[ad_1]
If we could observe our galaxy from the outside, hundreds of thousands of light years away, we would see several spiral arms forming an approximately circular disk. But depending on the position, we observe that the disc is not perfect: in addition to its mbadive center due to the concentration of stars and gas, the galactic aircraft is distorted, in the manner of. a wooden board that slanted in the rain.
This deformation of the Milky Way has been known since the late twentieth century, but as astronomers can only see the edges of the galaxy from the inside, they have not been able to describe precisely. A new map published in Nature Astronomy located 1,339 stars of the Milky Way in three dimensions to offer the first true vision of this warping.
"It is as if we were taking a soft plastic disc and Astronomer Francisco Garzón of the Canary Islands Institute of Astrophysics (Spain) did not participate in the research published in Nature Astronomy Several decades ago it was discovered that The galaxy was not flat due to the distribution of hydrogen in its periphery, but the new study does not rely on gas observations. Instead, it maps the position of individual stars as reference points distributed by the disk [19659004] Three-dimensional map of 1339 stars representing the chain of the Milky Way.Each blue point is an observable star in the visible spectrum, each red dot is an observable star in infrared spectrum The black arrow indicates the position of the Sun "srcset =" // ep00.epimg.net/t.gif 200w "data-srcset =" // ep01.epimg.net/elpais/imagenes / 2019/02/04 / ciencia / 154931 0038_743463_1549311324_sumario_normal_recorte1.jpg 1960w, //ep01.epimg.net/elpais/imagenes/2019/02/04/ciencia/1549310038_743463_1549311324_sumario_normal_recorte2.jpg 720w, //ep01.epimg.net/elpais/imagenes/2019/02/04/ciencia/ 1549310038_743463_1549311324_sumario_normal.jpg 980w "/>
The team of Chinese and Australian researchers is focused on the stars called Cepheid variables. These are stars that pulsate radially (like a beacon), with a very stable period, directly proportional to its brightness. This allows to know the intrinsic brightness of the star only by measuring the time interval between its pulsations. You can then calculate your distance from the Earth by comparing the observable brightness with the actual. These properties of the Cepheids, discovered by the calculator Henrietta Leavitt between 1908 and 1912, made them ideal objects to measure astronomical distances.
"It is notoriously difficult to determine the distances between the Sun and the areas of the outer disk of the Milky Way without knowing what form" said Xiaodian Chen, lead author of the study, attached to the Chinese Academy of Sciences Beijing. For this, he and his companions have chosen Cepheides 4 to 20 times more mbadive than our Sun and up to 100,000 times brighter. Some are observable in the visible spectrum and others only in the infrared.
The information they badyzed comes from the astronomical telescope WISE, launched by NASA in December 2009. They were also based on data from the space probe Gaia, the mission. since 2013. They used this data to eliminate the noise of the original sample and thus produce a clean map which "is not erased by worn objects" , according to Garzón
. confirms that the irregularities of the galactic edge are due to the interaction between the gravitational force and the centrifugal force of the dense nucleus of the stars. These are deformities that were not present when the Milky Way was younger. The new map, by its precision, makes it possible to discard certain models of formation and evolution of the galaxies, as well as to refine the predictions of the others.
For the first time, research reveals a hitherto unknown precession in the axis of empazamento of the galaxy. . This means that in addition to folding the edges of the galaxy in opposite directions, they also twist at the ends perpendicular to the disc. To visualize this phenomenon, one can consider the Milky Way as a disc composed of concentric rings, which bend differently so as to reach closer angles when they move away from the center.
This card covers a department. of about 20 kiloparsecs from the galactic center, or 65,230 light-years. It is the most complete picture ever obtained from the shape of the Milky Way, but it is known that the actual extent of the galaxy is larger, with a radius of over 40,000. minus 25 kiloparsecs. Our sun is about eight kiloparsecs from the center. Although warping does not occur in all galaxies, it is not unique to the Milky Way. In some galaxies that have a favorable orientation – those that are apart for us – we observe that the stars draw a kind of S in the firmament. However, no study has been studied as accurately as ours.
