Astronomers have observed two cosmic bubble phenomenon in the Milky Way Galaxy and far beyond. The infrared image from NASA’s Spitzer Space Telescope above shows a cloud of gas and dust full of bubbles, estimated to be 10 to 30 light-years across, which are inflated by wind and radiation from hundreds of thousand of young, massive stars which form from dense clouds of gas and dust. Black veins running throughout the cloud are regions of especially dense cold dust and gas where even more new stars are likely to form.
Determining the exact sizes of individual bubbles can be difficult, because their distance from Earth is challenging to measure and objects appear smaller the farther away they are. Flows of particles emitted by the stars, called stellar winds, as well as the pressure of the light the stars produce, can push the surrounding material outward, sometimes creating a distinct perimeter.
Beyond the Milky Way, The Daily Galaxy reported on April 5, 2019, that two mysterious globular structures were spotted in the galaxy NGC 3079, located 67 million light years from Earth. Scientists unveiled nuclear “superbubbles” thousand of light years wide that act like particle accelerators 100 times more powerful than the Large Hadron Collider, and are around 2,000 times longer, on average, than our solar system. The “bubbles,” according to a new study led by University of Michigan astronomer Jiangtao Li, are made of high-energy particles that stretch out across 4,900 light years on one side of the galaxy, and 3,600 light years on the other. To put that into perspective, the Sun’s influence extends for about two light years.
The extreme properties of the superbubbles suggest that they are produced by cataclysmic events like starbirth, or jets emitted from the galaxy’s central supermassive black hole. The structures may also be a source of cosmic rays, which are high-energy particles that originate outside the solar system and constantly hit Earth’s atmosphere.
Back to the Milky Way’s star incubators, in the annotated image below, the yellow circles and ovals outline more than 30 bubbles.
Spitzer sees infrared light, which isn’t visible to the human eye. Many interstellar nebulas (clouds of gas and dust in space) like this one are best observed in infrared light because infrared wavelengths can pass through intervening layers of dust in the Milky Way galaxy. Visible light, however, tends to be blocked more by dust.
This cloud of gas and dust is full of bubbles, which are inflated by wind and radiation from massive young stars. Yellow circles and ovals show the locations of more than 30 bubbles. Squares indicate bow shocks, red arcs of warm dust formed as winds from fast-moving stars push aside dust grains.
The colors in this image represent different wavelengths of infrared light. Blue represents a wavelength of light primarily emitted by stars; dust and organic molecules called hydrocarbons appear green, and warm dust that’s been heated by stars appears red.
Also visible are four bow shocks—red arcs of warm dust formed as winds from fast-moving stars push aside dust grains scattered sparsely through most of the nebula. The locations of the bow shocks are indicated by squares in the annotated image above and shown close up in the images below.
The bubbles and bow shocks in these images were identified as part of The Milky Way Project, a citizen science initiative on Zooniverse.org that seeks to map star formation throughout the galaxy. The full Milky Way Project catalogs, which list a total of 2,600 bubbles and 599 bow shocks, are described in a paper published recently in Monthly Notices of the Royal Astronomical Society.