Properties of the inner penumbral boundary and temporal evolution of a decaying sunspot

0499770 - ASÚ 2019 RIV FR eng J - Journal Article
Benko, M. - Manrique, S. J. G. - Balthasar, H. - Gömöry, P. - Kuckein, C. - Jurčák, Jan
Properties of the inner penumbral boundary and temporal evolution of a decaying sunspot.
Astronomy & Astrophysics. Roč. 620, December (2018), č. článku A191. ISSN 0004-6361. E-ISSN 1432-0746
Institutional support: RVO:67985815
Keywords : Sun * photosphere * activity
OECD category: Astronomy (including astrophysics,space science)
Impact factor: 6.209, year: 2018

We analyzed the evolution of the photospheric magnetic field properties of a decaying sunspot belonging to NOAA 11277 between August 28-September 3, 2011. The observations were acquired with the spectropolarimeter on-board of the Hinode satellite. We aim to prove the validity of the constant vertical magnetic-field boundary between the umbra and penumbra in decaying sunspots. We find a linear decay of the umbral vertical magnetic field, magnetic flux, and area. The penumbra showed a linear increase of the vertical magnetic field and a sharp decay of the magnetic flux. In addition, the penumbral area quadratically decayed. The vertical component of the magnetic field is weaker on the umbra-penumbra boundary of the studied decaying sunspot compared to stable sunspots. Its value seem to be steadily decreasing during the decay phase. Moreover, at any time of the sunspot decay shown, the inner penumbra boundary does not match with a constant value of the vertical magnetic field, contrary to what is seen in stable sunspots.

Permanent Link: http://hdl.handle.net/11104/0291957