Mira stars are only half as large as previously thought, according to a new study. Named for Mira, or Omicron Ceti, this class of stars contains variable red giants with periods ranging 80 to 1,000 days and apparent brightness fluctuating by as much as a factor of ten with each cycle, astronomy.com said.
Despite their immense sizes, Mira stars are mere pinpoints of light to the unaided eye, and even the largest telescopes cannot resolve their surfaces. Using interferometry, however, a technique that combines light from multiple telescopes, an international team of astronomers revealed the close environment of Mira stars--and their actual sizes.
The team, led by Guy Perrin of the Paris Observatory/LESIA and Stephen Ridgway of the National Optical Astronomy Observatory in Tucson, Arizona, observed five Mira stars--Chi Cygni, U Orionis, T Cephei, R Leonis, and Mira itself--in near-infrared wavelengths. These stars are among the brightest--and, in apparent size, largest--Mira variables visible in the Northern Hemisphere.
Miras have long been known as molecule and dust "factories." Their relatively cool temperatures allow molecules like water and oxides of carbon, silicon, and titanium to form.
Owing to their pulsation and overall large diameters, Miras lose mass at a billion times the rate of Sun-like stars, surrounding themselves with dense, complex shells of matter. When Miras finally bare their white-hot cores, these circumstellar envelopes light up as proto-planetary nebulae. Mira stars are interesting to astronomers because they show the fate of our own Sun in 5 billion years.
The astronomers used the Infrared-Optical Telescope Array (IOTA) of the Smithsonian Astrophysical Observatory in Arizona for their work. IOTA has two arms connected at 90¸ and three collectors, which can be positioned at different stations along the arms. To collect data at different wavelengths, the collectors were spaced 33-125 feet (10-38 meters) apart.

Rhodoliths, colorful marine algae, resembles coral.

While researchers in Alaska this summer used high-tech submersibles and huge ships to plumb the deep-ocean depths in search of new species, a team of scuba diving scientists working from an Alaska fishing boat has discovered an entirely new marine habitat just a stone's throw from shore, Science Daily reported.
The discovery in June of a single bed of rhodoliths, colorful marine algae that resemble coral, was made near Knight Island in Prince William Sound by scientists at the University of Alaska Fairbanks (UAF) School of Fisheries and Ocean Sciences (SFOS). Rhodolith beds have been found throughout the world's oceans, including in the Arctic near Greenland and in waters off British Columbia, Canada. But they have never been documented in Alaska waters.
"This is exciting because it represents a new type of habitat scientists had not identified before in Alaska," said Brenda Konar, associate professor of marine biology at SFOS and staff scientist with the West Coast and Polar Regions Undersea Research Center at UAF.
Globally, rhodoliths fill an important niche in the marine ecosystem, serving as a transition habitat between rocky areas and barren, sandy areas. Rhodoliths provide habitat for a wide variety of species, from commercial species such as clams and scallops to true corals. The discovery of rhodoliths in Alaska is likely to fuel the debate over the protection of seafloor habitats.
The discovery came after Konar and Katrin Iken, assistant professor of marine biology with the university's Institute of Marine Science, accidentally dropped a small strainer, or sieve, overboard.
The scientists had been conducting nearshore surveys of marine life as part of an international study sponsored by the Census of Marine Life NaGISA program and funded by the Gulf Ecosystem Monitoring program.
While scientists agree that ocean currents are key to distributing rhodoliths around the world, debate centers on where P. calcareum originated. Riosmena-Rodriguez says the species may have actually originated in Alaska waters. More research on the species' evolutionary history is needed to be sure.
The other rhodolith specimen collected by Konar and Iken is potentially a species new to science.
Scientists believe rhodoliths have been present in the world's oceans since at least the Eocene epoch, some 55 million years ago. Because rhodoliths probably grow very slowly in Alaska's cold waters, Riosmena-Rodriguez said they probably have been in Alaska a very long time, perhaps long enough to have evolved into an entirely new species.

Ice is sliding off the Antarctic continent much faster than it did during the 1990s, several teams of researchers have found, nature.com said.
On the Antarctic Peninsula that sticks out from the western side of the continent, the speeds at which several glaciers are surging into the sea have increased eight-fold between 2000 and 20031,2. And below the peninsula, in Western Antarctica, glaciers are now releasing 250 billion tonnes of ice into the Amundsen Sea each year--enough to raise global sea levels by 2 millimeters per decade3.
The results, which draw on satellite and aircraft measurements of glacier thickness and flow, highlight the disturbing potential consequences of recent climate warming in the Antarctic region.
The thick sheet of ice covering Western Antarctica is a focal point for fears about the effects of climate change on the frozen poles. It is particularly vulnerable because it rests on land that lies below sea level, and there is a danger that if the ice shelves surrounding it were to disintegrate, the entire ice sheet could slide into the sea.
If that happened, global sea level would rise by an awesome 5 meters: five times greater than the highest current prediction for the increase in sea level over the next century.
"The potential impacts of a major change in the West Antarctic Ice Sheet are severe," says David Vaughan of the British Antarctic Survey in Cambridge. "Sea level rise will be fantastically expensive for developed nations with coastal cities and dire for poor populations in low-lying coastal areas."

Scientists used a motorized hang glider to return the first Northern Bald Ibis colony to its historic migratory path more than 400 years after they died out in Europe, ananova.com said.
The hand-reared birds had no idea of the traditional routes their ancestors would have used to make the 500-mile migration from Austria to Italy for the winter.
The eight birds, raised in captivity, began their journey in Gruenau, Austria, and were led southwards by members of the team flying in the hang glider.
The journey ended 500 miles away in Tuscany, Italy, where the birds will stay until spring, when scientists hoped they would find their way back to Austria on their own.
After surviving storms and shots from hunters, the birds earlier in the week appeared to be losing their motivation just days before reaching the target in Maremma.
"They were suffering from migration stress," said the team's leader Johannes Fritz.
Four of the birds, also called Waldrapp Ibis, at one point refused to fly for several days, and a female named Kaja attempted to turn around and head back to Austria.
A male named Rudi also had to be driven by car the last leg after dislocating his hip joint.
Researchers feared the birds might prefer the "all-inclusive hotel" provided by the research laboratory in Austria to the wild, where they have to forage for food.
The hand-reared colony is part of an attempt to reintroduce the birds to Austria after their extinction in the area four hundred years ago.