Transcript Slide 1
Observing the Sun Observing the Sun Corona: EUV; X-rays Chromosphere: H, UV, EUV Photosphere: near UV, Visible light, infra-red Observing the Sun Radio Waves Solar flare on October 29, 2001 17 GHz, Nobeya Radioheliograph Observing the Sun Near Infrared National Solar Observatory (Kitt Peak) Helium I (10830 Å) weaker in coronal holes strong in active regions, filaments Observing the Sun Visible light: all wave lengths sharp boundary! opaque to transparent less material, less dense I I 0e density temperature All wave lengths Catania Astrophysical Observatory in Italy Photosphere: visible surface of the Sun sunspots, faculae Observing the Sun Visible light: filtered National Solar Observatory, Sacramento Peak in Sunspot, New Mexico Calcium K line 3933.7 Å Chromosphere: plages, supergranules,.. Observing the Sun Visible light: filtered H-alpha 6562.8 Å, 0.01 MK Chromosphere: filaments, plages,.. (e.g. Big Bear Solar Observatory) Observing the Sun Ultraviolet Layer of the Sun: upper chromosphere, lower corona Temperature: ~MK Active regions, loops, flares, .. Fe IX, 171 Å 1.3 MK Wavelength: ~10-~8 m e.g. SOHO/EIT Fe XII, 195 Å 1.6 MK Helium II 304 Å, ~0.1 MK Observing the Sun X-rays Layer of the Sun: corona Temperature: 2-4 MK Wavelength: ~10-9 m Active regions, coronal loops, flares Dark areas: coronal holes Satellites: e.g. Yohkoh, Trace Gamma-ray observations solar flares RHESSI Magnetograms line-of-sight component of magnetic flux at the photosphere. The fields are measured by Zeeman splitting in a suitable magnetically sensitive absorption line (e.g. Ca K line) National Solar Observatory (Kitt Peak) Coronagraph White-light corona “artificial” solar eclipse Plane of the sky projection - Skylab (first CME): 1973-1974 - Solwind: 1979-1980; 1984-1985 - SMM: 1980; 1984-1989 - SOHO/LASCO: 1996 → - STEREO/SECCHI 2007 → + ground based coronagraphs MK3 Mauna Loa Solar Observatory Observing the Sun Some on-going missions: • RHESSI: particle acceleration; solar flares; soft X-rays to gamma rays; launched February 2002 • TRACE: corona and transition region; X-ray and EUV; launched April 1998 • HINODE: solar magnetic fields; EUV, X-rays, optical telescope; launched September 2002 • SOHO: various instruments (see e.g. http://soho.esac.esa.int/about/instruments.html) launched December 1995 • SDO (Solar Dynamic Observatory): launched 2010 (see e.g. http://sdo.gsfc.nasa.gov/) The latest addition to solar observatories • NASA’s STEREO spacecraft launched on Oct 25 2006 3-D with STEREO An encounter with a comet STEREO-A records a CME ripping off comet Encke’s tail in April 20, 2007 See story and the movie: http://science.nasa.gov/headlines/y2007/01oct_encke.htm