Gomez helps Bieber celebrate 17th birthday

WENN, Wednesday, March 2, 2011, 12:22am (PST)

Justin Bieber and Selena Gomez stepped out in Los Angeles together for the second time in a week on Tuesday to mark the "Baby" hitmaker's birthday.

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The stars, who are rumored to have been dating since last year, attended Vanity Fair's post-Academy Awards bash on Sunday, and put their arms around each other as they posed for photographers on the red carpet.

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They were later pictured sitting side by side in the venue, with Gomez resting her hand on Bieber's left knee -- and they spent the evening in each other's company again on Tuesday to celebrate the pop hunk's 17th birthday.

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Gomez and Bieber were caught on camera heading to Maggiano's Little Italy restaurant in Los Angeles to mark Bieber's big day -- although the Disney star attempted to avoid photographers by covering her face with her hands.