Let $B_t$ be a Brownian motion process. Let $O_t = e^{-\alpha t} \int^t_0 e^{\alpha s} dB_s$ Find $\mathsf{E}[O_t]$ and show that $O_t$ is a Gaussian process.
I think $\mathsf{E}[O_t]=e^{-\alpha t} \mathsf{E}\left[ \int^t_0 e^{\alpha s} dB_s\right] = e^{-\alpha t} \times 0 = 0$ as the Ito integral is a martingale with expectation $0$ by definition. But I am not sure why it is a martingale in the first place...
No idea how to show it's a Gaussian process.
Please help!