It’s Christmas in the Cosmos

For astronomers peering into the depths of space, Christmas came a little early this year.

Using data from the James Webb Space Telescope, NASA an image released last month of a Christmas Tree Galaxy Cluster, a winking collection of galaxies 4.3 billion light-years from Earth. And last week an image of Cassiopeia A, the remains of a star that exploded 340 years ago. was also revealed by the first lady, Jill Biden, as part of a new one White House Advent Calendar.

These and other images follow a long tradition of astronomers and other stargazers connecting the light season with cosmic phenomena light years away from Earth. But there is genuine scientific wonder in some of these celebratory observations.

The Christmas Tree Galaxy Cluster was founded by astronomers’ detection of 14 stars that flicker for days or months – like the lights on a Christmas tree.

“Seeing an individual star in a distant galaxy is a big problem,” said Haojing Yan, an astronomer at the University of Missouri who led the study. “Almost like a miracle,” he added.

It’s not the first time distant stars have been detected, but it used to be a rare treat. “With Webb, this has become routine,” said Rogier Windhorst, an astronomer at Arizona State University who was involved in the discovery.

The observations are possible thanks to layers of gravitational lensing, an effect in which the gravity of structures in the universe distorts and magnifies the light from objects in the background, making them visible to astronomers. The flickering of the stars is a result of those ‘lenses’ moving in and out of focus.

Dr. Windhorst notes that the Earth and Sun are about the same age as the light coming from this twinkling cluster, which was already 9 billion years old at the time the light was emitted. Data from such distant stars helps astronomers compare the composition of old galactic neighborhoods with those closer to us, and how our solar system fits into what Dr. Windhorst calls the cosmic circle of life.

Unlike the Christmas Tree Galaxy Cluster, Cassiopeia A is a lot closer to home. Scientists have been eager to study the violent stellar explosion and others to figure out their role in cosmic evolution.

“They help galaxies grow,” Danny Milisavljevic, an astrophysicist at Purdue University who studies Cassiopeia A, wrote in an email. Supernova remnants also create the elements needed to sustain life, such as “the oxygen we breathe, the iron in our blood, the calcium in our bones,” he added.

Located 11,000 light-years from Earth, Cassiopeia A has been observed by a variety of space telescopes in visible, X-ray and infrared wavelengths. But the Webb’s new infrared vision offers a better view.

In April, NASA has released an image of the supernova remnant using the telescope’s mid-infrared instrument. The latest snapshot uses the Webb’s near-infrared camera, which captured gas, dust and molecules emitted at warmer temperatures.

The pink and orange structures, wrapped in smoky material against a glittering backdrop of stars, resemble an ornament hanging from a tree branch.

“Webb launched flawlessly on Christmas morning two years ago,” said Dr. Milisavljevic. “At the time I thought this was the best Christmas present ever.” But the telescope, he added, “is the gift that keeps on giving.”

Long before the Webb was launched, astronomers often discovered a seasonal spirit in space.

In 2008, the European Southern Observatory shared an image of a star cluster that resembles the sparkling trinkets you might put on a Christmas tree. The cluster, captured by the La Silla Observatory in Chile, is scattered among crimson clouds of gas. The appropriate name is at the bottom of the image Cone nebulaa star-forming region about 2,500 light-years from Earth.

The Hubble Space Telescope from NASA has also spread the holiday spirit. In 2010, the space agency released an image of a red bubble that looked like an ornament floating among the stars.

That bubble consists of gas that is blown away by a supernova at millions of kilometers per hour. Astronomers think the explosion was caused by a white dwarf – the core of a star that has run out of fuel – feeding on material from a neighboring star.

A year later, Hubble showed a breathtaking image of a cosmic snow angel: a star in our Milky Way flanked by wispy blue ‘wings’ of hot gas. Nestled in a stellar nursery, this region is home to hundreds of brown dwarfs, objects that do not accumulate enough material to form into a star.

Even the cosmos wishes you happy holidays.