Archive
Anti-Matter Belt Discovered Around Earth
Source: Anti-Matter Belt Discovered Around Earth
Our Galaxy May Have 50 Billion Exoplanets–and It’s Still Making More
Young. Old. Scalding hot. Icy cold. Terrestrial midgets. Gas giants. As the cavalcade of planets spotted beyond our solar system continues to grow, we get to see worlds of all sorts—and we get to speculate on the staggering number of exoplanets that might inhabit just our own galaxy.
Today’s first piece of otherworldly news involves baby exoplanets. Astronomer Christian Thalmann says his team may have spotted planets in the process of forming around three different stars, the first time scientists have spotted the process in action.
An infant star forms from a collapsing cloud of dust and gas and gathers a dense, flat disk of material that rotates with the star like a record album. The material in the disk will eventually clump up into nascent planets. Theoretical models of planet formation predicted that those protoplanets should suck up more gas and dust with their gravity, clearing a wide gap in the otherwise solid disk. [Wired]
Peering at young stars like T Chamaeleontis (T Cha) LkCa15 and AB Auriga, Thalmann and colleagues saw those telltale gaps in the dusty rings (their study is forthcoming in the Astrophysical Journal Letters). The stars are much like our own sun, so these pictures of infant solar systems could resemble what our own looked like as a baby. But though the stars are nearby in cosmic terms—T Cha lies just 350 light years away—the gaps are faint enough that it’s difficult to tell for certain if newly forming planets, and not the influence of binary stars or other objects, are creating them.
If Thalmann’s team is right, catching the birth of new worlds would be a great scientific coup. Our galaxy, however, isn’t exactly hurting for planets.
Earlier this month came the big announcement from NASA’s Kepler mission, when its scientists announced 1,200 new potential planets, including 54 found in the habitable region around their stars. Since then, project science head William Borucki has done a few back-of-the-envelope extrapolations based on Kepler’s findings, and produced some eye-popping planet tallies that he announced at last weekend’s American Association for the Advancement of Science (AAAS) annual conference in Washington: The total number of Milky Way planets could be on the order of 50 billion, with 500 million of those falling in the life-friendly Goldilocks zone.
Borucki and colleagues figured one of two stars has planets and one of 200 stars has planets in the habitable zone… And that’s a minimum because these stars can have more than one planet and Kepler has yet to get a long enough glimpse to see planets that are further out from the star, like Earth, Borucki said. For example, if Kepler were 1,000 light years from Earth and looking at our sun and noticed Venus passing by, there’s only a one-in-eight chance that Earth would also be seen, astronomers said. [AP]
Kepler—humankind’s best planet-hunter—surveys an area that accounts for just one-four-hundredth of the sky. And yet it produces a bonanza of worlds, the implications of which got extraterrestrial life enthusiasts buzzing at the same AAAS meeting. Howard Smith of the Harvard-Smithsonian Center for Astrophysics argued that the great distances and relative harshness of the universe makes humanity a de facto loner. Even if there are other civilizations, he said, we could never reach them in person or by electronic communication (at least, not without a hundred generations of humans awaiting the response). But Seth Shostak of the SETI Institute unsurprisingly saw the sunny side of a galaxy overflowing with planets.
Shostak cited an argument that says increases in computer power mean we’ll be able to analyse far more planetary data than has been possible until now. He was confident that within 24 years we would detect an alien civilisation. “There are maybe 10 21 Earth-like planets out there,” he said. “Believing there aren’t ETs is believing in miracles.” He bet the audience that we’d find ET within our lifetime or else he’d buy us a cup of Starbucks. [New Scientist]
I rarely turn down a strong cup of joe, but I hope Shostak is proved correct.
Image: L. Calçada/ESO
Source: Our Galaxy May Have 50 Billion Exoplanets–and It’s Still Making More
Found: Jupiter-sized Brown Dwarf, Hiding in a Tight Orbit Around a Young Sun
Imagine an infantile version of our 4.6 billion-year-old sun. Now picture a “failed star,” a brown dwarf, about the size of Jupiter, tightly orbiting that 12 million year old stellar baby–at the distance Uranus orbits our sun. Astronomers have just found such a duo: a star about the mass of our sun with an unusually close brown dwarf companion.
Of the similarly situated brown dwarfs that astronomers have imaged, most keep their distance, orbiting at about 50 AU (or 50 times the average distance from the Earth to the sun). A team of astronomers believe the distance between this young sun, called PZ Tel A, and its dwarf companion, PZ Tel B, is less than half that, a mere 18 AU.
A paper to appear in Astrophysical Journal Letters details the find, which was made using images from the Near-Infrared Coronagraphic Imager, on the Gemini-South telescope in Chile. The researchers predicted the orbit by using two observations, one in April of 2009 and another in May of 2010 and then calculated the brown dwarf’s motion using a computer model.
Because PZ Tel A is young and sun-like, researchers say, that it might present a good history lesson on our own solar system.
In fact, PZ Tel is young enough to still possess significant amounts of cold circumstellar dust, which may have been sculpted by the gravitational interaction with the young brown dwarf companion. This is the material that can form planets so the PZ Tel system is an important laboratory for studying the early stages of planetary system formation. [Gemini Observatory]
Astronomers say that the brown dwarf is about Jupiter’s size, but is around 36 times its mass. Though they have imaged PZ Tel A before, they couldn’t pick out its dim companion because of its proximity.
An older image, taken seven years ago and reanalyzed by Laird Close, a professor at UA’s Steward Observatory and the department of astronomy, showed PZ Tel B was obscured by the glare from its parent star as recently as 2003, indicating its orbit is more elliptical than circular.”Because PZ Tel A is a rare star being both close and very young, it had been imaged several times in the past,” said Close. “So we were quite surprised to see a new companion around what was thought to be a single star.” [University of Arizona]
The Near-Infrared Coronagraphic Imager gave them more power than previously possible, as its a high-contrast instrument designed for finding dim bodies circling bring stars, like exoplanets or brown dwarfs, and can pick out a companion up to one million times fainter than the host star.
The research team was able to take pictures so close to the star by using an adaptive optics system and coronagraph [a device to block out light from the brighter star] to block our excess starlight. They then applied specialized analysis techniques to the images to detect PZ Tel B and measure its orbital motion. . . “We are just beginning to glean the many configurations of solar systems around stars like the sun,” said Michael Liu, NICI campaign leader. “The unique capabilities of NICI provide us with a powerful tool for studying their constituents using direct imaging.” [Space.com]
An international team is now using the telescope to complete a 300-star survey, the largest such survey to date, so hopefully more brown dwarfs will come out of hiding soon.
Images: Jon Lomberg, provided by Gemini Observatory, and Beth Biller and the Gemini NICI Planet-Finding Campaign
Source: Found: Jupiter-sized Brown Dwarf, Hiding in a Tight Orbit Around a Young Sun
Spooky “Dark Flow” Tracked Deeper Into the Cosmos; No Word on What’s Tugging at Galaxies
A year and a half ago, the team led by Alexander Kashlinsky of NASA proposed the controversial and ominously named “dark flow,” a massive gravitational force that is tugging at galaxy clusters, and that Kashlinsky says could be coming from beyond the limits of our own visible universe. Now the team is back with a follow-up study in The Astrophysical Journal Letters, and Kashlinsky says the team has tracked the dark flow out twice as far as before.
A quick note on dark flow: The reason Kashlinsky noticed it thanks to the cosmic microwave background, a signature left over from 380,000 years after the Big Bang that permeates the universe. “The hot X-ray-emitting gas within a galaxy cluster scatters photons from the cosmic microwave background (CMB),” the NASA press release says. “Because galaxy clusters don’t precisely follow the expansion of space, the wavelengths of scattered photons change in a way that reflects each cluster’s individual motion.” Using data from the Wilkinson Microwave Anisotropy Probe (WMAP), which mapped the microwave background, the team managed to find this tiny effect when they looked at huge clusters of galaxies, and found something totally unexpected.
What the 2008 find showed was that these galaxies were moving in a way that the distribution of matter in our visible universe couldn’t explain, traveling a million miles per hour in a particular direction. Says Kashlinsky: “This is not something we set out to find, but we cannot make it go away” [US News & World Report]. The new study confirms this weird effect, and finds that it extends farther out, to at least 2.5 billion light years away. Where Kashlinsky’s first study relied upon three years of WMAP data and 700 galactic clusters, the new study grows those numbers to five years of data and double the number galactic clusters. The clusters appear to be zooming along on one particular line aimed at Hydra, Kashlinsky said, but “right now our data cannot state as strongly as we’d like whether the clusters are coming or going,” to or from Earth [USA Today].
While the universe itself keeps on expanding and expanding in all of the directions it can whiz, no one direction should be preferred, which is why the dark flow is to damned interesting. According to our best understanding of how the matter in the Universe was distributed, there’s no way of accounting for this flow. The obvious alternate explanation is a little unnerving: something outside of our visible universe is pulling on the matter that we can see [Ars Technica].
For another explanation of dark flow, check out Phil Plait’s at Bad Astronomy, written after the initial 2008 study.
Image: NASA, the Coma Galaxy Cluster
Source: Spooky “Dark Flow” Tracked Deeper Into the Cosmos; No Word on What’s Tugging at Galaxies