WFRF:(Joshi Jayant)
Sökning: WFRF:(Joshi Jayant) > Line formation of H...
Line formation of He I D3 and He I 10 830 Å in a small-scale reconnection event
-
- Libbrecht, Tine (författare)
- Stockholms universitet,Institutionen för astronomi
-
- Bjørgen, Johan P. (författare)
- Stockholms universitet,Institutionen för astronomi,University of Oslo, Norway
-
- Leenaarts, Jorrit (författare)
- Stockholms universitet,Institutionen för astronomi
- visa fler...
- Hansteen, Viggo (författare)
- Joshi, Jayant (författare)
- visa färre...
- (creator_code:org_t)
- 2021-08-25
- 2021
- Engelska.
- Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 652
- Tidskriftsartikel (refereegranskat)
Abstract
Ämnesord
Stäng
- Context. Ellerman bombs (EBs) and UV bursts are small-scale reconnection events that occur in the region of the upper photosphere to the chromosphere. It has recently been discovered that these events can have emission signatures in the He I D3 and He I 10 830 Å lines, suggesting that their temperatures are higher than previously expected.Aims. We aim to explain the line formation of He I D3 and He I 10 830 Å in small-scale reconnection events.Methods. We used a simulated EB in a Bifrost-generated radiative magnetohydrodynamics snapshot. The resulting He I D3 and He I 10 830 Å line intensities were synthesized in 3D using the non-local thermal equilibrium (non-LTE) Multi3D code. The presence of coronal extreme UV (EUV) radiation was included self-consistently. We compared the synthetic helium spectra with observed raster scans of EBs in He I 10 830 Å and He I D3 obtained at the Swedish Solar Telescope with the TRI-Port Polarimetric Echelle-Littrow Spectrograph.Results. Emission in He I D3 and He I 10 830 Å is formed in a thin shell around the EB at a height of ∼0.8 Mm, while the He I D3 absorption is formed above the EB at ∼4 Mm. The height at which the emission is formed corresponds to the lower boundary of the EB, where the temperature increases rapidly from 6 × 103 K to 106 K. The synthetic line profiles at a heliocentric angle of μ = 0.27 are qualitatively similar to the observed profiles at the same μ-angle in dynamics, broadening, and line shape: emission in the wing and absorption in the line core. The opacity in He I D3 and He I 10 830 Å is generated through photoionization-recombination driven by EUV radiation that is locally generated in the EB at temperatures in the range of 2 × 104 − 2 × 106 K and electron densities between 1011 and 1013 cm−3. The synthetic emission signals are a result of coupling to local conditions in a thin shell around the EB, with temperatures between 7 × 103 and 104 K and electron densities ranging from ∼1012 to 1013 cm−3. This shows that both strong non-LTE and thermal processes play a role in the formation of He I D3 and He I 10 830 Å in the synthetic EB/UV burst that we studied.Conclusions. In conclusion, the synthetic He I D3 and He I 10 830 Å emission signatures are an indicator of temperatures of at least 2 × 104 K; in this case, as high as ∼106 K.
Ämnesord
- NATURVETENSKAP -- Fysik (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences (hsv//eng)
Nyckelord
- Sun: chromosphere
- Sun: magnetic fields
- radiative transfer
- line: formation
Publikations- och innehållstyp
- ref (ämneskategori)
- art (ämneskategori)
Hitta via bibliotek
- Astronomy and Astrophysics (Sök värdpublikationen i LIBRIS)
Till lärosätets databas
Hitta mer i SwePub
- Av författaren/redakt...
- Libbrecht, Tine
- Bjørgen, Johan P ...
- Leenaarts, Jorri ...
- de la Cruz Rodrí ...
- Hansteen, Viggo
- Joshi, Jayant
- Om ämnet
-
- NATURVETENSKAP
- NATURVETENSKAP
- och Fysik
- Artiklar i publikationen
- Astronomy and As ...
- Av lärosätet
- Stockholms universitet
Sök utanför SwePub
- Sök vidare i:
- Google Book Search
- Google Scholar
Kungliga biblioteket hanterar dina personuppgifter i enlighet med EU:s dataskyddsförordning (2018), GDPR. Läs mer om hur det funkar här.
Så här hanterar KB dina uppgifter vid användning av denna tjänst.
- Copyright © LIBRIS - Nationella bibliotekssystem
- LIBRIS.kb.se
