COLUMBUS, Ohio – A study using a unique new instrument on the world’s largest optical telescope has revealed the likely origins of especially bright supernovae that astronomers use as easy-to-spot “mile markers” to measure the expansion and acceleration of the universe.
A study of 544 star-forming galaxies shows that disk galaxies like our own Milky Way reached their current state as orderly rotating pinwheels much later than previously thought, long after much of the universe’s star formation had ceased.
Galaxies are in no hurry to grow up, a team of astronomers has discovered. A comprehensive study of hundreds of galaxies observed by the Keck telescopes in Hawaii and NASA’s Hubble Space Telescope has revealed an unexpected pattern of change that extends back 8 billion years, or more than half the age of the universe.
Researchers say the distant blue galaxies they studied are gradually transforming into rotating disk galaxies like our own Milky Way. Until now, it had not been clear how a galaxy’s organization and internal motion change over time, said Benjamin Weiner, assistant astronomer at the UA Steward Observatory and co-author of the paper describing the findings, which are published in The Astrophysical Journal. (more…)
Piecing together the events of the farthest touchdown a manmade spacecraft has ever made on an alien world reveals new clues about Titan’s surface and helps plan future missions to moons and planets.
The Huygens probe, ferried to Saturn’s moon Titan by NASA’s Cassini spacecraft, bounced, slid and wobbled its way to rest in the 10 seconds after touching down on Titan in January 2005, a new analysis reveals. The moon’s surface is more complex than previously thought.
Scientists reconstructed the chain of events by analyzing data from a variety of instruments that were active during the impact, in particular changes in the acceleration experienced by the probe. The probe was supplied by the European Space Agency and named after the Dutch 17th century astronomer Christiaan Huygens. (more…)
Analysis of data from the National Science Foundation’s South Pole Telescope, for the first time, more precisely defines the period of cosmological evolution when the first stars and galaxies formed and gradually illuminated the universe. The data indicate that this period, called the epoch of reionization, was shorter than theorists speculated — and that it ended early.
“We find that the epoch of reionization lasted less than 500 million years and began when the universe was at least 250 million years old,” said Oliver Zahn, a postdoctoral fellow at the Berkeley Center for Cosmological Physics at the University of California, Berkeley, who led the study. “Before this measurement, scientists believed that reionization lasted 750 million years or longer, and had no evidence as to when reionization began.” (more…)
AUSTIN, Texas — A team of astronomers led by researchers from The University of Texas at Austin has confirmed the emission of gravitational waves from the second-strongest known source in our galaxy by studying the shrinking orbital period of a unique pair of burnt-out stars. Their observations tested Albert Einstein’s theory of general relativity in a new regime. The results will be published soon in The Astrophysical Journal Letters.
Last year, the same team discovered that the two white dwarf stars are so close together that they make a complete orbit in less than 13 minutes, and they should be gradually slipping closer. The system, called SDSS J065133.338+284423.37 (J0651 for short), contains two white dwarf stars, which are the remnant cores of stars like our sun. (more…)
Astronomers have witnessed for the first time a spiral galaxy in the early universe, billions of years before many other spiral galaxies formed. In findings reported July 19 in the journal Nature, the astronomers said they discovered it while using the Hubble Space Telescope to take pictures of about 300 very distant galaxies in the early universe and to study their properties. This distant spiral galaxy is being observed as it existed roughly three billion years after the Big Bang, and light from this part of the universe has been traveling to Earth for about 10.7 billion years.
“As you go back in time to the early universe, galaxies look really strange, clumpy and irregular, not symmetric,” said Alice Shapley, a UCLA associate professor of physics and astronomy, and co-author of the study. “The vast majority of old galaxies look like train wrecks. Our first thought was, why is this one so different, and so beautiful?” (more…)
Astronomers report a baffling discovery never seen before: An extraordinary amount of dust around a nearby star has mysteriously disappeared.
“It’s like the classic magician’s trick — now you see it, now you don’t,” said Carl Melis, a postdoctoral scholar at UC San Diego and lead author of the research. “Only in this case, we’re talking about enough dust to fill an inner solar system, and it really is gone!”
“It’s as if the rings around Saturn had disappeared,” said co-author Benjamin Zuckerman, a UCLA professor of physics and astronomy. “This is even more shocking because the dusty disc of rocky debris was bigger and much more massive than Saturn’s rings. The disc around this star, if it were in our solar system, would have extended from the sun halfway out to Earth, near the orbit of Mercury.” (more…)
PASADENA, Calif. – Astronomers have gathered the most direct evidence yet of a supermassive black hole shredding a star that wandered too close. NASA’s Galaxy Evolution Explorer, a space-based observatory, and the Pan-STARRS1 telescope on the summit of Haleakala in Hawaii were among the first to help identify the stellar remains.
Supermassive black holes, weighing millions to billions times more than the sun, lurk in the centers of most galaxies. These hefty monsters lie quietly until an unsuspecting victim, such as a star, wanders close enough to get ripped apart by their powerful gravitational clutches. (more…)
