Tag Archives: exoplanet

Hubble spots a pitch-black exoplanet

Astronomers using the Hubble Space Telescope have determined that an exoplanet is practically pitch black, reflecting almost no light.

NASA’s Hubble Space Telescope has observed a planet outside our solar system that looks as black as fresh asphalt because it eats light rather than reflecting it back into space. This light-eating prowess is due to the planet’s unique capability to trap at least 94 percent of the visible starlight falling into its atmosphere.

The oddball exoplanet, called WASP-12b, is one of a class of so-called “hot Jupiters,” gigantic, gaseous planets that orbit very close to their host star and are heated to extreme temperatures. The planet’s atmosphere is so hot that most molecules are unable to survive on the blistering day side of the planet, where the temperature is 4,600 degrees Fahrenheit. Therefore, clouds probably cannot form to reflect light back into space. Instead, incoming light penetrates deep into the planet’s atmosphere where it is absorbed by hydrogen atoms and converted to heat energy.

Because the exoplanet is tidally locked, with one side always facing its sun and the other always in nightime, the nighttime face is estimated to be about 2,000 degrees cooler, and actually shows evidence of the existence of water vapor and clouds.

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Astronomers find star with giant ringed planet

Astronomers now think that a sunlike star about 1,000 light years away dips in brightness every 2.5 years because an orbiting ringed planet or ringed dwarf star blocks the star’s light.

They discovered that every two and a half years, the light from this distant star – PDS 110 in the Orion constellation, which is same temperature and slightly larger than our sun – is reduced to thirty percent for about two to three weeks. Two notable eclipses observed were in November 2008 and January 2011. “What’s exciting is that during both eclipses we see the light from the star change rapidly, and that suggests that there are rings in the eclipsing object, but these rings are many times larger than the rings around Saturn,” says Leiden astronomer Matthew Kenworthy.

Assuming the dips in starlight are coming from an orbiting planet, the next eclipse is predicted to take place in September this year – and the star is bright enough that amateur astronomers all over the world will be able to witness it and gather new data. Only then will we be certain what is causing the mysterious eclipses.

If confirmed in September, PDS 110 will be the first giant ring system that has a known orbital period. [emphasis in original]

Just so no one is confused, this is not Tabby’s Star. There, the dips in light are seemingly random and follow no pattern, other than an overall dimming for the past century.

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Atmosphere detected around Earth-sized exoplanet

Worlds without end: Astronomers have detected an atmosphere around an Earth-sized exoplanet 39 light years away.

The researchers pored over measurements from the European Southern Observatory in Chile and found that at one wavelength band of light, the planet looked larger than at others, as it crossed the face of its parent star. “These things don’t pop up in the way you expect,” said John Southworth, an astronomer at Keele University in the UK. “We found evidence for the atmosphere at one wavelength band and that wasn’t what we were expecting.”

The observations point to an atmosphere that is rich in water or methane, but it will take more measurements with other telescopes to identify the chemicals present.

The planet is about 16% larger than Earth. There remain a lot of uncertainty here with this result, so we should not yet take it too seriously.

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Earthlike exoplanet discovered orbiting the nearest star

Worlds without end: An Earthlike exoplanet has been discovered in the habitable zone and orbiting Proxima Centauri, the nearest star to the Sun.

The CBC/AP story above doesn’t give many details, mainly because this story is breaking the Thursday embargo, when the actual science paper will be released. Expect a lot more news stories then about this, which probably ranks as one of the biggest science discoveries in history.

Since the embargo is broken, here are some facts from one of the press releases:

The planet, called Proxima b, orbits its parent star every 11 days and has a temperature suitable for liquid water to exist on its surface. This rocky world is a little more massive than the Earth, and is the closest planet outside our solar system. Planets around other stars are commonly referred to as exoplanets.

…Although Proxima b orbits much closer to its star than Mercury does to the Sun in the solar system, the star itself is far fainter than the sun. As a result Proxima b lies well within the habitable zone around the star and has an estimated surface temperature that would allow the presence of liquid water. Despite the temperate orbit of Proxima b, the conditions on the surface may be strongly affected by the ultraviolet and X-ray flares from the star — these would be far more intense than those the Earth experiences from the Sun.

They first had a hint of the planet’s existence in 2013 (which explains the unsourced rumors I’ve heard periodcally in the past few years about a exoplanet around Proxima Centauri) and spent the past two-plus years making absolutely sure they understood their data.

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Earth forming around sun-like star?

proto-planetary disk

Worlds without end: The ground-based telescope ALMA has imaged a proto-planetary disk around a sun-like star that suggests an exoEarth is forming there the same distance from the star as our Earth is from our Sun.

The star, TW Hydrae, is a popular target of study for astronomers because of its proximity to Earth (approximately 175 light-years away) and its status as a veritable newborn (about 10 million years old). It also has a face-on orientation as seen from Earth. This affords astronomers a rare, undistorted view of the complete disk. “Previous studies with optical and radio telescopes confirm that this star hosts a prominent disk with features that strongly suggest planets are beginning to coalesce,” said Sean Andrews with the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., and lead author on a paper published today in Astrophysical Journal Letters. “The new ALMA images show the disk in unprecedented detail, revealing a series of concentric dusty bright rings and dark gaps, including intriguing features that suggest a planet with an Earth-like orbit is forming there.”

Other pronounced gap features are located 3 billion and 6 billion kilometers from the central star, similar to the distances from the Sun to Uranus and Pluto in our own Solar System.

The image above right is the inner section of that disk, showing the gap at one astronomical unit, or about 100 million miles from the star, the same as the distance of the Earth from the Sun. Essentially, this relatively close star system is providing us a perfect opportunity to study the formation of a solar system not unlike our own.

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The first image of a newly formed exoplanet

Astronomers have captured the first image, using ground-based telescopes, of an exoplanet in the process of forming.

The star is 450 light years away, and the image is really a combined image using data taken by two different telescopes, one in infrared light and the other gathering visible light spectroscopy. So, this really isn’t a photograph like you’d take with your camera, but a re-creation. Nonetheless it provides us a first look at the star and the new planet forming in orbit around it.

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Astronomers measure 5,400 mph winds on exoplanet

Category 5! Astronomers have for the first time measured wind speeds on an exoplanet and they are a doozy!

Discovered on the exoplanet HD 189733b, the Warwick researchers measured the velocities on the two sides of HD 189733b and found a strong wind moving at over 5400 mph blowing from its dayside to its night side. Mr Louden explains: “HD 189733b’s velocity was measured using high resolution spectroscopy of the sodium absorption featured in its atmosphere. As parts of HD 189733b’s atmosphere move towards or away from the Earth the Doppler effect changes the wavelength of this feature, which allows the velocity to be measured.”.

This exoplanet was one of the first discovered by Kepler, which means its orbit transits its sun. In this case it does so every 2.2 days, and astronomers have taken advantage of these frequent transits to study the planet’s atmosphere as the star’s light travels through it. The result is that HD 187733b is probably one of the most studied exoplanets.

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An exoplanet with an orbit like Mars

Using Kepler astronomers have discovered a Uranus-sized exoplanet with the longest known orbit, 704 days.

Kepler-421b orbits an orange, type K star that is cooler and dimmer than our Sun. It circles the star at a distance of about 110 million miles. As a result, this Uranus-sized planet is chilled to a temperature of -135° Fahrenheit.

As the name implies, Kepler-421b was discovered using data from NASA’s Kepler spacecraft. Kepler was uniquely suited to make this discovery. The spacecraft stared at the same patch of sky for 4 years, watching for stars that dim as planets cross in front of them. No other existing or planned mission shows such long-term, dedicated focus. Despite its patience, Kepler only detected two transits of Kepler-421b due to that world’s extremely long orbital period.

The planet’s orbit places it beyond the “snow line” – the dividing line between rocky and gas planets. Outside of the snow line, water condenses into ice grains that stick together to build gas giant planets.

Posted from Bright Angel Lodge on the rim of the Grand Canyon.

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For the first time astronomers think they have measured the rotation rate of an exoplanet, thus determining the length of its day.

For the first time astronomers think they have measured the rotation rate of an exoplanet, thus determining the length of its day.

Ignas Snellen and his colleagues at Leiden University in the Netherlands report in Nature1 that a gaseous planet orbiting the star β Pictoris rotates at 25 kilometres per second at its equator — faster than any planet in the Solar System and about 50 times faster than Earth. A day on the planet, called β Pictoris b, lasts just over eight hours, even though the planet has a diameter more than 16 times that of Earth’s and carries more than 3,000 times Earth’s heft.

This result falls under my category of “the uncertainty of science.” Though quite cool, and based on real data, the uncertainties are great. Don’t bet the house that this result will stand up to closer observations in the future.

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Astronomers have found evidence of the remains of an exoplanet that they think was once wet and rocky.

Astronomers have found evidence of the remains of an exoplanet that they think was once wet and rocky.

Using observations obtained with the Hubble Space Telescope and the large telescopes of the W. M. Keck Observatory , they found an excess of oxygen – a chemical signature that indicates that the debris had once been part of a bigger body originally composed of 26 per cent water by mass. By contrast, only approximately 0.023 per cent of the Earth’s mass is water.

From what I can gather, the actual data here is somewhat skimpy, requring a lot of assumptions for the scientists to come to this conclusion. Nonetheless, the data is interesting and very tantalizing.

Posted from Memphis, Tennessee.

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Astronomers have found a super-earth exoplanet inside its star’s habitable zone.

Worlds without end: Astronomers have found a super-earth exoplanet inside its star’s habitable zone.

The planet is large enough that it might be more like Neptune, but if it should have any earth-sized moons they will definitely be capable of supporting life.

Update: The science paper included a wonderful graphic comparing the solar system of this star with that of our own solar system. I have posted this graphic below the fold. HD40307g is the potentially habitable planet.
» Read more

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A new study suggests that the exoplanet orbiting the star Formalhaut that was supposedly imaged and then later theorized to be nothing more than a dust cloud might be a planet after all.

The uncertainty of science: A new study suggests that the exoplanet orbiting the star Formalhaut that was supposedly imaged and then later theorized to be nothing more than a dust cloud might be a planet after all.

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Astronomers have discovered that the nearest star to the Earth, Alpha Centauri, has an exoplanet only slightly heavier than the Earth.

Big news: Astronomers have discovered that the nearest star to the Earth, Alpha Centauri, has an exoplanet only slightly heavier than the Earth.

Alpha Centauri is actually a triple star system, with two sunlike stars in a tight orbit around each other and a third star far out orbiting them both. The exoplanet orbits one of the inner stars every 3.2 days.

More details from Nature here.

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Astronomers have discovered the first exoplanet smaller than Earth.

Astronomers have discovered the first exoplanet smaller than Earth.

The University of Central Florida has detected what could be its first planet, only two-thirds the size of Earth and located right around the corner, cosmically speaking, at a mere 33-light years away. The exoplanet candidate called UCF 1.01, is close to its star, so close it goes around the star in 1.4 days. The planet’s surface likely reaches temperatures of more than 1,000 degrees Fahrenheit. The discoverers believe that it has no atmosphere, is only two-thirds the gravity of Earth and that its surface may be volcanic or molten.

What is especially remarkable about this discovery is that the scientists used the Spitzer Space Telescope to do it, detecting the planet’s transits across the star’s face, just like Kepler. Spitzer was not designed to be able to do this.

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