An international group of scientists led by Ivo Saviane from the European Southern Observatory has used Hubble’s Advanced Camera for Surveys and Wide Field Planetary Camera 2 to observe individual stars spawned by the colossal cosmic collision in the Antennae Galaxies.
They reached an interesting and surprising conclusion. By measuring the colours and brightnesses of red giant stars in the system, the scientists found that the Antennae Galaxies are much closer than previously thought: 45 million light-years instead of the previous best estimate of 65 million light-years.
The team targeted a region in the relatively quiescent outer regions in the southern tidal tail, away from the active central regions. This tail consists of material thrown from the main galaxies as they collided. The scientists needed to observe regions with older red giant stars to derive an accurate distance. Red giants are known to reach a standard brightness, which can then be used to infer their distance. The method is known as the tip of the red giant branch (TRGB).
The proximity of the Antennae system means it is the best-studied galaxy merger in the sky, with a wealth of observational data to be compared to the predictions of theoretical models. Saviane says: “All aspiring models for galaxy evolution must be able to account for the observed features of the Antennae Galaxies, just as respectable stellar models must be able to match the observed properties of the Sun. Accurate models require the correct merger parameters, and of these, the distance is the most essential”.
The previous canonical distance to the Antennae Galaxy was about 65 million light-years although values as high as 100 million light years have been used. Our Sun is only eight light-minutes away from us, so the Antennae Galaxies may seem rather distant, but if we consider that we already know of galaxies that are more than ten billion light-years away, the two Antennae Galaxies are really our neighbours.
The previous larger distance required astronomers to invoke some quite exceptional physical characteristics to account for the spectacular system: very high star-formation rates, supermassive star clusters, ultraluminous X-ray sources etc. The new smaller distance makes the Antennae Galaxies less extreme in terms of the physics needed to explain the observed phenomena. For instance, with the smaller distance its infrared radiation is now that expected of a “standard” early merging event rather than that of an ultraluminous infrared galaxy. The size of the star clusters formed as a consequence of the Antennae merger now agree with those of clusters created in other mergers instead of being 1.5 times as large.
The Antennae Galaxies are named for the two long tails of stars, gas and dust that resemble the antennae of an insect. These “antennae” are a physical result of the collision between the two galaxies. Studying their properties gives us a preview of what may happen when our Milky Way galaxy collides with the neighbouring Andromeda galaxy in several billion years. Although galaxy mergers today are not common, it is believed that in the past they were an important channel of galaxy evolution. Therefore understanding the physics of galaxy mergers is a very important task for astrophysicists.
The Antennae are located in the constellation of Corvus, the Crow.
Lars Christensen | alfa
First evidence on the source of extragalactic particles
13.07.2018 | Technische Universität München
Simpler interferometer can fine tune even the quickest pulses of light
12.07.2018 | University of Rochester
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
13.07.2018 | Event News
13.07.2018 | Materials Sciences
13.07.2018 | Life Sciences