[vsnet-chat 4610] Inclusion criteria for Name List 76...

[crawl@zoom.co.uk]

A quick look at Name List 76 suggests that a primary criterion for
inclusion is the giving of a variability type, albeit usually noted as
provisional and/or uncertain, by the authors/discoverers of the object.

This is somewhat interesting in the light of the fact that on occasion an
object reported to vsnet-newvar, for instance, may be said to be SR (ie
semiregular) simply based on half a dozen or so very widely spaced
magnitude measures that are of relatively low amplitude.  This is
especially the case if an IRAS or other infrared cross identification is made.

Although it is a little churlish to suggest that a more or less continually
varying low amplitude red star cannot be thought of as a semiregular
variable, for after all, what else could it be, this is still somewhat
interesting.

The object could of course be type L, or an RCB star for instance.

In similar circumstances a red star of high amplitude and some hint of
cyclicity, even if not even a rough period is evident, may be noted as
being likely to be a Mira star.  This is probably on somewhat safer ground.

But without sufficient data to show any level of repeatability within the
data the default assumption of SR for low amplitude red stars is not
necessarily the safest.

There may appear to be many more SR than L type stars in the sky, and L
type stars are often reclassified to SR when sufficient data becomes
available for cyclicity to be evident.  However, it should be noted that
some of the current detection techniques, whether photographic or CD, are
not necessarily the same as those used in the past which have led to the
discovery of variables, and different selection effects may exist with
respect to dynamic range of the detectors, sky coverage, magnitude depth,
etc.  Certainly there is a strong concentration within the Galactic plane
in the modern instances, as many of these new variables are consequential
discoveries to nova patrols.

Just a thought really.

Cheers

John

John Greaves
UK

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