ALMA as a Prominence Thermometer: First Observations

0556099 - ASÚ 2023 RIV US eng J - Journal Article
Heinzel, Petr - Berlicki, Arkadiusz - Bárta, Miroslav - Rudawy, P. - Gunár, Stanislav - Labrosse, N. - Radziszewski, K.
ALMA as a Prominence Thermometer: First Observations.
Astrophysical Journal Letters. Roč. 927, č. 2 (2022), č. článku L29. ISSN 2041-8205. E-ISSN 2041-8213
R&D Projects: GA ČR GA19-16890S; GA ČR(CZ) GA19-17102S; GA ČR(CZ) GC20-09922J; GA MŠMT(CZ) LM2018106
Institutional support: RVO:67985815
Keywords : ALMA * solar prominences * solar and stellar astrophysics
OECD category: Astronomy (including astrophysics,space science)
Impact factor: 7.9, year: 2022
Method of publishing: Open access

We present first prominence observations obtained with Atacama Large Millimeter Array (ALMA) in Band 3 at the wavelength of 3 mm. High-resolution observations have been coaligned with the MSDP H alpha data from Wroclaw-Bialkow large coronagraph at similar spatial resolution. We analyze one particular cotemporal snapshot, first calibrating both ALMA and MSDP data and then demonstrating a reasonable correlation between both. In particular, we can see quite similar fine-structure patterns in both ALMA brightness-temperature maps and MSDP maps of H alpha intensities. Using ALMA, we intend to derive the prominence kinetic temperatures. However, having current observations only in one band, we use an independent diagnostic constraint, which is the H alpha line integrated intensity. We develop an inversion code and show that it can provide realistic temperatures for brighter parts of the prominence where one gets a unique solution, while within faint structures, such inversion is ill conditioned. In brighter parts, ALMA serves as a prominence thermometer, provided that the optical thickness in Band 3 is large enough. In order to find a relation between brightness and kinetic temperatures for a given observed H alpha intensity, we constructed an extended grid of non-LTE prominence models covering a broad range of prominence parameters. We also show the effect of the plane-of-sky filling factor on our results.
Permanent Link: http://hdl.handle.net/11104/0330924