Emission cores in H and K lines |
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Authors: | R Grant Athay A Skumanich |
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Institution: | (1) High Altitude Observatory, Boulder, Colo., U.S.A. |
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Abstract: | Profiles of the H and K lines of Mgii and the K line of Ca ii are computed using a two-level atom for five model atmospheres distinguished from each other mainly by the location of the temperature minimum. In the five models the temperature minimum and the chromospheric temperature are adjusted to give best agreement between computed and observed profiles. The parameters and r
0 are prescribed as functions of from a density model of the atmosphere. By comparing computed and observed profiles of the K3, K2 and inner K1 components of the lines we determine both the approximate depth variation of
D and the best of the temperature models. We find that the Doppler width increases rapidly with height in the chromosphere beginning from a value of 1.6 km/sec at
0 10–2. This latter value corresponds closely to the thermal velocity of Mg atoms in the upper photosphere. The preferred temperature model is one for which the temperature minimum occurs near
0( 2800) 10–4–10–5 with a value T
min 4200 ° and which has a temperatu near 7000 ° at
0 = 10–6 where K2 is formed. The intensity in K3 is determined largely by d![Delta](/content/ug37573510up4k16/xxlarge916.gif)
D/d in the K2 and K3 regions. |
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