Exploring Cosmic Clouds of Light

Carina’s Starry Nebulous Beauty

The hot Wolf-Rayet star WR 22, part of the Carina Nebula's population of hot, massive stars. MPG/ESO La Silla.

Astronomers have their favorite places to study in the cosmos — places they return to again and again.  They do this not just because the places look pretty or are easy to spot.  Some places in the cosmos just command our attention because they have SO much going on and can teach us a great deal about processes like starbirth and star death.

Such is the case with the Carina Nebula. It lies a few thousand light-years from Earth and contains regions of starbirth, one very eye-catching example of incipient star death, and a lot of gorgeous clouds of gas and dust that are stellar nurseries.  Astronomers used the European Southern Observatory’s Wide-Field Imager to zero in on a very bright, very unusual star called WR 22.  It’s a Wolf-Rayet star, a rare and very massive (some 70 times the mass of the Sun) object that is shedding its atmosphere into surrounding space — contributing to the rich collection of recyclable star materials in the Carina Nebula. WR 22 is actually one member of a double star stystem.

WR 22 fronts a backdrop of glowing hydrogen and other gases. Heat and intense ultraviolet radiation from stars such as this one causes those clouds to light up. If the radiation is intense enough, it can eat away at the clouds.   This leaves less material to create new stars, resulting in a sort of cosmic cannibalism by the massive stars already in existence.  In the not-too-distant future, WR 22 will probably evolve to become what’s called a luminous blue variable star, and then spend much of its remaining time going through different phases of hydrogen and helium burning before dying as a Type Ic supernova.  Their future is a pretty standard one for stars of their mass and type.  But, since there are only a few hundred known Wolf-Rayet stars such as WR 22, they are objects that astronomers watch as much as possible, returning to them often to chart their progress down their evolutionary sequences.  For the rest of us, we get to peer over the shoulders of astronomers who study these babies — and we get to marvel at the gorgeous scenes in which these stars appear.

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