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Erratum
This article is an erratum for:
[https://doi.org/10.1051/0004-6361/202243774]

Issue
A&A
Volume 670, February 2023
Article Number C5
Number of page(s) 2
Section Letters to the Editor
DOI https://doi.org/10.1051/0004-6361/202243774e
Published online 17 February 2023

Erratum for: A&A, 661, L4 (2022), https://doi.org/10.1051/0004-6361/202243774

In the original paper, where we analyzed solar observations in bands 3, 6, and 7 of the Atacama Large Millimeter/submillimeter Array (ALMA), Eq. (1) is not accurate because the frequency variation of the Gaunt factor has been ignored. The correct expression for the reduction of data at different frequencies to a common reference frequency is asfollows:

T b ( ( f / f ref ) 2.16 μ , f ref ) = T b ( μ , f ) . $$ \begin{aligned} T_{\mathrm{b}}\left((f/f_{\mathrm{ref}})^{2.16}\mu ,f_{\mathrm{ref}}\right)=T_{\mathrm{b}}(\mu ,f) . \end{aligned} $$(1)

The value of the exponent in Eq. (1), 2.16 instead of 2 in the original paper, was determined empirically using the expression (6.1) of Zheleznyakov (1996; see also Lang 1980, p. 46) for the free-free absorption, together with the expression of Stallcop (1974) for H− absorption, in the pertinent range of the Fontenla et al. (1993) model C physical parameters. We note that this value is close to 2.1, proposed by Zirin et al. (1991).

The exact expression slightly changes the results presented in Fig. 3, Table 2, and Table 3. The corrected versions are given in this corrigendum.

We note that the electron temperature deduced from the inversion is now much closer to the prediction of model C of Fontenla et al. (1993; bottom panel of new Fig. 3). Moreover, the disk center brightness temperatures of 6271 K and 5985 K for ALMA Bands 6 and 7, respectively, are slightly lower than those reported in the original paper, which are 6347 K and 6085 K, respectively, but they are still well above the values recommended by ALMA science operations (5900 K and 5500 K, respectively).

thumbnail Fig. 1.

CLV observations and their inversion. Top row: Measured brightness temperature as a function of reference μ, for commissioning data and from the current data set. Middle row: Normalized data set. The solid line shows a third degree fit and the dash-dotted line shows a linear fit up to logμ100 = 0.8. Bottom row: Electron temperature as a function of the reference optical depth, deduced from the inversion of the observations. Model curves from Fontenla et al. (1993) and our results from Paper II are also plotted.

Table 2.

Disk center brightness temperatures.

Table 3.

Atmospheric parameters from ALMA inversion.

Acknowledgments

This paper makes use of the following ALMA data: ADS/JAO.ALMA#2019.1.01532.S. ALMA is a partnership of ESO (representing its member states), NSF (USA), and NINS (Japan), together with NRC (Canada) and NSC and ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO, and NAOJ. The authors are grateful to the AIA and GONG teams for the operation of these instruments and for making available the data to the community.

References

  1. Fontenla, J.M., Avrett, E.H., & Loeser, R. 1993, ApJ, 406, 319 (FAL93) [NASA ADS] [CrossRef] [Google Scholar]
  2. Lang, K. R. 1980, Astrophysical Formulae. A Compendium for the Physicist and Astrophysicist, XXIX (Berlin Heidelberg, New York: Springer-Verlag), Also Springer Study Edition, 783, 46 [CrossRef] [Google Scholar]
  3. Stallcop, J. R. 1974, ApJ, 187, 179 [Google Scholar]
  4. White, S. M., Iwai, K., Phillips, N. M., et al. 2017, Sol. Phys., 292, 88 [Google Scholar]
  5. Zheleznyakov, V. V. 1996, Astrophy. Space Sci. Lib., 204 [CrossRef] [Google Scholar]
  6. Zirin, H., Baumert, B. M., & Hurford, G. J. 1991, ApJ, 370, 779 [NASA ADS] [CrossRef] [Google Scholar]

© The Authors 2023

Licence Creative CommonsOpen Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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All Tables

Table 2.

Disk center brightness temperatures.

In the text
Table 3.

Atmospheric parameters from ALMA inversion.

In the text

All Figures

thumbnail Fig. 1.

CLV observations and their inversion. Top row: Measured brightness temperature as a function of reference μ, for commissioning data and from the current data set. Middle row: Normalized data set. The solid line shows a third degree fit and the dash-dotted line shows a linear fit up to logμ100 = 0.8. Bottom row: Electron temperature as a function of the reference optical depth, deduced from the inversion of the observations. Model curves from Fontenla et al. (1993) and our results from Paper II are also plotted.
In the text

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