[vsnet-alert 10378] YSOs from a Symbiotic Star catalogue

[bydra at Safe-mail.net]

Of course, it'd help if I'd remember to give a calibration, preferably against known types in the GCVS.

As usual the grey dots are the GCVS objects matched to CMC14 r' and 2MASS J and Ks (from CMC14) matched to one arcsecond radius (nearly 12000 variables)

http://i36.tinypic.com/2vbu7n5.jpg

the orange dots are all the objects in that group that are logged as some sort of YSO variable, or suspected of being one (ie have : at the end of their variability type).

There are a lot of them covering the normal sequence, which seems to be contradictory.  They do somewhat parallel the infrared excess objects though, so ostensibly these could be objects devoid of significant amounts of circumstellar matter.  Whether this is reflected in terms of a lack of Halpha emission for these objects too (a criterion for selection in the IPHAS Symbiotic Stars list) is not clear.

There are smatterings of orange dots in the red dwarf and red giant regions, which may well be misclassifications of variability type, colour plots of this kind can help reveal those.

Sweeping to the right are the expected trend of near infrared excess YSOs.

The black squares are the stars denoted as ZAND or ZAND: in the GCVS.  Most follow the redward edge of the red giant spur.

There are some exceptions.

The rightmost black square is V3929 Sgr, which SIMBAD and some literature sourced therefrom appear to confirm as a Symbiotic Star, so it's not entirely clear why it is over there in the colour plot.

The bottommost black square is somewhat easier, it's GH Gem, apparenly already known as a somewhat unique and uncharacteristic object, as it is a _yellow_ Symbiotic Star.  The larger star is it seems a very metal poor K giant.  The metal poor K giants are well known for being somewhat "bluer" than normal in Hertzsprung Russell Diagrams, etc.

The leftmost two objects, appearing too blue, are marked ZAND: for uncertain type.  Leftmost is V503 Her, which is in possible Symbiotic Star lists, but I'm not entirely clear if this object has been confirmed a Symbiotic star.  SIMBAD has it as a pulsating variable.  The ASAS3 lightcurve is interesting enough, with a strong eclipse event.

<http://www.astrouw.edu.pl/cgi-asas/asas_variable/173640+2318.2,asas3,0,0,1000,0>

The next leftmost object is the more familiar V1017 Sgr, sometimes called Nova Sgr 1919, and sometimes classed as a recurrent nova, and apparently G5III ep.  Seemingly not the usual MIII+(s)dBe Symbiotic Star.  Also :-

http://simbad3.u-strasbg.fr/cgi-bin/cdsbib4?1992Natur.358..563S

As usual with most of this stuff, there're are plenty of objects that don't fit the pattern, and the types taken into the GCVS aren't always necessarily correct (for instance, the ASAS3 lightcurve for V931 Sco, classed as IN in GCVS, and high left on the red giant spur in the plot, looks more like a Mira in ASAS3:-

<http://www.astrouw.edu.pl/cgi-asas/asas_variable/161146-2532.0,asas3,0,0,1000,0>

and the GCVS spectrum of M5.5 for V364 Sct just rightward and upward of it could easily be that of a red giant), but a general trend of NIR YSOs and a more firmer trend of red giant spur hugging Symbiotics does appear out of this calibration against known types.

John Greaves