| Issue |
A&A
Volume 389, Number 2, July II 2002
|
|
|---|---|---|
| Page(s) | 624 - 628 | |
| Section | Planets and planetary systems | |
| DOI | https://doi.org/10.1051/0004-6361:20020664 | |
| Published online | 27 June 2002 | |
A study of development of global solar activity in the 23rd solar cycle based on radio observations with the Nobeyama radio heliograph
II. Dynamics of the differential rotation of the Sun
1
Pulkovo Astronomical Observatory, 196140 Saint Petersburg, Russia,
2
Tuorla Observatory, 21500 Piikkiö, Finland,
3
Nobeyama Radio Observatory, Minamisaku, Nagano 384-13, Japan
Corresponding author: A. Riehokainen, alrieho@astro.utu.fi
Received:
15
November
2001
Accepted:
15
April
2002
An analysis of solar rotation as a function of heliographic
latitude and
time is
made using daily radio maps of the Sun at the wavelength of 1.76 cm.
Variations of the
velocity as a function of the latitude during the period 1992–2001 have been
studied.
The mean synodical rotation rate of the intensity features is best fit by
![\[ \omega = 13.41 - 1.66\sin^2 \theta -2.19 \sin^4 \theta \:\mbox {(deg/day)} \]](/articles/aa/abs/2002/26/aa2036/aa2036_tex_eq1.png)
where θ is the latitude. We have found alternating bands of faster and
slower rotation. They travel from higher latitudes towards the equator
during the current solar cycle.
Radio observations with high accuracy and reliability thus confirm the reality
of torsional oscillations in the higher levels of the solar atmosphere.
Key words: Sun: activity / Sun: rotations / Sun: radio radiation
© ESO, 2002
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