Great idea, not so great way.
23 hours only to come back is not quite a good idea, I think. If I regularly open the app before sleep, which is at 10pm, I will surely miss my star, which by the time I come back, the star has died. To only have 23 hours means, if I come to see my star at 10pm today, the next day I have to come back at max. 9pm, and so forth. Really?