I’m not an expert spectroscopist, but according to Russ Robb (and confirmed by eyeball by my advisor, Dr. Roberta Humphreys) this is a G-type star. Russ thought a G7 dwarf (although his original analysis suggested a giant). The proper motion is lively enough at 19 mas/yr to suggest it is close and dim versus far and bright. If this is a main sequence G-type dwarf it would have an un-dereddened distance of 200 pc.
 
The big surprise with this spectrum was the absence of emission in the CaII H&K lines. You can see the absorption but there is no trace of emission. If this was a heavily spotted star, we should have seen the H&K lines.
 
The radial velocity seems to be about –75 km/s based on the H and CaII lines. The tangential velocity, based on a distance of 200 pc and the proper motion, is about –20 km/s, giving a full space velocity near 80 km/s, coming mainly toward us.
 
This thing is in Cygnus and its galactic latitude and longitude are -6.9 and 90.5 respectively. So this star is in the disk. The reddening is E(B-V)=0.67 and AV=2.045 according to Schlegel et al. We measured this star at V-I=0.86 or so which implies a main sequence type of G2, B-V=0.63 and MV=+4.7. NOMAD has B-V of this star at B-V=0.58, in rather close agreement. Using these numbers we can compute a dereddened distance of about 105 pc.
 
Originally we thought this was an RR Lyrae star, based on the period and the shape of the light curve. As we got more data we figured out it wasn’t strictly periodic. For a while we thought it might be a double-mode RR Lyrae star (RRd) but at G7 it is too late to be an RR Lyrae star.
 
The other obvious choice is a fast-rotating heavily spotted star. This theory is bolstered by the fact that it is associated with a UV source. (It is also associated with an IR source.) The puzzle is – why no CaII H&K? Was the spectrum too low-rez? Did we get unlucky and observe at just the wrong time to catch them?
 
The universe of explanations is:
 
  1. 1.Pulsator
  2. 2.Rotator
  3. 3.One of the above in a binary system.
 
My theory, developed with the help of Grant Foster, is that this star has spots on roughly opposite sides of the star and that the rotation period is roughly P=0.767 days. The two spots give a false period of roughly half that at P=0.38 days. The spots change over time, getting bigger and smaller and moving around a little. This gives the “jiggle” in the periods.
 
I’ll also belatedly note that we do we the main periods in V-I, too:
 
 
OK, dudes, here is my rationale for this star with some supporting documentation.
 
First, the raw power spectrum:
 
GSC 3196-641
So what do you think?
Finally, in normalized flux units, is the binned (average) behavior of the star. If we explain it with 2 spots, one is causing a 5% drop in flux and the other an 8% drop in flux:
Now to the spectrum, courtesy of Russ Robb:
You can see there is a lot going on. There appear to be two primary modes. There is also a lot of scatter, much more than can be attributed to observational error. When you subtract out all of the frequencies listed above, it gets pretty flat:
Still kind of messy but considerably better. You can’t see it very well on the plot, but there are double-lines at 1.3 and 2.6, as discussed above. The other frequencies in the table above are also present.
 
If we phase the data at the frequency with the biggest amplitude we get a rational but messy looking result:
First of all you’ll note it is a mess. You can see the strongest frequency is near 1.3 cycles per day (c/d). There are also large amplitudes near 2.6 c/d. I used Grant Foster’s TS program to apply Fourier analysis of the data. I ended up with 7 main frequencies:
 
  Frequency                    Period                   Amplitude        Phase
  1.303814963+/-0.000018204     0.766980+/- 0.000011     0.0387+/-0.0007  0.2545
  2.604743237+/-0.000026889     0.383915+/- 0.000004     0.0262+/-0.0007  0.5244
  0.294420727+/-0.000049265     3.396500+/- 0.000568     0.0143+/-0.0007  0.1337
  1.308420998+/-0.000028407     0.764280+/- 0.000017     0.0248+/-0.0007  0.6664
  2.308935581+/-0.000059703     0.433100+/- 0.000011     0.0118+/-0.0007  0.7756
  2.610352659+/-0.000055039     0.383090+/- 0.000008     0.0128+/-0.0007  0.2724
  0.015337423+/-0.000060732    65.200001+/- 0.258175     0.0116+/-0.0007  0.9640
 
 
You can see a couple of interesting things from this. First of all, there are more than one frequency at both 1.3 c/d and 2.6 c/d. This means that there are modulations of those frequencies going on over time. If you subtract out all of these frequencies the power spectrum gets much more flat: