Ring by Stephen Baxter (1994)
This science fiction story is really two separate plots that don’t converge until almost the end of the 500-page novel.
One story is of a multi-generation ship and the trials and tribulations of its colorful crew as it makes its way to a distant artifact on the other side of the universe. During the centuries that pass, the population of the ship grows into three factions: the natives in the jungle who have given up their immortality, the immortal captain and her holographic husband, and an immortal race of engineers who have turned ship maintenance into a religion.
When the natives think the ship has reached its destination, they contact the engineers with the news and all hell breaks loose. They need help to survive the last leg to reach their destination. The captain and their crew help, but the engineers fight them at every turn.
In the second story, an AI, raised at an accelerated rate as a human girl, occupies a probe sent to uncover the secrets of the sun and discover why it’s dying millions of years too soon. She lives inside the sun while the ship is making it to the massive alien artifact called the Ring. Enjoying her thousands of years inside the sun, she discovers a race of sun-eaters, eating all the suns in the universe.
When the AI joins forces with the crew, they may have only one opportunity to survive passage through the Ring before all the suns are extinguished.
Stephen Baxter is very skilled at juggling science and interesting characters. I enjoyed both stories he presented in this novel. I think either of them could have been a novel on their own, but they were enjoyable together