Motions of Hα-spicules along the solar limb

✍ Scribed by G. M. Nikolsky; A. G. Platova

• Publisher: Springer
• Year: 1971
• Tongue: English
• Weight: 542 KB
• Volume: 18
• Category: Article
• ISSN: 0038-0938
• DOI: 10.1007/bf00149062

✦ Synopsis

A series of Ha-spectrograms obtained with the 21 in. Lyot coronagraph has been examined. Measurements of relative distances between spicules (nearly 50 features) embrace the time interval of about 21 min (38 pictures). It is found out that spicules oscillate along the limb with a characteristic time interval (period) about 1 min, characteristic amplitude of 1 arc sec and velocities about 10-15 km/s. The oscillations show no correlation for distant spicules.

As was established by numerous observators, Doppler velocities of many features change as a function of time (Mouradian, 1965, Pasachoff et al., 1968, Nikolsky and Sazanov, 1966). The latter two papers state that all spicules, or at least some part of them, reverse the sign of line-of-sight velocities during their life-time, the latter usually being several times longer than the characteristic time of the line-of-sight velocity evolution (see also Beckers, 1968).

The reasons for quasiperiodic oscillations of line-of-sight velocities are not clear. As was noted before by Nikolsky (1970) either (a) backward-translational mass movement along the spicule axis or (b) oscillations in the tangential direction (along the solar limb) are possible. The latter point of view seems more acceptable.

The first mention of observations of spicule motions along the limb was made by Pasachoffet al. (1968).