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Flows around sunspots and pores

Wang, Haimin and Zirin, Harold (1992) Flows around sunspots and pores. Solar Physics, 140 (1). pp. 41-54. ISSN 0038-0938. doi:10.1007/bf00148428.

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We report on three sequences of high-resolution white-light and magnetogram observations obtained in the summer of 1989. The duration of sub-arcsecond seeing was three to four hours on each day. Study of the white-light and magnetogram data yields the following results: (1) For all but one of the sunspots we have observed, both dark fibrils and bright grains in the inner part of the penumbra of sunspots move toward the umbra with a speed of about 0.5 km s⁻¹. In the outer part of the penumbra, movement is away from the umbra. The one exception is a newly formed spot, which has inflow only in its penumbra. (2) Granular flows converge toward almost every pore, even before its formation. Pores are observed to form by the concentration of magnetic flux already existing in the photosphere. The pores (or small sunspots), in turn, then move and concentrate to form bigger sunspot. (3) We followed an emerging flux region (EFR) from 29 to 31 July, 1989 that was composed of a large number of bipoles with magnetic polarities mixed over a large area in the first day of its birth. As time went on, polarities sorted out: the leading polarity elements moved in one direction; the following, the opposite. During the process a large number of cancellations occurred, with some sub-flares and surges observed simultaneously. After about 24 hours, the positive and negative fluxes were essentially separated. (4) We find two kinds of photospheric dark alignments in the region of new flux emergence: (a) alignments connecting two poles of opposite magnetic polarity form the tops of rising flux tubes; (b) alignments corresponding to the magnetic flux of one polarity, which we call elongated pores.

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Wang, Haimin0000-0002-5233-565X
Additional Information:© 1992 Kluwer Academic Publishers. Provided by the NASA Astrophysics Data System. Received 12 April, 1991; in revised form 27 January, 1992. We are grateful to the observing staff at BBSO and at Huairou Solar Observing Station for their support in the observations. We thank the referee for helpful comments and criticism. We are also grateful to Frances Tang, Sara Martin, and Leila Belkora for reading the manuscript and helpful comments. This work is supported by NSF under grant ATM-8816007 and by NASA under grants NAGW-1972 and NASG-27269.
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Subject Keywords:Fibril; Magnetic Flux; Outer Part; Flux Tube; Magnetic Polarity
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Official Citation:Wang, H., Zirin, H. Flows around sunspots and pores. Sol Phys 140, 41–54 (1992).
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:103359
Deposited By: Tony Diaz
Deposited On:20 May 2020 21:14
Last Modified:16 Nov 2021 18:20

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