2016

Sol Phys

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Spicules of the so-called type II were suggested to be relevant for coronal heating because of their ubiquity on the solar surface and their eventual extension into the corona. We investigate whether solar spicules are heated to transition-region or coronal temperatures and reach coronal heights (≫ 6 Mm) using multi-wavelength observations of limb spicules in different chromospheric spectral lines (Ca ii H, Hǫ, Hα, Ca ii IR at 854.2 nm, He i at 1083 nm) taken with slit-spectrographs and imaging spectrometers. We determine the line width of spectrally resolved line profiles in individual spicules and throughout the field of view and estimate the maximal height that different types of off-limb features reach. We derive estimates of the kinetic temperature and the non-thermal velocity from the line width of spectral lines from different chemical elements. We find that most regular -i.e., thin and elongated -spicules reach a maximal height of about 6 Mm above the solar limb. The majority of features found at larger heights are irregularly shaped with a significantly larger lateral extension -of up to a few Mm -than spicules. Both individual and average line profiles in all spectral lines show a decrease in their line width with height above the limb with very few exceptions. Both the kinetic temperature and the non-thermal velocity decrease with height above the limb. We find no indications that the spicules in our data reach coronal heights or transition-region or coronal temperatures.

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“…The Fe ii line near 396.94 nm reverts to emission, as do some of the other blends, but none as strong as this one (see Engvold & Halvorsen 1973;Rutten & Stencel 1980). This line is consequently interesting for detailed quantitative analyses as well (Lites 1974;Watanabe & Steenbock 1986), to avoid solely using the Ca ii H line core, even if Cram et al (1980) found a photospheric origin for the emission in this line.…”

Section: Average Off-limb Spectramentioning

confidence: 76%

Spectroscopy at the solar limb

Beck

Rezaei²

2011

A&A

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Aims. We present constraints on the thermodynamical structure of the chromosphere from ground-based observations of the Ca ii H line profile near and off the solar limb. Methods. We obtained a slit-spectrograph data set of the Ca ii H line with a high signal-to-noise ratio in a field of view extending 20 across the limb. We analyzed the spectra for the characteristic properties of average and individual off-limb spectra. We used various tracers of the Doppler shifts, such as the location of the absorption core, the ratio of the two emission peaks H 2V and H 2R , and intensity images at a fixed wavelength. Results. The average off-limb profiles show a smooth variation with increasing limb distance. The line width increases up to a height of about 2 Mm above the limb. The profile shape is fairly symmetric with nearly identical H 2V and H 2R intensities; at a height of 5 Mm, it changes into a single Gaussian without emission peaks. We find that all off-limb spectra show large Doppler shifts that fluctuate on the smallest resolved spatial scales. The variation is more prominent in cuts parallel to the solar limb than on those perpendicular to it. As far as individual structures can be unequivocally identified at our spatial resolution, we find a specific relation between intensity enhancements and Doppler shifts: elongated brightenings are often flanked all along their extension by velocities in opposite directions. Conclusions. The average off-limb spectra of Ca ii H present a good opportunity to test static chromospheric atmosphere models because they lack the photospheric contribution that is present in disk-center spectra. We suggest that the observed relation between intensity enhancements and Doppler shifts could be caused by waves propagating along the surfaces of flux tubes: an intrinsic twist of the flux tubes or a wave propagation inclined to the tube axis would cause a helical shape of the Doppler excursions, visible as opposite velocity at the sides of the flux tube. Spectroscopic data allow one to distinguish this from a sausage-mode oscillation where the maximum Doppler shift and the tube axis would coincide.

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New identifications of disk emission lines in the Ca ii H and K line wings

Cited by 6 publications

References 7 publications

Sun‐as‐a‐Star Spectrum Variations 1974–2006

Sun‐as‐a‐Star Spectrum Variations 1974–2006

Spectroscopy at the Solar Limb: II. Are Spicules Heated to Coronal Temperatures?

Spectroscopy at the solar limb

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