Pages Navigation Menu

SHOWFUN - Show & Fun & More!

Celestial fireworks: Hubble observes firestorm of new star formation in an old galaxy

The Hubble Space Telescope has been in orbit for more than a quarter century at this point, but it’s still sending back stunning photos of celestial objects. One of the latest images shows “fireworks” in the dwarf galaxy Kiso 5639, just in time for the 4th of July in the US. Of course these aren’t anything akin to fireworks. The bright regions in this elongated little galaxy are actually vast star-forming regions that are extremely rare in the nearby universe.

Located about 82 million light years away, Kiso 5639 is one of a class of galaxies sometimes called “tadpoles” due to their elongated appearance with increased stellar activity at one end. These galaxies were very prevalent in the early universe, but they’re much less so now. In fact, if you look at the Hubble Ultra Deep Field image, about 10% of the galaxies in that shot are tadpoles. That’s because the deep field images are looking at extremely distant objects, the light from which was released billions of years ago.

Researchers have speculated that tadpoles were more common in the past because more galaxies were still in the process of forming. The infusion of gas into a young galaxy could cause it to become lopsided as star formation picked up faster on one end. Researchers from Vassar College used Hubble’s Wide Field Planetary Camera 3 to observe and analyze some of the few nearby tadpole galaxies like Kiso 5639 in order to confirm this accretion-induced star formation.

The bright spots toward the left of Kiso 5639 are areas of intense star formation, and Hubble’s data suggests the gas in this region is very low in heavy elements like oxygen and iron compared with the rest of the galaxy. All the heavier elements than helium are produced in older stars, so the low concentration of these elements indicates that the stars in this region of Kiso 5639 are indeed very young. The researchers estimate that most stars in this 2,700 light year expanse are less than 1 million years old.

1322_1616

According to the study, this old galaxy appears to have encountered a filament of hydrogen gas with its leading edge about a million years ago (observationally). As it pulled the new matter in, star formation was kicked off as it would be in a very young galaxy. This could be what the early universe looked like, and it’s quite close in astronomical terms.

Galaxies tend to rotate over the eons, though. That means Kiso 5639 could eventually spin to expose another region to the intergalactic gas cloud, leading to another round of star formation. This all happened millions of years ago, so perhaps Kiso 5639 looks much less tadpole-like today.

Leave a Comment

Captcha image