Astronomers using the National Science Foundation’s Green Bank Telescope (GBT) in West Virginia, along with data from other large radio telescopes, have discovered that our nearest galactic neighbors, the dwarf spheroidal galaxies, are devoid of star-forming gas, and that our Milky Way Galaxy is to blame.
These new radio observations, which are the highest sensitivity of their kind ever undertaken, reveal that within a well-defined boundary around our Galaxy, dwarf galaxies are completely devoid of hydrogen gas; beyond this point, dwarf galaxies are teeming with star-forming material.
The Milky Way Galaxy is actually the largest member of a compact clutch of galaxies that are bound together by gravity. Swarming around our home Galaxy is a menagerie of smaller dwarf galaxies, the smallest of which are the relatively nearby dwarf spheroidals, which may be the leftover building blocks of galaxy formation.
Further out are a number of similarly sized and slightly misshaped dwarf irregular galaxies, which are not gravitationally bound to the Milky Way and may be relative newcomers to our galactic neighborhood.
“Astronomers wondered if, after billions of years of interaction, the nearby dwarf spheroidal galaxies have all the same star-forming ‘stuff’ that we find in more distant dwarf galaxies,” said astronomer Kristine Spekkens, assistant professor at the Royal Military College of Canada and lead author on a paper published in the Astrophysical Journal Letters.
Previous studies have shown that the more distant dwarf irregular galaxies have large reservoirs of neutral hydrogen gas, the fuel for star formation. These past observations, however, were not sensitive enough to rule out the presence of this gas in the smallest dwarf spheroidal galaxies.
By bringing to bear the combined power of the GBT (the world’s largest fully steerable radio telescope) and other giant telescopes from around the world, Spekkens and her team were able to probe the dwarf galaxies that have been swarming around the Milky Way for billions of years for tiny amounts of atomic hydrogen.
“What we found is that there is a clear break, a point near our home Galaxy where dwarf galaxies are completely devoid of any traces of neutral atomic hydrogen,” noted Spekkens. Beyond this point, which extends approximately 1,000 light-years from the edge of the Milky Way’s star-filled disk to a point that is thought to coincide with the edge of its dark matter distribution, dwarf spheroidals become vanishingly rare while their gas-rich, dwarf irregular counterparts flourish.
There are many ways that larger, mature galaxies can lose their star-forming material, but this is mostly tied to furious star formation or powerful jets of material driven by supermassive black holes. The dwarf galaxies that orbit the Milky Way contain neither of these energetic processes. They are, however, susceptible to the broader influences of the Milky Way, which itself resides within an extended, diffuse halo of hot hydrogen plasma.
The researchers believe that, up to a certain distance from the galactic disk, this halo is dense enough to affect the composition of dwarf galaxies. Within this “danger zone,” the pressure created by the million-mile-per-hour orbital velocities of the dwarf spheroidals can actually strip away any detectable traces of neutral hydrogen. The Milky Way thus shuts down star formation in its smallest neighbors.
"These observations therefore reveal a great deal about size of the hot halo and about how companions orbit the Milky Way," concludes Spekkens.
Contact: Charles E. Blue, Public Information Officer
(434) 296-0314; firstname.lastname@example.org
Charles Blue | Eurek Alert!
Heating quantum matter: A novel view on topology
22.08.2017 | Université libre de Bruxelles
Engineering team images tiny quasicrystals as they form
18.08.2017 | Cornell University
Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.
As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...
Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.
Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...
For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.
While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...
An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.
The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...
A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.
Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...
16.08.2017 | Event News
04.08.2017 | Event News
26.07.2017 | Event News
22.08.2017 | Health and Medicine
22.08.2017 | Materials Sciences
22.08.2017 | Life Sciences