When was the milky way created

Or the disk may have started taking shape when the halo did, nearly 1 billion years ahead of schedule. To see which was more probable, he connected with Tobias Buck , a researcher at the Leibniz Institute for Astrophysics in Potsdam, Germany, who specializes in crafting digital galaxy simulations. Past efforts had generally produced halos first and disks second, as expected. But these were relatively low-resolution efforts.

In these digital simulations, a Milky Way—like galaxy forms and evolves over The leftmost column shows the distribution of invisible dark matter; the center column the temperature of gas where blue is cold and red is hot ; and the right column the density of stars.

Each row highlights a different size scale: The top row is a zoomed-in look at the galactic disk; the center column a mid-range view of the galactic halo; and the bottom row a zoomed-out view of the environment around the galaxy. Buck increased the crispness of his simulations by about a factor of At that resolution, each run demanded intensive computational resources.

He repeated the exercise six times. Two of those featured substantial numbers of metal-poor disk stars. How did those ancient stars get into the disk?

Simply put, they were stellar immigrants. Some of them were born in clouds that predated the Milky Way. Then the clouds just happened to deposit some of their stars into orbits that would eventually form part of the galactic disk. The results, which the group published in November , suggest that the classic galaxy formation models were incomplete.

Gas clouds do collapse into spherical halos, as expected. But stars arriving at just the right angles can kick-start a disk at the same time. With Gaia, astronomers have found direct evidence of cataclysmic collisions. Astronomers assumed that the Milky Way had a hectic youth, but Helmer Koppelman , an astronomer now at the Institute for Advanced Study in Princeton, New Jersey, used the Gaia data to help pinpoint specific debris from one of the largest mergers.

He processed the data on Thursday, and by Friday he knew he was on to something big. In every direction, he saw a huge number of halo stars ping-ponging back and forth in the center of the Milky Way in the same peculiar way — a clue that they had come from a single dwarf galaxy.

Beryllium is one of the lightest elements [2] - the nucleus of the most common and stable isotope Beryllium-9 consists of four protons and five neutrons. Only hydrogen, helium and lithium are lighter. But while those three were produced during the Big Bang, and while most of the heavier elements were produced later in the interior of stars, Beryllium-9 can only be produced by "cosmic spallation".

That is, by fragmentation of fast-moving heavier nuclei - originating in the mentioned supernovae explosions and referred to as energetic "galactic cosmic rays" - when they collide with light nuclei mostly protons and alpha particles, i. The galactic cosmic rays travelled all over the early Milky Way, guided by the cosmic magnetic field. The resulting production of Beryllium was quite uniform within the galaxy.

The amount of Beryllium increased with time and this is why it might act as a "cosmic clock". The longer the time that passed between the formation of the first stars or, more correctly, their quick demise in supernovae explosions and the formation of the globular cluster stars, the higher was the Beryllium content in the interstellar medium from which they were formed.

Thus, assuming that this Beryllium is preserved in the stellar atmosphere, the more Beryllium is found in such a star, the longer is the time interval between the formation of the first stars and of this star. The Beryllium may therefore provide us with unique and crucial information about the duration of the early stages of the Milky Way. So far, so good. The theoretical foundations for this dating method were developed during the past three decades and all what is needed is then to measure the Beryllium content in some globular cluster stars.

But this is not as simple as it sounds! The main problem is that Beryllium is destroyed at temperatures above a few million degrees. When a star evolves towards the luminous giant phase, violent motion convection sets in, the gas in the upper stellar atmosphere gets into contact with the hot interior gas in which all Beryllium has been destroyed and the initial Beryllium content in the stellar atmosphere is thus significantly diluted.

To use the Beryllium clock, it is therefore necessary to measure the content of this element in less massive, less evolved stars in the globular cluster. And these so-called "turn-off TO stars" are intrinsically faint. In fact, the technical problem to overcome is three-fold: First, all globular clusters are quite far away and as the stars to be measured are intrinsically faint, they appear quite faint in the sky.

Secondly, there are only two Beryllium signatures spectral lines visible in the stellar spectrum and as these old stars do contain comparatively little Beryllium, those lines are very weak, especially when compared to neighbouring spectral lines from other elements.

And third, the two Beryllium lines are situated in a little explored spectral region at wavelength nm, i. Astronomers think that this is how many larger galaxies have come to be the size they are today.

In fact, the Milky Way is currently gobbling up another galaxy , and a stellar cluster at this very moment. Called the Canis Major Dwarf Galaxy, the remnant stars are 45, light years from the galactic center, and a mere 25, light years from our Sun.

Younger stars in the galaxy are located in the disk, evidence that as it started to get heavier, the mutual orbit of material started the galaxy spinning, which resulted in the spiral one sees in representations of the Milky Way.

By comparing them, we can begin to understand how galaxies and their stars are born, how they change and how they die over time.

How Old Are Galaxies? If you liked this, you may like: What Is a Galaxy? Types of Galaxies. What Is a Satellite Galaxy?