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HINODE Operation Plan (HOP)

accepted on


 HOP No.

 HOP title

HOP 0405

Interaction between inclined magnetic fields and convection

plan term


@ @


 name : Rivas, Vissers @  e-mail : rivas[at]asu.cas.cz, gregal.vissers[at]astro.su.se

contact person in HINODE team

 name : DeRosa, Shine @  e-mail : derosa[at]lmsal.com, shine[at]lmsal.com

 abstract of observational proposal
Main Objective:
Analysis of the effects of inclined magnetic fields on different convective modes.

Scientific Justification:
The influence of inclined magnetic fields on convection was derived by Chandrasekhar (1961, Hydrodynamic and hydromagnetic stability); he showed that the convection mode is sensitive to the vertical magnetic field (Bver), whereas the convective cells' shape is sensitive to the horizontal component (Bhor). Gough & Tayler (1966) described the role of Bver in the convective instability criterion.

A constant value of the vertical magnetic field (Bcrit) was found in a statistical analysis of umbra-penumbra boundaries of stable sunspots (Jurcak et al. 2018). This study and previous studies (Jurcak 2011; Jurcak et al. 2015; Jurcak et al. 2017) lead to the formulation of Jurcak criterion, an empirical law stating that the umbral boundary of stable sunspots can be equivalently defined by a continuum intensity or a vertical magnetic field component |Bver|. In other words, in areas with |Bver| > Bcrit , only the umbral mode of convection exists, hindering other modes of magneto-convection. A conjecture can also be stated from these findings: umbral areas with |Bver| < Bcrit are unstable against more vigorous modes of convection, that is, they are prone to vanish (Schamssmann et al. 2018).

We aim to study inclined magnetic fields on different convective modes and analyse their influence.

 request to SOT
SOT-SP is required. Fast mode maps. FoV of 164" x 164"

 request to XRT

 request to EIS

 other participating instruments
Program B1
Target: AR granulation
3620256363  |  Medium dense 96-step raster 31.35x60 96s  C II   Mg II h/k   Mg II w s  |     504.26    |     469.56    |      0.63     |  5.3+/-0.1 |  504+/-0   | 12.6+/-4.3 |  0.0+/-0.0 | 10.5+/-0.1 | 63.0+/-0.0

Program B2
Target: QS granulation
3620506363  |  Medium dense 96-step raster 31.35x60 96s  C II   Mg II h/k   Mg II w s  |     496.02    |     373.34    |      0.51     |  5.2+/-0.1 |  496+/-0   | 12.4+/-4.3 |  0.0+/-0.0 | 10.3+/-0.1 | 62.0+/-0.0

Swedish Solar Telescope (SST) /CRISP
POC: Vissers, Gregal <gregal.vissers@astro.su.se>

Dates: 24 - 30 August 2020
Time window: Observations at SST telescope are expected to run from 07:00 UT to 15:00 UT.

Target(s) of interest: Target of opportunity: active regions. From emerging active regions to pores and sunspots.

Previous HOPs: HOP 0384

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