death throes of a star are observable for only a few years

An example of an extended metaphor used in formal science writing:

"The time required for a star to consume its nuclear fuel is so long (many billions of years in most cases) that only a few stars die in our galaxy per century; and the evolution of a star from the end point of thermonuclear burning to its final dead state is so rapid that its death throes are observable for only a few years."

Kip Thorne: Gravitational Collapse and the Death of a Star

Thorne, K. S. (1965). Gravitational collapse and the death of a star. Science, 150 (3704), 1671-1679. http://www.jstor.org.ezp.lib.cam.ac.uk/stable/1717408 (Read 'The passing of stars: Birth, death, and afterlife in the universe')