Johnny Carson interviewed Groucho Marx as his first Tonight Show guest

US TV star Johnny Carson has died at the age of 79, after losing a battle with the respiratory disease emphysema .

The legendary former host of NBC's Tonight Show was surrounded by family and died peacefully, his nephew said.

Carson retired from the top-rated late-night entertainment show in 1992 after 30 years as one of the most popular TV personalities in the US.

In 2002 Carson, who often smoked during his show, was diagnosed with emphysema - a disease associated with smoking.

"Mr Carson passed away peacefully early Sunday morning," said his nephew, Jeff Sotzing.

"He was surrounded by his family, whose loss will be immeasurable. There will be no memorial service."

Carson began his career on television stations in his home state of Nebraska in the late 1940s.

His boyish looks won over both audiences and guests on the Tonight Show, with Carson's appearance on set announced by sidekick Ed McMahon's catchphrase: "Heeeeere's Johnny!"

Other television projects included variety series the Johnny Carson Show in 1955.

He remained popular until his retirement in May 1992, when an estimated 55 million viewers watched him hand over the Tonight Show host duties to comic Jay Leno.

Carson told the audience: "And so it has come to this. I am one of the lucky people in the world. I found something that I always wanted to do and I have enjoyed every single minute of it."

His personal life did not match his career success, however. Carson was married four times, divorced three times, and in 1991 one of his three sons, 39-year-old Ricky, was killed in a car accident.

He choose to let the Tonight Show stand as his finale, withdrawing into a quiet retirement and refusing to become involved in other showbusiness projects.

In 1993, Carson explained his absence from the limelight to the Washington Post newspaper.

"I have an ego like anybody else," he said, "but I don't need to be stoked by going before the public all the time."

He was inducted into the Television Hall of Fame in 1987 and awarded the Presidential Medal of Freedom in 1992.

(Agencies)

emphysema: an abnormal condition of the lungs marked by decreased respiratory function; associated with smoking or chronic bronchitis or old age（肺氣腫）

pass away : pass from physical life and lose all all bodily attributes and functions necessary to sustain life（去世）