Tag: exoplanets

Solar system of ancient Earths found

8:49 am

Worlds without end: Using archived Kepler data astronomers have identified a solar system of five Earth-sized exoplanets, orbiting a red dwarf star about 117 light years from Earth.

The paper describes Kepler-444, a star that’s 25 percent smaller than our sun and is 117 light years from Earth. The star’s five known planets have sizes that fall between Mercury and Venus. Those planets are so close to their star that they complete their orbits in fewer than 10 days. At that distance, they’re all much hotter than Mercury and aren’t habitable.

The important detail from this discovery is that the star is very ancient, more than 11 billion years old, which means these planets are that old as well. In other words, planets began forming the same time as the first stars. Which also means that there has been plenty of time in the universe for other intelligent life to form, besides our own.

2 comments

More Earthlike exoplanets found

8:29 am

Worlds without end: Using Kepler astronomers have discovered a red dwarf star 150 light years away with three Earth-like exoplanets, one of which is in the habitable zone.

The three planets are 2.1, 1.7 and 1.5 times the size of Earth. The outermost planet, at 1.5 Earth radii, is the smallest of the bunch and orbits far enough from its host star that it receives levels of light from its star similar to those received by Earth from the sun, said UC Berkeley graduate student Erik Petigura, who discovered the planets Jan. 6 while conducting a computer analysis of the Kepler data NASA has made available to astronomers. He calculated that the three planets receive 10.5, 3.2, and 1.4 times the light intensity of Earth. “Most planets we have found to date are scorched. This system is the closest star with lukewarm transiting planets,” Petigura said. “There is a very real possibility that the outermost planet is rocky like Earth, which means this planet could have the right temperature to support liquid water oceans.”

These planets were found by Kepler in its present reconfigured mission, which once again illustrates the incredible effectiveness of an optical telescope in space. If only we were building some.

Leave a comment

Travel posters for alien worlds

8:46 am

NASA has produced retro-style travel posters for three alien exoplanets which you can download and print.

The posters are quite cool, which is not surprising, considering that, in the past four decades, the best interplanetary travel that NASA has been able to achieve has been its graphic power-point and pr images. Unfortunately, for NASA actually going there has not been so easy.

Leave a comment

More Earthlike exoplanets confirmed

8:28 am

Worlds without end: Astronomers have confirmed from Kepler data the existence of 8 new exoplanets, all capable of having liquid water on their surface, with two more like Earth than any previous discovery.

These findings nearly double the number of known planets in the habitable zone, but researchers are especially excited about two of the new exoplanets: Their size, location, and star type means they could be rocky planets like Earth — which means they could have evolved life as we recognize it.

One of the planets, Kepler-438b, is only 12 percent bigger than Earth in diameter. That means it’s quite likely a rocky planet. Scientists have given it a 70 percent chance. Kepler-442b is a bit bigger at around 33 percent larger than Earth, but still has a 60 percent chance of being rocky.

But while 438b hits the sweet spot in size, 442b has it beat when it comes to distance from the sun. Both planets orbit a small red dwarf star, cooler than Earth’s Sun, but they also orbit more closely. 438b gets 40 percent more light than Earth, which means it has around a 70 percent chance of being able to hold liquid water. But with 66 percent as much light as our own planet, 442b has a 97 percent chance of being in the habitable zone.

Leave a comment

The planet debate continues

8:22 am

In a public debate about the scientific definition of a planet, the IAU’s definition, imposed about eight years ago to expressly prevent Pluto from being called one, was soundly defeated when the votes were counted.

Science historian Dr. Owen Gingerich, who chaired the IAU planet definition committee, presented the historical viewpoint. Dr. Gareth Williams, associate director of the Minor Planet Center, presented the IAU’s viewpoint [which is the definition that is presently considered official by scientific bureaucrats]. And Dr. Dimitar Sasselov, director of the Harvard Origins of Life Initiative, presented the exoplanet scientist’s viewpoint.

Gingerich argued that “a planet is a culturally defined word that changes over time,” and that Pluto is a planet. Williams defended the IAU definition, which declares that Pluto is not a planet. And Sasselov defined a planet as “the smallest spherical lump of matter that formed around stars or stellar remnants,” which means Pluto is a planet.

After these experts made their best case, the audience got to vote on what a planet is or isn’t and whether Pluto is in or out. The results are in, with no hanging chads in sight.

According to the audience, Sasselov’s definition won the day, and Pluto IS a planet.

Notice that two of the three debaters considered Pluto a planet even before the vote was taken. Notice also that the first debater, Gingerich, was on the very committee that the IAU had created to come up with a definition and then ignored completely when its definition decided that Pluto was a planet.

In the end, it will be the people who speak the language that will decide, not IAU bureaucrats. This little public relations event and vote tells me that the bureaucrats will lose.

2 comments

An exoplanet that was once like a star

8:43 am

Astronomers, using WISE data, have discovered a strange exoplanet that is now as cool as a rocky planet, but was once as hot as a red dwarf star.

The current temperature of the object is 100-150 degrees Celsius, intermediate between that of the Earth and Venus. But the object shows evidence of a possible ancient origin, implying that a large change in temperature has taken place. In the past this object would have been as hot as a star for many millions of years.

Called WISE J0304-2705, the object is a member of the recently established “Y dwarf” class – the coolest stellar temperature class yet defined, added to the end of the sequence OBAFGKMLT (for historical reasons this is not in alphabetical order but follows a decline in temperature from O to T). Although its temperature is not far off that of our own world, the object is not like the rocky Earth-like planets and instead is a giant ball of gas like Jupiter.

As cool as this discovery is (no pun intended), I am most enlightened by the information in the second paragraph above. I had not realized that astronomers had added L, T, and Y classes to the low temperature end of their stellar classification system. For those new to astronomy, you remember the sequence of the first seven classes with the phrase “O Be A Fine Girl Kiss Me”. I wonder what how we can amend this phrase to include the L, T, Y, classes?

Leave a comment

Exoplanets with no water

6:43 pm

The uncertainty of science: Though planet formation theories said they should have water, in looking for water on three exoplanets astronomers were surprised to discover practically none there.

The three planets, known as HD 189733b, HD 209458b, and WASP-12b, are between 60 and 900 light-years away from Earth and were thought to be ideal candidates for detecting water vapor in their atmospheres because of their high temperatures where water turns into a measurable vapor. These so-called “hot Jupiters” are so close to their star they have temperatures between 1,500 and 4,000 degrees Fahrenheit, however, the planets were found to have only one-tenth to one one-thousandth the amount of water predicted by standard planet-formation theories.

“Our water measurement in one of the planets, HD 209458b, is the highest-precision measurement of any chemical compound in a planet outside our solar system, and we can now say with much greater certainty than ever before that we’ve found water in an exoplanet,” said Nikku Madhusudhan of the Institute of Astronomy at the University of Cambridge, England. “However, the low water abundance we have found so far is quite astonishing.” Madhusudhan, who led the research, said that this finding presents a major challenge to exoplanet theory. “It basically opens a whole can of worms in planet formation. We expected all these planets to have lots of water in them. We have to revisit planet formation and migration models of giant planets, especially “hot Jupiters,” and investigate how they’re formed.”

Leave a comment

Two exoplanets disappear

4:53 pm

The uncertainty of science: Two exoplanets orbiting Gliese 581, both thought to be in the habitable zone, have now been proven to not even exist.

“We’ve proven that some of the controversial signals from Gliese 581 don’t come from two proposed Goldilocks planets, but instead are coming from activity within the star itself masquerading as planets,” lead study author Paul Robertson, an astronomer at Pennsylvania State University in University Park, told Space.com.

This result should serve as a strong reminder: Though it is likely that many if not most of the so far discovered exoplanets are real, it is also likely that many will turn out to be false positives. We won’t have solid real knowledge about them until we can actually get a close look at them, which will require far better telescopes in space, and maybe even interstellar missions to them.

Leave a comment

The existence of a Kepler-found earth-sized planet in the habitable zone has been confirmed.

1:42 pm

Worlds without end: The existence of a Kepler-found earth-sized planet in the habitable zone has been confirmed.

The newfound planet, called Kepler-186f, was first spotted by NASA’s Kepler space telescope and circles a dim red dwarf star about 490 light-years from Earth. While the host star is dimmer than Earth’s sun and the planet is slightly bigger than Earth, the positioning of the alien world coupled with its size suggests that Kepler-186f could have water on its surface, scientists say.

In this new work, the Keck and Gemini ground-based telescopes confirmed Kepler’s discovery.

One comment

Using archived Kepler data combined with statistical modeling, scientists have proposed the discovery of another 715 exoplanets.

12:26 am

Using archived Kepler data combined with statistical modeling, scientists have proposed the discovery of another 715 exoplanets.

This announcement is neat, but despite the many news stories about it today, it should be taken with a grain of salt. What the scientists have really done is pinpoint 715 stars where further research is likely to produce good exoplanet results. It is not guaranteed, however, that a scientist looking at these stars will actually see an exoplanet.

Leave a comment

A renowned astronomer reminds everyone — the public, the astronomy community, and most importantly the press — that the data collected on most exoplanets is far more uncertain than often claimed.

10:26 pm

The uncertainty of science: A renowned astronomer reminds everyone — the public, the astronomy community, and most importantly, the press — that the data collected on most exoplanets so far are far more uncertain than is often claimed.

A planet’s atmosphere is the gateway to its identity, including how it was formed, how it developed and whether it can sustain life, stated Adam Burrows, author of the review and a Princeton University professor of astrophysical sciences. But the dominant methods for studying exoplanet atmospheres are not intended for objects as distant, dim and complex as planets trillions of miles from Earth, Burrows said. They were instead designed to study much closer or brighter objects, such as planets in Earth’s solar system and stars.

Nonetheless, scientific reports and the popular media brim with excited depictions of Earth-like planets ripe for hosting life and other conclusions that are based on vague and incomplete data, Burrows wrote in the first in a planned series of essays that examine the current and future study of exoplanets. Despite many trumpeted results, few “hard facts” about exoplanet atmospheres have been collected since the first planet was detected in 1992, and most of these data are of “marginal utility.”

The good news is that the past 20 years of study have brought a new generation of exoplanet researchers to the fore that is establishing new techniques, technologies and theories. As with any relatively new field of study, fully understanding exoplanets will require a lot of time, resources and patience, Burrows said. “Exoplanet research is in a period of productive fermentation that implies we’re doing something new that will indeed mature,” Burrows said. “Our observations just aren’t yet of a quality that is good enough to draw the conclusions we want to draw. “There’s a lot of hype in this subject, a lot of irrational exuberance. Popular media have characterized our understanding as better than it actually is,” he said. “They’ve been able to generate excitement that creates a positive connection between the astrophysics community and the public at large, but it’s important not to hype conclusions too much at this point.” [emphasis mine]

Burrows’ point is absolutely right. Every single story describing the atmosphere or make-up of any particular exoplanet at this point in time is essentially fantasy. The data are too weak or vague, and hardly robust enough to come to any solid conclusions. In fact, this research repeatedly reminds me of the conclusions many scientists drew from the flimsy spectrographic data that was gathered before the space age about the solar system’s planets. When we finally got spacecraft to those planets, we found those conclusions were routinely wrong.

This is not to say that our new knowledge of exoplanets is not exciting or significant. It is both. We just shouldn’t put too much faith in it at this time.

2 comments

Europe approves its own more advanced version of Kepler to launch in 2024 and hunt for exoplanets across half the sky.

11:27 am

Europe approves its own more advanced version of Kepler to launch in 2024 and hunt for exoplanets across half the sky.

During its six year long planned mission, PLATO will observe one million stars, leading to the likely discovery and characterisation of thousands of new planets circling other stars. PLATO will scan and observe about half the sky, including the brightest and nearest stars.

PLATO consists of an array of 34 individual telescopes mounted on an observing platform in the space probe. The satellite will be positioned at one of the so-called Lagrangian Points , where the gravitational pull of the Sun and the Earth cancel each other out so the satellite will stay at a fixed position in space. Each of the 34 telescopes has an aperture of 12 centimeters. The individual telescopes can be combined in many different modes and bundled together, leading to unprecedented capabilities to simultaneously observe both bright and dim objects. PLATO will be equipped with the largest camera-system sensor ever flown in space, comprising 136 charge-coupled devices (CCDs) that have a combined area of 0.9 square metres.

More here and here.

What I like about this is that this project is essentially putting another optical telescope in space. The more of these we have the more discoveries we will make, as even a tiny optical telescope in the vacuum of space is more productive than a giant ground-based telescope looking through the foggy atmosphere of Earth.

Leave a comment

Astronomers have discovered the first exoplanets orbiting a star almost identical to the Sun.

2:13 pm

Astronomers have discovered the first exoplanet orbiting a star almost identical to the Sun.

Astronomers have used ESO’s HARPS planet hunter in Chile, along with other telescopes around the world, to discover three planets orbiting stars in the cluster Messier 67. Although more than one thousand planets outside the Solar System are now confirmed, only a handful have been found in star clusters. Remarkably one of these new exoplanets is orbiting a star that is a rare solar twin — a star that is almost identical to the Sun in all respects.

This discovery is interesting in that some astronomers have proposed that our Sun itself was born in M67, the open galactic star cluster where these exoplanets were found. My March 2012 cover story for Sky & Telescope was on this very subject.

Leave a comment

Astronomers, using Kepler data, have identified dozens of exoplanets between 1 and 4 times the mass of the Earth.

3:23 pm

Worlds without end: Astronomers, using Kepler data, have identified dozens of exoplanets between 1 and 4 times the mass of the Earth.

One of those planets has the same mass as the Earth, but is far less dense.

The significant fact however that came out of the press conference announcing these results is the belief by astronomers that, based on this data, they expect that 1 in 5 solar systems will have an Earth-sized planet.

4 comments

Scientists think they have found cloudy skies on a nearby super Earth.

9:25 am

Scientists think they have found cloudy skies on two nearby exoplanets.

One planet is a super Earth, while the other is Neptune-sized.

This finding, as fascinating as it is, is also incredibly uncertain. The data suggests clouds, but the data is quite thin. We are barely seeing what’s there. Without doubt, the reality is far more complex — and interesting — than presently theorized.

Leave a comment

Using Kepler data, astronomers have discovered a solar system with seven planets and configured similar to our own, with rocky planets close to the star and gas giants farther away

9:20 am

Using Kepler data, astronomers have discovered a solar system with seven planets and configured similar to our own, with rocky planets close to the star and gas giants farther away.

The system is far more compact than ours, with the gas giants in orbits similar to Mercury, Venus, and Earth.

Leave a comment

The number of candidate exoplanets found by Kepler has now risen to 3,500.

11:09 am

Worlds without end: The number of candidate exoplanets found by Kepler has now risen to 3,500.

According to this new analysis, researchers estimate about 70% of stars are host to at least one planet, making planets a common cosmic occurrence. There are now 1,750 candidates that are super-Earth-size or smaller, and 1,788 are Neptune-size or larger. Only 167 of the 3,538 candidates are confirmed to be planets, but Kepler has a good track record: the vast majority of these are probably real.

Two dozen of these candidates are in the habitable zone, ten of which are thought to be close to Earth-sized.

12 comments

The first Earth-sized exoplanet, just discovered, makes no sense to scientists.

1:14 pm

The first Earth-sized exoplanet, just discovered, makes no sense to scientists.

Kepler-78b is a planet that shouldn’t exist. This scorching lava world circles its star every eight and a half hours at a distance of less than one million miles – one of the tightest known orbits. According to current theories of planet formation, it couldn’t have formed so close to its star, nor could it have moved there. “This planet is a complete mystery,” says astronomer David Latham of the Harvard-Smithsonian Center for Astrophysics (CfA). “We don’t know how it formed or how it got to where it is today. What we do know is that it’s not going to last forever.”

The planet itself is only 20 percent larger than the Earth, with a comparable density that suggests its composition is similar as well.

2 comments

The weather on an exoplanet: Cloudy and clear.

3:09 pm

The weather on an exoplanet: Cloudy and clear.

Astronomers using data from NASA’s Kepler and Spitzer space telescopes have created the first cloud map of a planet beyond our solar system, a sizzling, Jupiter-like world known as Kepler-7b. The planet is marked by high clouds in the west and clear skies in the east. Previous studies from Spitzer have resulted in temperature maps of planets orbiting other stars, but this is the first look at cloud structures on a distant world.

This result is cool, but no one should take it too seriously. They have detected evidence of that to the scientists “suggest” clouds, but no one really knows.

Leave a comment

The engineering tests to try to save Kepler have found that the mission is essentially over.

11:16 am

The engineering tests to try to save Kepler have found that the mission is essentially over.

A headline at this New York Times article, “NASA’s Kepler Mended, but May Never Fully Recover” is wrong, as the telescope has not been “mended.” They have found they might be able to do some limited science, at the most. NASA is going to review this possibility, weighing the cost versus the benefit, and decide in the fall.

3 comments
1 … 4 5 6 7 8 9