The Milky Way has many satellite galaxies, most notably the Large and Small Magellanic Clouds. They’re both visible to the naked eye from the southern hemisphere. Now astronomers have discovered another satellite that’s the smallest and dimmest one ever detected. It may also be one of the most dark matter-dominated galaxies ever found.
Continue reading “The Milky Way’s Smallest, Faintest Satellite Galaxy Found”Dwarf Galaxies Could be the Key to Explaining Dark Matter
If you have a view of the southern celestial sky, on a clear night you might see two clear smudges of light set off a bit from the great arch of the Milky Way. They are the Large and Small Magellanic Clouds, and they are the most visible of the dwarf galaxies. Dwarf galaxies are small galaxies that typically cluster around larger ones. The Milky Way, for example, has nearly two dozen dwarf galaxies. Because of their small size, they can be more significantly affected by dark matter. Their formation may even have been triggered by the distribution of dark matter. So they can be an excellent way to study this mysterious unseen material.
Continue reading “Dwarf Galaxies Could be the Key to Explaining Dark Matter”Dwarf Galaxies Banished the Darkness and Lit Up the Early Universe
During the Universe’s Dark Ages, dense primordial gas absorbed and scattered light, prohibiting it from travelling. Only when the first stars and galaxies began to shine in energetic UV light did the Epoch of Reionization begin. The powerful UV light shone through the Universe and punched holes in the gas, allowing light to travel freely.
New observations with the James Webb Space Telescope reveal how it happened. The telescope shows that faint dwarf galaxies brought an end to the darkness.
Continue reading “Dwarf Galaxies Banished the Darkness and Lit Up the Early Universe”Mystery Solved. How We Get Ultra-Compact Dwarf Galaxies
I have been fascinated by galaxies for most of my adult life. I find it amazing that, just as we can ascertain the lifecycle of a tree by closely studying the trees in a forest, it is possible to study a sample of galaxies and understand galactic evolution. A team of astronomers using the Gemini North Telescope have recently solved a long standing galactic mystery, namely how we get ultra-compact dwarf galaxies (UCDs to use their catchy acronym).
Continue reading “Mystery Solved. How We Get Ultra-Compact Dwarf Galaxies”The Perfect Tidal Tail Connects These two Galaxies Seen by Hubble
Sometimes it’s tempting to imagine a supernatural hand behind the arrangement of celestial bodies. But the Universe is big, huge even, and nature’s flow presents many fascinations.
So it is with the galactic triplet Arp 248, an arrangement of interacting galaxies that’s both visually and scientifically fascinating.
Continue reading “The Perfect Tidal Tail Connects These two Galaxies Seen by Hubble”Dwarf Galaxies Found Without Influence From Dark Matter
Ask astronomers about dark matter and one of the things they talk about is that this invisible, mysterious “stuff” permeates the universe. In particular, it exists in halos surrounding most galaxies. The mass of the halo exerts a strong gravitational influence on the galaxy itself, as well as on others in the neighborhood. That’s pretty much the standard view of dark matter and its influence on galaxies. However, there are problems with the idea of those halos. Apparently, some oddly shaped dwarf galaxies exist that look like they have no halos. How could this be? Do they represent an observationally induced challenge to the prevailing ideas about dark matter halos?
Continue reading “Dwarf Galaxies Found Without Influence From Dark Matter”A Nearby Dwarf Galaxy has a Surprisingly Massive Black Hole in its Heart
Since the 1970s, scientists have known that within the cores of most massive galaxies in the Universe, there beats the heart of a Supermassive Black Hole (SMBH). The presence of these giant black holes causes these galaxies to be particularly energetic, to the point where their central regions outshine all the stars in their disks combined – aka. Active Galactic Nuclei (AGN). The Milky Way galaxy has its own SMBH, known as Sagittarius A*, which has a mass of over 4 million Suns.
For decades, scientists have studied these objects in the hopes of learning more about their role in galactic formation and evolution. However, current research has shown that SMBHs may not be restricted to massive galaxies. In fact, a team of astronomers from the University of Texas at Austin’s McDonald Observatory recently discovered a massive black hole at the heart of a dwarf galaxy that orbits the Milky Way (Leo I). This finding could redefine our understanding of how black holes and galaxies evolve together.
Continue reading “A Nearby Dwarf Galaxy has a Surprisingly Massive Black Hole in its Heart”It Took 50 Nights of Observations to Capture New Data on the Magellanic Clouds
The Magellanic Clouds are two of our closest neighbours, in galactic terms. The pair of irregular dwarf galaxies were drawn into the Milky Way’s orbit in the distant past, and we’ve been looking up at them since the dawn of humanity. Some of our ancestors even gathered pigments and created images of them in petroglyphs and cave paintings.
Following in the footsteps of those ancient artists, astronomers recently used the Dark Energy Camera (DECam) to capture an in-depth portrait of the pair of galaxies.
Continue reading “It Took 50 Nights of Observations to Capture New Data on the Magellanic Clouds”7% of the Stars in the Milky Way’s Center Came From a Single Globular Cluster That Got Too Close and Was Broken Up
The heart of the Milky Way can be a mysterious place. A gigantic black hole resides there, and it’s surrounded by a retinue of stars that astronomers call a Nuclear Star Cluster (NSC). The NSC is one of the densest populations of stars in the Universe. There are about 20 million stars in the innermost 26 light years of the galaxy.
New research shows that about 7% of the stars in the NSC came from a single source: a globular cluster of stars that fell into the Milky Way between 3 and 5 billion years ago.
Continue reading “7% of the Stars in the Milky Way’s Center Came From a Single Globular Cluster That Got Too Close and Was Broken Up”This Dwarf Galaxy is all by Itself
In these days of social distancing, it appears this beautiful little galaxy is leading by example, sitting all by itself in the middle of a cosmic void.
KK 246, also known as ESO 461-036, is a dwarf irregular galaxy, and ESA aptly described this picture as looking like “glitter spilled across a black velvet sheet.”
But the serene view can be deceiving.
Continue reading “This Dwarf Galaxy is all by Itself”