Ultraviolet Observations Of Stellar Chromospheric Activity

view Abstract Citations (81) References (52) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Ultraviolet observations of stellar chromospheric activity. Hartmann, L. ; Dupree, A. K. ; Raymond, J. C. Abstract A survey is presented of chromospheric and transition region (TR) line emission in late-type stars obtained with the IUE satellite. A wide variation in TR emission (ions formed near T = 100,000 K) at a given position in the H-R diagram is found, contradicting theories that incorporate only acoustic energy generation and deposition. The behavior of the Hyades giants is thought to suggest that age does not uniquely determine emission levels. The data are consistent with the picture advanced by many others that rapid rotation appears to result in enhanced fluxes. Emission in TR lines is correlated with chromospheric emission; the range in observed surface fluxes from different stars increases with the temperature of line formation. It is noted that although emission measures of high temperature gas generally decline with decreasing stellar gravity, it is not possible to define a sharp division in the H-R diagram between stars with TR emitting regions and those without. Publication: The Astrophysical Journal Pub Date: January 1982 DOI: 10.1086/159549 Bibcode: 1982ApJ...252..214H Keywords: Chromosphere; Emission Spectra; Late Stars; Stellar Spectra; Stellar Structure; Ultraviolet Astronomy; Dwarf Stars; Hertzsprung-Russell Diagram; Iue; Line Spectra; Radiant Flux Density; Stellar Envelopes; Stellar Evolution; Stellar Gravitation; Stellar Temperature; Transition Points; Astrophysics full text sources ADS | data products SIMBAD (31) MAST (1) INES (1)