Guest star type determination: Vend6

[Peter Somogyi]

Hello,

I have got an interesting request about guest star hunting to determine the type (which in this case already suspected not to be M via colour index - hence the spectroscopy effort would be reasonable).
The name of the star here is "Vend6" (GSC 02643-02835) found as a new variable, should be between 13-14 mag (GSC says 13).

After my 1st attempt (cloudy 3 x 10min) now I have a 2nd attempt at ideal conditions with 19 x 10 min (this gave me the chance to exercise my 150/mm grating with the LHires III for the first time - exploring the limits with the 35um slit).

Result:

vend6_v2_gnuplot.png (30.02 KiB) Viewed 1660 times

(I think at the very blue the emission-like features must be just noise. The LHires also doesn't seem to be usable below 420nm - too narrow region to focus by the doublet - applying the 150/mm grating.)
Unfortunately no emission - so the pressure of higher SNR is demanding, especially in blue.

Guide view:

vend6_v2_guide.jpg (33.73 KiB) Viewed 1660 times

Best fit:

vend6_v2_cmp_k3III.jpg (136.56 KiB) Viewed 1660 times

To confirm not an M type:

vend6_v2_cmp_m0III.jpg (152.19 KiB) Viewed 1660 times

Type G8 has a better fit in blue, but weak signal questioning it, continuum slope and missing H-alpha hole tells at least the main component is not this type:

vend6_v2_cmp_g8iii.jpg (95.55 KiB) Viewed 1660 times

I took 3 ref. star (1.: Vega, 2nd: 1-Sge, 3.: 1-Sge) and used their average.
Had to disable "wavelength registration" as it was misbehaving at this noise level (should have gone for 20 minutes then).

Note: I was already able to guess as K3III (+/-1) for the 1st noisy attempt of 3 x 10 minute, too. Obviously tried the V variants as well.
If anybody have further insights how to confirm this or search for other components (longterm observation - at minimal SNR ? higher resolution??), pls let me know.

Cheers,
Peter