The first galaxies lit up, with the bright flames of myriad stars, long ago. The oldest galaxies were about a tenth the size of our great spiral galaxy, the Milky Way, but they were just as bright, because they were fiercely giving birth to a great multitude of scorching hot baby stars. These extremely bright protogalaxies they served as the “seeds” of mature galaxies like our own, spinning like star-studded pinwheels in the darkness of intergalactic space. In November 2013, astronomers announced that they had put together a detailed portrait of how our Milky Way galaxy was formed, using images of the venerable Hubble Space Telescope (HST)which captured the growth of 400 similar galaxies at different stages of evolution.
How did our Milky Way galaxy assemble into the majestic, starlit, whirlpool-like structure it is now?
“For the first time we have direct images of what the Milky Way was like in the past. Of course, we cannot see the Milky Way itself in the past. We select galaxies billions of light-years away that will become galaxies. like the Milky Way. By tracing the Milky Way’s siblings, we found that our galaxy built 90 percent of its stars between 11 billion and 7 billion years ago, which is something that hasn’t been directly measured before.” study co-director Dr. Peter G. van Dokkum explained in a November 14, 2013 Hubble site press release. Dr. Dokkum is from Yale University in New Haven, Connecticut.
HST The resolving power allowed astronomers to observe how the structure of our galaxy evolved over time. A scale model of the Milky Way can be imagined as an egg “sunny side up”. The egg yolk represents the central bulge of our galaxy, which is the domain of mostly old stars, and also the secret home of a supermassive black hole, weighing millions of times more than our star. The supermassive black hole in our galaxy, called Sagittarius A*, it probably grew up along with the rest of our Galaxy. The white of the fried egg represents the disk of our Milky Way, where our own Solar System is located, in its far suburbs, in one of its spiral arms.
Tea HST the images indicate that the disk and the central bulge of our Milky Way galaxy evolved simultaneously. “You can see that these galaxies are fluffy and spread out,” said study co-leader Dr. Shannon Patel of Leiden University in the Hubble press release. Leiden University is located in the Netherlands.
“There is no evidence of a diskless bulge, around which the disk later formed. These galaxies show us that the entire Milky Way grew at the same time, unlike more massive elliptical galaxies, in which the central bulge was form first,” the team said. member Dr. Erica Nelson noted in the same Hubble site press release. Dr. Nelson is also from Yale University.
The survey shows that billions of years ago, our galaxy was most likely a faint, blue, low-mass structure containing a large amount of gas. This gas was the stuff that stars were made of. The blue hues of our galaxy’s ancestors indicate rapid star birth. This occurred when the Universe was only about 4 billion years old; today it is almost 14 billion years old. Ancient galaxies similar to the Milky Way produced about 15 stars each year. Our galaxy today forms only one new lone stellar inhabitant annually.
The most favored model of galaxy formation in the ancient Universe is humorously called the “bottom up” theory. This model suggests that large galaxies, like our own Milky Way, were rare in the early Cosmos, and only finally managed to reach their huge, majestic, mature sizes, after having gobbled up smaller galactic morsels.
Our Universe was born almost 14 billion years ago in the inflationary Big Bang, when it inflated exponentially like a balloon on steroids, growing from an exquisitely tiny Patch, smaller than a proton, to reach macroscopic size in a fraction of a second. . It has been expanding and cooling ever since, and is now accelerating its expansion at a much slower and more majestic pace than during its fabulous inflationary birth.
The star-filled galaxies caught fire at the end of a mysterious era, called the Cosmic Dark Ages–and a very murky and gloomy scene finally ended, as the Cosmos lit up with dazzling starlight. The first light-emitting objects put an end to Dark Age of the very old universe, which occurred between 380,000 and 150,000 million years after the explosion. The oldest galaxies are thought to have been opaque, dark clouds composed mostly of hydrogen gas, accumulating slowly, quietly, and relentlessly in the secret hearts of dark matter halos, and these primordial patches of dark gas attracted the first generation of burning baby stars , with its powerful gravity traps. Fiery newborn stars and extremely hot, dazzling gas lit up the ancient Universe and made it transparent.
dark matter it is a transparent, invisible and mysterious matter; it is not the familiar so-called “ordinary” atomic matter that makes up the planets, moons, and people, and everything else that is made up of the elements of the familiar family. Periodic table. However, “ordinary” atomic matter is, in fact, extraordinary. Although atomic matter constitutes an insignificant 4% of the mass energy content of the Cosmos, it gave life to our Universe.
Our Milky Way and the Andromeda Galaxy (M31) are the two largest and most majestic inhabitants of the local group of galaxies, which also contains about 20 smaller galaxies. Both our Milky Way and Andromeda are spinning spirals. Andromeda is currently 2 million light-years from our Milky Way. However, this will not always be the case. The relentless pull of gravity is pulling Andromeda towards our unfortunate Milky Way galaxy, at the monumental speed of about 100 kilometers per second. In about 4 billion years, the two galaxies will collide and merge, becoming a huge elliptical galaxy: twice the size of the Milky Way and Andromeda today.
Our galaxy in space!
To identify the distant galaxies and study them in detail, the team of astronomers used three of the largest HST programs: the 3D-HST survey, the Cosmic Assembly Near Infrared Deep Extragalactic Legacy Survey (CANDELS)and the Deep Survey of the Origins of Great Observatories (GOODS). These studies of the ancient and remote Cosmos combined spectroscopy with visible and near-infrared imaging by HST Wide Field Camera 3 Y Advanced Camera for Surveys. The team’s study involved measuring the sizes and distances of the galaxies.
The team of astronomers then determined the mass of each individual galaxy from its brightness and colors. They then chose the galaxies in their study from a catalog they had compiled of more than 100,000 galaxies. The surveyed galaxies are consistent with computer models, which indicate that the bulges, and likely black holes, that spiral galaxies sport in their young and formative years were built mostly at the same time as the disks.
“In these observations, we are capturing most of the evolution of the Milky Way. These deep surveys allow us to see the smallest galaxies. In previous observations, we were only able to see the most luminous galaxies in the distant past, and now we can look into more normal galaxies. Hubble gives us the shapes and colors of these spirals, as well as their distances from Earth. We can also measure the rates at which each part of the galaxies grew. All of this is difficult to do from the ground,” explained team member Dr. Joel Leja on the November 14, 2013 Hubble site press release. Dr. Leja is from Yale University.
Studying these galaxies from their infancy will bring the infrared eye to the sky from NASA’s next project. James Webb Space Telescopecurrently scheduled for release in 2018.
Tea HST The images also reinforce the theory that the great mergers that occur between spiral galaxies were not crucial in building them up to their current majestic sizes. Computer simulations indicate that the mergers would have shattered the disks. Instead, this survey shows that the juvenile spirals grew through star formation. This model of galaxy formation is very different from the way massive elliptical galaxies form.
“These observations show that there are at least two galaxy formation trajectories. Massive ellipticals form a very dense core in the early stages of the Universe, including a black hole, presumably, and the rest of the galaxy slowly builds up around them, fueled by mergers with others. But from our survey we found that galaxies like our Milky Way show a different and more uniform path of growth into the majestic spirals we see today,” explained Dr. van Dokkum in the November 14 2013 Hubble site press release.
The astronomers’ results were published on July 10, 2013 in The Astrophysical Journal Letters. A second article appears in the November 11, 2013, online edition of The Astrophysical Journal.
