Want to know what early or extraterrestrial life might look like? You might try looking at Earth’s extremes: the coldest, highest, and deepest places on our planet. One unmanned research vehicle just tried the last of these strategies, and took samples from a hydrothermal vent plume 16,000 feet under the sea–about 2,000 feet deeper than the previous record-holding vent.

A research team led by Woods Hole Oceanographic Institution (WHOI) and including scientists at NASA’s Jet Propulsion Laboratory studied three hydrothermal vents, found along an underwater ridge in the Caribbean called the Mid-Cayman Rise. They published their findings yesterday in The Proceedings of the National Academy of Sciences.

Hydrothermal vents are usually found in spots where the Earth’s tectonic are moving away from each other, creating a weird zone of raw chemistry. A mixture of hot vent fluids and cold deep-ocean water form plumes, which can contain dissolved chemicals, minerals, and microbes. Instead of searching the entire 60-mile-long ridge with the vehicle, the team scouted for chemicals from the plume to zero-in on the vents.

“Every time you get a hydrothermal system, it’s wet and hot, and you get water and rocks interacting. Wherever this happens on the seafloor, life takes advantage,” said geophysicist Chris German of the Woods Hole Oceanographic Institute. “Every time you find seawater interacting with volcanic rock, there’s weird and wonderful life associated with it.” [Wired]

Researchers were surprised to find along the ridge three very different types of vents–each type being characterized by the kind of rock where the vent appears.

Chris German, a WHOI geochemist … has pioneered the use of autonomous underwater vehicles (AUVs) to search for hydrothermal vent sites. “Finding evidence for three sites was quite unexpected–but then finding out that our data indicated that each site represents a different style of venting–one of every kind known, all in pretty much the same place–was extraordinarily cool.” [WHOI]

The researchers have found deep-sea bacteria in water samples from these vents’ plumes, and they hope to one day send vehicles further into the depths–but that will require upgraded vehicles that can maneuver at such extreme depths. It sounds like such an effort would be worth it: NASA researcher and study coauthor Max Coleman says at least one of the vents may have conditions similar to Europa’s seafloor.

“Most life on Earth is sustained by food chains that begin with sunlight as their energy source. That’s not an option for possible life deep in the ocean of Jupiter’s icy moon Europa, prioritized by NASA for future exploration. However, organisms around the deep vents get energy from the chemicals in hydrothermal fluid, a scenario we think is similar to the seafloor of Europa, and this work will help us understand what we might find when we search for life there.” [NASA]

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Image: Woods Hole Oceanographic Institution

Yellow-bellied marmots are taking to global warming just fine—so far. A Nature study of the hibernating Rocky Mountain-dwellers found that over the last 30-plus years, the marmots have grown both in girth and in population, and the researchers think they know why.

Study author Arpat Ozgul says that the marmots have limited time to accomplish the things on their summertime agenda—namely, eating, mating, and giving birth before they crawl back into their seven- to eight-month hibernation.

But as the Colorado summers have grown longer, so too has the time the marmots have to do all of these things—and do them better. This extra preparation (and reproduction) time means that “they are more likely to succeed and survive,” said Ozgul [Scientific American].

Because of the extra time, marmots studied grew in average weight from approximately 6.8 pounds to 7.5. And since 2001 the marmot population has exploded, adding an average of 14 individuals each year; in the previous 25 years the population growth rate was only .56 per year.

However, there are confounding factors that make it hard to be sure that the changes in the marmots are tied just to temperature and waking early from hibernation. Take the example Marcel Visser points out in an accompanying commentary:

The population of one of the marmot’s foods, tall bluebell flowers, began to decline in 2000, just before the marmot population surged; this might have altered the marmots’ diet, leading them towards fattier foods [Nature].

There’s such a thing as too many marmots, also. But, coauthor Daniel Blumstein says, this will probably sort itself out.

As Blumstein reminded, “before we start worrying about being knee-deep in marmots, populations of predators and prey are often linked, and we’ve had a concomitant increase in the predators (foxes and coyotes) in some of our colonies” [Discovery News].

And besides the good times for their predators, marmots face another threat: drought. They don’t cope well with drought in the late summer, so if their habitat gets drier, that could reverse the good fortune that a warmer climate seems to bring them.

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Image: Wikimedia Commons

Welcome to the Tarantula Nebula, home to heavy-weight stars. Using data from the Hubble Space Telescope and Very Large Telescope in Chile, scientists have found a star estimated at about 265 times the mass of the sun. That makes it by far the most massive star ever found, and challenges astronomers’ notions of just how big a star can get.

The Tarantula Nebula is 165,000 light years away in the the Large Magellenic Cloud galaxy. This star, called R136a1, is located in the R136 stellar cluster; with 10 million times the luminosity of the sun, it’s the brightest of a bevy of massive stars recently discovered. The finding, published earlier this month in the Monthly Notices of the Royal Astronomical Society, may require scientists to come up with a new stellar life cycle for the most massive stars. The life a star leads depends on its mass, and the previously estimated mass limit was thought to be around 150 times the sun’s mass.

Lead author Paul Crowther explains that the big guy falls into the stellar category of “blue supergiants,” which are still a mystery from start to finish: It’s not clear whether a star can be born this big, or whether it grows through mergers.

Supergiants also remain as much of a puzzle at the end of their lives. Although all will eventually go supernova, the type of explosion they will generate is unknown. They could form neutron stars or black holes or obliterate themselves. Whatever their fate is, he says, “We still can’t say.” [ScienceNOW]

Finding such massive stars is difficult, given their scarcity and relative short-lives. Many don’t live long enough to escape the crowd of their stellar birthplace, making them hard to spot and making it possible for scientists to confuse two closely paired stars for one bigger star. The team doesn’t think they’ve made that mistake.

Scientists said the authors had made a strong case, arguing that the solar material being thrown off from feuding stars in a binary system would produce much more powerful X-rays than have been detected. [AP]

Just like spotting the stars, measuring their mass is also difficult. With a star that is part of a binary system, scientists can look at how one influences the orbit of the other to determine mass, but the team had no such convenient companions for R136a1. They instead used a model to predict the star’s mass based on analysis of the light coming from it, which yields a less exact result.

That means we can’t be sure just how massive R136a1 is, or how massive it was when it was born. “I think they’ve gotten a very believable answer,” says Philip Massey of the Lowell Observatory in Flagstaff, Arizona. “It’s certainly a very significant find,” he adds, though he says many astronomers already suspected that 150 solar masses was not a hard limit. “I think most people will view this [with] glee and say ‘I told you so’.” [New Scientist]

What might it be like to live around such a massive star? Scientists say it’s unlikely that such stars could ever have planetary neighbors, but that living near R136a1 would certainly be bright.

“Planets take longer to form than these stars take to live and die. Even if there were planets, there would be no astronomers on them because the night sky would be almost as bright as the day in these clusters,” Professor Crowther joked. . . . “Some of these big stars are relatively close to each other, so even at ‘night’ you’d have another very bright star shining on you.” [BBC]

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Images: ESO