Posted on 11/11/2017 11:34:42 PM PST by ETL
Astronomers have uncovered an ancient cosmic artifact 11 billion light-years from Earth: the oldest spiral galaxy ever seen.
The newly discovered galaxy, known as A1689B11, is an ancestor of modern spiral galaxies like our own Milky Way, which are defined by long tentacles of gas, dust and stars that wrap around the galaxy's central bulge.
"Spiral galaxies are exceptionally rare in the early universe, and this discovery opens the door to investigating how galaxies transition from highly chaotic, turbulent discs to tranquil, thin discs like those of our own Milky Way galaxy," Renyue Cen, a co-author of the new paper describing the findings and a senior research astronomer at Princeton University, said in a statement.
Galaxies come in many different shapes and sizes, and researchers think many spiral galaxies form mainly through mergers of smaller elliptical galaxies, although many factors can affect how a galaxy changes its shape over time, according to NASA. Elliptical galaxies are disks that can be mostly circular or very elongated but lack the arm-like features of spiral galaxies.
Astronomer Edwin Hubble was one of the first people to theorize that elliptical galaxies evolved to form spiral galaxies, although he did not fully appreciate the complexity of galaxy evolution, according to the European Space Agency's Hubble Space Telescope website. Nonetheless, researchers still refer to the time in cosmic history when spiral galaxies began to form from elliptical galaxies as "the Hubble sequence."
"Studying ancient spirals like A1689B11 is a key to unlocking the mystery of how and when the Hubble sequence emerges," Cen said in the statement from Swinburne University in Australia (where some of the other co-authors are based). Previously, researchers reported finding spiral galaxies that date back 10.7 billion years.
The newly discovered galaxy is too far away to be observed directly with modern instruments. So the researchers took advantage of a natural phenomenon known as gravitational lensing, in which the gravity of a massive object (like a galaxy or a cluster of galaxies) bends and amplifies the light from an object that lies beyond it (as seen by an observer). In this way, the authors of the new research paper were able to detect light from the very distant spiral galaxy A1689B11 by looking for the effects of gravitational lensing around the edge of a galaxy cluster that is nearer to Earth.
The observations were conducted using an instrument called the Near-infrared Integral Field Spectrograph on the Gemini North telescope, located on Mauna Kea in Hawaii. The researchers were able to "look 11 billion years back in time and directly witness the formation of the first, primitive spiral arms of a galaxy," Cen said in the statement.
Because light travels at a finite speed, the light from A1689B11 left that galaxy 11 billion years ago, when the universe was less than 3 billion years old. In this way, astronomers can look back in time and learn about the history of the universe through direct observations.
And intimately related to the material of which we are made.
Definitely
That’s how far away it was 11 billion years ago.
Even that may not be entirely true. After all, the rate of the expansion over the course of 11 billion years has supposedly changed a few times. First there was the "Inflation" period, where the rate was many times faster than light. Then, sometime after that, the rate apparently slowed considerably, then started speeding up again to be where it's supposedly at today, accelerating.
From an earlier post...
“Astronomers (and other people) are not always very clear about what they mean when they talk about an object’s “distance”, leading to a lot of confusion about this topic. Read on for a further explanation.
First of all, the expansion of the universe doesn’t consist of galaxies moving through some static space, but rather the “stretching” of the space itself.
The light is moving through this expanding space and has to travel the initial distance plus whatever distance is added due to the universe’s expansion during the course of the journey.
It’s like running on a racetrack that is being stretched — if the racetrack started off 100 meters long but got stretched to a final length of 400 meters as you were running from start to finish, then the total distance you’ve run is more than 100 meters.
In fact, when you talk about the “distance” between the start and finish lines in this racetrack, you might mean several different things:
(1) You could mean 100 meters, since that’s the distance when you start running; it’s also what the markings on the track say the distance is.
(2) You could mean 400 meters, since that’s the distance between start and finish at the moment you reach the finish line.
(3) You could mean the actual distance you’ve run, which is more than 100 meters (since the track stretches while you’re running on it), but less than 400 meters (since some of the stretching happens on parts of the track you’ve already passed through).”
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