Junior officer of carabinier, Ferdinand de Lariboisière, First Empire,

From painting of Antoine Jean Gros: "Le général de Lariboisière (1759-1812) faisant ses adieux à son fils, lieutenant au 1er régiment de carabiniers, au début de la bataille de La Moskowa, le 7 septembre 1812" .

Breastplate on painting is covered with copper, as it was for officer....But there is also, normally, a sun.
Hole to fix it is at its place.
It can mean that the painter suppressed it, as sun will never rise again for the young man and will disappear from heart of his father, who died some months later, exhausted and devasted by sorrow