Tag: exoplanets

NASA uses computer model to find exoplanets

11:26 am

Garbage in, garbage out: Using statistical computer modeling only, NASA today announced that they are certain that almost a third of Kepler’s candidate exoplanets are really exoplanets.

Analysis was performed on the Kepler space telescope’s July 2015 planet candidate catalog, which identified 4,302 potential planets. For 1,284 of the candidates, the probability of being a planet is greater than 99 percent – the minimum required to earn the status of “planet.” An additional 1,327 candidates are more likely than not to be actual planets, but they do not meet the 99 percent threshold and will require additional study. The remaining 707 are more likely to be some other astrophysical phenomena. This analysis also validated 984 candidates previously verified by other techniques.

This is actually a stupid announcement. They haven’t learned a damn thing from this statistical analysis, but are merely saying that because Kepler found a lot of candidates, a lot of those candidates must be real planets. Worse, NASA is also implying here that confirming some of these candidate exoplanets by hard observations is now really unnecessary, since they can do it statistically.

This smacks of the corruption that has ruined much of climate research, allowing a computer model to replace actual observations. Big mistake. But I also suspect this announcement occurred for the same reasons: NASA wishes to justify its work and its funding, and thus decided to make a big deal about this very minor statistical analysis in order to puff up the discoveries of Kepler, even though there is no reason to do so.

I expect a lot of mainstream news organizations to write big puff pieces extolling this announcement in the coming days, which will once again prove that almost no one in journalism today has the slightest ability to apply their own independent analysis to the press releases they receive.

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Mercury’s transit today

8:50 am

Here are a few links on today’s transit of the Sun by Mercury, which is going on right now.

I could give more, but this event is hardly as important as many new media are saying. It is interesting, and rare, and important in that it helps scientists get a better understanding of the uncertainties in their exoplanet research, but hardly important scientifically.

Consider this however: Mercury’s real orbit has it circle the sun every 88 days. If we could only detect it by the transits seen from Earth, we would only see it cross the Sun in 2006, 2016, 2019, and 2032. Figuring out its real orbit from that data would likely be impossible. Now, I realize that these seemingly random transits are partly determined by the Earth’s own orbit around the Sun, but they still illustrate that our use of transits to detect and characterize exoplanets has its limits. And in science one must always be aware of one’s limits.

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Exoplanets found nearby

5:26 pm

Worlds without end: Astronomers have identified three planets close to the habitable zone on a star only 39 light years away.

A year on the two inner planets lasts just a couple of days. Data on the third world are sparse; it could take anywhere between 4.5 and 72.8 days to trek around its sun. The star, designated 2MASS J23062928−0502285, is roughly the size of Jupiter — about one-tenth as wide as our sun — and about 3,200 degrees Celsius cooler than the sun. Such runts make up about 15 percent of the stars in the galaxy, though astronomers had not found planets around one before. All three planets were discovered as periodic dips in starlight in late 2015 using TRAPPIST, a telescope at La Silla Observatory in Chile.

If anything does crawl or grow on these worlds, it bathes in mostly infrared light. The innermost planets receive several times as much energy from their star as Earth does from our sun, which technically puts them outside the star’s habitable zone (SN: 4/30/16, p. 36). But the planets are huddled up so close to the star that gravity might keep them from spinning, creating a temperate zone along the line where day turns to night, the researchers suggest.

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Exoplanet with cometlike orbit

8:57 am

Worlds without end: Astronomers detect an exoplanet with an orbit so eccentric that the orbit is more like a comet’s.

The eccentricity of a planet’s orbit is measured on a scale of 0 to 1, with 0 representing a perfectly circular orbit, and figures closer to one indicative of increasingly elliptical orbits. Earth’s orbital eccentricity, for example, is 0.017, and the most eccentric planet in our solar system – Mercury, assuming that we no longer class Pluto a planet – has an eccentricity of 0.205.

Our new friend, HD 20782, on the other hand, has an orbital eccentricity of 0.96, meaning its ellipse as it travels to and from its star is almost flat; and when it does finally return to its sun, after a 597-day orbital journey, it careers furiously round the star to slingshot back into space. “It’s around the mass of Jupiter, but it’s swinging around its star like it’s a comet,” said Dr. Kane.

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Honing the search for alien civilizations

9:30 am

Worlds without end: In order to increase the odds of contacting extraterrestrial civilizations, astronomers have calculated the area in the sky where an alien-built Kepler could have seen the Earth transit the sun, thus increasing the chances that those alien-astronomers have discovered Earth and have tried to contact us.

“The key point of this strategy is that it confines the search area to a very small part of the sky. As a consequence, it might take us less than a human life span to find out whether or not there are extraterrestrial astronomers who have found the Earth. They may have detected Earth’s biogenic atmosphere and started to contact whoever is home,” explains René Heller from the MPS.

Not every star is equally well suited as a home of extraterrestrial life. The more massive a star, the shorter is its life span. Yet, a long stellar life is considered a prerequisite for the development of higher life forms. Therefore the researchers compiled a list of stars that are not only in the advantageous part of the sky but also offer good chances of hosting evolved forms of life, that is, intelligent life. The researchers compiled a list of 82 nearby Sun-like stars that satisfy their criteria. This catalogue can now serve as an immediate target list for SETI initiatives.

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Hubble measures the rotation of an exoplanet

3:03 pm

Worlds without end: Using the Hubble Space Telescope astronomers have measured the daily rotation of a super Jupiter exoplanet 170 light years away.

They estimate, based upon brightness variations attributed to clouds in the upper atmosphere, that the rotation rate is about 10 hours long. We should all recognize however the significant uncertainty of this number. Clouds change, as do weather conditions. The data only gives us a hint at what is going on here.

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Astronomers make first analysis of a SuperEarth’s atmosphere.

9:32 am

Worlds without end: Using the Hubble Space Telescopes astronomers have made the first chemical analysis of a SuperEarth’s atmosphere.

The planet, 55 Cancri e, is estimated to have a mass of eight Earths. Its atmosphere was found to have hydrogen, helium, and the molecule hydrogen cyanide. No water was detected.

Astronomers have used Hubble to detect the components of a number of exoplanets, but these have all been giant planets more like Jupiter. This is the first measurement of an exoplanet whose mass is small enough that it might be rocky, like Earth.

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More data says no alien civilization at KIC 8462852

9:32 am

New observations of the star KIC 8462852 to see if an alien civilization had produced laser signals has produced a null result, reinforcing the conclusion that the erratic dimming of the star is not caused by alien megastructures.

On six nights between October 29 and November 28, 2015, scientists searched for pulses as short as a billionth of a second at the Boquete Optical SETI Observatory in Panama, using a 0.5 m Newtonian telescope. The observatory’s relatively small telescope uses a unique detection method having enhanced sensitivity to pulsed signals. If any hypothetical extraterrestrials had beamed intentional laser pulses in the visible spectrum toward Earth, the Boquete observatory could have detected them so long as they exceeded the observatory’s minimum detectable limit.

KIC 8462852 has puzzled astronomers because it shows irregular dimming unlike anything seen for another star. The anomalous light curve was measured using NASA’s Kepler telescope, as part of its search for exoplanets. However, even though a planet the size of Jupiter would cause dimming of approximately 1%, the dimming observed for KIC 8462852 was far greater – up to 22%. Just as strange, the dimming didn’t follow the regular pattern of a planet orbiting a star, but instead was unpredictable. The best explanation to date is that the dimming may have been caused by cometary fragments in a highly elliptical orbit around KIC 8462852, intercepting starlight at the same time the Kepler mission was observing it.

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More than half Kepler planet candidates false positives

9:40 am

The uncertainty of science: In attempting to confirm the giant exoplanet candidates in the Kepler telescope database a team of scientists has found that more than half are not planets at all but false positives.

An international team1 led by Alexandre Santerne from Instituto de Astrofísica e Ciências do Espaço (IA), made a 5-year radial velocity campaign of Kepler’s giant exoplanet candidates, using the SOPHIE spectrograph (Observatory of Haute-Provence, France), and found that 52,3% were actually eclipsing binaries, while 2,3% were brown dwarfs. Santerne (IA & University of Porto), first author of this paper commented: “It was thought that the reliability of the Kepler exoplanets detection was very good – between 10 and 20% of them were not planets. Our extensive spectroscopic survey, of the largest exoplanets discovered by Kepler, shows that this percentage is much higher, even above 50%.

The news article above is unclear about the number of candidates total this study actually looked at and pinned down. It appears they began looking at the full database of almost 9,000 candidates, but then narrowed it to 125. Were 50% of the 9,000 false positives, or of the 125? The article is unclear.

At first glance, this study appears to tell us that there might be fewer giant Jupiter-sized exoplanets out there than previously thought. Then again, the data is uncertain enough that this conclusion could easily be wrong. The real take-away is that the science of exoplanets has only just begun, and that sweeping generalizations about the nature of solar systems in the galaxy are exceedingly unreliable. We simply don’t know enough yet.

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Earth-sized exoplanet found only 39 light years away

10:01 pm

Worlds without end: Astronomers have discovered an exoplanet only slightly bigger then the Earth, and it’s only 39 light years away.

Berta-Thompson and the others estimate that GJ 1132b has a diameter of about 9,200 miles, slightly bigger than Earth. Its mass, however, is thought to be 60 percent greater than Earth’s. Its home star — GJ 1132 — is a red dwarf one-fifth the size of our sun. The planet circles every 1.6 days from just 1.4 million miles out, thus the heat wave. A slight dip in the starlight every 1.6 days was the giveaway for the observing team. “Our ultimate goal is to find a twin Earth,” said astronomer David Charbonneau of the Harvard-Smithsonian Center for Astrophysics, one of the authors, “but along the way we’ve found a twin Venus.”

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Earth might be one of the universe’s first habitable planets

9:57 pm

The uncertainty of science: An analysis of data from the Hubble Space Telescope and Kepler suggests that the Earth might be one of the first planets in the universe to harbor life.

I label this result uncertain because it is based on what I consider to be a very poor sampling of exoplanets as seen by Kepler. Kepler might have found a lot of exoplanets, but the numbers are still small and skewed by the limited types of suns observed and the short time frame of its observations. Moreover, the data from Hubble is rich, but also quite small, leaving great uncertainties for all of these conclusions.

At the same time, this conclusion might help explain why, after almost a half century of looking, we have yet to detect any evidence of radio communications from any other civilizations. You would think we would have detected something by now. Maybe they don’t exist, and we are the first.

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Astronomers photograph an exoplanet

2:14 pm

51 Eridani b

Cool image time! Astronomers have used the Gemini Telescope on Mauna Kea to take the clearest image yet of a Jupiter-sized gas giant orbiting another star 96 light years away.

Once the astronomers zeroed in on the star, they blocked its light and spotted 51 Eri b orbiting a little farther away from its parent star than Saturn does from the sun. The light from the planet is very faint — more than one million times fainter than its star – but GPI can see it clearly. Observations revealed that it is roughly twice the mass of Jupiter. Other directly imaged planets are five times the mass of Jupiter or more. In addition to being the lowest-mass planet ever imaged, it’s also the coldest — about 800 degrees Fahrenheit — and features the strongest atmospheric methane signal on record. Previous Jupiter-like exoplanets have shown only faint traces of methane, far different from the heavy methane atmospheres of the gas giants in our solar system.

All of these characteristics, the researchers say, point to a planet that is very much what models suggest Jupiter was like in its infancy.

The exoplanet is the bright spot near the bottom of the image.

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Astronomers confirm existence of Earthlike exoplanet 21 light years away

12:22 pm

Worlds without end: Astronomers have confirmed the existence of a rocky Earthlike exoplanet only 21 light years away.

HD 219134b is also the closest exoplanet to Earth to be detected transiting, or crossing in front of, its star and, therefore, perfect for extensive research. “Transiting exoplanets are worth their weight in gold because they can be extensively characterized,” said Michael Werner, the project scientist for the Spitzer mission at NASA’s Jet Propulsion Laboratory in Pasadena, California. “This exoplanet will be one of the most studied for decades to come.”

The planet has a mass 4.5 times that of Earth, and orbits its sun every three days, which means it is not likely to harbor life. Its sun also harbors three other small exoplanets, but little is known of them.

Expect a lot more news coming from HD 219134b, however. With transits every three days, astronomers are going to have a lot of opportunities to study its atmosphere and make-up.

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Worlds without end

1:01 pm

Last week’s fly-by of Pluto by New Horizons illustrated forcefully once again the power of exploration on the human mind, and how that exploration always carries surprises that delight and invigorate us.

First of all, the images from that fly-by demonstrated clearly that the decision by the International Astronomical Union (IAU) to declare Pluto a non-planet was very much premature. Even project scientist Alan Stern himself enthusiastically noted at the start of Friday press conference that Pluto-Charon was a “double planet system”.

The IAU definition itself was faulty and difficult to apply. The clause that required a planet to have “cleared the neighborhood around its orbit” made little sense in the real universe, as even the Earth has not successfully cleared its orbit after several billion years. Was the IAU suggesting the Earth was not a planet?

New Horizons’s discovery last week that even a small object like Pluto, orbiting the Sun on its own with no gas giant nearby to provide tidal heating, can still exhibit significant and on-going geological activity, shows that our understanding of what defines a planet is at this time quite limited. We simply don’t know enough about planetary evolution and formation to definitively define the term. Nor do we have enough knowledge to determine if Pluto falls into that category, though the data strongly suggests that it does.

Are planets made up of only gas giants, rocky terrestrial planets like the Earth, and dwarf planets like Ceres and Pluto? Or are there numerous other as yet unknown categories?
» Read more

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Astronomers confirm Kepler discovery of near twin of Earth

10:08 am

Worlds without end! In the release today of another set of Kepler data, astronomers have announced the discovery in that dataset of a new twin of Earth.

The newly discovered Kepler-452b is the smallest planet to date discovered orbiting in the habitable zone — the area around a star where liquid water could pool on the surface of an orbiting planet — of a G2-type star, like our sun. The confirmation of Kepler-452b brings the total number of confirmed planets to 1,030. …

Kepler-452b is 60 percent larger in diameter than Earth and is considered a super-Earth-size planet. While its mass and composition are not yet determined, previous research suggests that planets the size of Kepler-452b have a good chance of being rocky. While Kepler-452b is larger than Earth, its 385-day orbit is only 5 percent longer. The planet is 5 percent farther from its parent star Kepler-452 than Earth is from the Sun. Kepler-452 is 6 billion years old, 1.5 billion years older than our sun, has the same temperature, and is 20 percent brighter and has a diameter 10 percent larger.

While this exoplanet is certainly not identical to Earth, it is close enough that the possibility of alien life — really alien life — could very likely exist upon it.

The dataset also included 11 other Earth twin candidate exoplanets that still need to be confirmed.

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Astronomers find exoplanet twin of Jupiter

4:03 pm

Worlds without end: Astronomers have discovered an exoplanet with the same mass as Jupiter orbiting its star in a very similar orbit.

Not only that, but:

The planet’s host, the solar twin HIP 11915, is not only similar in mass to the Sun, but is also about the same age. To further strengthen the similarities, the composition of the star is similar to the Sun’s. The chemical signature of our Sun may be partly marked by the presence of rocky planets in the Solar System, hinting at the possibility of rocky planets also around HIP 11915.

I immediately wonder if this star also has rocky inner planets.

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Astronomers have discovered an exoplanet smaller than Earth

11:45 am

Worlds without end: Scientists have measured the size and mass of the smallest exoplanet yet, a Mars-sized planet orbiting a star about 200 light years away.

The planet, named Kepler-138 b, is the first exoplanet smaller than the Earth to have both its mass and its size measured. It is one of three planets that orbit the star Kepler-138 and that pass in front of it on every orbit as viewed from Earth — a maneuver that astronomers call a transit. “Each time a planet transits the star, it blocks a small fraction of the star’s light, allowing us to measure the size of the planet,” said Dr. Daniel Jontof-Hutter, a research associate in astronomy at Penn State who led the study.

“We also measured the gravity of all three planets, using data from NASA’s Kepler mission, by precisely observing the times of each transit,” Jontof-Hutter said. The astronomers also were able to measure the masses of these planets. “Each planet periodically slows down and accelerates ever so slightly from the gravity of its neighboring planets. This slight change in time between transits allowed us to measure the masses of the planets,” Jontof-Hutter explained. After measuring both the mass and size of an exoplanet, astronomers then can calculate its density and its bulk composition.

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A solar system like our own, but when it was a baby

9:28 am

Astronomers have discovered a very young 15 million year old star only 360 light years away that has a debris disk about the size of our solar system’s Kuiper Belt.

The ring is about the same distance from its parent star as the Kuiper belt is from the Sun, and receives roughly the same amount of light. Its blue-grey colour hints that it could consist of ices and rocky silicates such as those found in the Kuiper belt, says lead author Thayne Currie, an astronomer at the Subaru Telescope in Hawaii, which is run by the National Astronomical Observatory of Japan. “This is absolutely the closest example we have of a young Kuiper belt,” he says.

The best part of this discovery however might be how it was made, by using a new instrument on the ground-based Gemini telescope on Mauna Kea in Hawaii.

The instrument, which is part of the Gemini South telescope in Chile, uses a disk called a coronagraph to blot out the glare of bright stars. That allows it to take multi-wavelength pictures of faint, orbiting planets and debris disks around stars, by recording near-infrared light from the parent star as it scatters off the debris. The researchers discovered the disk around HD 115600 fewer than 6 months after the GPI began operation. A similar instrument, known as SPHERE, began operating in May 2014 on the European Southern Observatory’s Very Large Telescope in Chile and has also begun to make discoveries.

Assuming protesters don’t force Gemini to close, we should be getting a lot more exoplanetary discoveries from it in the coming years.

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An exoplanet that shouldn’t exist

10:06 am

Worlds without end: Astronomers have discovered an exoplanet that is too big for its tiny host star.

Present theory says that a Jupiter-sized planet should not have formed around this M-class dwarf star. But it has. In addition, the planet has the mass of Saturn but has been puffed up to the size of Jupiter. Yet, the star doesn’t provide it enough heat to cause it to puff up in this manner.

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IAU contest to name 20 exoplanets moves forward

9:08 am

Under pressure from many circles to open up its processes for naming objects in space, the International Astronomical Union (IAU) has started a contest to allow non-profits and “registered clubs” to compete to name 20 exoplanets.

Each organisation can submit one naming proposal, for one ExoWorld only. The number of names that need to be submitted depends on which system is selected. For single- and multiple-planet systems, a name for each planet must be submitted, as well as one for the host star. In the 20 ExoWorlds list, five stars already have common names. Consequently, these five stars cannot be considered for public naming. There are 15 stars and 32 planets (47 objects in total) available for naming. The name of the 20 host stars are explained and personal messages from some discoverers are also available here.

To participate in the contest, clubs and non-profit organisations must first register with the IAU Directory of World Astronomy. The deadline for registrations has been extended to 23:59 UTC on 1 June 2015.

You will note that this contest is not open to the public, but to clubs and organizations that the IAU approves. This is typical of the IAU, which wants to retain its power to name everything in space. They are thus keeping this whole process close to the vest and tightly controlled.

In the end it won’t matter, as the names will eventually be chosen by those who go there, or by those who make the discoveries. It would be nice, however, if the IAU would simply recognize this fact.

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