Raisa Gorbachev is something new for the Soviet Union: Not only does she look different than the wives of previous leaders, but the Soviet people actually know what she looks like.

The gradual unveiling of the Kremlin's "first lady," who arrived here with her husband today, has been a startling phenomenon of the Gorbachev era. She is rarely identified by name at home, but her presence by her husband's side on his travels and on Soviet television has been unmistakable and often novel.

From a society that worries that its manners are still not quite up to snuff, Gorbachev's wife has emerged as an advertisement for a new self-assurance. People sense it, and Soviets are both proud and relieved that the stereotype of the fat, homely babushka, a slang term meaning grandmother, has at last been replaced.

Soviet television watchers have seen her on the evening news, walking through institutes and factories in Leningrad, Minsk, Kiev and Tyumen, getting off the plane in Paris and in the audience listening to her husband's speeches.

And Soviet citizens, with their talent for gleaning information from scattered facts, quickly deduced the identity of the slim, auburn-haired woman on their television screens. While they have had less opportunity to see the wife of their leader than television viewers in the West have had, they have had enough of a glimpse of her to gain their own impression.

Raisa Gorbachev, 53, a former professor with a doctorate in philosophical sciences, comes across to viewers as well dressed, poised and intelligent -- or as one young Russian woman said in Moscow with earnest pride, "well brought-up."

Last December, when the Gorbachevs were in London, one young man back in the Soviet capital asked what impression they had made. When told that Gorbachev's wife -- then completely unknown to the Soviet public -- had been a big hit with her looks and her intelligence, the young man was clearly pleased that the country was projecting a new image. "Good for him," he exclaimed, evidently referring to Gorbachev.

During her stays in both Paris and London, Raisa Gorbachev showed herself to be a forceful personality in her own right. According to one account, she debated the meaning of John Locke's philosophy in England, and in Paris, switched her schedule to make sure her first visit to a French couturier was to Pierre Cardin.

Born Raisa Maximovna Titarenko, she was a student in Moscow with the young Mikhail Gorbachev in the 1950s: he was in the law faculty at Moscow State University, while she was at the Lenin Pedagogical Institute.

The two later moved to Stavropol, Mikhail Gorbachev's hometown. There Raisa Gorbachev wrote one of the three books to her name, a doctoral thesis on two sovkhozes, or state farms, in the northern Caucasus with an analysis on how families spend their money (43 percent on food, 18 percent on clothing and 4.8 percent on hard liquor and tobacco).

Upon their return to Moscow in 1978, Raisa Gorbachev taught political philosophy at Moscow University, although she apparently has not been teaching recently.

The Gorbachevs have one daughter, Irina, who teaches at a medical institute and is married to a doctor. The family, including granddaughter Oksanna, 5, have appeared together on several occasions, once to vote in Soviet elections last February and on May Day this year when Gorbachev's wife, daughter and granddaughter stood near the foreign press corps on Moscow's Red Square.

Such deliberately planned public appearances by Raisa Gorbachev undoubtedly serve her husband's political purposes. They make the leader more human and less remote, in keeping with the jocular style he has displayed during his walkabouts in the streets of Leningrad and Kiev.

More important, Raisa Gorbachev provides a model for the modern Soviet woman, who rarely sees anything but men in close-ups of the country's ranking leadership. On International Women's Day last March, for instance, only one woman, the former cosmonaut Valentina Tereshkova, stood among the ranks of gray-suited men.

Other leaders' wives have appeared in public before: Lenin's wife, Nadezhda Krupskaya, has her own place in the national iconography. Khrushchev's wife Nina Petrovna was considered popular. Leonid Brezhnev's wife Viktoria was thought to wield behind-the-scenes clout.

But publicly, their roles were passive, mostly restricted to events of state or ceremonies where protocol demanded their presence. Otherwise, they stayed out of the limelight. In the case of Yuri Andropov, the penchant for privacy was extreme: it was not until his funeral that it became known that his wife was alive.

Given Soviet aversion to mixing personality and politics in the public sphere, Raisa Gorbachev has to keep her appearances within bounds: Too much assertiveness would give the impression that she, and by extension her husband, put themselves above the party line.

As it is, rumors have already circulated in Moscow about Raisa Gorbachev -- that she is really the niece of Soviet President Andrei Gromyko, or the late Kremlin ideologist Mikhail Suslov, that she spent 10,000 French francs on clothes in Paris, or that she is Gorbachev's second wife.

A senior Soviet official in Moscow went out of his way yesterday to deny the last rumor. Other aspects of her life and origins are harder to pin down -- including her birthplace. In some ways, Soviet reluctance to reveal personal details has not changed.

Still, Raisa Gorbachev has managed to stake a claim to her right to participate in public life, and in that sense may be the first to establish a role, however limited, for the Soviet "first lady.