Deep Infrared ZAMS Fits to Benchmark Open Clusters Hosting delta Scuti
  Stars
  This research aims to secure precise distances for cluster delta Scutis in
order to investigate their properties via a VI Wesenheit framework. Deep JHKs
colour-colour and ZAMS relations derived from ~700 unreddened stars featuring
2MASS photometry and precise HIP parallaxes (d<~25 pc) are applied to establish
distances to several benchmark open clusters that host delta Scutis: Hyades,
Pleiades, Praesepe, alpha Per, and M67 (d=47+-2,138+-6,183+-8,171+-8,815+-40
pc). That analysis provided constraints on the delta Sct sample's absolute
Wesenheit magnitudes (W_VI,0), evolutionary status, and pulsation modes (order,
n). The reliability of JHKs established cluster parameters is demonstrated via
a comparison with van Leeuwen 2009 revised HIP results. Distances for 7 of 9
nearby (d<250 pc) clusters agree, and the discrepant cases (Pleiades & Blanco
1) are unrelated to (insignificant) Te/J-Ks variations with cluster age or
[Fe/H]. JHKs photometry is tabulated for ~3x10^3 probable cluster members on
the basis of proper motions (NOMAD). The deep JHKs photometry extends into the
low mass regime (~0.4 Msun) and ensures precise (<5%) ZAMS fits. Pulsation
modes inferred for the cluster delta Scutis from VI Wesenheit and independent
analyses are comparable (+-n), and the methods are consistent in identifying
higher order pulsators. Most small-amplitude cluster delta Scutis lie on VI
Wesenheit loci characterizing n>~1 pulsators. A distance established to NGC
1817 from delta Scutis (d~1.7 kpc) via a universal VI Wesenheit template agrees
with estimates in the literature, assuming the variables delineate the n>~1
boundary. Small statistics in tandem with other factors presently encumber the
use of mmag delta Scutis as viable distance indicators to intermediate-age open
clusters, yet a VI Wesenheit approach is a pertinent means for studying delta
Scutis in harmony with other methods.
