You speak as though they exist. Quark stars are hypothesised, but none have as yet been found, though there is one candidate star, previously thought to be a neutron star, that may perhaps be reclassified as a quark star. Quark stars, were they to exist, would be intermediate between neutron stars and black holes in size and density. . . They would be most unusual if they did exist, as the principle of containment suggests that quarks are not found alone as separate particles but are found bonded together in threes as hadrons (protons, neutrons and electrons). But who knows what the effect of enormous pressure can produce, as regards matter continuing to obey the established laws of physics?. . Do you perhaps mean Quasars? (originally called QUASi-stellAR objects, but contracted to quasars) Are you under the impression that quasar is a contraction of Quark Star?. . Properties of quasars. More than 60 000 quasars are known, all observed spectra have shown considerable redshifts, ranging from 0.06 to the recent maximum of 6.4. Therefore, all known quasars lie at great distances from us, the closest being 240 Megaparsecs (780 million ly) away and the farthest being 4 Gigaparsecs(13 billion ly) away. . . Most quasars are known to lie above 1.0 Gigaparsecs in distance; since light takes such a long time to cover these great distances, we are seeing quasars as they existed long ago—the universe as it was in the distant past.. . Although faint when seen optically, their high redshift at great distance imply that quasars are the brightest objects in the known universe. The currently brightest known quasar is the ultraluminous 3C 273 in the constellation of Virgo. It has an average apparent magnitude of 12.8 (when observing with a telescope), but it has an absolute magnitude of −26.7. . . So from a distance of 10 parsecs, this object would shine in the sky about as bright as our sun. This quasar's luminosity is, therefore, about 2 trillion (2 × 10^12) times that of our sun, or about 100 times that of the total light of average giant galaxies like our Milky Way.