Found 2 talks width keyword Hinode

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Tuesday June 8, 2021
Mapping the Sun's upper photosphere with artificial neural networks
IAC

Abstract

In this talk I'll present results from a recent paper in which we have developed a new analysis technique for solar spectra based on artificial neural networks. Our first test applications yielded some unexpected and interesting results. The fine-scale network of temperature enhancements in the quiet middle and upper photosphere have a reversed pattern. Hot pixels in the middle photosphere, possibly associated with small-scale magnetic elements, appear cool at higher levels (log(tau)=-3 and -4), and vice versa. We also find hot arcs on the limb side of magnetic pores, which we interpret as the first direct observational evidence of the "hot wall" effect. Hot walls are a prediction of theoretical models from the 1970s which had not been observed until now.
Archived in: Stars - Keywords:Machine learning, atomic processes, magnetic fields, quantum mechanics, radiative transfer, scattering, stellar dynamics, turbulence, stars spots, stellar activity, Hinode, polarimeters, spectrographs, solar granulation, solar magnetic fields, solar photosphere, sunspots
Abstract


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Friday January 30, 2009
Quiet Sun magnetism and Alfven waves as observed with Hinode
National Astronomical Observatory, Japan

Abstract

The magnetic landscape of the polar region (Tsuneta et al, 2008) is characterized by vertical kilogauss patches with super-equipartition field strength, a coherence in polarity, lifetimes of 5-15 hr, and ubiquitous weaker transient horizontal fields (Lites et al 2008, Ishikawa & Tsuneta, 2008, 2009). Polar region in 2007 have abundant vertical fields much stronger than the quiet Sun. Unipolar appearance and disappearance of the kG vertical patches must be closely related to properties of the horizontal flow field in the polar region. Difference and similarity between the quiet sun and the polar region are summarized, and its implication for solar dynamo will be discussed. All the open field lines forming the polar coronal hole essentially originate from such magnetic patches, and the fast solar wind would emanate from these vertical flux tubes seen in the photosphere. We conjecture that vertical flux tubes with large expansion around the photospheric-coronal boundary serve as efficient chimneys for Alfven waves that accelerate the solar wind. Indeed, we discovered propagating Alfven waves (kink mode) with magneto-acoustic waves (sausage mode) in the solar photosphere with period of 4-13 minutes with Hinode spectro-polarimeter (Fujimura and Tsuneta, 2009). We found that these fluctuations are superposition of ascending and descending Alfven waves with almost equal intensities from the analysis of the phase relationship between transverse magnetic and velocity fluctuations. Aflven waves along flux tubes in the quiet sun appear to be efficiently reflected back probably at photosphere-corona boundary. It would be very interesting to measure possible change in the reflectivity of Alfven waves depending on the magnetic environment.

Archived in: The Sun - Keywords:solar magnetic fields, solar interior, Hinode
Abstract


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