successively

In Ten Tantalizing Truths, by John Gribbin, the author discusses the origin of stars:

But for stars with a few times more mass than the Sun, when the hydrogen is used up, the star shrinks a little, gets hotter thanks to the Kelvin–Helmholtz effect, and the pressure inside triggers further reactions, based on building up more elements by fusing alpha particles with one another and with successively more complex nuclei.

Does it mean "increasingly" here?

Ahmed Samir Darwish said:

In Ten Tantalizing Truths, by John Gribbin, the author discusses the origin of stars:


Does it mean "increasingly" here?

"Successively more" does mean, in effect, "increasingly."

Each one comes from the one before. That's the idea of successively. But it also happens to be true that each one is more complex than the previous one. That doesn't have to be the case in all situations of "successively", but it is true in this case.

Element A + alpha particle = element B

Element B + alpha particle = element C

Element C + alpha particle = element D

Adding an alpha particle in each case makes a bigger nucleus with more protons and neutrons, which in that sense is more complex. You can't go straight from A to D. You have to go through a succession of intermediate steps.