TESS mission adds ‘sub-Neptune’ to discovery list

TESS probe
An artist’s conception shows NASA’s Transiting Exoplanets Survey Satellite, or TESS, with an assortment of exoplanets. (NASA / GSFC / MIT Illustration)

Less than a year after NASA’s TESS spacecraft was launched, the scientists behind the mission have unveiled their third confirmed planet, a weird alien world that’s between Earth and Neptune in size. And hundreds of additional potential finds are in the pipeline.

The latest exoplanet on the list is HD 21749b, which orbits a star that’s about 80 percent as massive as our sun, located about 53 light-years away in the southern constellation Reticulum. Its 36-day orbital period is a record high for the TESS mission.

The “sub-Neptune” planet is about three times Earth’s size, but 23 times its mass. In comparison, Neptune is almost four times as wide as Earth but only 17 times as massive.

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Climate analysis checks for most livable exoplanets

TRAPPIST-1 planets
This illustration shows the seven Earth-size planets of TRAPPIST-1, an exoplanet system about 39 light-years away. The image shows the relative sizes of planets b through h, from left to right, but does not represent their orbits to scale. (NASA / JPL-Caltech Illustration)

If you had to pick a place to set up shop amid the seven planets in the TRAPPIST-1 star system, 39 light-years from Earth, the fourth rock from that alien sun is the best place to start.

That Earth-sized world, known as TRAPPIST-1 e, came out on top in a recent round of exoplanetary climate modeling, detailed in a paper published Nov. 1 by the Astrophysical Journal.

Not that anyone’s planning on setting up shop there soon: Unless there’s a breakthrough that allows us to travel at a significant fraction of the speed of light, it would take hundreds of thousands of years to get to TRAPPIST-1. But the climate modeling methods developed for the TRAPPIST-1 system could help scientists decide which planets to target first with telescopes capable of analyzing alien atmospheres.

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Scientists report super-Earth at Barnard’s Star

Barnard's Star b
An artist’s conception shows what the surface of the reported planet known as Barnard’s Star b might look like. (ESO Illustration / M. Kornmesser)

The astronomical team that found the nearest exoplanet at Proxima Centauri has done it again with the reported detection of a super-Earth orbiting Barnard’s Star, the second-closest star system to our own.

The discoverers acknowledge, however, that they’re not completely sure yet.

“After a very careful analysis, we are 99 percent confident that the planet is there,” Spanish astronomer Ignasi Ribas, lead author of a study about the detection published today by the journal Nature, said in a news release. “However, we’ll continue to observe this fast-moving star to exclude possible, but improbable, natural variations of the stellar brightness which could masquerade as a planet.”

Assuming it exists, Barnard’s Star b would be at least 3.2 times as massive as Earth, tracing a 233-Earth-day orbit. It would be as close to its parent star as Mercury is to our own sun — but because Barnard’s Star is a dim red dwarf, surface conditions would be far too chilly for life as we know it. The surface temperature would be about 275 degrees below zero Fahrenheit (-170 degrees Celsius).

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Planet-hunting Kepler telescope runs out of gas

Kepler space telescope
Stylized artwork shows NASA’s Kepler space telescope among planetary systems. (NASA Illustration / Wendy Stenzel / Daniel Rutter)

NASA’s Kepler planet-hunting telescope now belongs to the ages, with its fuel completely spent and its instruments shut down — but the planet quest continues, thanks to a treasure trove of downloaded data as well as a new generation of robotic planet-hunters.

Space agency officials declared the end of spacecraft operations today, nine and a half years after the car-sized probe was launched. The hydrazine fuel ran out about two weeks ago, signaled by a sharp drop in pressure readings for the propulsion system.

“In the end, we didn’t have a drop of fuel left over for anything else,” Charlie Sobeck, project system engineer at NASA’s Ames Research Center, said during a teleconference.

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Planet search turns up a dwarf called ‘The Goblin’

Subaru Telescope
The International Space Station leaves a streak above the Subaru Telescope in a long-exposure image. Observations using the Subaru Telescope led to the discovery of the mini-world known as The Goblin. (Subaru Telescope / NAOJ Photo / Hideaki Fujiwara)

While searching for a hypothetical Planet Nine, astronomers found a distant mini-world that’s been given a spooky nickname: “The Goblin.”

The icy object was found at a distance of about 80 astronomical units from the sun, which translates to 7.4 billion miles. (One astronomical unit, or AU, equals 93 million miles, which is the distance between Earth and the sun.) That’s more than twice as far away as dwarf planet Pluto.

A research team led by Scott Sheppard of the Carnegie Institution of Science first spotted The Goblin just before Halloween in 2015. That timing, plus the fact that it was given the numerical designation 2015 TG387, gave rise to the trick-or-treat nickname. (T.G. … Get it?)

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TESS probe finds its first potential planets

TESS spacecraft
An artist’s conception shows NASA’s Transiting Exoplanet Survey Satellite, or TESS, with an alien sun and planet in the background. (NASA / GSFC Illustration)

Astronomers on the team for NASA’s Transiting Exoplanet Survey Satellite mission, or TESS, are reporting their first potential planet discoveries, just days after the spacecraft’s first science image was unveiled.

The first reported candidate planet was detected orbiting a star known as Pi Mensae, a sunlike yellow dwarf star nearly 60 light-years from Earth that was already known to harbor a world that’s more than 10 times as massive as Jupiter.

The newly detected prospect is closer to its parent star in the southern constellation Mensa, making a complete orbit every 6.3 Earth days.

In a paper published on the ArXiv pre-print website and submitted to the journal Astronomy & Astrophysics, the team’s scientists say Pi Mensae c appears to be about twice as wide as Earth and 4.5 times as massive.

Its density is estimated as roughly equal to water’s density, which suggests the planet is a super-Earth that “may have held on to a significant atmosphere,” the scientists say.

The second candidate planet orbits a red dwarf star known as LHS 3844, 49 light-years away in the constellation Indus. LHS 3844 b is thought to be a “hot Earth,” with a diameter about a third wider than Earth’s. It swings around its sun every 11 hours.

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Scientists spot planet orbiting Spock’s home star

Planet at HD 26965
An artist’s conception shows a super-Earth in orbit around HD 26965, which is Mr. Spock’s home star in “Star Trek” lore. (University of Florida Illustration)

Has the planet Vulcan been found? Vulcan’s most famous fictional inhabitant, Mr. Spock of “Star Trek” fame, would certainly raise an eyebrow if he heard that astronomers have detected a potentially habitable super-Earth orbiting the star that’s associated with him.

The world orbits a sunlike star that’s a mere 16 light-years away, known as HD 26965 or 40 Eridani A, according to the team behind the Dharma Planet Survey.

In the current Star Trek canon, 40 Eridani A is the star that harbors Spock’s home planet. Some early references pointed to a different star, known as Epsilon Eridani(which is also thought to host at least one exoplanet). But in a 1991 essay, Star Trek creator Gene Roddenberry and a group of astronomers argued that 40 Eridani A, the brightest star in a triple-star system, was a better fit because its 4 billion years of existence provided a wider window for pointy-eared intelligent life to evolve.

The latest findings suggest Roddenberry made the right choice: The planet found at 40 Eridani A is roughly twice Earth’s size, completes an orbit around its parent star every 42 Earth days, and lies just inside the star’s optimal habitable zone, said University of Florida astronomer Jian Ge.

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NASA unveils first science images from TESS probe

TESS images
NASA’s Transiting Exoplanet Survey Satellite, or TESS, captured this snapshot of the Large Magellanic Cloud (right) and the star R Doradus (left) with a single detector on one of its four wide-field cameras on Aug. 7. (NASA / MIT / TESS Photo)

The first science images from NASA’s Transiting Exoplanet Survey Satellite focus on a strip of southern sky that includes the two nearest dwarf galaxies and plenty of potential targets in the probe’s planet search.

“In a sea of stars brimming with new worlds, TESS is casting a wide net and will haul in a bounty of promising planets for further study,” Paul Hertz, astrophysics division director at NASA Headquarters, said today in a news release. “This ‘first light’ science image shows the capabilities of TESS’ cameras, and shows that the mission will realize its incredible potential in our search for another Earth.”

TESS was launched from Florida in April by a SpaceX Falcon 9 rocket, and the mission team has been spending the past few months getting the spacecraft ready for what’s expected to be a two-year mission.

The newly released imagery was captured by TESS’ four wide-field cameras during a 30-minute session on Aug. 7. The mosaic shows parts of a dozen constellations in the southern hemisphere, from Capricornus to Pictor.

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Historical study revisits debate over Pluto

Pluto and Charon
A composite image from NASA’s New Horizons spacecraft shows enhanced-color views of Pluto at lower right and Charon, its largest moon, at upper left. (NASA / JHUAPL / SwRI Photo)

Twelve years after the International Astronomical Union voted in a definition of planethood that reclassified Pluto, the debate goes on.

A newly published study uses the historical record to take aim at the definition’s most controversial clause: the idea that a planet in the solar system has to “clear the neighborhood of its orbit,” so that no other worlds are at a similar orbital distance.

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Planet-hunting space telescope wins vote of support

Telescope with starshade
An artist’s conception shows a planet-hunting space telescope accompanied by an umbrella-like starshade that blocks the glare of the planet’s parent star. (NASA / JPL Illustration)

NASA should add a large, technologically advanced space telescope to its lineup to capture direct images of Earthlike planets beyond our solar system, astronomers say in a congressionally mandated report issued today.

The report, published under the aegis of the National Academies of Sciences, Engineering and Medicine, also calls on the National Science Foundation to invest in the next-generation Giant Magellan Telescope and the Thirty Meter Telescope.

The GMT is being built in Chile, with completion set for 2025. The TMT is also due to go into service in the mid-2020s, although the current plan to build it on the top of Hawaii’s Mauna Kea volcano has run into controversy.

Authors of the report, led by Harvard’s David Charbonneau and Ohio State University’s B. Scott Gaudi, voiced support for two space telescopes already in the works — NASA’s James Webb Space Telescope and the Wide-Field Infrared Survey Telescope, or WFIRST. They also said NASA’s recently launched Transiting Exoplanet Survey Satellite, or TESS, would provide valuable information about Earth-size exoplanets as well.

But the report makes clear that the search for alien planets will have to focus down on direct images of planets, as well as detailed analysis of exoplanet atmospheres, in order to address questions about the existence of life beyond our solar system.

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