Infrared photometry of R CrB during its recent decline.

Wing, R. F.; Baumert, J. H.; Strom, S. E.; Strom, K. M.

doi:10.1086/129400

Cited by 4 publications

(9 citation statements)

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“…In addition to the 2001 June observation reported here, it was also observed in 1972 March and May (6 mag below maximum light), 1978 January (1 mag below maximum light), 1978 July (at maximum light for 100 days), and 1996 May (3.5 mag below maximum light) (Wing et al 1972;Querci & Querci 1978, Zirin 1982Rao et al 1999). The He i 10830 line is present at all four epochs.…”

Section: Discussionsupporting

confidence: 72%

“…He i 10830 was detected in R CrB 30 yr ago, when it was just below maximum light (Wing et al 1972;Querci & Querci 1978;Zirin 1982). The line showed a P Cygni profile with a violet displacement of more than 200 km s À1 .…”

Section: Introductionmentioning

confidence: 97%

“…The emission lines suggest at least two temperature regimes: a cool ($5000 K) inner region likely to be the site of neutral and singly ionized species producing a narrow line spectrum and a much hotter outer region indicated by the presence of broad emission lines such as C iii 1909, C iv 1550, and He i 10830 4 (Wing et al 1972;Querci & Querci 1978;Zirin 1982;Clayton et al 1992;Lawson et al 1999). Other broad lines, such as Na i D and Ca ii H and K, imply a cooler region.…”

Section: Introductionmentioning

confidence: 99%

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Winds in R Coronae Borealis Stars

Clayton

Geballe

Bianchi

2003

ApJ

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We present new spectroscopic observations of the He I $\lambda$10830 line in R Coronae Borealis (RCB) stars which provide the first strong evidence that most, if not all, RCB stars have winds. It has long been suggested that when dust forms around an RCB star, radiation pressure accelerates the dust away from the star, dragging the gas along with it. The new spectra show that nine of the ten stars observed have P-Cygni or asymmetric blue-shifted profiles in the He I $\lambda$10830 line. In all cases, the He I line indicates a mass outflow - with a range of intensity and velocity. Around the RCB stars, it is likely that this state is populated by collisional excitation rather than photoionization/recombination. The line profiles have been modeled with an SEI code to derive the optical depth and the velocity field of the helium gas. The results show that the typical RCB wind has a steep acceleration with a terminal velocity of \Vinf = 200-350 \kms and a column density of N $\sim10^{12}$ cm$^{-2}$ in the He I $\lambda$10830 line. There is a possible relationship between the lightcurve of an RCB star and its He I $\lambda$10830 profile. Stars which have gone hundreds of days with no dust-formation episodes tend to have weaker He I features. The unusual RCB star, V854 Cen, does not follow this trend, showing little or no He I absorption despite high mass-loss activity. The He I $\lambda$10830 line in R CrB itself, which has been observed at four epochs between 1978 and 2001, seems to show a P-Cygni or asymmetric blue-shifted profile at all times whether it is in decline or at maximum light.Comment: 14 pages, 4 figures, ApJ in pres

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Section: Discussionsupporting

confidence: 72%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

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Winds in R Coronae Borealis Stars

Clayton

Geballe

Bianchi

2003

ApJ

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“…Prior to the small survey by Clayton et al (2003), very few observations of the He I λ10830 line in RCB stars had been reported. R CrB, itself, however, was observed at five epochs between 1972 and 1978, and showed a P-Cygni or asymmetric blue-shifted profile at all times, whether in decline or at maximum light (Wing et al 1972;Querci & Querci 1978;Zirin 1982). R CrB showed emission at He I λ10830 in three spectra obtained during a decline in 1972 March-May when it was between V = 9 and 12 mag (Wing et al 1972).…”

Section: Previous Observations Of He I λ10830mentioning

confidence: 90%

Variable Winds and Dust Formation in R Coronae Borealis Stars

Clayton

Geballe

Zhang

2013

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We have observed P-Cygni and asymmetric, blue-shifted absorption profiles in the He I λ10830 lines of twelve R Coronae Borealis (RCB) stars over short (1 month) and long (3 year) timescales to look for variations linked to their dust-formation episodes. In almost all cases, the strengths and terminal velocities of the line vary significantly and are correlated with dust formation events. Strong absorption features with blue-shifted velocities ∼400 km s −1 appear during declines in visible brightness and persist for about 100 days after recovery to maximum brightness. Small residual winds of somewhat lower velocity are present outside of the decline and recovery periods. The correlations support models in which recently formed dust near the star is propelled outward at high speed by radiation pressure and drags the gas along with it.

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“…The obscuration can be due to dust as well as carbon grains. Models ranging from those involving ejection of material by some mechanism (e.g., Alexander et al, 1972, Feast andGlass, 1973) to those which propose semipermanent blotches in orbit around the star (Wing et al, 1972) have been considered.…”

Section: Introductionmentioning

confidence: 99%

R Coronae Borealis Pulsations

King

1980

Space Sci Rev

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The Cepheid-like pulsations of some of the R CrB stars should in principle make it possible to determine their masses and hence to place constraints on possible evolution scenarios. We briefly review the evidence for these pulsations and discuss the problem of how these lowmass, hydrogen-deficient carbon stars could have evolved to their present position in the H-R diagram. Linear and nonlinear pulsation calculations are reviewed. It is found that for these large luminosity to mass ratio (L/M) stars a region of pulsation instability extends considerably hotter than for normal high luminosity Cepheids. The envelopes of these models are so nonadiabatic that the identification of modes becomes very difficult since there is frequently no clearly defined nodal structure. For the most extreme L/M cases it is found that the models are unstable in the sense that they appear on the verge of ejecting the outer layers.

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Infrared photometry of R CrB during its recent decline.

Cited by 4 publications

References 0 publications

Winds in R Coronae Borealis Stars

Winds in R Coronae Borealis Stars

Variable Winds and Dust Formation in R Coronae Borealis Stars

R Coronae Borealis Pulsations

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