Posts Tagged ‘exoplanets’
Kepler Analysis Projects One-Third of Sun-Like Stars Have an Earth-Like Planet Orbiting
If that turns out to be the case, that’s big news of course. The habitable zone, or the “goldilocks zone” as it’s often known (not to close to the star, not too far away), is the orbital range where it’s possible for liquid water to exist. Thus, it’s the range where life as we know it could feasibly take root.
The planet-hunting Kepler observatory is designed specifically to seek out planets orbiting distant stars, and thus far its been a boon for exoplanetary science. In 136 days it has scanned some 150,000 target stars looking for the signature wobble exerted on those stars by orbiting satellites. In doing so, it has found 1,235 potential planets.
It’s from that data that Traub has extracted his conclusion. He looked particularly at the stars that are most like our sun--those classified F, G, or K. He then looked at the kinds of planets that are most often found orbiting them and at what ranges they orbit. In his analysis, he notes many interesting (and somewhat expected) things, like the fact that nearly a third of the planets Kepler has found orbit their stars in less than 42 days, putting them too close to be in the habitable zone (this is also because planets closer to their stars are easier for Kepler to see).
Larger terrestrial planets out there in the habitable zone are harder for Kepler to spot, but that doesn’t mean they’re not there. And Traub says his number crunching allows us to get a pretty good idea of how many there should be. Using some math we don’t pretend to understand, he plugged in the numbers for longer orbits--orbits in the habitable zone--into his analysis. The finding: "About one-third of FGK stars are predicted to have at least one terrestrial, habitable-zone planet."
That’s not to say they are inhabited, or that they do have liquid water, or that they even exist. But Traub’s math suggests that they should exist, at least until more data changes the equation. And for now, that spells a lot of potential goldilocks planets. Read the full paper via .
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Kepler Spots a Planet Orbiting Two Suns, Just Like Star Wars’ Tatooine
Using data from the Kepler space observatory, scientists at the Harvard-Smithsonian Center for Astrophysics and SETI have discovered for the first time a planet orbiting a binary star system, passing in front of both its parent stars along its orbit.
The planet, Kepler-16b, resembles Saturn in its mass and gaseous makeup. That mostly rules out the possibility of any living beings being present to enjoy the double sunset view, although chances are good Kepler-16b has an icy, non-gaseous satellite or two, as Saturn does.
The two stars in the system are 20% and 69% as massive as our sun, respectively. The planet orbits at a distance analogous to Venus's orbit in our solar system, which typically would place it within the "habitable zone" of planets that could support life. But since the combined mass of the two stars is still less than our sun, Kepler-16b's Venus-like orbit is most likely a cold one.
An animation of Kepler-16b's orbit:
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Binary star systems, first cataloged at length by English astronomer William Herschel in the early 19th century, are key to our understanding of distant stars, since it's easy to derive each star's mass by studying their linked orbit (the two stars in a binary system both orbit around their shared center of mass). But whether or not such systems, which by some estimates account for about half of the stars in the known universe, could form and support orbiting planets has been a contentious topic--making today's finding significant not just for Star Wars fans.
"It's been pretty much a split vote amongst the theorists," said Alan Boss, a theoretical astrophysicist at the Carnegie Institution for Science, and a co-author of the Kepler 16-b paper. "Some say 'Yeah, we think it's possible to make a Saturn-mass object [in a binary star system].' Other papers say 'Well, no, we don't think it's going to work at all, because those changing gravitational forces from that central binary are going to screw up the process of trying to get little bodies to run into each other and grow bigger and bigger.'"
"One of the exciting things about this is: Kepler, as usual, has answered the question for us," said Boss.
The mission is to find and analyze potential Earth-like exoplanets throughout the universe. Today's discovery now significantly expands the working set of stars that could potentially harbor orbiting planets. That means more work for Kepler as it continues what has so far been an extremely successful mission.
The paper, authored primarily by Laurence Doyle of the SETI institute, appears in the journal Science today.
New ‘Goldilocks’ Exoplanet Could be the Most Earth-Like We’ve Yet Seen
Just a question of cloud cover
And by “among,” we mean really one of just two (or three, depending on how you feel about ). Of the hundreds of exoplanets astronomers have recently discovered orbiting distant stars, only one----has been of the proper mass and distance from its star to be considered a strong candidate for habitability. Nearby Gliese 581g was once thought to be even more Earth-like than 581d, until some scientists asserted that 581g doesn’t even exist--a point that is still under debate.
HD85512b was discovered by the ESO’s High Accuracy Radial velocity Planet Searcher, or HARPS, in Chile (it’s the same instrument that found Gliese 581d. The data show that HD85512b is roughly three-and-a-half times the mass of Earth and rings its planet on the inner fringe of the so-called “goldilocks zone” that is not to distant and not too close to harbor liquid water. It’s size is also indicative of an Earth-like atmosphere of oxygen and nitrogen rather than the hydrogen and helium that dominate the atmospheres of larger worlds.
That alone makes it a potential candidate for life, but HD85512b has a couple of other characteristics working for it. For one, its orbit is almost perfectly circular and stable, so any climate on the planet wouldn’t swing wildly as it orbits. The planetary system is older than our own--a full one billion years older--so clearly it’s had enough time for life to potentially have developed there. in the same vein, its star is also more mature than our sun so it is less prone to violent solar activity that could destabilize the planet’s atmosphere.
Of course, there’s no way to tell if it actually has an atmosphere with modern instruments, and atmosphere is a critical ingredient here. Since HD85512b is orbiting on the inner portion of the goldilocks zone, it is more akin to Venus than to Earth in the amount of solar energy it’s taking on. But scientists speculate that cloud cover of fifty percent or more could offset that proximity enough to allow life to thrive--albeit a kind of life more suited to a balmy, hot environment (relative to Earth’s).
On average, Earth boasts 60 percent cloud cover so the idea of HD85512b having 50 percent isn’t so far-fetched. In fact, it’s probably more likely than the idea of humans building a light-speed spacecraft and then making the 31-year journey to go in for a closer look at the weather. But it’s fun to think about.
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Blackest Planet Ever Found, Absorbs Nearly 100% of Light That Reaches It
But TrES-2b is not completely black. It emits an extremely faint red glow, like that of a hot ember. And it turns out that heat is the main culprit behind this darkest of dark planets. TrES-2b orbits its star at a distance of just 3 million miles (by comparison, we’re about 93 million miles from our sun), which leads to surface temperatures on TrES-2b of more than 1,800 degrees.
That’s too hot for the formation of ammonia clouds that would reflect some of that incoming radiation as they do on Jupiter. Rather, TrES-2b’s atmosphere is made up of things like vaporized sodium, potassium, and titanium oxide--things that actually compound the problem by absorbing heat. But even these don’t fully explain the planet’s extreme blackness, which is still puzzling astronomers. There's some kind of strange chemistry going on out there that even Kepler can't see.
SETI Turns Radio Telescopes Toward Kepler Candidate Planets, Listening for Signs of Life
Listening to places where conditions are right for life
The SETI Institute is looking at Earth-like (rocky) planets with a focus on those with temperatures between 0 and 100 °C (32° and 212 °F), where liquid water can exist. As far as our Earth-biased science can tell us, that’s a crucial ingredient for life.
SETI has been listening to parts of the sky for decades, but pointing directly at Kepler findings stands among the project’s best-informed attempts yet. The Arecibo telescope in Puerto Rico looks at stars like the sun, hoping they might have planets around them.
“But we’ve never had a list of planets like this before,” said physicist Dan Werthimer, director of the SETI project at Arecibo, in an .
In February, Kepler scientists announced they had found orbiting sun-like stars in the Milky Way, including 68 approximately Earth-size and 288 super-Earth-size. Scientists have been verifying and refining the measurements in the months since.
The Robert C. Byrd Green Bank Telescope will gather 24 hours of data on each of 86 planets identified this spring by the Kepler space telescope science team as potential Earth-like planets in “Goldilocks” orbits, where conditions are neither too hot nor too cold for liquid water.
SETI has its own telescopes, too, but apparently they’ve gone dark for a lack of funding, according to the AFP — SETI announced last month it was shutting down its 42-dish Allen Telescope Array because of a budget shortfall, AFP reports. While the 4-year-old, $50 million project is on hiatus, the Green Bank telescope will assume its responsibilities.
While Arecibo will also keep listening, Green Bank can hear a lot more — it scans 300 times the range of frequencies that Arecibo can, so it can collect as much data in one day as Arecibo could in one year.
The Kepler listening project will take about a year, AFP reports. SETI@home users will help crunch the data; the program uses small bits of unused processing power from idle Internet-connected computers to run calculations. You can find out more, and sign up to help, by .
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SETI Turns Radio Telescopes Toward Kepler Candidate Planets, Listening for Signs of Life
Listening to places where conditions are right for life
The SETI Institute is looking at Earth-like (rocky) planets with a focus on those with temperatures between 0 and 100 °C (32° and 212 °F), where liquid water can exist. As far as our Earth-biased science can tell us, that’s a crucial ingredient for life.
SETI has been listening to parts of the sky for decades, but pointing directly at Kepler findings stands among the project’s best-informed attempts yet. The Arecibo telescope in Puerto Rico looks at stars like the sun, hoping they might have planets around them.
“But we’ve never had a list of planets like this before,” said physicist Dan Werthimer, director of the SETI project at Arecibo, in an .
In February, Kepler scientists announced they had found orbiting sun-like stars in the Milky Way, including 68 approximately Earth-size and 288 super-Earth-size. Scientists have been verifying and refining the measurements in the months since.
The Robert C. Byrd Green Bank Telescope will gather 24 hours of data on each of 86 planets identified this spring by the Kepler space telescope science team as potential Earth-like planets in “Goldilocks” orbits, where conditions are neither too hot nor too cold for liquid water.
SETI has its own telescopes, too, but apparently they’ve gone dark for a lack of funding, according to the AFP — SETI announced last month it was shutting down its 42-dish Allen Telescope Array because of a budget shortfall, AFP reports. While the 4-year-old, $50 million project is on hiatus, the Green Bank telescope will assume its responsibilities.
While Arecibo will also keep listening, Green Bank can hear a lot more — it scans 300 times the range of frequencies that Arecibo can, so it can collect as much data in one day as Arecibo could in one year.
The Kepler listening project will take about a year, AFP reports. SETI@home users will help crunch the data; the program uses small bits of unused processing power from idle Internet-connected computers to run calculations. You can find out more, and sign up to help, by .
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SETI Turns Radio Telescopes Toward Kepler Candidate Planets, Listening for Signs of Life
Listening to places where conditions are right for life
The SETI Institute is looking at Earth-like (rocky) planets with a focus on those with temperatures between 0 and 100 °C (32° and 212 °F), where liquid water can exist. As far as our Earth-biased science can tell us, that’s a crucial ingredient for life.
SETI has been listening to parts of the sky for decades, but pointing directly at Kepler findings stands among the project’s best-informed attempts yet. The Arecibo telescope in Puerto Rico looks at stars like the sun, hoping they might have planets around them.
“But we’ve never had a list of planets like this before,” said physicist Dan Werthimer, director of the SETI project at Arecibo, in an .
In February, Kepler scientists announced they had found orbiting sun-like stars in the Milky Way, including 68 approximately Earth-size and 288 super-Earth-size. Scientists have been verifying and refining the measurements in the months since.
The Robert C. Byrd Green Bank Telescope will gather 24 hours of data on each of 86 planets identified this spring by the Kepler space telescope science team as potential Earth-like planets in “Goldilocks” orbits, where conditions are neither too hot nor too cold for liquid water.
SETI has its own telescopes, too, but apparently they’ve gone dark for a lack of funding, according to the AFP — SETI announced last month it was shutting down its 42-dish Allen Telescope Array because of a budget shortfall, AFP reports. While the 4-year-old, $50 million project is on hiatus, the Green Bank telescope will assume its responsibilities.
While Arecibo will also keep listening, Green Bank can hear a lot more — it scans 300 times the range of frequencies that Arecibo can, so it can collect as much data in one day as Arecibo could in one year.
The Kepler listening project will take about a year, AFP reports. SETI@home users will help crunch the data; the program uses small bits of unused processing power from idle Internet-connected computers to run calculations. You can find out more, and sign up to help, by .
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