Globular clusters (GCs) are spherical groups of stars held together by mutual gravity. Large ones can have millions of stars, and the stars tend to be older and have lower metallicity. The Milky Way contains more than 200 globulars, possibly many more, and most of them are in the galaxy’s halo, the outer reaches of the galaxy.
But they’re not all in the halo, and astronomers are keen to find ones nearest the galactic centre. Now, researchers have found one GC that’s plunging toward the Milky Way’s Centre.
The JWST is taking a break from studying the distant Universe and has trained its infrared eye on the heart of the Milky Way. The world’s most powerful space telescope has uncovered some surprises and generated some stunning images of the Milky Way’s galactic center (GC.) It’s focused on an enormous star-forming region called Sagittarius C (Sgr C).
Thanks to its infrared capabilities, the James Webb Space Telescope (JWST) allows astronomers to peer through the gas and dust clogging the Milky Way’s center, revealing never-before-seen features. One of the biggest mysteries is the star forming region called Sagittarius C, located about 300 light-years from the Milky Way’s supermassive black hole. An estimated 500,000 stars are forming in this region that’s being blasted by radiation from the densely packed stars. How can they form in such an intense environment?
To understand the Universe, we need to understand the extreme processes that shape it and drive its evolution. Things like supermassive black holes (SMBHs,) supernovae, massive reservoirs of dense gas, and crowds of stars both on and off the main sequence. Fortunately there’s a place where these objects dwell in close proximity to one another: the Milky Way’s Galactic Center (GC.)
At the center of the Milky Way, there is a massive persistent radio source known as Sagittarius A*. Since the 1970s, astronomers have known that this source is a supermassive black hole (SMBH) roughly 4 million times the mass of our Sun. Thanks to advancements in optics, spectrometers, and interferometry, astronomers have been able to peer into Galactic Center. In addition, thanks to the international consortium known as the Event Horizon Telescope (EHT), the world got to see the first image of Sagittarius A* (Sgr A*) in May 2022.
These efforts have allowed astronomers and astrophysicists to characterize the environment at the center of our galaxy and see how the laws of physics work under the most extreme conditions. For instance, scientists have been observing a mysterious elongated object around the Sgr A* (named X7) and wondered what it was. In a new study based on two decades’ worth of data, an international team of astronomers with the UCLA Galactic Center Group (GCG) and the Keck Observatory have proposed that it could be a debris cloud created by a stellar collision.
In the 17th century, Galileo Galilee aimed his telescope at the stars and demonstrated (for the first time) that the Milky Way was not a nebulous band but a collection of distant stars. This led to the discovery that our Sun was merely one of the countless stars in a much larger structure: the Milky Way Galaxy. By the 18th century, William Herschel became the first astronomer to create a map that attempted to capture the shape of the Milky Way. Even after all that time and discovery, astronomers are still plagued by the problem of perspective.
While we have been able to characterize galaxies we see across the cosmos with relative ease, it is difficult for astronomers to study the size, shape, and population of the Milky Way because of how our Solar System is embedded in its disk. Luckily, there are methods to circumvent this problem of perspective, which have provided astronomers with clues to these questions. In a recent paper, a team from the Astronomical Observatory at the University of Warsaw (AstroUW) used a large collection of Mira variable stars to trace the shape of the Milky Way, which yielded some interesting results!
It all began with the discovery of Sagittarius A*, a persistent radio source located at the Galactic Center of the Milky Way that turned out to be a supermassive black hole (SMBH). This discovery was accompanied by the realization that SMBHs exist at the heart of most galaxies, which account for their energetic nature and the hypervelocity jets extending from their center. Since then, scientists have been trying to get a better look at Sag A* and its surroundings to learn more about the role SMBHs play in the formation and evolution of our galaxy.
This has been the goal of the GRAVITY collaboration, an international team of astronomers and astrophysicists that have been studying the core of the Milky Way for the past thirty years. Using the ESO’s Very Large Telescope Interferometer (VLTI), this team obtained the deepest and sharpest images to date of the region around Sag A*. These observations led to the most precise measurement yet of the black hole’s mass and revealed a never-before-seen star that orbits close to it.
The Milky Way is 13 BILLION years old. Some of our Galaxy’s oldest stars were born near the beginning of the Universe itself. During all these eons of time, we know at least one technological civilization has been born – US!
But if the Galaxy is so ancient, and we know it can create life, why haven’t we heard from anybody else? If another civilization was just 0.1% of the Galaxy’s age older than we are, they would be millions of years further along than us and presumably more advanced. If we are already on the cusp of sending life to other worlds, shouldn’t the Milky Way be teeming with alien ships and colonies by now?
Maybe. But it’s also possible that we’ve been looking in the wrong place. Recent computer simulations by Jason T. Wright et al suggest that the best place to look for ancient space-faring civilizations might be the core of the Galaxy, a relatively unexplored target in the search for extra terrestrial intelligence.
Like other spiral galaxies, the Milky Way has a bulging sphere of stars in its center. It’s called “The Bulge,” and it’s roughly 10,000 light-years in radius. Astronomers have debated the bulge’s origins, with some research showing that multiple episodes of star formation created it.
But a new survey with the NOIRLab’s Dark Energy Camera suggests that one single epic burst of star formation created the bulge over 10 billion years ago.
The center of our very own galaxy might be one of the Universe’s most mysterious places. Astronomers have to probe through thick dust to see what’s going on there. All that dust makes life difficult for astronomers who are trying to understand all the radiation in the center of the Milky Way, and what exactly its source is.
A new study based on 20 years of data—and a hydrogen bubble where there shouldn’t be one—is helping astronomers understand all that energy.