Well, most of the time a Tier 9 weapon is decent against a corvette...I don't think a corvette is planet sized. I mean, technically by what I'm assuming is your scale (damage over a massive amount of time) then even a handgun could destroy a building. Just shoot enough bullets into a structural support.
High end Tier 6/7 PA weapons (like Yamatai's giant bazooka laser cannon) can reliably wipe out a sturdy concrete house. It'll cause massive damage, be "potentially lethal" as per DRv3, and yes it can blow up a city, but you'll have to march through the streets in your power armor blowing stuff up.
Not even Yamatai can destroy a world. They "glass" them, if you recall your SARP history. This means that they orbitally bombard it until the planet's silicates melt and form glass, but it doesn't actually destroy the planet itself. If you mined through that thick layer of glass you'd probably find a few resources still around.
And oh, dear lord, you really can't kill a star with a Plumeria...
We calculated the DR of a planet due to the submission of the Izanagi dreadnought, a battleship with a Tier 17 weapon on a Tier 15 dreadnought. And if Tier 15 was a dreadnought, assuming some form of exponential or logarithmic function, we plotted it out and got that the earth is somewhere around Tier 19 or 20. I forgot the proper number. The sun, OUR sun, is therefore most likely around Tier 23 or 24.
The Plumeria's main gun is Tier 13.
Good luck.