The Milky Way’s ‘yellowballs’ are clusters of baby stars

The babies blow bubbles of charged gases, which has helped citizen scientists spot them

The Milky Way’s ‘yellowballs’ are clusters of baby stars

Astronomers have cracked a curious cosmic case: What are “yellowballs”? These mysterious space objects were first thought to be signs of young, supermassive stars. Scientists now have confirmed that they do mark stellar nurseries. But these birthplaces for stars can host many types of stars with a wide range of masses.

Researchers shared their discovery April 13 in The Astrophysical Journal.

The stars in the clusters are relatively young, only about 100,000 years old. “I think of these as stars in utero,” says Grace Wolf-Chase. She’s an astronomer at the Planetary Science Institute and lives in Naperville, Ill. For comparison, massive stars forming in the Orion nebula are already 3 million years old. Our sun, at 4.6 billion years old, is considered middle-aged.

Volunteers with the Milky Way Project were the first to spot the unknown objects. The splotches showed up in pictures of the galaxy taken by the Spitzer Space Telescope. That telescope, which worked until last year, saw the cosmos in infrared light. And Spitzer’s images were like a sort of stellar ultrasound. They let astronomers “probe what’s going on in these cold environments before the stars are actually born,” explains Wolf-Chase.

Astronomers first thought “yellowballs” (circled left) were precursors to gas bubbles blown around massive, young stars (right). A new study instead suggests yellowballs are actually clusters of smaller stars.JPL-Caltech/NASA

Citizen scientists had been scouring the images for signs of baby stars and their birthplaces. The babies were expected to be at least 10 times the mass of our sun. And they blow giant bubbles of gas that is electrically charged, or ionized. A year or two into the project, some users noted small yellow blobs in the false-color images. They began tagging the objects #yellowballs. Between 2010 and 2015, the volunteers found 928 such yellowballs.

Wolf-Chase’s team first thought the balls signaled early-stage gas bubbles. But the researchers wanted more data to get a better look. The first yellowballs to be tagged were a lucky discovery. The researchers knew they probably hadn’t caught enough of them to definitively ID these objects. In 2016, the team asked volunteers with the Milky Way Project to find more. By the next year, that group had spotted more than 6,000 additional yellowballs.

Wolf-Chase and colleagues studied about 500 of those balls more closely. They compared the balls to catalogs of star clusters and other known structures to figure out what they were. “Now we have a good answer: They’re infant star clusters,” Wolf-Chase says. The clusters blow ionized gas bubbles of their own. Their bubbles are similar to the ones blown by single young, big stars.

Wolf-Chase hopes the work will help researchers spot yellowballs with newer telescopes. One, the James Webb Space Telescope, is due to launch in October. Such images could reveal more about the balls’ physical traits.

Source : Science News for Students More   

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Let’s learn about lightning

Around 100 times a second, every hour of every day, lightning strikes somewhere on Earth. It’s beautiful — and deadly.

Let’s learn about lightning

Around 100 times a second, every hour of every day, lightning strikes somewhere on Earth. It might strike over the ocean, far from where anyone might see it. It might hit the beach, perhaps forming a beautiful deposit of fulgurite. It might strike a tree, setting off a wildfire. And on rare occasions, it might hit a person, injuring or even killing them.

In fact, some 24,000 people are killed each year by lightning. This is why you should seek cover any time there’s a thunderstorm in the area. Even if the storm doesn’t appear close, you might still get struck.

See all the entries from our Let’s Learn About series

Lightning comes in many forms. There are the big bolts from cloud to the ground, of course, but also plenty that travel between clouds in the sky. There’s also blue jets, red sprites and ball lightning. (There’s also lightning in space: Jupiter has its own light shows of “sprites” and “elves.”)

While most lightning appears and disappears in a flash, some can last longer. An extreme bolt over Argentina on March 4, 2019 lasted 16.73 seconds, setting a record. And while lightning can form anywhere, scientists have mapped where the biggest bolts tend to strike — Europe is one hot spot.

And while lightning can do a lot of damage, it’s not all bad. Scientists have reported these bolts can forge atmosphere-cleaning chemicals called oxidants. Those chemicals help pollutants rain out of the sky. And that’s especially good since climate change is expected to bring us more of those big bolts.

Lightning is more complex than a simple bolt that goes from cloud to ground. It also travels between clouds, can occur in a ball or even be colored red or blue.

Want to know more? We’ve got some stories to get you started:

Here’s how lightning may help clean the air Airplane observations show that storm clouds can generate huge quantities of air-cleansing chemicals known as oxidants. (5/18/2021) Readability: 6.8

Space station sensors saw how weird ‘blue jet’ lightning forms A mysterious type of lightning in the upper atmosphere has been traced to a brief, bright flash of light at the top of a storm cloud. (2/2/2021) Readability: 7.4

Where will lightning strike? When lightning strikes, the results can be deadly. But nature’s dazzling light show also can provide scientists with insights into when and where the next thunderbolt might strike. (9/16/2014) Readability: 7.0

Explore more

Scientists Say: Fulgurite

Scientists Say: Radiation

Explainer: What is thundersnow?

Hotspots found for lightning’s superbolts

Lightning strikes will surge with climate change

Lightning megaflashes set big new distance and duration records


Word find

Learn more about how lightning forms and see how much you can create with this game from SciJinks, a site all about the weather from NASA and the National Oceanic and Atmospheric Administration.

Source : Science News for Students More   

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