Astronomy and Astrophysics – Astrophysics
Scientific paper
Jul 1995
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1995sao..reptq....g&link_type=abstract
Progress Report, 1 Jul. 1994 - 30 Jun. 1995 Smithsonian Astrophysical Observatory, Cambridge, MA.
Astronomy and Astrophysics
Astrophysics
Chromosphere, Coronas, Plasma Dynamics, Solar Atmosphere, Stellar Models, X Rays, Absorptivity, Neutral Gases, Photosphere, Scale Height, X Ray Telescopes
Scientific paper
The Normal Incidence X-ray Telescope (NIXT) obtained a unique set of high resolution full disk solar images which were exposed simultaneously by X-rays in a passband at 63.5 A and by visible light. The perfect alignment of a photospheric visible light image with a coronal X-ray image enables us to present observations of X-ray intensity vs an accurately determined height above the visible limb. The height at which the observed X-ray intensity peak varies from 4000 km in active regions to 9000 km in quiet regions of the sun. The interpretation of the observations stems from the previously established fact that, for the coronal loops, emission in the NIXT bandpass peaks sharply just above the footpoints. Because there is not a sharp peak in the observed X-ray intensity vs off limb height, we conclude that the loop footpoints, when viewed at the limb, are obscured by absorption in chromospheric material along the line of sight. We calculate the X-ray intensity vs height predicted by a number of different idealizations of the solar atmosphere, and we compare these calculations with the observed X-ray intensity vs height. The calculations use existing coronal and chromospheric models. In order for the calculations to reproduce the observed off limb X-ray intensities, we are forced to assume an atmosphere in which the footpoints of coronal loops are interspersed along the line of sight with cooler chromospheric material extending to heights well above the loop footpoints. We argue that the absorption coefficient for NIXT X-rays by chromospheric material is roughly proportional to the neutral hydrogen density, and we estimate an average neutral hydrogen density and scale height implied by the data.
No associations
LandOfFree
Structure and dynamics of coronal plasmas does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Structure and dynamics of coronal plasmas, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Structure and dynamics of coronal plasmas will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1529704