old question: detect evil trump invis?

[Gerion of Mercadia]

Well - if you can "touch" a flame - I think it qualifies. Flame can certainly "touch" you. I don't think that you must have a solid as the RAW uses the word.

IIRC somewhere in defining creatures the rules specify that if *something* lacks a Wisdom/Cha score then it is an "object" albeit not necessarily a "tangible" one.

Edit: Typos

 

[James McMurray]

Flames are not objects by the rules, they're energy. So if auras are like flames, they aren't objects either.

What is the hardness and hit points of an aura?

 

[Salthorae]

That then raises the question of whether an aura is a "something"? My opinion is that a "thing" whether "some" or not, requires physicality. Even though to a human, a cloud of smoke may be "intangible" passing your hand through it still affects it (swirls the smoke) so it has physicality.

As for fire, it's not a "thing", as Redcloak says it's a chemical reaction. and therefore can't be "touched" in the normal sense.