In findings that help astrophysicists understand our corner of the galaxy, an international research team has shown that the soft X-ray glow blanketing the sky comes from both inside and outside the solar system.
The source of this “diffuse X-ray background” has been debated for the past 50 years. Does it originate from the solar wind colliding with interplanetary gases within our solar system? Or is it born further away, in the “local hot bubble” of gas that a supernova is believed to have left in our galactic neighborhood about ten million years ago?
The scientists found evidence that both mechanisms contribute, but the bulk of the X-rays come from the bubble. The solar wind, a stream of charged particles continuously emitted by the Sun, appears to be responsible for at most 40 percent of the radiation, according to new findings published in the journal Nature.
“The overarching science goal of our work is to try to answer questions like: What does the local astrophysical environment look like? And what is the environment in which the Sun was born?” said Susan Lepri, an associate professor of atmospheric, oceanic and space sciences in the University of Michigan College of Engineering.
“It’s part of trying to understand our place in the universe.” Read more…
There are billions of stars and planets in the universe. A star is a glowing sphere of gas, while planets like Earth are made up of solids. The planets are formed in dust clouds that swirled around a newly formed star. Dust grains are composed of elements like carbon, silicon, oxygen, iron, and magnesium. But where does the cosmic dust come from? New research from the Niels Bohr Institute at the University of Copenhagen and Aarhus University shows that not only can grains of dust form in gigantic supernova explosions, they can also survive the subsequent shockwaves they are exposed to. The results are published in the prestigious scientific journal Nature. Read more…
A group of astronomers has been able to follow stardust being made in real time — during the aftermath of a supernova explosion. For the first time they show that these cosmic dust factories make their grains in a two-stage process, starting soon after the explosion, but continuing for years afterwards. The team used ESO’s Very Large Telescope (VLT) in northern Chile to analyze the light from the supernova SN 2010jl as it slowly faded. The new results are published online in the journal Nature on 9 July 2014.
The origin of cosmic dust in galaxies is still a mystery . Astronomers know that supernovae may be the primary source of dust, especially in the early universe, but it is still unclear how and where dust grains condense and grow. It is also unclear how they avoid destruction in the harsh environment of a star-forming galaxy. But now, observations using ESO’s VLT at the Paranal Observatory in northern Chile are lifting the veil for the first time. Read more…
An observatory run by the University of Utah found a “hotspot” beneath the Big Dipper emitting a disproportionate number of the highest-energy cosmic rays. The discovery moves physics another step toward identifying the mysterious sources of the most energetic particles in the universe.
Astrophysical Journal Letters
“This puts us closer to finding out the sources — but no cigar yet,” says University of Utah physicist Gordon Thomson, spokesman and co-principal investigator for the $25 million Telescope Array cosmic ray observatory west of Delta, Utah. It is the Northern Hemisphere’s largest cosmic ray detector.
“All we see is a blob in the sky, and inside this blob there is all sorts of stuff — various types of objects — that could be the source” of the powerful cosmic rays, he adds. “Now we know where to look.” Read more…
Mysteries about controversial signals coming from a dwarf star considered to be a prime target in the search for extraterrestrial life now have been solved in research led by scientists at Penn State University. The scientists have proven, for the first time, that some of the signals, which were suspected to be coming from two planets orbiting the star at a distance where liquid water could potentially exist, actually are coming from events inside the star itself, not from so-called “Goldilocks planets” where conditions are just right for supporting life.
The study will be published by the journal Science in its online Science Express issue [http://www.sciencemag.org/content/early/recent] on July 3, 2014, and in a future print edition of the journal [http://www.sciencemag.org].
“This result is exciting because it explains, for the first time, all the previous and somewhat conflicting observations of the intriguing dwarf star Gliese 581, a faint star with less mass than our Sun that is just 20 light-years from Earth,” said lead author Paul Robertson, a postdoctoral fellow at Penn State who is affiliated with Penn State’s Center for Exoplanets and Habitable Worlds. As a result of this research, the planets now confirmed to be orbiting this dwarf star total exactly three. Read more…