Astronomy and Astrophysics – Astrophysics
Scientific paper
2003-06-04
Astrophys.J. 595 (2003) 412-417
Astronomy and Astrophysics
Astrophysics
14 pages, 4 figures, ApJ in press
Scientific paper
10.1086/377336
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.
Bianchi Luciana
Clayton Geoffrey C.
Geballe Thomas Ronald
No associations
LandOfFree
Winds in R Coronae Borealis Stars does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Winds in R Coronae Borealis Stars, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Winds in R Coronae Borealis Stars will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-24422