October 2, 2022


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A "sliver" 3,000 light-years long was found in the arm of the Milky Way

A “sliver” 3,000 light-years long was found in the arm of the Milky Way

| Astronomy / Physics

A previously unknown structure has been discovered in one of the arms of the Milky Way. It turned out to be a bow arm It emerges from a ‘sliver’ formed from a 3,000-light-year-long cluster of young stars and gas cloudsWhere stars are formed. This is the first large structure in our galaxy with a completely different orientation than the arm itself.


Astronomers know more or less what the individual arms of the Milky Way look and size. However, there are many things we do not know. We are unable to observe the entire galaxy because we are inside it.

The authors of the latest research decided to take a closer look at the regions near the arc arm. They used data from the Spitzer Space Telescope, and it was collected, before his retirement In January 2020. They focused on finding young stars hidden in the clouds of gas and dust in which they were born. Spitzer was able to observe such things because he worked in infrared.

Until now, it was believed that young stars and nebulae closely follow the shape of the arms of the galaxy in which they are located. Researchers from the California Institute of Technology (Caltech) have combined data from Spitzer with the latest information from the European Gaia mission, which accurately measures distances from stars. In doing so, they note that the long, thin structure attached to the arm of Sagittarius is made up of young stars traveling at roughly the same speed and in the same direction.

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The main characteristic of a galaxy’s spiral arms is how tightly they wrap around the center of the galaxy. Most models of the Milky Way indicate that the arc arm forms a spiral with a tilt angle of about 12 degrees. However, the angle of inclination of the structure we observed was about 80 degreessays lead author of the study Michael Kuhn.

Similar structures, sometimes called feathers or outcrops, are often found in the arms of other spiral galaxies. Until now, scientists have wondered whether the arms of the Milky Way also contain these structures, or if they are smooth.

The observed structure includes four nebulae known for their beauty: the Eagle Nebula with the famous Pillars of Creation, the Omega Nebula, the Three-leaf Clover Nebula, and the Lake Nebula. In the 1950s, scientists made distance measurements to some stars in these nebulae and deduced from them the existence of the Sagittarius arm, one of the first evidence that the Milky Way is a spiral galaxy.

Measuring distance is one of the most difficult tasks in astronomy. Only the latest direct measurements by Gaia have revealed the geometry of the structure we have describedStudy co-author Alberto Crohn-Martins says. By integrating data from Gaia and Spitzer, we obtained a detailed 3D map. Now we can see that this area is more complex than it looksCone adds.

Astronomers still do not fully understand how the spiral arms of galaxies are formed. It is possible that the stars in the newly observed structure formed at a similar time, in a similar region, and were influenced by intragalactic forces, including those related to the rotation of the galaxy.

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Here we see how much we don’t know about the structure of the Milky Way. This shows us that we need to look at the details if we want to get a sense of the bigger picture. The structure studied here is a small part of the Milky Way, but it can tell us a lot about the galaxy as a whole., dodaje Robert Benjami z University of Wisconsin Whitewater.

Sagittarius Arm Milky Way Eagle Nebula Trifoliate Clover Nebula