Stretched out like a 10,000 light-year stellar bridge, the Cepheus spur is a region of blue stars never seen before.
It has been discovered by a team of Spanish researchers from the Center for Astrobiology (CAB, CSIC-INTA), who have produced the most detailed map to date of massive blue stars in the solar neighborhood.
Surprising facts about our galaxy
This detailed map, thanks to the data obtained by the European Gai a space telescope, has allowed us to find something that no one had seen until now: a structure formed by massive blue stars that extends from Orion towards Perseus.
It is a branch that moves from our arm in a spiral towards the outer direction of the Milky Way, where the next arm is located. At nearly 8,000 light-years long, this type of filament is not exactly coplanar with the disk, but rather rises above the galactic plane . These types of interarm structures are often called ‘spurs’ (spur in English) and this, in particular, has been baptized as ‘Cepheus spur ‘, since it is in this constellation where it can be better appreciated, projected on the vault light blue .
“We have thoroughly reviewed the original catalog, updating and systematizing it with modern data from Gaia. And while this was the purpose of the study, having such an up-to-date sample of stars led us to take a look at the data to see which aspects of our galactic environment were manifesting more clearly. And that’s when the surprise arose ”, explains Miguel Ángel Pantaleoni González, leader of the study that includes the Monthly Notices of the Royal Astronomical Society magazine.
Astronomers want to know the detailed distribution of different types of stars and their relationship to larger galactic structures, such as the disk, spiral arms or the galactic halo. And it is that in these components the long history of the formation and evolution of the Milky Way is written by which we can decipher the main episodes of the complex history of our galactic home.
The blue stars , which are distributed along the spiral arms of galaxies, where interstellar clouds abound like star nurseries, have a fairly short life, so they do not go very far from their place of formation. Hence, blue stars are large, very massive and bright, and they help us to delimit the most active regions of the galaxy.
The team has carried out “a comprehensive update” of the ALS ( Alma Luminous Stars) catalog, the largest existing catalog of massive blue stars in our galaxy. The catalog contains almost 200,000 objects. The new data has allowed astronomers to draw the most detailed map of the spiral arms of the Milky Way for the first time.
The galactic plane is not so flat
These works show that the galactic plane is not as flat as previously thought. The Cepheus spur and the Radcliffe ripple (discovered by a team led by Joo Alves of the University of Vienna, who were studying the distribution of gas in the galaxy and identified a kind of filament perpendicular to the galactic plane that is part of a ripple that protrudes in the direction perpendicular to the plane), we might think that the galactic plane is similar to a wrinkled cloth placed on the ground , and the corrugations will be the bumps that rise above the horizontal plane.
Referencia: The Alma catalog of OB stars. II. A cross-match with Gaia DR2 and an updated map of the solar neighbourhood.
M Pantaleoni González, J Maíz Apellániz, R H Barbá, B Cameron Reed
Monthly Notices of the Royal Astronomical Society, stab688, https://doi.org/10.1093/mnras/stab688
Published: 19 March 2021
