Title: An IUE survey of activity in red giants and supergiants
Abstract: view Abstract Citations (9) References (38) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS An IUE Survey of Activity in Red Giants and Supergiants Oznovich, I. ; Gibson, D. M. Abstract Chromospheric and transition region line activity is examined in apparently single red giants and supergiants using the IUE archives. Low-resolution, large-aperture spectra (mostly short-wavelength) were used to search for variations of emission-line fluxes in time. A series of automatic processing procedures were implemented in order to uniformly calibrate a large number of spectra, fit continua to each of them, determine the fluxes of as many as 18 emission lines, and compare them at different epochs. A method is offered to compute the overall error in the integrated flux, a critical measure of activity, independent of the observing and processing details. This processing was applied to above 120 images of 26 stars taken over a period of 7 yr (1978-1984). Four stars showed UV emission-line flux variations. Alpha Aqr, Beta Peg, and Sigma Oph showed a single enhanced-emission event in all detectable emission lines. Gamma Aql exhibited an increase in the flux level of the O I (1641 A) line in mid-1981 with no comparable change in any other lines. These four stars lie in a region of the H-R diagram in which time-dependent circumstellar absorption lines appear. Publication: The Astrophysical Journal Pub Date: August 1987 DOI: 10.1086/165462 Bibcode: 1987ApJ...319..383O Keywords: Late Stars; Red Giant Stars; Stellar Activity; Stellar Spectrophotometry; Supergiant Stars; Ultraviolet Spectra; Emission Spectra; Error Analysis; Iue; Line Spectra; Spaceborne Astronomy; Astrophysics; STARS: CHROMOSPHERES; STARS: EMISSION-LINE; STARS: LATE-TYPE; ULTRAVIOLET: SPECTRA full text sources ADS | data products SIMBAD (26) MAST (1) INES (1)