منابع مشابه
Helicity at Photospheric and Chromospheric Heights
In the solar atmosphere the twist parameter α has the same sign as magnetic helicity. It has been observed using photospheric vector magnetograms that negative/positive helicity is dominant in the northern/southern hemisphere of the Sun. Chromospheric features show dextral/sinistral dominance in the northern/southern hemisphere and sigmoids observed in X-rays also have a dominant sense of rever...
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In this topical review I revisit the “chromospheric flare”. This should currently be an outdated concept, because modern data seem to rule out the possiblity of a major flare happening independently in the chromosphere alone, but the chromosphere still plays a major observational role in many ways. It is the source of the bulk of a flare’s radiant energy – in particular the visible/UV continuum...
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We have studied the evolution of magnetic helicity and chirality in an active region over three consecutive solar rotations. The region when it first appeared was named NOAA10923 and in subsequent rotations it was numbered NOAA 10930, 10935 and 10941. We compare the chirality of these regions at photospheric, chromospheric and coronal heights. The observations used for photospheric and chromosp...
متن کاملChromospheric Oscillations
We show results from NSO/Sacramento Peak data to discuss three issues: (i)—the spatial occurrence of chromospheric 3–min oscillations; (ii)—the validity of Ca II H&K line-center Doppler Shift measurements; (iii)—the significance of oscillation power and phase at frequencies above 10 mHz.
متن کاملMg ii chromospheric radiative loss rates in cool active and quiet stars
The Mg ii k emission line is a good indicator of the level of chromospheric activity in late–type stars. We investigate the dependence of this activity indicator on fundamental stellar parameters. To this purpose we use IUE observations of the Mg ii k line in 225 late–type stars of luminosity classes I–V, with different levels of chromospheric activity. We first re–analyse the relation between ...
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ژورنال
عنوان ژورنال: Symposium - International Astronomical Union
سال: 1968
ISSN: 0074-1809
DOI: 10.1017/s0074180900021604