High-resolution sunspot observations

H. Zirin, Haimin Wang

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


A high-resolution six-hour sequence for a stable round sunspot 22 deg from disk center reveals the following properties: 1. 1)|The inflow of penumbral material to the umbra is limited to the inner half of the penumbra. 2. 2)The outer half of the penumbra shows the Evershed effect outward flow, extending beyond the penumbra. Both proper motions and Doppler shifts of these elements are observed. The Evershed flow peaks in discrete elements, which are clearly associated with regions of stronger and more horizontal magnetic field in the outer penumbra. 3. 3)From the apparent reversal of field sign in the penumbra, we estimate that field lines emerge at angle of at least 22° to the horizontal throughout the penumbra. 4. 4)The MMF (moving magnetic features) are generally associated with bright K-line elements. While some are bipolar and most show the penumbral polarity associated with horizontal field, there are many exceptions. 5. 5)The "orphan penumbra" shows motions similar to the normal penumbra.

Original languageEnglish (US)
Pages (from-to)225-231
Number of pages7
JournalAdvances in Space Research
Issue number5
StatePublished - 1991

All Science Journal Classification (ASJC) codes

  • Aerospace Engineering
  • Astronomy and Astrophysics
  • Geophysics
  • Atmospheric Science
  • Space and Planetary Science
  • General Earth and Planetary Sciences


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