NDLI: Variations in the Solar Coronal Rotation with Altitude

Content Provider	Springer Nature Link
Author	Bhatt, Hitaishi Trivedi, Rupal Sharma, Som Kumar Vats, Hari Om
Copyright Year	2017
Abstract	Here we report an in-depth reanalysis of an article by Vats et al. (Astrophys. J. 548, L87, 2001) that was based on measurements of differential rotation with altitude as a function of observing frequencies (as lower and higher frequencies indicate higher and lower heights, respectively) in the solar corona. The radial differential rotation of the solar corona is estimated from daily measurements of the disc-integrated solar radio flux at 11 frequencies: 275, 405, 670, 810, 925, 1080, 1215, 1350, 1620, 1755, and 2800 MHz. We use the same data as were used in Vats et al. (2001), but instead of the twelfth maxima of autocorrelograms used there, we use the first secondary maximum to derive the synodic rotation period. We estimate synodic rotation by Gaussian fit of the first secondary maximum. Vats et al. (2001) reported that the sidereal rotation period increases with increasing frequency. The variation found by them was from 23.6 to 24.15 days in this frequency range, with a difference of only 0.55 days. The present study finds that the sidereal rotation period increases with decreasing frequency. The variation range is from 24.4 to 22.5 days, and the difference is about three times larger (1.9 days). However, both studies give a similar rotation period at 925 MHz. In Vats et al. (2001) the Pearson’s factor with trend line was 0.86, whereas present analysis obtained a ${\sim}\,0.97$ Pearson’s factor with the trend line. Our study shows that the solar corona rotates more slowly at higher altitudes, which contradicts the findings reported in Vats et al. (2001).
Starting Page	1
Ending Page	8
Page Count	8
File Format	PDF
ISSN	00380938
Journal	Solar Physics
Volume Number	292
Issue Number	4
e-ISSN	1573093X
Language	English
Publisher	Springer Netherlands
Publisher Date	2017-03-30
Publisher Place	Dordrecht
Access Restriction	One Nation One Subscription (ONOS)
Subject Keyword	Solar radio flux Flux modulation method Gaussian fit Sidereal rotation period Astrophysics and Astroparticles Atmospheric Sciences Space Sciences (including Extraterrestrial Physics, Space Exploration and Astronautics)
Content Type	Text
Resource Type	Article
Subject	Astronomy and Astrophysics Space and Planetary Science

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