Passage: Stars within the portion of the instability strip that crosses the main sequence are called Delta Scuti variables. These are named after the prototypical star for such variables: Delta Scuti. Delta Scuti variables typically range from spectral class A2 to F8, and a stellar luminosity class of III (subgiants) to V (main sequence stars). They are short-period variables that have a regular pulsation rate between 0.025 and 0.25 days. Delta Scuti stars have an abundance of elements similar to the Sun's (see Population I stars) and between 1.5 and 2.5 M☉. The pulsation rate of IK Pegasi A has been measured at 22.9 cycles per day, or once every 0.044 days.Astronomers define the metallicity of a star as the abundance of chemical elements that have a higher atomic number than helium. This is measured by a spectroscopic analysis of the atmosphere, followed by a comparison with the results expected from computed stellar models. In the case of IK Pegasus A, the estimated metal abundance is [M/H] = +0.07 ± 0.20. This notation gives the logarithm of the ratio of metal elements (M) to hydrogen (H), minus the logarithm of the Sun's metal ratio. (Thus if the star matches the metal abundance of the Sun, this value will be zero.) A logarithmic value of 0.07 is equivalent to an actual metallicity ratio of 1.17, so the star is about 17% richer in metallic elements than the Sun. However the margin of error for this result is relatively large.

Question: Stars referred to as Delta Scuti variables exist in what portion of space?
instability strip