EDP Sciences
Free access
Volume 426, Number 1, October IV 2004
Page(s) 329 - 331
Section The Sun
DOI http://dx.doi.org/10.1051/0004-6361:20047120

A&A 426, 329-331 (2004)
DOI: 10.1051/0004-6361:20047120

Research Note

Brightness temperature and size of the quiet Sun at 34.5 MHz

K. R. Subramanian

Indian Institute of Astrophysics, Bangalore, 560 034, India
    e-mail: subra@iiap.res.in

(Received 22 January 2004 / Accepted 17 June 2004)

We present observations of the quiet Sun made at 34.5 MHz during the solar minimum period June-July 1986 and May-June 1987 with the Gauribidanur radio telescope and a grating array. The brightness temperature of the quiet Sun varied from 1.0  $\times$ 105 K to 4.5  $\times$ 105 K and the East-West diameter from 39 to 66 arcmin during the above periods. Only a weak inverse correlation is found to exist between the brightness temperature and the diameter of the quiet Sun and it does not strongly support the scattering hypothesis used to explain the low brightness temperature of the quiet Sun at decametric wavelengths.

Key words: Sun: radio radiation -- Sun: corona -- radiation mechanisms: thermal -- scattering

© ESO 2004