While poking around looking at GAIA3 spectra, I notice the star IRAS 18449+4207 has what seem to be unusual emission lines/bands. The spectrum looks mainly like an M5III, but has possible H-alpha and HeII (?) emission. It seems possible this is an unrecognized symbiotic star or some other peculiar sort. It is an ASAS variable (about V mag 12.5 or 13) with period about 400 days, and up in the evening just now. If anyone can get a spectrum across the visible, I would look forward to seeing it.
LAMOST has at least two spectra of this object, too.
Neither appeared to me to show strong Balmer lines from a quick visual inspection. Some catalogs on Vizier suggested weak H-alpha emission in one epoch and absorption in the other. Some other catalogs on Vizier suggest it may be magnetically active. It’s not in any radio or X-ray catalogs, and my guess without really digging into this is that it should be in VLASS if it’s a symbiotic star that is that bright.
I’d guess that this is just magnetic activity, rather than mass transfer.
Also, I think there is reasonably good evidence that it is a binary, just not so clear that it’s a symbiotic unless it was unusually quiescent during the LAMOST epochs. It does have astrometric excess noise of 0.2 masec in Gaia, with 80 sigma significance that that’s different from zero. That’s about the same as the parallax, so that means that the wobble is about an AU, which would tie in reasonably with the ~400 day period being orbit if the companion is a ~solar mass dwarf star.
Gaia DR4 should have epoch spectra, and will be out in a few months, and that might be the best way to get a handle on the H-alpha variability. If it’s from a stellar flare or two, then it should be very strongly and sporadically variable, while if it’s a highly eccentric symbiotic with strong accretion only near periastron, then it should be smoothly variable.
Thanks to Tom Maccarone for the additional comments. He is absolutely correct! Yes, there are the LAMOST spectra, much better than the GAIA spectra, which I should have looked at before saying anything. The star looks completely ordinary there (M5III), so “never mind” about the peculiarity of the GAIA3 spectrum. The GAIA spectrum definitely looks odd, but evidently there is some instrumental ‘funny’ in the trace. I have examined tens of thousands of these, and compare against MK standards, so the patterns are familiar to me. This was a good reminder, however, to not become overconfident in my interpretations!