DY Centauri: Stellar evolution while you watch
In 1930, Dorrit Hoffleit reported that star number #4749 in the Harvard List of variables had faded four times between 1897 and 1929, and identified it as an R Coronae Borealis (RCB) variable. RCB stars are luminous low-mass stars (red giants) with surfaces around 5,000—7,000 K—not much hotter than the sun. They are remarkable for having little or no hydrogen on their surfaces; this is replaced by helium and carbon. They dim by factors of 100 or more every so often by ejecting clouds of carbon, or “soot.” When thrown towards Earth, soot clouds block the starlight, until they expand enough to let the light through once more. Being in the constellation of Centaurus, H.V. 4749 was given the variable star name DY Centauri, or DY Cen for short.
phys.org
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2020-05-20
