purpose: devise a method for using rotation-color relationship to determine stellar age for stars in isolation.
Introduction:
- In order to develop an accurate description of the relationship between B-V color and stellar rotation period (NOT including the sin(i) term), one must use stars in clusters for calibration
- in the past, available clusters for study have produced equations for stars younger (hotter/brighter) than the Sun
- Using space-based telescopes (Kepler in particular), this group aims to develop equations to describe this relationship for stars as old and older than the Sun (type F, G, K, M dwarfs)
- By defining a curve in (B-V)-P(rot) space, one can assign an age to the curve, much like an isochrone
Method:
- measure stellar rotation periods for cluster members
- long baseline/ high frequency photometric observations to avoid aliasing
- make sure to remove non-members/close binaries/other outliers
- estimate cluster age using isochrones to calibrate equation
M34 and M35:
- These clusters (200 Myr, 150 Myr) were used to calibrate equation
- details of this method are found in Meibom and Mathieu 2005
- Time series data was taken at the WIYN telescope at Kitt Peak
- target stars had 12
- these observations were paired with radial velocity period measurements from a spectroscopic survey
- solved the equation: P(t,B-V) = g(t) * f(B-V) ...... f(B-V) = a((B-V)-b)^c
- they found a=.77 and c=.6. From Barnes 2007, b=.4, g(t)=t^(.52)
- b-values form the "Kraft Curve" (Kraft 1967)
- for G dwarfs, Skumanich spin-down works (Prot ~ t^.5)
- K dwarfs spin down differently (slower) --> check Irwin (year?)
The Future:
- Kepler should focus on older clusters to get relations for different types of stars
- should specifically focus NGC 6866, 6811, 6819, 6791
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