[vsnet-alert 22054] Re: TCP J19083989+1210033: new transient (11.4 mag) in Aquila

[Brian Skiff]

On Thu, 2018-04-05 at 11:25 +0200, roberto nesci wrote:
>  From the 2MASS magnitudes (J=10.884 H=10.293 K=10.010) the star is an M4 V, so 
> likely a flare star.

     Prof Nesci is surely correct here:  along with the colors,
there is also modest proper motion and significant H-alpha
emission inferred from the IPHAS photometry.  The ROSAT source
is possibly associated.  Barbara Harris's follow-up photometry
showing it back to normal state also implies this was a
short-lived flare on the M dwarf.
     See this plot for a "textbook" example of an M-dwarf
flare --- interesting on their own, but not a cv or ordinary
galactic nova!

ftp://ftp.lowell.edu/pub/bas/vardat/G_167-54-flare.jpg



\Brian