H and K lines in the sunspot umbra: A source function and Doppler width

Teplitskaja, R. B.; Efendieva, S. A.

doi:10.1007/bf00152354

Cited by 6 publications

(2 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A consistent treatment of line formation in non-LTE (NLTE) is, however, at the limits of both the theoretical description and the commonly available computational resources (Solanki et al 1991;Carlsson & Stein 2002;Leenaarts et al 2009;Martínez-Sykora et al 2012). After a few A&A 549, A24 (2013) attempts for a direct analysis of Ca ii spectra in the quiet Sun (QS) (Liu & Skumanich 1974) or active regions (e.g., Teplitskaja & Efendieva 1975) in the 70 s and 80 s, the topic has not received much attention in recent years. Apart from the inversion code for Ca ii K spectra described in Rouppe van der Voort (2002) that is based on Shine & Linsky (1974a) and the manual inversion method for the line wings of Ca ii H and K used in Sheminova et al (2005) and Sheminova (2012), only the group led by Prof. Teplitskaya seems to have continued with the development of analysis and/or inversion tools for Ca ii H and K (Grigoryeva et al 1991(Grigoryeva et al , 2000).…”

Section: Introductionmentioning

confidence: 99%

The energy of waves in the photosphere and lower chromosphere

Beck

Rezaei

Puschmann

2012

A&A

View full text Add to dashboard Cite

Context. The Ca ii H line is one of the strongest lines in the solar spectrum, and it provides continuous information on the solar atmosphere from the photosphere to the lower chromosphere.Aims. We describe an inversion approach that reproduces observed Ca ii H spectra by assuming local thermal equilibrium (LTE). Methods. We developed an inversion strategy based on the SIR code that reproduces Ca ii H spectra in the LTE approximation. The approach uses a two-step procedure with an archive of pre-calculated spectra to fit the line core and a subsequent iterative modification to improve the fit mainly in the line wing. Simultaneous spectra in the 630 nm range can optionally be used to fix the continuum temperature. The method retrieves one-dimensional (1D) temperature stratifications while neglecting lateral radiative transport. Lineof-sight velocities are included post facto with an empirical approach.Results. An archive of about 300 000 pre-calculated spectra is more than sufficient to reproduce the line core of observed Ca ii H spectra both in the quiet Sun and in active regions. The subsequent iterative adjustment of the thermodynamical stratification matches observed and best-fit spectra to a level of about 0.5% of I c in the line wing and about 1% of I c in the line core. Conclusions. The successful application of the LTE inversion strategy suggests that inversion schemes based on pre-calculated spectra allow a reliable and relatively fast retrieval of solar properties from observed chromospheric spectra. The approach can be easily extended to a 1D non-LTE (NLTE) case by a simple exchange of the pre-calculated archive spectra. Using synthetic NLTE spectra from numerical three-dimensional (3D) simulations instead will finally allow one to extend the approach from the static 1D-case to dynamical atmosphere models, including the complete 3D radiative transport.

show abstract

Section: Introductionmentioning

confidence: 99%

The energy of waves in the photosphere and lower chromosphere

Beck

Rezaei

Puschmann

2012

A&A

View full text Add to dashboard Cite

show abstract

“…A consistent treatment of line formation in non-LTE (NLTE) is, however, at the limits of the theoretical description and the commonly available computational resources (Solanki et al 1991;Carlsson & Stein 2002;Leenaarts et al 2009;Martínez-Sykora et al 2012). After a few attempts for a direct analysis of Ca ii spectra in quiet Sun (QS) (Liu & Skumanich 1974) or active regions (e.g., Teplitskaja & Efendieva 1975) in the 70's and 80's, the topic has not received much attention in the recent years. Apart from the inversion code for Ca ii K spectra described in Rouppe van der Voort (2002) that is based on Shine & Linsky (1974a) and the manual inversion method for the line wings of Ca ii H and K used in Sheminova et al (2005) and Sheminova (2012), only the group led by Prof. Teplitskaya seems to have continued with the development of analysis and/or inversion tools for Ca ii H and K (Grigoryeva et al 1991(Grigoryeva et al , 2000(Grigoryeva et al , 2009.…”

Section: Introductionmentioning

confidence: 99%

The energy of waves in the photosphere and lower chromosphere: III. Inversion setup for Ca II H spectra in local thermal equilibrium

Beck,

Rezaei,

Puschmann

2012

Preprint

View full text Add to dashboard Cite

Context. The Ca ii H line is one of the strongest lines in the solar spectrum and provides continuous information on the solar atmosphere from the photosphere to the lower chromosphere. Aims. We describe an inversion approach that reproduces observed Ca ii H spectra assuming local thermal equilibrium (LTE). Methods. We developed an inversion strategy based on the SIR code that reproduces Ca ii H spectra in the LTE approximation. The approach uses a two-step procedure with an archive of pre-calculated spectra to fit the line core and a subsequent iterative modification to improve the fit mainly in the line wing. Simultaneous spectra in the 630 nm range can optionally be used to fix the continuum temperature. The method retrieves one-dimensional (1D) temperature stratifications neglecting lateral radiative transport. Line-of-sight velocities are included post-facto by an empirical approach.Results. An archive of about 300.000 pre-calculated spectra is more than sufficient to reproduce the line core of observed Ca ii H spectra both in quiet Sun and in active regions. The subsequent iterative adjustment of the thermodynamical stratification matches observed and best-fit spectra to a level of about 0.5 % of I c in the line wing and about 1 % of I c in the line core. Conclusions. The successful application of the LTE inversion strategy suggests that inversion schemes based on pre-calculated spectra allow one a reliable and relatively fast retrieval of solar properties from observed chromospheric spectra. The approach can be easily extended to an 1D non-LTE (NLTE) case by a simple exchange of the pre-calculated archive spectra. Using synthetic NLTE spectra from numerical three-dimensional (3D) simulations instead will finally allow one to extend the approach from the static 1D-case to dynamical atmosphere models including the complete 3D radiative transport.

show abstract

Depth-dependence of turbulence in stellar atmospheres

Stencel

Stellar Turbulence

View full text Add to dashboard Cite

I am very pleased to have this opportunity to present some recent observational work bearing on the depth dependence of motions in stellar atmospheres, I thank Dr.Gray for this invitation and also wish to acknowledge the patronage of the NAS-NRC. PhotospheresThe bulk of the work published on the depth dependence of turbulence, v(h) in stellar photospheres has tended to concern microturbulence alone. The solar case is perhaps the most well studied as both horizontal and vertical components of both micro-and macro-turbulence can be examined with depth. The recent summaries by Beckers (1975) and Canfield (1975) disclose a nearly constant 1 -2 km/s turbulence through the solar photosphere, possibly rising slightly into the upper chromosphere.Other late type stars can be compared against this best case.Arcturus is probably the next best studied case, Figure I collects several of the efforts to determine depth dependence of turbulence in its photosphere, A distinction among the types of motions measured should be noted: some techniques deliver mlcroturbulence, while others deliver a total non-thermal velocity (including micro, meso and macro-velocities). Classical curve of growth studies, such as that by Griffin and Griffin (1967), yield a mean microturbulence, a depth-averaged value probably applicable to around log optlcal depth (5000A) of -I, as deduced from moderate strength metal lines. The Goldberg-Unno (1958, 1959, which uses pairs of lines in multiplets, has been applied by Sikorski (1976) and Stenholm (1977) to deduce the variation in v(h). Curiously, despite the similarity of spectroscopic materials and method, these solutions diverge somewhat. This may suggest a limitation of the Goldberg-Unno method in non-sollr cases. A thoughrough discussion of the accuracy

show abstract

H and K lines in the sunspot umbra: A source function and Doppler width

Cited by 6 publications

References 5 publications

The energy of waves in the photosphere and lower chromosphere

The energy of waves in the photosphere and lower chromosphere

The energy of waves in the photosphere and lower chromosphere: III. Inversion setup for Ca II H spectra in local thermal equilibrium

Depth-dependence of turbulence in stellar atmospheres

Contact Info

Product

Resources

About