Table 1.

Desirable Key Properties to Know About the Host Star and Exoplanetary System

Stellar properties	Exoplanetary system properties
Age	Physical exoplanet properties
Spectral type (including effective temperature)	Mass and radius: hence mean density and bulk composition
Stellar luminosity	Presence of a surface
Panchromatic spectrum, particularly the UV flux
Activity	Orbit and spin parameters
Rotation rate (related to age and X-ray flux, which correlates with emission of strong UV lines)	Orbital eccentricity
	Rotation rate
Elemental composition	Obliquity
Whether in a multiple star system, e.g., a binary star system	Other planets in the system, and their physical and orbital properties (e.g., to determine resonances)