| Issue |
A&A
Volume 607, November 2017
|
|
|---|---|---|
| Article Number | C3 | |
| Number of page(s) | 1 | |
| Section | The Sun | |
| DOI | https://doi.org/10.1051/0004-6361/201730413e | |
| Published online | 16 November 2017 | |
Measuring the magnetic field of a trans-equatorial loop system using coronal seismology (Corrigendum)
1 UCL–Mullard Space Science Laboratory, Holmbury House, Holmbury St. Mary, Dorking, Surrey, RH5 6NT, UK
e-mail: david.long@ucl.ac.uk
2 Mathematics, Physics and Electrical Engineering, Northumbria University, Newcastle Upon Tyne, NE1 8ST, UK
3 Instituto de Astronomía y Física del Espacio (IAFE), CONICET-UBA, Buenos Aires, Argentina
4 Facultad de Ciencias Exactas y Naturales (FCEN), UBA, Buenos Aires, Argentina
Key words: Sun: corona / Sun: magnetic fields / Sun: oscillations / errata, addenda
It has been brought to our attention (B. Roberts, 2017, priv. comm.) that the formula used in Eq. (2) of our paper (Long et al. 2017) was incorrect. This equation should instead have read 
(1)where B is the magnetic field strength, L is the loop length, P is the period of the oscillation, ρin is the internal density of the loop system and ρex is the external density of the surrounding corona (cf. Roberts et al. 1984; Nakariakov & Ofman 2001; Van Doorsselaere et al. 2008a; Aschwanden & Schrijver 2011). As a result of the incorrect equation used, the value of the magnetic field strength estimated using the oscillation of the transequatorial loop system quoted in Sect. 5.1 of Long et al. (2017) is also incorrect. It should instead be B ≈ 2.4 ± 0.6 G.
Although this value is lower than the original (incorrect) value quoted in Long et al. (2017), it does not affect the qualitative results or conclusions of the paper. The magnetic field strength estimated using the oscillation of the transequatorial loop system is still comparable to the values estimated using both the independent magnetoseismology approach of Morton et al. (2015, 2016) and the extrapolated magnetic field obtained from both the HMI and GONG magnetograms. This indicates that the approach is still sound, albeit with a lower estimated value.
References
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© ESO, 2017
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