RR Lyrae distance estimate of . This type of low-mass star has consumed the hydrogen at its core, evolved away from the main sequence, and passed through the red giant stage. Energy is now being produced by the thermonuclear fusion of helium at its core, and the star has entered an evolutionary stage called the horizontal branch (HB). The effective temperature of an HB star's outer envelope will gradually increase over time. When its resulting stellar classification enters a range known as the instability strip—typically at stellar class A—the outer envelope can begin to pulsate. RR Lyrae shows just such a regular
Red Star OS commands on the computer if the user clicks on a correspondingly prepared link. This is probably due to a problem when processing URLs that perform functions such as Mailto or calendar without the parameters to clean up unwanted code fragments. Red Star OS Red Star OS () is a North Korean Linux distribution, with development first starting in 1998 at the Korea Computer Center (KCC). Prior to its release, computers in North Korea typically used Red Hat Linux and Windows XP Version 3.0 was released in the summer of 2013, but , version 1.0 continues to be more widely used.