One of the most difficult things for non native speakers are the definite / indefinite articles. I have doubts how to use the definite article when listing few things. The particular sentence is:
In particular, I investigated the temperature of black holes and thermal emission, gravitational lensing, gravitational red-shift and gravitational waves.
The first occurrence of the definite article seems intuitively correct
to me i.e.
I investigated the temperature, but shouldn't I use the
definite article with the other nouns from the listing?
In particular, I investigated the temperature of black holes and thermal emission, the gravitational lensing, the gravitational red-shift and the gravitational waves.
The latter case seems to be wrong, but since I would like to include it in my motivation letter, I would like to have a second opinion. For instance, if I had something like
the gravitational lensing from black holes, the definite article would be fine.
Thank you for your help.