Read about the coolest discoveries, research updates, and images of this week’s astronomy: A new JWST brown dwarf, the first ever detection of gas in a planetary disk, and a new image of colliding galaxies from Gemni North Observatory
A new distant and cold brown dwarf from JWST
Using the James Webb Space Telescope (JWST), an international team of astronomers have detected a new faint, distant, and cold brown dwarf. The newly found object, designated GLASS-JWST-BD1, turns out to be about 31 times more massive than Jupiter.
Brown dwarfs are intermediate objects between planets and stars. Astronomers generally agree that they are substellar objects occupying the mass range between 13 and 80 Jupiter masses. One subclass of brown dwarfs (with effective temperatures between 500 and 1,500 K) is known as T dwarfs, and represents the coolest and least luminous substellar objects so far detected. Studies of T dwarfs could help astronomers better understand objects near the disputed planet/star boundary, for instance, giant exoplanets. However, although many brown dwarf have been detected to date, T dwarfs are not so common, as only about 400 such objects have been identified.
Now, a group of astronomers report the discovery of a new brown dwarf that is most likely of T dwarf subclass. According to the study, GLASS-JWST-BD1 has a mass of about 31.43 Jupiter masses and an effective temperature of some 600 K. The age of this brown dwarf was estimated to be 5 billion years.
In analyzing such a faint object so far away, the astronomers confirmed the power of JWST to probe the very low-mass end of the stellar and substellar mass function in the Galactic thick disk and halo, enabling exploration of metallicity dependence on low-mass star formation and the evolution of brown dwarf atmospheres.
If you want to learn more, you can read the original paper here: https://arxiv.org/pdf/2207.14802.pdf
First-ever detection of gas in a circumplanetary disk
Scientists using the Atacama Large Millimeter/submillimeter Array (ALMA) and partners at the National Radio Astronomy Observatory (NRAO) have made the first-ever detection of gas in an circumplanetary disk. What’s more, the detection also suggests the presence of a very young exoplanet.
Circumplanetary disks are an amassing of gas, dust, and debris around young planets. These disks give rise to moons and other small, rocky objects, and control the growth of young, giant planets. Studying these disks in their earliest stages may help shed light on the formation of our own solar system, including that of Jupiter’s Galilean moons, which scientists believe formed in a circumplanetary disk of Jupiter around 4.5 billion years ago.
While studying AS 209, a young star located roughly 395 light-years from Earth in the constellation Ophiuchus, scientists observed a blob of emitted light in the middle of an otherwise empty gap in the gas surrounding the star. That led to the detection of the circumplanetary disk surrounding a potential Jupiter-mass planet.
Scientists are watching the system closely, both because of the planet’s distance from its star and the star’s age. The exoplanet is located more than 200 astronomical units, or 18.59 billion miles, away from the host star, challenging currently accepted theories of planet formation. And if the host star’s estimated age of just 1.6 million years holds true, this exoplanet could be one of the youngest ever detected. Further study is needed, and scientists hope that upcoming observations with the James Webb Space Telescope will confirm the planet’s presence.
If you want to learn more, you can read the original paper here: https://iopscience.iop.org/article/10.3847/2041-8213/ac7fa3
Colliding galaxies from Gemini North Observatory
An evocative new image captured by the Gemini North telescope in Hawai’i reveals a pair of interacting spiral galaxies—NGC 4568 and NGC 4567—as they begin to clash and merge. These galaxies are entangled by their mutual gravitational field and will eventually combine to form a single elliptical galaxy in around 500 million years. Also visible in the image is the glowing remains of a supernova that was detected in 2020.
As NGC 4568 and NGC 4567 draw together and coalesce, their dueling gravitational forces will trigger bursts of intense stellar formation and wildly distort their once-majestic structures. Over millions of years, the galaxies will repeatedly swing past each other in ever-tightening loops, drawing out long streamers of stars and gas until their individual structures are so thoroughly mixed that a single, essentially spherical, galaxy emerges from the chaos. By that point, much of the gas and dust (the fuel for star formation) in this system will have been used up or blown away.