[vsnet-chat 4720] re Typology of variable stars

[crawl@zoom.co.uk]

Hello Emile

>I wish to know the correct type of the variable stars
>AUR KR
>LEO RZ
>LYR HR
>UMA EI
>VIR HS
>wich are classified as pec, NR, Na, Nl and NL respectively ind GCVS 4th. 
>edition. Thanks in advance.

Well, let's see, according to the latest online version of the GCVS we have:-

AUR KR       =       *   (where * means unique type)

The remarks file of the GCVS says this:-

>KR    Aur    <B - V> =  +0.10, <U - B> =  -0.95. SB (P = 0.1628d
>             [9045]). Spectrum description
>             [8169, 8170].
>             Wide hydrogen emission lines.
>             Long maxima and minima lasting for years are
>             superimposed by rapid light variations by 1 - 2m
>             in several days or fortnights and by 0.5m in do -
>             zens of seconds [8168, 8170]. The source of soft
>             X-rays [5191].

Whilst the latest online Downes and Shara gives it a 'VY' classification,
which suggests a novalike variable of VY Sculptoris subclass, which more or
less fits with the remarks quoted above.

As you probably know, CV people seem to classify stars more deeply than the
official GCVS system allows, with many subclasses for various varieties.

LEO RZ

The latest GCVS still calls this object NR, but Downes and Shara classify
it as "UGWZ".

That is, a cataclysmic variable of the WZ Sge subclass.  This I think is a
partway official subclass including objects like EG Cnc and AL Com...
...and of course WZ Sge itself.  Objects that undergo quite rare (many
years between outbursts) high amplitude outbursts, and usually exhibit
superhumps too.

(I irrelevantly note that 1018 Arnolda lies 2' due south of RZ Leo at 19h
UT tonight)

LYR HR  =  Na

This is in fact Nova Lyrę 1919, and as it is cross identified as HD 175268
I can only assume it was discovered on a photographic objective plate
during the making of the Henry Draper catalogue.  If I remember rightly
there are a couple of novae and CVs with HD numbers due to being caught in
outburst by that survey.

I find no indication of any post-outburst activity (for example, in the
sense of GK Per, formerly Nova Persei 1901 and now a CV)

UMA EI

Online GCVS has NL or novalike, online Downes & Shara has simply UG, whilst
Ritter's Cataclysmic Binaries' catalogue has 'DN UG' as well.  It is a
bright xray source of apparently small visual amplitude, so it could be a
'polar' or even intermediate-polar for all I know.

VIR HS

GCVS has novalike but Downes and Shara online and Ritter both go for UGSU,
with Ritter going further and claiming ER UMa sub-subclass [ER UMa stars
are a very small group of SU UMa stars with a very short superoutburts
cycle time].


CV classification is tricky and differs depending on who you ask!  Others
may not agree on some of the above types, and it would be interesting to
know how Brian Warner classifies some of the above in his 'Cataclysmic
Variables' book.

Also, people who are actively observing some of these objects may be better
able to advise you on the current behaviour of the stars in question: for
example, does HR Lyr actually do anything anymore?

Otherwise, I hope this helps more than confuses the issue.


Cheers

John

John Greaves
UK

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