The Sky Cave

Yet another volume of space ceases to be a mere void to be traversed and becomes instead a space-scape with interesting features to be observed and approached. Flandry knows that, although the nebula where a star is condensing is a near-vacuum, size and distance make its dust and gas resemble receding caverns with "...walls and roofs larger than planetary systems..."
-Poul Anderson, Sir Dominic Flandry: The Last Knight Of Terra (New York, 2012), p. 284.

He sees great black clouds with gulfs, canyons and steeps redly illuminated by the infra-star. His ship passes between the walls and under the roofs of the caverns. The haze and light thicken until he sees the sable-spotted crimson disc edged with "...coronal arabesques...," shining as yet only by gravitational energy because its core has not yet condensed enough to start the nuclear fusion that will ignite a new star, a "nova stella" in the literal sense. A few more million years are necessary. Meanwhile, Terra and Merseia contend for what they call the "Imperial Stars," to quote the excellent title of one Flandry omnibus volume.