Solar radius variations: New look on the wavelength dependence

Jean Pierre Rozelot, Alexander Kosovichev, Ali Kilcik

Research output: Contribution to journalArticlepeer-review


The possibility that the Sun's radius is changing, even at a faint level, has been discussed over a long time. As the solar radius is certainly one of the most important basic pieces of astrophysical information, it is crucial to determine the physical mechanisms that may cause shrinking or expansion of the solar envelope. The wavelength dependence has been poorly inspected up to now. Here we examine recent solar radius determinations from space observations, mainly from Mercury and Venus transits, made by different teams in 2006, 2012 and 2014. Seemingly, the results are not consistent: authors interpreted the discrepancies because of the different methods of analysis used in their work. However, looking at the wavelength dependence, adding other available observations, from X-EUV up to radio, a typical relationship between the radius and the wavelength can be found, reflecting the different heights at which the lines are formed. Possible explanations are discussed. Such results can be interesting for studying solar-stellar connections.

Original languageEnglish (US)
Pages (from-to)342-350
Number of pages9
JournalProceedings of the International Astronomical Union
Issue numberS320
StatePublished - Aug 1 2015

All Science Journal Classification (ASJC) codes

  • Medicine (miscellaneous)
  • Astronomy and Astrophysics
  • Nutrition and Dietetics
  • Public Health, Environmental and Occupational Health
  • Space and Planetary Science


  • Sun: fundamental parameters
  • Sun: general
  • Sun: photosphere
  • Sun: radio radiation
  • astrometry


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