Posts Tagged ‘exoplanets’

Largest known planet to orbit two suns is discovered

June 15, 2016 Leave a comment
Kepler planet comparison - courtesy NASA GSFC, graphic by Lynette Cook

This graphic shows the relative size of several known circumbinary planets. Kepler-1647b is about the size of Jupiter. Courtesy NASA Goddard Space Flight Center, graphic by Lynette Cook.

Scientists have found a planet about the size of Jupiter orbiting two stars in a nearby solar system, marking the largest known example of a world with multiple suns.

The circumbinary planet, which has been named Kepler-1647b, is in the constellation Cygnus, about 3,700 light years from Earth. Astronomers used the Kepler Space Telescope to discover it.

“It’s a bit curious that this biggest planet took so long to confirm, since it is easier to find big planets than small ones,” Dr. Jerome A. Orosz, an astronomer at San Diego State University and a co-author of a paper documenting the discovery, said. “But it is because its orbital period is so long.”

Kepler-1647b’s orbital period is 1,107 days, which means it takes longer to orbit its stars than any other known exoplanet takes to orbit either one star or two.

The planet’s circumbinary orbit made it more difficult to find than would be the case with an exoplanet that circles one star.

“The transits are not regularly spaced in time and they can vary in duration and even depth,” Dr. William F. Welsh, another SDSU astronomer and co-author of the paper explaining the discovery, said.

Kepler-1647b orbit

This graphic provides a “bird’s eye” view comparison of the orbits of the Kepler circumbinary planets. Kepler-1647 b’s orbit, shown in red, is much larger than the other planets (shown in gray). For comparison, Earth’s orbit is shown in blue. Graphic courtesy NASA Goddard Institute for Space Studies, graphic by B. Quarles.

A gas giant, Kepler-1647b is has a similar age as Earth – about 4.4 billion years. The two stars it orbits are similar to our sun, with one being a little larger than the Sun and the other slightly smaller than Earth’s star.

The discovery of Kepler-1647b is described in a paper to be published in Astrophysical Journal.





Researchers discover possible Earth-like exoplanet orbiting ultracool dwarf star

MIT - May 2016 - Earthlike exoplanets

This illustration depicts an artist’s imagined view of the three planets orbiting an ultracool dwarf star just 40 light-years from Earth. The exoplanets were discovered using the TRAPPIST telescope at European Southern Observatory’s La Silla Observatory. In the illustration, one of the inner planets is seen in transit across the disc of its tiny and dim parent star. Image courtesy European Southern Observatory, artist’s conception by M. Kornmesser.

Astronomers have discovered three exoplanets in a nearby star system that may be comparable to the size of Earth and Venus and one of them may also be located at distance from its star to experience temperatures similar to our planet.

The planets are about 40 light years from our planet and orbit a dwarf star that is about one-eighth the size of our sun, or approximately the size of Jupiter. The dwarf star, which astronomers consider to be “ultracool,” is so much cooler than our sun that the system’s habitable zone is much closer to it than in our solar system.

A star’s habitable zone is the area of its star system in which temperatures may be hospitable to environmental conditions amenable to life.

Two of the exoplanets have orbital periods of less than three days; they probably receive two-to four times the amount of solar radiation that Earth does.

The third and most distant of the exoplanets experiences a year that is at least four and as many as 73 days long.

“These planets are so close, and their star so small, we can study their atmosphere and composition, and further down the road, which is within our generation, assess if they are actually inhabited,” Julien de Wit, a postdoctoral researcher at Massachusetts Institute of Technology and a co-author of the paper announcing the discovery, said.

The two exoplanets closest to their star are likely tidally locked to it, meaning that one side of the planet always faces the star. Those two planets are generally too hot on their day-sides, and too cold on their night sides, to support life, though the team of scientists that published the paper describing them said that there may be small areas on their western hemispheres that might be temperate enough to do so.

The third planet from the star could be in its habitable zone, meaning liquid water could occur on its surface.

The three exoplanets are the first ever discovered orbiting an ultracool dwarf star.

Researchers used the TRAPPIST instrument in Chile to find the exoplanets. Because their star emits so little radiation, compared to larger stars, it cannot be seen with an optical telescope.

TRAPPIST, which is an acronym for TRAnsiting Planets and PlanetesImals Small Telescope, detects radiation in the infrared band of the spectrum. Starting in September 2015 the scientists periodically detected a lessening of the amount of the star’s infrared radiation detected by the instrument. That indicated the likelihood that several objects were passing in front of it.

The paper describing the discovery of the exoplanets was published online in the May 12 edition of Nature.


Water discovered in asteroid remnants

October 11, 2013 Leave a comment

Scientists have found, for the first time, evidence of water on a rocky celestial body outside of our solar system.

The study focused on dust and debris found orbiting a white dwarf star about 170 million light years away.

“This planetary graveyard swirling around the embers of its parent star is a rich source of information about its former life,” Boris Gaensicke, a professor of physics at the University of Warwick in the United Kingdom, said. “In these remnants lie chemical clues which point towards a previous existence as a water-rich terrestrial body.”

“Those two ingredients — a rocky surface and water — are key in the hunt for habitable planets outside our solar system so it’s very exciting to find them together for the first time outside our solar system.”

The debris probably came from a planet with a diameter of at least 90 kilometers. The planet may have been much bigger than that, but scientists are limited in their ability to estimate its size by the amount of debris that can now be detected.

Oxygen signatures in the debris indicates that the planet would have been, as a proportion of its mass, about 26 percent water.

Water accounts for about 0.023 percent of Earth’s mass.

Scientists had earlier found evidence of water outside our solar system in gas giants. This discovery is significant because it is the first indication that water may be found on rocky exoplanets.

A possible parallel in our solar system is the dwarf planet Ceres, which has ice buried under its crust.

The star around which the debris is accumulated, GD 61, once hosted a planetary system. It became a white dwarf about 200 million years ago.

The discovery of the GD 61 system planetary remnants is the twelfth known example of planetary fragments circling a white dwarf elsewhere in our galaxy.

Researchers used the Hubble Space Telescope and the large Keck Telescope in Hawaii to make the observations in the study.

The paper can be found here.

This artist's conception shows an asteroid fragment around the distant white dwarf GD 61.

This artist’s conception shows an asteroid fragment around the distant white dwarf GD 61.

Artist’s conception (c) Mark A. Garlick, courtesy University of Warwick and University of Cambridge.

Note: A version of this story has also been published at

Astronomers map clouds of distant planet

October 1, 2013 Leave a comment

Scientists have, for the first time, mapped the cloud cover of a planet beyond our solar system.

The distant world, known as Kepler-7b, has high altitude cloud cover in its western hemisphere and generally clear skies in its eastern hemisphere.

“Kepler-7b reflects much more light than most giant planets we’ve found, which we attribute to clouds in the upper atmosphere,” Thomas Barclay, a scientist at NASA’s Ames Research Center who has been involved in the research, said. “Unlike those on Earth, the cloud patterns on this planet do not seem to change much over time — it has a remarkably stable climate.”

Kepler-7b’s clouds were discerned by using the Kepler and Spitzer Space Telescopes. For three years astronomers used Kepler to gather data on the light reflected by the planet. Meanwhile, Spitzer’s capability of observing infrared radiation from a celestial object allowed the researchers to pinpoint a temperature range for the planet.

It is not cool on Kepler-7b. Data indicates that the planet has a temperature of between 1,500 and 1,800 degrees Fahrenheit. Considering that Kepler-7b is quite close to its sun – only about 0.06 astronomical units (Earth is one AU from our sun) – it is actually surprising that the planet is not hotter than it is.

That temperature range is too low to be the source of the light detected by Kepler. Astronomers therefore concluded that high-altitude clouds must be reflecting radiation from the system’s star into space.

Kepler-7b is a gas giant and has a radius about one and one-half times that of Jupiter. It is the largest of the six known planets in its system.

The Kepler Space Telescope’s mission ended earlier this year when a wheel integral to its operations failed.

Researchers at NASA, Massachusetts Institute of Technology, California Institute of Technology, and other universities will publish a technical paper about the discovery in Astrophysical Journal Letters.


Graphic comparing Kepler-7b to Jupiter courtesy NASA, Jet Propulsion Laboratory-California Institute of Technology, Massachusetts Institute of Technology.

NASA’s Kepler spacecraft might be at end of mission

The Kepler space telescope, which has been instrumental in the discovery of more than 2,000 exoplanets, may be at a sudden end of its extended mission.

The spacecraft has suffered a malfunction involving a device that stabilizes its camera.

“With the failure of a second reaction wheel, it’s unlikely that the spacecraft will be able to return to the high pointing accuracy that enables its high-precision photometry,” NASA said in a statement Wednesday.

The probe was launched in 2009 and completed its initial mission last autumn.

Earth-size exoplanet found in Alpha Centauri, nearest star system to Earth

October 20, 2012 1 comment

There’s a new planet in the stellar neighborhood next door.

Astronomers said this week that the exoplanet, which is in the triple-star Alpha Centauri system, has a mass comparable to that of Earth. It is the closest exoplanet to Earth yet discovered.

Yale University astronomer Debra Fischer told the New York Times that the find is “the story of the decade.”

“I’d bet $100 that there are other planets that are there as well,” she is quoted as saying in the story published in the Times’ Oct. 16 edition.

While the newly-discovered exoplanet is about the same size as Earth, it would not be a comfortable place for human beings. The planet orbits Alpha Centauri-B, one of the Alpha Centauri system’s three suns, at a distance of about six million kilometers.

That is so close that its surface temperature would exceed 2,000 degrees Fahrenheit.

By comparison, Mercury is about 46 million kilometers from the Sun at its perihelion. The closest planet to the Sun, the daytime surface temperature on Mercury can exceed 800 degrees Fahrenheit.

Astronomers used a technique that involves measuring slight changes in the star’s motion caused by the gravitational pull of an object orbiting the star.

The newly-discovered exoplanet causes only a tiny wobble in the motion of Alpha Centauri-B. According to a press release issued by the European Southern Observatory, the star’s movement is altered by only about 51 centimeters per second.

“Our observations extended over more than four years using the HARPS instrument and have revealed a tiny, but real, signal from a planet orbiting Alpha Centauri B every 3.2 days,” Xavier Dumusque, a researcher at Geneva Observatory in Switzerland and Centro de Astrofisica da Universidade do Porto in Portugal and the lead author of the paper, said. “It’s an extraordinary discovery and it has pushed our technique to the limit.”

HARPS refers to the High Accuracy Radial Velocity Planet Searcher, a spectrograph attached to the 3.6 meter telescope at the La Silla Observatory in Chile’s Atacama Desert.

Alpha Centauri is located 4.3 light years, or about 25.6 trillion miles, from Earth – a distance that is about 600,000 times farther from our planet than is the Sun.

That means it would not be easy to travel to the newly-discovered planet.

If a spaceship traveling at the maximum velocity achieved by the space shuttles during their missions in Earth orbit, a journey to the Alpha Centauri system would take approximately 165,000 years to complete.

The significance of the planet isn’t limited to its size relative to Earth. It is also the lightest exoplanet among the more than 800 confirmed so far.

Astronomers announced the find this week in an article published in the prestigious journal Nature.Image

Artist’s conception courtesy European Southern Observatory, L. Calcada, Nick Risinger.

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