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HINODE Operation Plan (HOP)

accepted on


 HOP No.

 HOP title

HOP 0087

Too: Structure and dynamics of penumbral filaments

plan term


@ @


 name : Socas-Navarro, Carnonell, Centeno Puschmann, Cobo @  e-mail : hsocas[at]iac.es

contact person in HINODE team

 name : Berger @  e-mail : berger[at]lmsal.com

 abstract of observational proposal
The filamentary structure of the penumbra remains largely enigmatic, although important advances have been done recently thanks to the high resolution capabilities of modern solar instrumentation such as the discovery of the dark cores and the observation of the bright filaments internal structure. Still, we are not at a point where we can compare with magneto-convection simulations, partly because it is not clear what their actual shape is, their magnetic properties, the nature of the Evershed flow, the supersonic flows that are sometimes observed, etc.

One needs spectro-polarimetric observations in order to reconstruct a 3D picture via application of inversion techniques. This was first done by Westendorp Plaza et al (1998) applying the code SIR to ASP observations. Advances have been made during this last decade both in instrumentation and in the inversion procedures. However, a big issue that remains to be solved is how to transform the results from the optical depth scale to a common geometrical height scale because, even though the inversions give us the depth stratification of the atmosphere at each observed pixel in the field of view this is done on an optical depth scale. And what is even more complicated is that one then needs to find a common reference height for neighboring pixels. Fortunately, a new method has been derived recently (Puschmann et al, in preparation) that uses the div(B)=0 condition to establish the 3D height scale. This method has been satisfactorily tested with Hinode SP observations of a sunspot.

We intend to use the inversion techniques mentioned above, including the new method to obtain the height stratification, to derive the 3D structure of a bundle of penumbral filaments and repeat the process for several successive scans so that we can observe the evolution with time of their structure. The work consists of two parts, one in which we use very short scans (about 10 slit positions) to try to resolve oscillations in time, and another one with wider scans (about 50 slit positions) to observe a larger field of view and look at the evolution on longer time scales.

 request to SOT
Required Hinode instruments: SOT SP with Q75 jpeg compression. Field of view along the slit restricted to sunspot size, probably no larger than 40h. Simultaneous BFI data with CaII H line core would be desirable.

 request to XRT

 request to EIS

 other participating instruments

Time period of observations: No specific requirement
Time window in day: No specific requriement
Target of interest: Sunspot (if possible round, near disk center)

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