The one star he actually named
The single largest, brightest “star,” out toward the center of the sky, just to the right of the central cypress
This is not a star at all but the planet Venus, the morning star, the one celestial body Van Gogh names in his letter to Theo, where he wrote that he had seen the countryside before sunrise with nothing but the morning star, which looked very big. It is the single element on the canvas you can tie to a documented observation, and astronomical records confirm Venus was prominent at dawn in Provence that spring.