mass, radius, and angular momentum – that for certain well-studied stars and stellar systems can be anchored firmly in observables and simple physics – stellar ages for stars other than the Sun have no firm basis. Ages are critical, however, for many investigations involving time scales including formation and evolution of planetary systems, evolution of debris disks, and interpretation of low mass stars, brown dwarfs, and so-called planetary mass objects that are now being detected routinely as faint point sources near bright stars in high contrast imaging surveys.

The Era of Direct Imaging of Exoplanets {#subsec:directimaging}
---------------------------------------

Intermediate-mass stars ($1.5-3.0\ M_{\odot}$) have proven themselves attractive targets for planet search work. Hints of their importance first arose during initial data return from IRAS in the early 1980s, when several A-type stars (notably Vega but also $\beta$ Pic and Fomalhaut) as well K-star Eps Eri – collectively known as “the fab four” – distinguished themselves by showing mid-infrared excess emission due to optically thin dust in Kuiper-Belt-like locations. Debris disks are signposts of planets, which dynamically stir small bodies resulting in dust production. Spitzer results in the late 2000s solidified the spectral type dependence of debris disk presence (e.g. @carpenter2006 [@wyatt2008]) for 