Universität zu Köln

Miyamoto, Mayu, Imamura, Takeshi, Tokumaru, Munetoshi, Ando, Hiroki, Isobe, Hiroaki, Asai, Ayumi, Shiota, Daikou ORCID: 0000-0002-9032-8792, Toda, Tomoaki, Haeusler, Bernd, Paetzold, Martin, Nabatov, Alexander and Nakamura, Masato (2014). RADIAL DISTRIBUTION OF COMPRESSIVE WAVES IN THE SOLAR CORONA REVEALED BY AKATSUKI RADIO OCCULTATION OBSERVATIONS. Astrophys. J., 797 (1). BRISTOL: IOP PUBLISHING LTD. ISSN 1538-4357

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Abstract

Radial variations of the amplitude and the energy flux of compressive waves in the solar corona were explored for the first time using a spacecraft radio occultation technique. By applying wavelet analysis to the frequency time series taken at heliocentric distances of 1.5-20.5 R-S (solar radii), quasi-periodic density disturbances were detected at almost all distances. The period ranges from 100 to 2000 s. The amplitude of the fractional density fluctuation increases with distance and reaches similar to 30% around 5 R-S, implying that nonlinearity of the wave field is potentially important. We further estimate the wave energy flux on the assumption that the observed periodical fluctuations are manifestations of acoustic waves. The energy flux increases with distance below similar to 6 R-S and seems to saturate above this height, suggesting that the acoustic waves do not propagate from the low corona but are generated in the extended corona, probably through nonlinear dissipation of Alfven waves. The compressive waves should eventually dissipate through shock generation to heat the corona.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Miyamoto, Mayu UNSPECIFIED UNSPECIFIED UNSPECIFIED Imamura, Takeshi UNSPECIFIED UNSPECIFIED UNSPECIFIED Tokumaru, Munetoshi UNSPECIFIED UNSPECIFIED UNSPECIFIED Ando, Hiroki UNSPECIFIED UNSPECIFIED UNSPECIFIED Isobe, Hiroaki UNSPECIFIED UNSPECIFIED UNSPECIFIED Asai, Ayumi UNSPECIFIED UNSPECIFIED UNSPECIFIED Shiota, Daikou UNSPECIFIED orcid.org/0000-0002-9032-8792 UNSPECIFIED Toda, Tomoaki UNSPECIFIED UNSPECIFIED UNSPECIFIED Haeusler, Bernd UNSPECIFIED UNSPECIFIED UNSPECIFIED Paetzold, Martin UNSPECIFIED UNSPECIFIED UNSPECIFIED Nabatov, Alexander UNSPECIFIED UNSPECIFIED UNSPECIFIED Nakamura, Masato UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-420329
DOI:	10.1088/0004-637X/797/1/51
Journal or Publication Title:	Astrophys. J.
Volume:	797
Number:	1
Date:	2014
Publisher:	IOP PUBLISHING LTD
Place of Publication:	BRISTOL
ISSN:	1538-4357
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language ELECTRON-DENSITY FLUCTUATIONS; FARADAY-ROTATION MEASUREMENTS; POLARIZED ALFVEN WAVES; SOUNDING EXPERIMENTS; MAGNETIC-FIELD; MAGNETOHYDRODYNAMIC WAVES; FREQUENCY FLUCTUATIONS; CIRCUMSOLAR PLASMA; FINITE-AMPLITUDE; VENUS ORBITER Multiple languages Astronomy & Astrophysics Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/42032