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High-resolution optical spectra of R CrB obtained in 2003 March is discussed. The 2003 spectra are compared with the extensive collection of spectra from the 1995-1996 minimum. Spectroscopic features common to the two minima include sharp emission lines of neutral and singly-ionized atoms, broad emission lines including He {sc i}, [N {sc ii}] 6583 AA, Na D, and Ca {sc ii} H & K lines, and blueshifted aborption lines of Na D, and K {sc i} resonance lines. Prominent differences between the 2003 and 1995-96 spectra are seen. The 2003 profiles of Na D, Ca II H & K are fit by a single Gaussian but in 1995-1996 two Gaussians separated by about 200 km s$^{-1}$ were required. However, the He {sc i} broad emission lines are fit by a single Gaussian at all times; the emitting He and Na-Ca atoms are probably not colocated. The C$_2$ Phillips 2-0 lines are detected as sharp absorption lines in 2003 indicating presence of gas at 1300 K.The 2003 spectra show C {sc i} sharp emission lines at minimum light with a velocity changing in five days by about 20 km s$^{-1}$ when the velocity of `metal sharp lines is unchanged; the C {sc i} emission may arise from shock-heated gas. Spectra at maximum shows extended blue wings to strong lines with the extension dependent on a lines lower excitation potential a signature of stellar wind. Changes in the cores of the resonance lines of Al {sc i} and Na D and the Ca {sc ii} IR lines suggest complex flow patterns near the photosphere. The spectroscopic differences at the two mimima show the importance of continued scrutiny of the declines of R CrB.
We present an extended optical spectropolarimetry of R CrB from 1998 January to 2003 September. The polarization was almost constant in the phase of maximum brightness, being consistent with past observations. We detected, however, temporal changes o
The R Coronae Borealis (RCB) stars are rare hydrogen-deficient, carbon-rich, supergiants, best known for their spectacular declines in brightness at irregular intervals. Efforts to discover more RCB stars have more than doubled the number known in th
Neutral fluorine (F I) lines are identified in the optical spectra of several R Coronae Borealis stars (RCBs) at maximum light. These lines provide the first measurement of the fluorine abundance in these stars. Fluorine is enriched in some RCBs by f
The R Coronae Borealis (RCB) stars are rare hydrogen--deficient, carbon--rich supergiants. They undergo extreme, irregular declines in brightness of many magnitudes due to the formation of thick clouds of carbon dust. It is thought that RCB stars res
Optical high-resolution spectra of the R Coronae Borealis star V CrA at light maximum and during minimum light arediscussed. Abundance analysis confirms previous results showing that V CrA has the composition of the small subclass of R Coronae Boreal