NASA in the spotlight: A beautiful cosmic “bubble” in today’s astronomical picture

The Dolphin Head Nebula is visible in the image that NASA has featured on the website today’s picture This Wednesday (29). It is designated “Sh2-308” and was formed by a Wolf-Rayet star, a class known for its active stars and tens of times more massive than the Sun.

Located about 5,000 light-years away from us in the constellation of Canis Major, Sh2-308 is a nebula that has finished this bubble shape thanks to EZ Canis Majoris, the brightest star visible near the center of the nebula.

It emits high-speed stellar winds that “push” slow-moving material left over from an early stage in the star’s evolution. The radiation emitted from it, more intensely and continuously, causes the bubble to expand more and more.

Currently, the edges of the nebula are about 60 light-years away. In the image, there are light, diffuse chromatic emissions, which indicate that the ionized oxygen atoms glow in shades of blue.

Wolf-Rayet stars

Wolf-Rayet stars are known for their evolutionary processes, which cause them to rapidly lose mass. They usually have a mass of more than 25 solar masses and have a short lifetime, which makes them rare objects. Its winds are so intense that they shoot about 10 solar masses of matter from stars every million years, traveling at over 3,000 km/s.

Astronomers believe that winds from these stars, like the one responsible for the nebula in the image above, are caused by radiation pressure. They have average temperatures above 249,000°C, and they shine so intensely that their luminosity is millions of times that of the Sun.

To date, there are approximately 220 known stars in the Milky Way, but it is estimated that there may be thousands of them, most of which appear to be hidden by dust.

source: APOD