|© ESA / Hubble; Andrey Zolotov (artwork)|
Astronomers discover (mini-) galaxies mini-compact elliptical galaxies galaxies fuitegalaxies runaway 0 comments By exploiting the public records of the Sloan digital sky survey (SDSS) and the GALEX satellite, two astronomers with a researcher from the Research Institute in Astrophysics and Planetology (IRAP - CNRS / Université Paul Sabatier Toulouse 3) have successfully identified nearly 200 new compact ellipticals and 11 mini-galaxies at large. These are the largest galaxies remains that have lost most of their stars and have been catapulted to join the intergalactic void. Such objects are extremely rare since to date only one had been found! This research demonstrates the fundamental role of reading programs celestial objects such as the SDSS and general Virtual Observatories in astronomical research.
The study conducted by two researchers initially aimed to identify new compact ellipticals. As she helped to discover nearly 200 against only 30 known before, the surprise came from these mini-galaxies leak that could be discovered at number 11 with this work against a single known earlier! Artist view schematic of the expulsion phenomenon of mini-universes as described by the three body interaction model of this research: a spiral galaxy intruder approaching a system composed of an elliptical galaxy mini orbiting a giant elliptical galaxy. During his visit, the intruder acts as a gravitational catapult that changes the orbit of the mini-galaxy. The latter is then propelled out of the system while the spiral galaxy is absorbed by the giant elliptical galaxy.
Compact elliptical galaxies are small galaxies are typically a hundred times smaller and less massive than a galaxy like the Milky Way. Normally always within the groups consisting of several galaxies: clusters. But here, many of them turned out to be mini-galaxies at large, found far from any larger galaxy or a cluster. If the first compact elliptical galaxies had previously all been found in clusters, it is simply because it is there that they had sought. By expanding the search field, the two researchers were able to discover the unexpected.
Indeed, theorists believed that these mini-galaxies could come from larger galaxies that would have been stripped of most of their stars during an interaction with an even more massive galaxy. So she had to be necessarily found near large galaxies.
In the image of a satellite that would leave its orbit around the Earth, to escape from its host system, an object is to gain some speed called the "liberation". If that was the origin of a runaway galaxy, the host would be a normal sized galaxy and the release rate would exceed 10 million kilometers per hour (2,500 km / s). Not only the newly discovered in this study mini-galaxies are found to be isolated, but they move much faster than their counterparts located within clusters.
The researchers then examined the mechanisms that could lead to the ejection of a mini-universes of its host galaxy. The solution was then found in the classic "3-body interaction." Indeed, for example, a hyperrapide star can be created in the Milky Way if a binary star system passes near the central black hole in the galaxy: a 2 Star is captured by the black hole while the other is catapulted to a staggering speed.
Similarly, when a compact elliptical galaxy pairs with a second larger galaxy, it is stripped of its stars. If a third galaxy enters the dance, the compact galaxy may be expelled from the system while leaving the intruder being absorbed by the large galaxy.
This discovery is a remarkable success of Virtual Observatories through which data from large astronomical surveys are made available to all the research and provide community by the exploitation and analysis of these data, never anticipated discoveries.