hihi, "đèn ông sao" is a kind of light which children use in mid-autumn holiday.
In mid-autumn night, the Moon is fullest and brightest. So that we have a holiday called mid-autumn holiday. In that night, people (in family) gather together, adults look (with admiration) the moon, and children play together with "đèn ông sao" (they often bring it to roads by roads, and sing some mid-autumn songs loudly, this activity is called "rước đèn ông sao"). It's very happy!
At first, "Đèn ông sao" constructed by bamboo and paper, it was lighted by one (or some) candle(s), that parents (generally adults) can made it by themselves for their children in family. This handmade kind is often imitated star shape, so that they call it "đèn ông sao" (ông sao, or sao = star; đèn = light, in "traffic lights"). Nowadays, "đèn ông sao" made-in-China is popular, it made of plastic, and batteries help it sound (some melodies) and light, and the shape is variable from cartoon character to house-things-imitating.
I do not know how to translate "rước đèn ông sao" into English. Hope that my explanation above will help you.
You come from China, so that it's easier for you to go through this, right?
đèn ông sao: 5-pointed star shaped lantern rước đèn ông sao: celebrate the Mid-Autumn Festival with traditional 5-pointed star shaped lantern
Take a look at this Wikipedia article. In the Vietnamese version section, you'll see what a "đèn ông sao" (5-pointed star shaped lantern) looks like:
I understand that activity quite well, although after looking at the image from Wikipedia I even could not tell it in Chinese, because such kind of lanterṇ("or light") is very rare in northern China, maybe tểt Trung Thu doesn't mean children's day here as in Vietnam.
Thanks a lot.