[vsnet-chat 2995] RE: R CrB stars

[Sebasti若n Otero <varsao@fullzero.com.ar>]

----- Original Message -----
From: Taichi Kato <tkato@kusastro.kyoto-u.ac.jp>
To: <vsnet-chat@kusastro.kyoto-u.ac.jp>
Sent: Sunday, May 28, 2000 9:56 AM
Subject: [vsnet-chat 2991] Re: R CrB stars


>    Whether it will be adequate or not to call sudden fadings caused by
> dust formation as the R CrB type variablity, this process has been widely
> observed in different sort of objects (R CrB stars themselves, carbon
stars,
> RVB minimum (possible), DQ Her-type novae etc.).
>
>    However, the population of R CrB stars definitely exists, sharing some
> common characterstics (see Clayton's review).  It is not clear whether
> this class of variable represents a single or multiple classes of objects
> (e.g. in evolution), or whether the class has a definite borderline
between
> R CrB stars and other variable stars.
>
> Regards,
> Taichi Kato


It seems to be at least two main kinds of RCB behaviour: the RCB that fall
from grace and the one-time performers. V366 Lac faded deeply but there is
another star I can't recall now that also "dissapeared" from the sky. And we
have V4334 Sgr, Sakurai's Object, that appeared suddenly and vanished
showing RCB behaviour but with too great amplitude. Or we have FG Sge, that
has changed its spectrum from B to K. Are we observing examples of real time
evolution? May a star go through this evolutinary phase that fast? And if
they are really examples of RCB, why do other stars spend more time behaving
like that?

Best regards,
Sebastian Otero.

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