Poster Open Access

THE SUBTERAHERTZ SOLAR CYCLE: POLAR AND EQUATORIAL RADII DERIVED FROM SST AND ALMA

Menezes, Fabian

At subterahertz frequencies – i.e., millimeter and submillimeter wavelengths – there is a gap of mea- surements of the solar radius as well as other parameters of the solar atmosphere. As the observational wavelength changes, the radius varies because the altitude of the dominant electromagnetic radiation is produced at different heights in the solar atmosphere. Moreover, radius variations throughout long time series are indicative of changes in the solar atmosphere that may be related to the solar cycle. Therefore, the solar radius is an important parameter for the calibration of solar atmospheric models enabling a better understanding of the atmospheric structure. In this work we use data from the So- lar Submillimeter-wave Telescope (SST) and from the Atacama Large Millimeter/submillimeter Array (ALMA), at the frequencies of 100, 212, 230, and 405 GHz, to measure the equatorial and polar radii of the Sun. The radii measured with extensive data from the SST agree with the radius-vs-frequency trend present in the literature. The radii derived from ALMA maps at 230 GHz also agree with the radius-vs-frequency trend, whereas the 100-GHz radii are slightly above the values reported by other authors. In addition, we analyze the equatorial and polar radius behavior over the years, by determin- ing the correlation coefficient between solar activity and subterahertz radii time series at 212 and 405 GHz (SST). The variation of the SST-derived radii over 13 years are correlated to the solar activity when considering equatorial regions of the solar atmosphere, and anticorrelated when considering polar regions. The ALMA derived radii time series for 100 and 230 GHz show very similar behaviors with those of SST.

Files (1.3 MB)
Name Size
Menezes_Fabian.jpg
md5:1c3804dbbfbfbab1ee41da03abf1a9c5
673.4 kB Download
Menezes_Fabian.pdf
md5:22b49835d1c8cacedc2566b110383d49
634.6 kB Download
18
11
views
downloads
All versions This version
Views 1818
Downloads 1111
Data volume 7.1 MB7.1 MB
Unique views 1414
Unique downloads 1111

Share

Cite as