[vsnet-unknown 14] Re: re LO Cep and CT Vul

[Taichi Kato <tkato>]

Re: [vsnet-unknown 12] re LO Cep and CT Vul

> INA variables, ie "early Orion variables", are said to have occasional
> abrupt fadings. Possibly LO Cep is only classed as IA because it has no
> specific nebulosity associated with it.  Certainly bright nebulosity on
> the edge of Sharpless 129 is not too distant.
> 
> There is a thin borderline twixt type ISA & INA, for eg.
> 
> Re the cause of variability: swirling clouds of protostellar material
> occasionally occulting these YSOs?????????  That'd fit the short
> timescales, and the quasiRCB nature of the fadings...

    Early-type YSOs with pronounced variability usually have emission lines
(as in Herbig Ae/Be stars).  See WW Vul, RR Tau etc.  This is not apparently
the case for LO Cep and CT Vul, as I understand from published spectroscopy.
The lack of IRAS detections may be mildly (for such faint objects) against
the YSO interpretation.

    Well, there are apparently YSO-type ISA stars without strong emission
lines, such as IP Per, but they are usually less active photometrically.

Regards,
Taichi Kato

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