One of the surprises coming from the discoveries of the class of exoplanets known as “Hot Jupiters” is that they are puffed up beyond what would be expected from their temperature alone. The interpretation of these inflated radii is that extra energy must be being deposited in the regions of the atmosphere with large amounts of circulation. This extra energy would be deposited as heat, causing the atmosphere to expand. But from where was this extra energy coming? New research is suggesting that ionized winds passing through magnetic fields may create this process. Continue reading “Electric Resistance May Make Hot Jupiters Puffy”
Scientists Predict Earth-Like Habitable Exoplanet Will Be Found in 2011
[/caption]
Two astronomers have written a paper and say that the first Earth-like, habitable exoplanet will be announced in May of 2011. Do they have inside information, a crystal ball, or amazing powers of prediction? No, they base their projection on math and trends from the past 15 years of exoplanet discoveries. And if the discoveries continue at their present rate, the researchers say next year is the year of the long awaited holy grail of finding another Earth-like planet out in the cosmos.
Samuel Arbesman from Harvard Medical School in Boston and Gregory Laughlin at the University of California, Santa Cruz take a scientometric approach to their prediction. Scientometrics is the science of measuring and analyzing science, and is often done using bibliometrics which is a measurement of the impact of scientific publications. Arbesman and Laughlin said this type of work highlights the usefulness of predictive scientometric techniques to understand the pace of scientific discovery in many fields.
They use the properties of previously discovered exoplanets along with external estimates for the discovery of the first potentially habitable extrasolar planet.
In their paper they indicate that since astronomers have been discovering extrasolar planets at an increasing rate since 1995 and the discoveries follow a well understood pattern, it should be easy to predict when planet searchers will hit the jackpot.
The first exoplanets found were the massive Jupiter or larger-sized planets which were the easiest to find, and then as techniques improved over the past 15 years, astronomers have found smaller planets, some just a few times more massive than Earth.
Arbesman and Laughlin took that rate of discovery, and they also needed to factor in all the variables for what we think will make a planet habitable: the surface temperature must allow liquid water to exist, so that life as we know it can appear, and that depends on the size of the star, how far the planet orbits from its star, and what type of surface the exoplanet has.
They conclude there is a 66 per cent probability of finding another Earth by 2013, a 75 per cent probability by 2020, and a 95 per cent probability by 2264, but the median date of discovery is in May 2011. And not just sometime in May, but “early May.”
In June 2010, the Kepler Telescope team revealed they had found 750 exoplanet candidates, and a fair number of those confirmed might be Earth-sized. They expect they can confirm and announce some of these candidates in February 2011. But Arbesman and Laughlin predict it might take longer. “Because of the limited time base line of the mission to date, the Kepler planet candidates to published in February 2011 may be too hot to support significant values for H (which is their habitability metric),” they wrote in their paper.
So, if their prediction comes true, that might mean another team, such as the HARPS, or Keck, or CoRoT, or other exoplanet-finding wizards might make the discovery.
“It must be noted that by publicizing our prediction, there is a concern that it will become accurate,” Arbesman and Laughlin write in their paper, “simply due to the well-studied Hawthorne Effect. However, due to the large number of observations and long periods of time required to confirm an extrasolar planet discovery, it is unlikely that our prediction at this time will appreciably affect the announcement of the discovery of an Earth-like planet. Therefore, it is reasonable to use the habitability metric curve as a rough prediction for when the first potentially habitable planet will be discovered, in this case, as early as May 2011, and likely by the end of 2013.”
It will be interesting to see how accurate their prediction turns out to be!
Additional Source: Technology Review Blog
Does Tidal Evolution Cause Stars to Eat Planets?
[/caption]
With the success of the Kepler mission, the viability of looking for planets via transits has reached maturity. However, Kepler is not the first intensive study. Previously, other observatories have employed transit searches. To increase the chances of discovery, studies often concentrated on large clusters in which thousands of stars could be observed simultaneously. Based on the percentage of stars with super Jovian planets in the Sun’s vicinity, a Hubble observation run on the globular cluster 47 Tuc expected to find roughly 17 “hot Jupiters”. Yet not a single one was found. Follow-up studies on other regions of 47 Tuc, published in 2005, also reported a similar lack of signals.
Could the subtle effect of tidal forces have caused the planets to be consumed by their parent stars?
Within our solar system, the effects of tidal influences are more subtle than planetary destruction. But on stars with massive planets in tight orbits, the effects can be very different. As a planet would orbit its parent star, its gravitational pull would pull the star’s photosphere towards it. In a frictionless environment, the raised bulge would remain directly under the planet. Since the real world has real friction, the bulge will be displaced.
If the star rotates slower than the planet orbits (a likely scenario for close in planets since stars slow themselves via magnetic breaking during formation), the bulge will trail behind the planet since the pull has to compete against the photospheric material through which its pulling. This is the same effect that happens between the Earth-Moon system and is why we don’t have tides whenever the moon is overhead, but rather, the tides occur some time later. This lagging bulge creates a component of the gravitational force opposed to the direction of motion of the planet, slowing it down. As time goes on, the planet gets dragged closer to the star by this torque which increases the gravitational force and accelerating the process until the planet eventually enters the star’s photosphere.
Since transit discoveries rely on the planets orbital plane being exactly in line with its parent star and our planet, this favors planets in a very tight orbit since planets further out are more likely to pass above or below their parent star when viewed from Earth. The result of this is that planets that could potentially be discovered by this method are especially prone to this tidal slowing and destruction. This effect with the combination of the old age of 47 Tuc, may explain the dearth of discoveries.
Using a Monte-Carlo simulation, a recent paper explores this possibility and finds that, with the tidal effects, the non-detection in 47 Tuc is completely accounted for without the need to include additional reasons (such as metal deficiency in the cluster). However, to go beyond simply explaining a null result, the team made several predictions that would serve to confirm the destruction of such planets. If a planet were wholly consumed, the heavier elements should be present in the atmospheres of their parent star and thus be detectable via their spectra in contrast with the overall chemical composition of the cluster. Planets that were tidally stripped of atmospheres by filling their Roche Lobes could still be detected as an excess of rocky, super Earths.
Another test could inolve comparison between several of the open clusters visible in the Kepler study. Should astronomers find a decrease in the probability of finding hot Jupiters corresponding with a decrease with cluster age, this would also confirm the hypothesis. Since several such clusters exist within the area planned for the Kepler survey, this option is the most readily accessible. Ultimately, this result make sit clear that, should astronomers rely on methods that are best suited for short period planets, they may need to expand their observation window sufficiently since planets with a sufficiently short period may be prone to being consumed.
Extrasolar Volcanoes May Soon be Detectable
[/caption]
We’ve all seen pictures of erupting terrestrial volcanoes from space, and even eruptions on Jupiter’s moon Io in the outer solar system, but would it be possible to detect an erupting volcano on an exoplanet? Astronomers say the answer is yes! (with a few caveats)
It’s going to be decades before telescopes will be able to resolve even the crudest surface features of rocky extrasolar planets, so don’t hold your breath for stunning photos of alien volcanoes outside our solar system. But astronomers have already been able to use spectroscopy to detect the composition of exoplanet atmospheres, and a group of theorists at the Harvard-Smithsonian Center for Astrophysics think a similar technique could detect the atmospheric signature of exo-eruptions.
By collecting spectra right before and right after the planet goes behind its star, astronomers can subtract out the star’s spectrum and isolate the signal from the planet’s atmosphere. Once this is done, they can look for evidence of molecules common in volcanic eruptions. Models suggest that sulfur dioxide is the best candidate for detection because volcanoes produce it in huge quantities and it lasts in a planet’s atmosphere for a long time.
Still, it won’t be easy.
“You would need something truly earthshaking, an eruption that dumped a lot of gases into the atmosphere,” said Smithsonian astronomer Lisa Kaltenegger. “Using the James Webb Space Telescope, we could spot an eruption 10 to 100 times the size of Pinatubo for the closest stars,” she added.
In 1991 Mount Pinatubo in the Philippines belched 17 million tons of sulfur dioxide into the stratosphere. Volcanic eruptions are ranked using the Volcanic Explosivity Index (VEI). Pinatubo ranked ‘colossal’ (VEI of 6) and the largest eruption in recorded history was the ‘super-colossal’ Tambora event in 1815. With a VEI of 7 it was about 10 times as large as Pinatubo. Even larger eruptions (more than 100 times larger than Pinatubo) on Earth are not unheard of: geologic evidence suggests that there have been 47 such eruptions in the past 36 million years, including the eruption of the Yellowstone caldera about 600,000 years ago.
The best candidates for detecting extrasolar volcanoes are super-earths orbiting nearby, dim stars, but the Kaltenegger and her colleagues found that volcanic gases on any earth-like planet up to 30 light years away might be detectable. Now they just have to wait until the James Webb Space Telescope is launched 2014 to test their prediction.
The Origin of Exoplanets
[/caption]
We truly live in an amazing time for exoplanet research. It was only 18 years ago the first planet outside our solar system was discovered. Fifteen since the first confirmation of one around a main sequence star. Even more recently, direct images have begun to sprout up, as well as the first spectra of the atmospheres of such planets. So much data is becoming available, astronomers have even begun to be able to make inferences as to how these extra solar planets could have formed.
In general, there are two methods by which planets can form. The first is via coaccretion in which the star and the planet would form from gravitational collapse independently of one another, but in close enough proximity that their mutual gravity binds them together in orbit. The second, the method through which our solar system formed, is the disk method. In this, material from a thin disk around a proto-star collapses to form a planet. Each of these processes has a different set of parameters that may leave traces which could allow astronomers to uncover which method is dominant. A new paper from Helmut Abt of Kitt Peak National Observatory, looks at these characteristics and determines that, from our current sampling of exoplanets, our solar system may be an oddity.
The first parameter that distinguishes the two formation methods is that of eccentricity. To establish a baseline for comparison, Abt first plotted the distribution of eccentricities for 188 main-sequence binary stars and compared that to the same type of plot for the only known system to have formed via the disk method (our Solar System). This revealed that, while the majority of stars have orbits with low eccentricity, this percentage falls off slowly as the eccentricity increases. In our solar system, in which only one planet (Mercury) has an eccentricity greater than 0.2, the distribution falls off much more steeply. When Abt constructed the distribution for the 379 planets with known eccentricity, it was nearly identical to that for binary stars.
A similar plot was created for the semi major axis of binary stars and our solar system. Again, when this was plotted for the known extra solar planets the distribution was similar to that of binary star systems.
Abt also inspected the configuration of the systems. Star systems containing three stars generally contained a pair of stars in a tight binary orbit with a third in a much larger orbit. By comparing the ratios of such orbits, Abt quantified the orbital spacing. However, instead of simply comparing to the solar system, he considered the analogous situation of formation of stars around the central mass of the galaxy and built a similar distribution in this manner. In this case, the results were ambiguous; Both modes of formation produced similar results.
Lastly, Abt considered the amount of heavy elements in the more massive body. It is widely known that most extra-solar planets are found around metal-rich stars. While there’s no reason planets forming in a disk couldn’t be formed around high mass stars, having a metal-rich cloud from which to form stars and planets is a requirement for the coaccretion model because it tends to accelerate the collapse process, allowing giant planets to fully form before the cloud was dissipated as the star became active. Thus, the fact that the vast majority of extra-solar planets exist around metal-rich stars favors the coaccretion hypothesis.
Taken together, this provides four tests for formation models. In every case, current observations suggest that the majority of planets discovered thus far formed from coaccretion and not in a disc. However, Abt notes that this is most likely due to statistical biases imposed by the sensitivity limits of current instruments. As he notes, astronomers “do not yet have the radial velocity sensitivity to detect disk systems like the solar system, except for single large planets, like Jupiter at 5 AU.” As such, this view will likely change as new generations of instruments become available. Indeed, as instruments improve to the point that three dimensional mapping becomes available, and orbital inclinations can be directly observed, astronomers will be able to add another test to determine the modes of formation.
EDIT: Following some confusion and discussion in the comments, I wanted to add one further note. Keep in mind this is only the average of all systems currently known that looks like coaccreted systems. While there are undoubtedly some in there that did form from disks, their rarity in the current data makes them not stand out. Certainly, we know of at least one system that fits a strong test for the disk method. This recent discovery by Kepler, in which three planets have been observed transiting their host star demonstrates that all of these planets must lie in a disk which does not conform to expectations of independent condensation. As more systems like this are discovered, we expect that the distributions of the tests described above will become bimodal, having components that match each formation hypothesis.
Young Exoplanet is Cloudy With a Chance of Heat Waves
[/caption]
Back in 2008, the first multi-planet system of extrasolar planets was imaged, and further study of the planets in this very young system is yielding some puzzling results. Astronomers using the Keck Observatory have been able to obtain the spectrum of one planet, HR 8799 b, revealing the temperature, chemical composition, and atmospheric properties of the planet. The planet’s atmosphere is unlike that of any previously studied extrasolar planet, and it appears the planet is extremely cloudy, and also quite hot, even though it is very far from its host star.
“We are at a point where not only can we directly image planets around other stars, but we can begin to study the properties of their atmospheres in detail. Direct spectroscopy of exoplanets is the future of this field,” said Brendan Bowler, a graduate student at the University of Hawaii and the lead author of the study.
Although over 500 planets have been discovered around other stars, only six planets have been directly imaged.
HR 8799 b, is one of those imaged, and is one of three gas-giant planets orbiting the star HR 8799, located 130 light-years away from Earth in the constellation Pegasus. Bowler and his team said the properties of the planet’s atmosphere can’t be explained by current theoretical models of gas giant exoplanets, even those with what is considered a normal amount of thick or dusty atmospheres. From the new data on this planet, the astronomers believe that this exoplanet is extremely cloudy, and perhaps, all young gas-giant planets exhibit the same type of cloud cover in their atmospheres.
The technique the team used to determine the planet’s temperature relies on the chemistry of the planet’s atmosphere. Specifically, the presence or absence of gaseous methane can be used as a thermometer. The team found that HR 8799 b shows little or no methane in its atmosphere. Based on their spectrum and previously obtained images of the planet, and by comparing the observations to theoretical models of low-temperature atmospheres, they estimate the coolest possible temperature for the planet is about 1200 Kelvin (about 1,700 degrees Fahrenheit).
This planet is quite far from the star, 67 times the Earth-sun separation from the host star.
Current theoretical models predict HR 8799 b should be about 400 Kelvin cooler than they measured, based on the age of the planet and the amount of energy it is currently emitting. The team suspects the discrepancy arises because the planet is much more dusty and cloudy than expected by current models.
“Direct studies of extrasolar planets are just in their infancy. But even at this early stage, we are learning they are a different beast than objects we have known about previously,” said University of Hawaii astronomy professor Michael Liu, coauthor of the study.
The planets around HR 8799 are incredibly faint, about 100,000 times dimmer than their parent star. To obtain the spectrum of HR 8799 b, the team relied on the adaptive optics system of the Keck II Telescope, and focused on the star for several hours. Then they used the Keck facility instrument called OSIRIS, a special kind of spectrograph, to precisely separate the spectrum of the planet from the light of its parent star.
A paper describing the study will be published in the Astrophysical Journal later this year, but you can read the team’s abstract here.
Source: Keck Observatory
Kepler Discovers Multi-Planet System
[/caption]
The Kepler mission has discovered a system of two Saturn size planets with perhaps a third planet that is only 1.5 times the radius of Earth. While the news of this discovery is tempered somewhat with the announcement by a team from the European Southern Observatory of a system with five confirmed Neptune-sized planets and perhaps two additional smaller planets, both discoveries highlight that the spacecraft and techniques astronomers are using to find exoplanets are getting the desired results, and excitingly exoplanet reseach now includes the study of multiplanet systems. This discovery is the first time multiple planets were found by looking at transit time variations, which can provide more information about planets, such as their masses.
“What is particularly special about this system, is that the variations in transit times are large enough, that we can use these transit timing to detect the masses of these bodies” said Matthew Holman, Kepler team lead for the study of star Kepler-9, speaking on the AAAS Science podcast. Additionally, these findings should provide the tools astronomers need to determine even more physical conditions of these planets — and others — in the future.
The inner world weighs in at 0.25 Jupiter mass (80 Earths) while the outer world is a slimmer 0.17 Jupiter mass (54 Earths).
The team analyzed seven months of data from the orbiting Kepler telescope, and the two large confirmed planets—Kepler-9b and Kepler-9c— are transiting the parent star at unstable rates. The planets’ 19.2- and 38.9-day transition periods are increasing and decreasing at average, respective rates of four and 39 minutes per orbit.
“One thing that caught our attention right off, is when we do preliminary estimates at the time of the transit, we saw large variations in this particular system. Not only did we see more than one planet transiting, but one planet seemed to be speeding up and one slowing down,” Holman said.
Because period one is roughly twice the other, they have a signature of what is called a 2:1 orbital resonance, where astronomers expect to see large timing variation, due to the orbital gravitational push and pull the systems has on all the objects.
“The variation in transit times depend upon the masses of the planets,” Holman told reporters in a news conference announcing the findings. “The larger the mass the larger the variations. These variations allows us to determine the mass of the objects and we can confirm that they are planets.”
The team also confirmed the objects were planets with radial velocity observations with the Keck I telescope.
The third planet, with a mass several times that of the Earth, is transiting the star in a more interior orbit, but further analysis will be necessary to confirm that this signature is actually a planet.
“We are being very careful at this point to only call it a planet candidate, rather than a confirmed planet,” Holman said. “If it is confirmed it would only have a radius of about 1.5 that of Earth’s. It has a much shorter orbital period of 1.6 days, so it is very close to its host star, so we should be able to see evidence of many transits.”
Holman added that this discovery — regardless of whether they are able to confirm that this is a planet or not — highlights the sensitivity of Kepler to very small signatures.
Holman said the planets have probably migrated to be closer to the star from where they started out when they formed. “Likely they formed with the star, but likely they formed farther out at the “snow line” several times farther away from the star than the Earth is, and by a dynamical process move in closer,” he said in the Science podcast.
The resonance is a signature that some kind of migration had occurred, called convergent migration, where planets are moving towards the star and also coming closer to each other.
From all the transit timing information that has been gathered so far, astronomers are piecing together the migration history of this planetary system. “The whole history of that system may be encoded in the information we have,” said Alycia Weinberger, from the Department of Terrestrial Magnetism at the Carnegie Institution. “Isn’t it cool that what the planetary system looks like today has much to tell us about its history?”.
Kepler looks for the signatures of planets by measuring tiny decreases in the brightness of stars when planets cross in front of, or transit them. The size of the planet can be derived from the change in the star’s brightness. In June, mission scientists announced the mission has identified more than 700 planet candidates, including five systems with more than one planet candidate. This is the first of those systems to be confirmed.
Kepler principal investigator William Borucki said the team is working hard to get these candidates “turned into confirmed planets.”
Asked about why the public seems to be so interested in the Kepler mission, Borucki said, “We addressing a very important question, which is, are there other earths out there and are they frequent? Any answer is important. If we get zero that might mean there is very little life out there in the universe.”
Sources: Science, AAAS Science podcast, NASA,
Updated Exoplanet iPhone App
[/caption]
Just in time for the announcement yesterday of the multi-planet solar system discovery, and an upcoming exoplanet announcement by the Kepler team comes a new version of a free exoplanet app for iPhone and iPad. We got a note from Hanno Rein, who developed “Exoplanet,” and who just finished his PhD in astrophysics at the University of Cambridge. “It lists all discovered extrasolar planets with a lot of background information, many visualizations and animations,” he said. Other highlights include an easy search and filter for the database, real telescope images of the host star, visualizations of the orbits and the habitable zone, interactive 3D size comparison to our own solar system and much more.
With all the exoplanet news lately, “Exoplanet” is updated daily and push notifications are sent out whenever a new planet is discovered (although they can be turned off if you don’t want to get notifications). Pretty much everything known about any exoplanet is included, such as physical parameters, along with various visualizations and background information, which make this exciting subject accessible for a wider audience.
New for version 3.9 are direct links to planets and planetary systems, links to other planets of the same multi-planetary system have been added, and you can now link from any e-mail or website directly to this application by using a URL form of the exoplanet, for example, ://Fomalhaut
Rein developed this app while a student, and wanted to keep it free (knowing how hard it is to be a poor student!) so there are ads on the app. But a non-ad version is available for only $.99 USD.
I don’t have an iPhone or iPad (yet!) but Fraser does, and he said the Exoplanet app is very cool!
For more information, or to download, find Exoplanet at the iTunes Store.
Another Solar System Like our Own?
There is another Sun-like star out there with an intriguing family of planets orbiting about and it could be the closest parallel to our own solar system that astronomers have found yet. European astronomers discovered a planetary system containing at least five planets, orbiting the star HD 10180, with evidence that two other planets may be present. If confirmed, one of those would have the lowest mass ever found.
“We have found what is most likely the system with the most planets yet discovered,” says Christophe Lovis, who led the team. “This remarkable discovery also highlights the fact that we are now entering a new era in exoplanet research: the study of complex planetary systems and not just of individual planets. Studies of planetary motions in the new system reveal complex gravitational interactions between the planets and give us insights into the long-term evolution of the system.”
To make this system even more intriguing, the team also found evidence that the distances of the planets from their star follow a regular pattern, as also seen in our Solar System. “This could be a signature of the formation process of these planetary systems,” said team member Michel Mayor.
HD 10180, is located 127 light years away in the southern constellation of Hydrus. The five confirmed planets are large, about the size of Neptune — between 13 and 25 Earth masses —with orbital periods ranging from between six and 600 days. The planets’ distances from the star ranges from 0.06 and 1.4 times the Earth–Sun distance.
“We also have good reasons to believe that two other planets are present,” said Lovis. One would be a Saturn-like planet (with a minimum mass of 65 Earth masses) orbiting in 2200 days. The other would be the least massive exoplanet ever discovered, with a mass of about 1.4 times that of the Earth. It is very close to its host star, at just 2 percent of the Earth–Sun distance. One “year” on this planet would last only 1.18 Earth-days.
“This object causes a wobble of its star of only about 3 km/hour— slower than walking speed — and this motion is very hard to measure,” says team member Damien Ségransan. If confirmed, this object would be another example of a hot rocky planet, similar to Corot-7b.
The team used the planet-finding HARPS spectrograph, attached to ESO’s 3.6-metre telescope at La Silla, Chile, and made observations of HD 10180 for six years.
The newly discovered system of planets around HD 10180 is unique in several respects. First of all, with at least five Neptune-like planets lying within a distance equivalent to the orbit of Mars, this system is more populated than our Solar System in its inner region, and has many more massive planets there. Furthermore, the system probably has no Jupiter-like gas giant. In addition, all the planets seem to have almost circular orbits.
With this new announcement, the total number of exoplanets found is 472.
The team’s paper was submitted to Astronomy and Astrophysics (“The HARPS search for southern extra-solar planets. XXVII. Up to seven planets orbiting HD 10180: probing the architecture of low-mass planetary systems” by C. Lovis et al.).
Source: ESO
Tight Binaries are ‘Death Stars’ for Planets
[/caption]
Astronomers studying double star systems where the two stars are extremely close have found a pattern of destruction. While there probably isn’t a Star Wars-like Death Star roaming the Universe, tight binary systems might provide the equivalent of Darth Vader’s favorite weapon. “This is real-life science fiction,” said Jeremy Drake of the Harvard-Smithsonian Center for Astrophysics. “Our data tell us that planets in these systems might not be so lucky — collisions could be common. It’s theoretically possible that habitable planets could exist around these types of stars, so if there happened to be any life there, it could be doomed.”
Using the Spitzer Space Telescope, Drake and his team spotted a surprisingly large amount of dust around three mature, close-orbiting star pairs, that might be the aftermath of tremendous planetary collisions.
Drake is the principal investigator of the research, published in the Aug.19 issue of the Astrophysical Journal Letters.
The particular class of binary stars in the study are extremely close together. Named RS Canum Venaticorums, or RS CVns for short, they are separated by only about 3.2-million kilometers (two-million miles ), or two percent of the distance between Earth and our sun. The binaries orbit around each other every few days, with one face on each star perpetually locked and pointed toward the other.
These stars are familiarly like our own Sun – about the same size and probably about a billion to a few billion years old — roughly the age of our sun when life first evolved on Earth. But these stars spin much faster, and, as a result, have powerful magnetic fields, and giant, dark spots. The magnetic activity drives strong stellar winds — gale-force versions of the solar wind — that slow the stars down, pulling the twirling duos closer over time.
This is not a good scenario for planetary survival.
As the stars cozy up to each other, their gravitational influences change, and this could cause disturbances to planetary bodies orbiting around both stars. Comets and any planets that may exist in the systems would start jostling about and banging into each other, sometimes in powerful collisions. This includes planets that could theoretically be circling in the double stars’ habitable zone, a region where temperatures would allow liquid water to exist. Though no habitable planets have been discovered around any stars beyond our sun at this point in time, tight double-star systems are known to host planets; for example, one system not in the study, called HW Vir, has two gas-giant planets.
“These kinds of systems paint a picture of the late stages in the lives of planetary systems,” said Marc Kuchner, a co-author from NASA Goddard Space Flight Center. “And it’s a future that’s messy and violent.”
The temperatures around these systems measured by Spitzer are about the same as molten lava. The astronomers says that dust normally would have dissipated and blown away from the stars by this mature stage in their lives. They conclude that something — most likely planetary collisions — must therefore be kicking up the fresh dust. In addition, because dusty disks have now been found around four, older binary systems, the scientists know that the observations are not a fluke. Something chaotic is very likely going on.
If any life forms did exist in these star systems, and they could look up at the sky, they would have quite a view. Marco Matranga, lead author of the paper, also from Harvard-Smithsonian said, “The skies there would have two huge suns, like the ones above the planet Tatooine in ‘Star Wars.'”
The research was published in the Aug.19 issue of the Astrophysical Journal Letters.
Source: JPL