Last year, astronomers discovered a quiescent black hole in a distant galaxy that erupted after shredding and consuming a passing star. Now researchers have identified a distinctive X-ray signal observed in the days following the outburst that comes from matter on the verge of falling into the black hole.

This tell-tale signal, called a quasi-periodic oscillation or QPO, is a characteristic feature of the accretion disks that often surround the most compact objects in the universe -- white dwarf stars, neutron stars and black holes. QPOs have been seen in many stellar-mass black holes, and there is tantalizing evidence for them in a few black holes that may have middleweight masses between 100 and 100,000 times the sun's.

Until the new finding, QPOs had been detected around only one supermassive black hole -- the type containing millions of solar masses and located at the centers of galaxies. That object is the Seyfert-type galaxy REJ 1034+396, which at a distance of 576 million light-years lies relatively nearby.

"This discovery extends our reach to the innermost edge of a black hole located billions of light-years away, which is really amazing. This gives us an opportunity to explore the nature of black holes and test Einstein's relativity at a time when the universe was very different than it is today," said Rubens Reis, an Einstein Postdoctoral Fellow at the University of Michigan in Ann Arbor. Reis led the team that uncovered the QPO signal using data from the orbiting Suzaku and XMM-Newton X-ray telescopes, a finding described in a paper published August 2 in Science Express.

Type Ia supernovae are violent stellar explosions. Observations of their brightness are used to determine distances in the universe and have shown scientists that the cosmos is expanding at an accelerating rate. But there is still too little known about the specifics of the processes by which these supernovae form. New research, led by Stella Kafka of the Carnegie Institution for Science in the United States, identifies a star system, prior to explosion, which will possibly become a type Ia supernova.

The work will appear in the journal Monthly Notices of the Royal Astronomical Society.

The widely accepted theory is that type Ia supernovae are thermonuclear explosions of a white dwarf star that's part of a binary system -- two stars that are physically close and orbit around a common centre of mass. The white dwarf has mass gradually donated to it by its companion. When the white dwarf mass eventually reaches 1.4 times that of the sun, it explodes to produce a type Ia supernova. The crucial questions are: What is the nature of the donor star and how does this white dwarf increase its mass. Also, how would that process affect the properties of the explosion?

With these questions in mind, scientists have been searching for candidate systems that could become type Ia supernovae. There are thousands of possibilities in the candidate pool, none of which have yet been observed to produce an explosion. Recent studies, some of which involved scientists at Carnegie observatories, have identified sodium gas associated with type Ia supernovae. This gas might be ejected from the binary's donor star and linger around the system to be detected after the white dwarf explodes. This provides a clue to the progenitor. Even so, Kafka still compared the search to "looking for a needle in a stellar haystack."

U.S. scientists studied Cascadia quakes going back 10,000 years and believe that a major quake is likely within 50 years

Two separate geological studies released this week suggest the earth-quake hazard in the transboundary region of the Pacific Coast of North America - including southern British Columbia - is significantly greater than previously believed.

Both teams of U.S. scientists are urging heightened readiness throughout the region for a future offshore "mega-thrust" event that could compare with the one that triggered Japan's earth-quake-tsunami-nuclear catastrophe last year.

In one study - a 13-year comprehensive analysis of the Cascadia earth-quake-prone zone between Vancouver Island and Northern California - a team of researchers concluded the "clock is ticking" ahead of a potentially devastating earthquake in the region within the next 50 years.

Two of three key signs of changes expected to occur at the boundary of interstellar space have changed faster than at any other time in the last seven years, according to new data from NASA's Voyager 1 spacecraft.

For the last seven years, Voyager 1 has been exploring the outer layer of the bubble of charged particles the sun blows around itself. In one day, on July 28, data from Voyager 1's cosmic ray instrument showed the level of high-energy cosmic rays originating from outside our solar system jumped by five percent. During the last half of that same day, the level of lower-energy particles originating from inside our solar system dropped by half. However, in three days, the levels had recovered to near their previous levels.

A third key sign is the direction of the magnetic field, and scientists are eagerly analyzing the data to see whether that has, indeed, changed direction. Scientists expect that all three of these signs will have changed when Voyager 1 has crossed into interstellar space. A preliminary analysis of the latest magnetic field data is expected to be available in the next month.

Scientists have discovered a potential cause of Earth's "icehouse climate" cooling trend of the past 45 million years. It has everything to do with the chemistry of the world's oceans.

"Seawater chemistry is characterized by long phases of stability, which are interrupted by short intervals of rapid change," said geoscientist Ulrich Wortmann of the University of Toronto, lead author of a paper reporting the results and published in the journal Science.

"We've established a new framework that helps us better interpret evolutionary trends and climate change over long periods of time. The study focuses on the past 130 million years, but similar interactions have likely occurred through the past 500 million years."

Wortmann and co-author Adina Paytan of the University of California - Santa Cruz point to the collision between India and Eurasia approximately 50 million years ago as one example of an interval of rapid change.

This collision enhanced dissolution of the most extensive belt of water-soluble gypsum on Earth, stretching from Oman to Pakistan and well into western India. Remnants of the collision are exposed in the Zagros Mountains in western Iran.

The dissolution or creation of such massive gypsum deposits changes the sulfate content of the ocean, according to the scientists, affecting the amount of sulfate aerosols in the atmosphere and thus climate.

It may not seem like elephants and Barry White would have much in common.

But it appears that both use bass singing to set the mood.

Researchers have found that elephants use an ultrasound rumble - often too low for humans to hear - to keep the herd together and for males to find mates.

It allows the animals to communicate over distances of up to six miles.

The low-pitched elephant calls, occupying a frequency range below 20 Hertz, may seem to have little in common with human singing.

But researchers have confirmed that both are produced in exactly the same way.

Experts had wondered whether, like a cat's purr, elephant infrasound was generated by muscular 'twitching' movements of the vocal cords.

Weather has been lousy this year, with droughts, heat and killer storms. But a solar superstorm could be far worse.

A monster blast of geomagnetic particles from the sun could destroy 300 or more of the 2,100 high-voltage transformers that are the backbone of the U.S. electric grid, according to the National Academy of Sciences (NAS). Even a few hundred destroyed transformers could disable the entire interconnected system.

There is impetus for a group of federal agencies to look for ways to prepare for such a storm this year as the sun moves into an active period called solar maximum, expected to peak in 2013.

U.S. experts estimate as much as a 7 percent chance of a superstorm in the next decade, which seems a slight risk, but the effects would be so wide-ranging - akin to a major meteorite strike - that it has drawn official concern.

Power blackouts can cause chaos, as they did briefly in India when more than 600 million people lost electricity for hours on two consecutive days in July. However, the kind of long-duration outage that might happen in the case of a massive solar storm would have more profound and costly effects.

Bowhead whales are now thought to have song repertoires rivaling those of birds, except the tunes sound more like psychedelic Jimi Hendrix guitar licks than avian tweets.

Listen and see what you think:

Bowhead Whale Song #1

Bowhead Whale Song #2

Note how the whales appear to sing with "two voices." They simultaneously produce high and low frequency sounds. Like Phish and other jam bands, the whales also sometimes repeat the same tune for hours at a time.

But Kate Stafford, an oceanographer with the University of Washington's Applied Physics Lab, discovered even more. The adventure began when she and her colleagues decided to count the number of bowhead whales traveling through Fram Strait, an inhospitable icy sea region between Greenland and the northern islands of Norway.

When a damaging earthquake struck the area of L'Aquila in central Italy in 2009, it was the latest in the region's long history of strong and persistent quakes. The rich recorded history of settlement in the area, along with oral traditions, archaeological excavations, inscriptions and medieval texts, and offer insight into how often the region might expect destructive earthquakes. But according to a new study by Emanuela Guidoboni and colleagues, the historical record on ancient and medieval earthquakes comes with its own shortcomings that must be addressed before the seismic history of L'Aquila can be useful in assessing the current seismic hazard in this area.

To illustrate some of these potential gaps in knowledge, the researchers combed through written records and information from archaeological excavations, covering the period from ancient Roman occupation in the first century A.D. to the late Middle Ages of the 15th century A.D. The authors say, researchers must piece together information ranging from collapsed roofs within an ancient Roman city, to the evidences of rebuilding damaged baths and cisterns. In later years, better written records offer more detail on the specific location and size of earthquakes occurring in 1349, 1456, and 1461 (a long seismic sequence).

The authors say that the early to middle Middle Ages, in particular, have a dearth of information that needs to be addressed to have a more complete picture of the region's seismic history. Overall, the records confirm that the region appears to have been host to a high number of strong earthquakes. The authors also point out a tendency in the area to produce multiple and nearly simultaneous seismic events that vary considerably in their impact.

Whether you're gay, straight or somewhere else on the spectrum, the truth of who attracts you could be in your eyes.

Pupil dilation is an accurate indicator of sexual orientation, a new study finds. When people look at erotic images and become aroused, their pupils open up in an unconscious reaction that could be used to study orientation and arousal without invasive genital measurements.

The new study is first large-scale experiment to show that pupil dilation matches what people report feeling turned on by, said study researcher Ritch Savin-Williams, a developmental psychologist at Cornell University.

"So if a man says he's straight, his eyes are dilating towards women," Savin-Williams told LiveScience. "And the opposite with gay men, their eyes are dilating to men."