Category Archives: stellar ages

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.

A Seagull (or is it a Lizard?) in Space

WISE Studies a Nebula

The Seagull Nebula as seen by the WISE spacecraft. Courtesy NASA/JPL-Caltech/WISE Team

I’ve talked about star formation many times in this blog. It’s a fascinating topic and there are many, many star-forming regions in our galaxy (and others) for astronomers to study!  The Wide-field Infrared Survey Explorer (WISE) released a very cool infrared image of a star-forming cloud near the constellations of Monoceros and Canis Major called IC 2177, nicknamed the Seagull Nebula. The image is a mosaic — meaning that it’s made from several smaller images.  Now, if this doesn’t look like a seagull, look at another orientation of the image.

Re-oriented to show the seagull.

Now, see the seagull? It’s a somewhat  fanciful vision of a very complex place where stars are forming as we speak. And, the infrared view reveals the sites of the stellar nurseries. For example, astronomers can tell that the pink, oval-shaped region near the seagull’s eye (or lizard’s hip) is one such nursery. It’s called NGC 2327, and it contains a cluster of stars born about 1.5 million years ago. The center of the eye is the brightest and hottest of the newborn stars in the entire nebula. Its intense heat and radiation are warming the dust in the surrounding cloud and causing it to glow in infrared light. Infrared light is not blocked by dust or gas, which makes it a very useful tool for peeking into starbirth nurseries to understand the processes by which all stars — including our Sun — come into being.