| Автор | Herbert Friedman |
| Дата выпуска | 1962-01-01 |
| dc.description | Rocket spectroscopy has mapped the solar spectrum from the ground level cut-off near 3000 Å down to the short wavelength limit of the X-ray region. The spectrum has been photographed to 84 Å and scanned photoelectrically to somewhat shorter wavelengths. Throughout most of the ultra-violet the spectrum is known with a resolution of about half an ångström. The profile of Lyman-α has been measured with a resolution of 0·03 Å. In the X-ray region, the spectrum is known only in broad outline from measurements made with narrow-band photometers.Fraunhofer lines disappear near 1500 Å, beyond which chromospheric and coronal emission lines dominate the spectrum. The strongest lines observed are H Lyman-α (1216 Å) and He II Lyman-α (304 Å). In the X-ray region the total flux (1-100 Å) varied by a factor of 7 over the past solar cycle under quiet conditions and exhibited a progressive hardening with increasing solar activity. From sunspot minimum to maximum the flux in a 2-8 Å bandwidth increased several hundred times. At 8-18 Å the increase was a factor of 40 to 60. Solar flares were accompanied by large over-all increases in X-ray flux and especial enhancements of the shorter wavelengths.Solar disk photographs in H Lyman-α and X-rays show that short wavelength emissions are intensified over active regions. In the ultra-violet, the intensity from plage areas averages four times the background brightness. In the X-ray spectrum, active regions may be eighty times as bright as the quiet background. A strong correlation exists between X-ray sources and centimetre wave sources. |
| Формат | application.pdf |
| Издатель | Institute of Physics Publishing |
| Название | Solar observations obtained from vertical sounding |
| Тип | rev |
| DOI | 10.1088/0034-4885/25/1/305 |
| Electronic ISSN | 1361-6633 |
| Print ISSN | 0034-4885 |
| Журнал | Reports on Progress in Physics |
| Том | 25 |
| Первая страница | 163 |
| Последняя страница | 217 |
| Аффилиация | Herbert Friedman; U.S. Naval Research Laboratory, Washington 25, D.C., U.S.A. |
| Выпуск | 1 |
