Hello! I am wondering what studies are done of established variables that use multi-band photometry vs. single band.
I use 8" LX200 classic with ST-402 with BVIC filters. It is a marvelous setup.
I've been considering upgrading to a system that provides a wider field, but there appears to be limitations in the availability of filters at this time.
As I've reviewed how my past measurements of established variables have been used, they often seem to be used for period analysis, since a star's indices do not (or should not) change. A standard G filter in an uncooled DSLR would do this type of work quite well.
I would appreciate folks' insights/comments on how data for established variable stars are used and the value of multi-band vs. single band photometry for such stars. Best regards.
Mike
Fifteen years ago my…
Mike:
Fifteen years ago my first foray into the photometric study of variable stars employed an orange Celestron C8 classic and SBIG ST-402ME. Despite the relatively small FOV it's still a great combination suitable for most variable stars in the V-mag range 9-12. If you haven't done so already, you may want to consider adding a focal reducer (f/6.3) to the optical train which can significant increase the FOV. Assuming your filters are photometric BVIc then I would strongly recommend acquiring light curve (LC) data in all three colors. An important combination is B and V since the difference (B-V) corrected for reddening (E(B-V)) can be used to estimate the effective temperature (Teff) of the variable system. Alternatively, the color index (V-Ic) can also be used to estimate Teff and can provide good supporting data to confirm any (B-V)_0 determination. A Teff value is critical for modeling LCs that can ultimately lead to estimates for mass, mass ratio, orbital inclination, and size (radii) of some eclipsing binary stars. In addition, some variable star types are strongly constrained by effective temperature. A Teff value helps with stellar classification when spectral data are not available. Furthermore, LC data which allows one to calculate times-of-minimum (EBs) or times-of-maximum (pulsators) can be used with data from other sources to determine whether the orbital period (in the case of eclipsing binaries) or the fundamental oscillation period (in the case of pulsators) is changing over time. Secular changes may result from mass exchange, angular momentum loss (AML), the influence of additional unseen but gravitationally-bound objects and magnetically induced cycles. Depending on the specific circumstances, all these data can be used to build a story about the previous history, present behavior and potential future of a variable system.
Kevin
Thank you!
Mike