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Studies of K line filtergrams

Zirin, H. (1974) Studies of K line filtergrams. Solar Physics, 38 (1). pp. 91-108. ISSN 0038-0938. doi:10.1007/bf00161827.

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High resolution filtergrams made with a 0.3 Å K line filter at Big Bear are discussed. The dark K3 clouds noted in spectra by Bappu and Sivaraman (1971) are confirmed; they cover about 1/3 of the inside of supergranule cells, and oscillate (mainly horizontally) with 3–4 min period. Their vertical extent of about 3000 km produces a sharp broadening of K3 at the extreme limb and obscuration of bright features. Spicules also produce K3 absorption, but they occur in emission more often than in Hα, particularly near the limb. Apart from these differences the structures seen in Hα and K generally correspond. A fine structure of granule size, also oscillating with 3–4 min period, is seen in K1. This structure is also obscured near the extreme limb, possibly by the same clouds seen in K1. The bright K232 network does not appear to oscillate significantly in brightness, except through covering and uncovering by the overlying dark clouds. Some bright spicules, and many dark ones, are seen over all elements of the K network, as in Hα. In active regions the structure in K is very close to Hα; all plagettes and plages are bounded by systems of strongly inclined bright and dark fibrils apparently marking the lines of force. The fibrils are the same (bright or dark) in Hα and K3; they are not seen in K2. Umbral flashes are much less visible in Hα. There is, however, a finer, granular umbral structure in Hα which does not oscillate. Running penumbral waves are not seen in K. The penumbra and surrounding areas are bright in K3. Every bright point in K3 corresponds to a magnetic field spot, except for the intranetwork area, where the magnetograms cannot detect possible fields. Flares are the same in K and Hα. The formation of the K double reversal at the limb is exhaustively discussed.

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Additional Information:© 1974 Kluwer Academic Publishers. Provided by the NASA Astrophysics Data System. Received 27 May 1974; Issue Date September 1974. I wish to thank Dr Ronald Moore for many stimulating discussions. This work was supported by NASA under NASA NGL 05 002 034, the Atmospheric Sciences section of NSF under Ga. 24015 and by AFCRL under F19628-73C-0085.
Funding AgencyGrant Number
NASANGL 05 002 034
NSFGA 24015
Air Force Cambridge Research Laboratories (AFCRL)F19628-73C-0085
Subject Keywords:Flare; Fibril; Granule Size; Bright Point; Vertical Extent
Issue or Number:1
Record Number:CaltechAUTHORS:20200630-073903732
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Official Citation:Zirin, H. Studies of K line filtergrams. Sol Phys 38, 91–108 (1974).
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:104153
Deposited By: Tony Diaz
Deposited On:30 Jun 2020 17:46
Last Modified:16 Nov 2021 18:28

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