We've always known that Bix was cool, but now the Smithsonian is making it official.

A portrait of Bix Beiderbecke hangs with 99 others in a new exhibit called American Cool at the National Portrait Gallery of the Smithsonian Institution in Washington, D.C.

The exhibit opened last week and continues through Sept. 7.

At the gallery's website, American Cool gets a definition:

"What do we mean when we say someone is cool? To be cool means to exude the aura of something new and uncontainable. Cool is the opposite of innocence or virtue. Someone cool has a charismatic edge and a dark side. Cool is an earned form of individuality.

"Each generation has certain individuals who bring innovation and style to a field of endeavor while projecting a certain charismatic self-possession. They are the figures selected for this exhibition: the successful rebels of American culture."

And Bix is right there with other notables in a variety of fields: James Dean, Steve Jobs, Muhammad Ali, Tony Hawk, Angela Davis among them.

The portrait of Bix was taken around 1920, according to the exhibit list and was at the Institute of Jazz Studies at Rutgers University. The artist is unknown.

Bix is part of "The Roots of Cool," those deemed cool before "cool" became cool, which was in 1940s. The next group is in "The Birth of Cool," from 1940 to 1959 after jazz saxophonist Lester Young "disseminated the word and concept of cool into jazz culture in the early 1940s." Then there's "Cool and the Counterculture" from 1960 to 1979, followed by "The Legacies of Cool," which is from 1980 to the present.

The gallery's website also includes the Alt100, a list of another 100 people whom gallery officials argued over before dropping them from the exhibit. Here's what they say about that:

"'American Cool' is not the last word on cool but rather the first step toward a new national conversation on this singular American self-concept. Who’s on your cool list? Here are two questions to consider:

"(1) Did this person bring something entirely new into American culture?

"(2) Will this person’s work or art stand the test of time and history?"

With that the exhibitors invite you to add your thoughts about American Cool. Just go to www.npg.si.edu/exhibit/cool.