The Structure of Solar Active Regions from EUV and Soft X-Ray Observations

Jordan, C.

doi:10.1007/978-94-010-1802-9_14

Cited by 11 publications

(1 citation statement)

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“…Cargill (1994) and Cargill & Klimchuk (2004) predicted that the EM(T) resulting from nanoflare heating should be wide, with a maximum value at T = T m ∼10 6.5 K and have a faint, high-temperature (8-10 MK) component. Below T m , there is a scaling EM(T)∼T a over a temperature range 10 6 TT m , a result first discussed by Jordan (1975). Observations from instruments on board the Solar Dynamics Observatory (SDO; Pesnell et al 2012) and Hinode spacecraft (Kosugi et al 2007) have shown that 2a5, with T m ≈10…”

Section: Introductionmentioning

confidence: 81%

Inference of Heating Properties From “Hot” Non-Flaring Plasmas in Active Region Cores. Ii. Nanoflare Trains

Barnes

Cargill

Bradshaw

2016

ApJ

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Despite its prediction over two decades ago, the detection of faint, high-temperature ("hot") emission due to nanoflare heating in non-flaring active region cores has proved challenging. Using an efficient two-fluid hydrodynamic model, this paper investigates the properties of the emission expected from repeating nanoflares (a nanoflare train) of varying frequency as well as the separate heating of electrons and ions. If the emission measure distribution (EM(T)) peaks at T = T m , we find that EM(T m ) is independent of details of the nanoflare train, and EM(T) above and below T m reflects different aspects of the heating. Below T m , the main influence is the relationship of the waiting time between successive nanoflares to the nanoflare energy. Above T m , power-law nanoflare distributions lead to an extensive plasma population not present in a mono-energetic train. Furthermore, in some cases, characteristic features are present in EM(T). Such details may be detectable given adequate spectral resolution and a good knowledge of the relevant atomic physics. In the absence of such resolution we propose some metrics that can be used to infer the presence of "hot" plasma.

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