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Observations of R Coronae Borealis stars in decline - Empirical arguments for dust formation near the stellar surface

1992; IOP Publishing; Volume: 397; Linguagem: Inglês

10.1086/171821

1538-4357

Geoffrey C. Clayton, B. A. Whitney, S. A. Stanford, J. S. Drilling,

Astro and Planetary Science

view Abstract Citations (54) References (40) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Observations of R Coronae Borealis Stars in Decline: Empirical Arguments for Dust Formation near the Stellar Surface Clayton, Geoffrey C. ; Whitney, Barbara A. ; Stanford, S. A. ; Drilling, John S. Abstract We present new IUE observations which monitor the spectroscopic evolution of RY Sgr through a deep decline. These data, along with other IUE, visible, and infrared observations of declines in RY Sgr, R CrB, and V854 Cen, are considered in an attempt to understand the dust formation process and the source of the narrow- and broad-line emission seen during declines. Spectroscopic, photometric, and polarimetric data covering 10 declines of these stars have been analyzed. The evolution of the UV emission spectrum is similar to that found in the visible. Previous models of dust formation assume that dust forms around 20 stellar radii, where gas ejected from the star is cool enough to condense. However, the spectral evolution, and the dispersal times of dust implied by the light curve are consistent with dust forming within a few stellar radii and moving outward due to radiation pressure. The expanding dust cloud eclipses the photosphere and parts of the emission line region, causing the observed spectral evolution. Publication: The Astrophysical Journal Pub Date: October 1992 DOI: 10.1086/171821 Bibcode: 1992ApJ...397..652C Keywords: Cosmic Dust; Interstellar Matter; R Coronae Borealis Stars; Stellar Envelopes; Stellar Evolution; Emission Spectra; Iue; Light Curve; Stellar Atmospheres; Stellar Spectra; Stellar Spectrophotometry; Astrophysics; ISM: DUST; EXTINCTION; STARS: CIRCUMSTELLAR MATTER; STARS: VARIABLES: OTHER R CORONAE BOREALIS; ULTRAVIOLET: STARS full text sources ADS | data products SIMBAD (3) MAST (1) INES (1)