According to Phys.org, Astronomers have made an interesting new discovery — a gas giant orbiting a brown dwarf. The exoplanet has been dubbed OGLE-2017-BLG-1522Lb. The newly discovered gaseous body has about 25% less mass than Jupiter, while its parent pseudo-star is about 46 times more massive than our own Jove.

Exoplanets are already pretty tough to spot. Unlike stars, planets don’t naturally give off any light, which means that scientists have to get a little creative when looking for them. Often they use something called the “Transit Method” wherein they follow a star as it crosses in front of its parents light, and watch how and where the image dims to get a rough estimate of its properties.

But this one was a bit different. Here, researchers used gravitational microlensing. Because gravity isn’t really a force, as Einstein demonstrated, but a curvature of space-time, in the same way a lens can be used to magnify an image, gravity can be used to accomplish the same. This technique requires solid understanding of the masses in the system being studied, but it’s extraordinarily effective and quite useful to spot a planet near a brown dwarf — which emit very little light naturally.

OGLE-2017-BLG-1522 was observed in August of last year as part of the Optical Gravitational Lensing Experiment (OGLE). The team used one of the telescopes at the Las Campanas Observatory in Chile, and, following the data collection, an international team of astronomers analyzed the data and found that the system likely had a brown dwarf and a gas giant.

“We report the discovery of a giant planet in the OGLE-2017-BLG-1522 microlensing event. The planetary perturbations were clearly identified by high-cadence survey experiments despite the relatively short event timescale of tE ~ 7.5 days,” the researchers wrote.

What matters here is that brown dwarfs aren’t generally thought to have the kind of nebulae that cause planet formation. There is a boundary, known as the “snow line,” past which planets tend to form. And while the astrophysics behind that gets a little complicated, these astronomers are fairly confident that their discovery is the first giant planet orbiting a brown dwarf with the right proportions. More observations will need to be made to confirm that the star is, indeed, brown, i.e. it doesn’t have enough mass to sustain hydrogen fusion in its core. If so, this could be a major new addition to our understanding of astrophysics and how planets form.

Let us know what you like about Geek by taking our survey. </s> Light curve of OGLE-2017-BLG-1522. Credit: Jung et al., 2018.

Using microlensing technique, astronomers have found a new giant planet orbiting a brown dwarf located in the bulge of the Milky Way galaxy. The newly discovered exoplanet, designated OGLE-2017-BLG-1522Lb, is most likely 25 percent less massive than Jupiter. The finding is reported March 14 in a paper published on arXiv.org.

Based on the gravitational lens effect, the microlensing method is mainly used to detect planetary and stellar-mass objects regardless of the light they emit. This technique is therefore sensitive to the mass of the objects, especially to low-mass planets orbiting beyond the so-called "snow line" around relatively faint host stars like M dwarfs or brown dwarfs. Such planets are of special interest for astronomers, as just beyond this line, the most active planet formation occurs.

The OGLE-2017-BLG-1522 microlensing event was detected August 7, 2017 by the Optical Gravitational Lensing Experiment (OGLE) using the 1.3m Warsaw telescope at the Las Campanas Observatory in Chile. Afterward, an international team of astronomers, including scientists from the OGLE Collaboration and the Korea Microlensing Telescope Network (KMTNet) Collaboration, has analyzed the event and found a system composed of a brown dwarf orbited by a giant planet.

"We report the discovery of a giant planet in the OGLE-2017-BLG-1522 microlensing event. The planetary perturbations were clearly identified by high-cadence survey experiments despite the relatively short event timescale of t E ~ 7.5 days," the researchers wrote in the paper.

According to the study, OGLE-2017-BLG-1522Lb is a giant planet with a mass of about 0.75 Jupiter masses, orbiting its host at a distance of about 0.59 AU. The researchers noted that they are 75 percent sure that the host is a brown dwarf approximately 46 times more massive than our solar system's biggest planet. Therefore, additional observations should be conducted in order to definitely confirm whether the host is a low-mass star or a an intermediate-mass brown dwarf.

The projected companion-host separation indicates that OGLE-2017-BLG-1522Lb is placed beyond the snow line—the distance at which molecular species freeze, thus where the planet formation starts. Moreover, the authors of the paper calculated that the system is located in the galactic bulge.

In concluding remarks, the astronomers underlined the importance of their discovery, noting that OGLE-2017-BLG-1522Lb could be the first giant planet orbiting around a brown dwarf host having a planetary mass ratio.

"Planet formation scenarios combined with the small companion-host mass ratio q ∼ 0.016 and separation suggest that the companion could be the first discovery of a giant planet that formed in a protoplanetary disk around a brown dwarf host," the scientists concluded.

Explore further Extremely massive exoplanet discovered in the Milky Way's bulge

More information: OGLE-2017-BLG-1522: A giant planet around a brown dwarf located in the Galactic bulge, arXiv:1803.05095 [astro-ph.EP] OGLE-2017-BLG-1522: A giant planet around a brown dwarf located in the Galactic bulge, arXiv:1803.05095 [astro-ph.EP] arxiv.org/abs/1803.05095 Abstract

We report the discovery of a giant planet in the OGLE-2017-BLG-1522 microlensing event. The planetary perturbations were clearly identified by high-cadence survey experiments despite the relatively short event timescale of tE∼7.5 days. The Einstein radius is unusually small, θE=0.065mas, implying that the lens system either has very low mass or lies much closer to the microlensed source than the Sun, or both. A Bayesian analysis yields component masses (Mhost,Mplanet)=(46+79−25,0.75+1.26−0.40) MJ and source-lens distance DLS=0.99+0.91−0.54 kpc, implying that this is a brown-dwarf/Jupiter system that probably lies in the Galactic bulge, a location that is also consistent with the relatively low lens-source relative proper motion μ=3.2±0.5 mas yr−1. The projected companion-host separation is 0.59+0.12−0.11 AU, indicating that the planet is placed beyond the snow line of the host, i.e., asl∼0.12 AU. Planet formation scenarios combined with the small companion-host mass ratio q∼0.016 and separation suggest that the companion could be the first discovery of a giant planet that formed in a protoplanetary disk around a brown dwarf host.

© 2018 Phys.org </s> Scientists have discovered a planet a lot like Jupiter orbiting a dim star, if you can even call it a star—it’s nothing like our sun. The finding once again makes us wonder: what is a planet, anyway?

A team of researchers from two collaborations, KMTNet and the OGLE, or Optical Gravitational Lensing Experiment, announced their new planet-brown dwarf pair, calling it the “OGLE-2017-BLG-1522 microlensing event.” Brown dwarfs are either the lightest, dimmest stars or the heaviest, hottest planets. They have been spotted with companions before, but this would be largest mass difference between a brown dwarf and its companion yet, with the brown dwarf being perhaps over 60 times the size of the orbiting planet.

“OGLE-2017-BLG-1522Lb could be the first giant planet orbiting around a brown-dwarf host having a planetary mass ratio,” the authors write in the paper published on the arXiv preprint server.

That means that the planet could have formed from a ring of dust around the brown dwarf, rather than the two objects forming together as a sort of binary. “That’s the fundamental question,” Jennifer Yee, astrophysicist at the Harvard-Smithsonian Center for Astrophysics, told Gizmodo. “That’s why it’s important. We don’t know how you would form these things,” she said, referring to planets orbiting brown dwarfs.

The OGLE discovered the object on August 7, 2017, using their Warsaw telescope in Chile. Another network of telescopes in Chile, South Africa, and Korea, called the Korea Microlensing Telescope Network Survey, also monitored the event.

Essentially, the researchers saw another star, located behind the brown dwarf and planet, brighten in a characteristic pattern, one most likely due to the pair passing in front of it. The gravity from the closer objects would bend the light of the star behind them. The researchers attributed their results to a planet around three-quarters the mass of Jupiter orbiting a brown dwarf 46 or so times the mass of Jupiter. They calculated that the two are separated by about 0.6 times the distance between the Earth and the Sun.

This new paper hasn’t been published in its peer-reviewed form yet, and has some pretty large uncertainties; for example, the paper includes the line “the probability that the host is a brown dwarf is [approximately] 76%.” We’ll update this post with further comment when we hear back.



But the event brings up yet again the debate about what constitutes a “planet” and what doesn’t—a redefinition of the term planet stripped Pluto of its title, you might remember. It’s especially difficult to figure out the difference on the heavier end of things, though, when something is too big to be called a planet and just massive enough to become a star. How something forms is of crucial importance to understanding whether something is a planet or not, since planets tend to form from disks around stars, while stars form from the centers of the disks themselves.

Given the uncertainty, there’s still lots more research to be done, said Yee, since we can’t see the whole process from start to finish. “By finding a bunch of these thing, we can relate them back to the whole corse of their evolution,” she said. </s> UPDATE: A mistake about an exoplanet's exact position has been corrected

Astronomers have found over 4,000 planets in other star systems, but almost all of these "exoplanets" are massive compared to Earth. In fact, 96% of them are larger than Earth. Mostly, astronomers have found gas giants like Neptune or Jupiter, but very few small planets. So the announcement this week that 18 exoplanets have been discovered that fall into the broad category of Earth-sized planets is big news.

The even bigger news is that one of them is slightly smaller than our planet. Have we just found Earth 2.0?

What do we know about this planet?

The candidate for an "Earth twin" is called EPIC 201497682.03. It resides around a red dwarf star called EPIC 201497682 that’s 831 light years from our solar system between the constellations Leo and Virgo. It’s 69% of the size of the Earth, the closest fit in the 18 exoplanets found by scientists at the Max Planck Institute for Solar System Research (MPS), the Georg August University of Göttingen, and the Sonneberg Observatory, whose results have been published in Astronomy & Astrophysics.

What about its host star?

"EPIC” stands for “Ecliptic Planet Input Catalog”, which was a list of targets that the Kepler Space Telescope's K2 mission was supposed to observe. However, EPIC 201497682 is also known in other star catalogs as UCAC4 453-051784, 2MASS J11154478+0029171, and Gaia DR2 3810098271767907840. "When we look at the star now we see the light that emerged from this system about 300 years before Christopher Columbus reached The Americas," said Dr. Rene Heller from MPS, first author of the paper. "It’s quite compelling that we were able to find a rock just slightly larger than Mars around this remote star."

Why are small exoplanets hard to find?

Small planets are harder to track down than big ones. Exoplanet-hunters find their targets by detecting a drop in brightness as a planet travels (transits) in front of its host star. However, while large planets cause sudden drops in brightness that is easy to detect, small planets cause such a tiny change in brightness that it's hard to separate it from the natural brightness fluctuations of the star. "Standard search algorithms attempt to identify sudden drops in brightness," said Heller. "In reality, however, a stellar disk appears slightly darker at the edge than in the center. When a planet moves in front of a star, it therefore initially blocks less starlight than at the mid-time of the transit. The maximum dimming of the star occurs in the center of the transit just before the star becomes gradually brighter again," he said.

How were these new exoplanets found?

As well as the "sub-Earth" planet EPIC 201497682.03, the scientists found 17 planets slightly larger than Earth, all of them found in data from the Kepler Space Telescope using a new search algorithm called transit least-squares (TLS). "Our new algorithm helps to draw a more realistic picture of the exoplanet population in space," summarises Michael Hippke of Sonneberg Observatory. The new algorithm looks for gradual darkening, not the abrupt brightness drops that algorithms usually look for. This makes the new transit search algorithm significantly more sensitive to very small planets the size of the Earth. "This method constitutes a significant step forward, especially in the search for Earth-like planets,” said Hippke.

What is the Kepler Space Telescope?

The researchers used data from NASA’s Kepler Space Telescope as a test bed for their new algorithm. In its first mission phase from 2009 to 2013, Kepler recorded the light curves of more than 100,000 stars, resulting in the discovery of over 2,300 planets. After a technical defect, the telescope had to be used in an alternative observing mode, called the K2 mission, but it still managed to monitor more than 100,000 more stars by the end of the mission in 2018. The researchers decided to re-analyze all 517 stars from K2 that were already known to host at least one transiting planet.

Could these exoplanets be habitable?

Most of them are probably too hot. Most of the new planets detected in the old data orbit their star closer than other known planets. The surfaces of these new planets therefore likely have temperatures well in excess of 100ºC/212ºF, while some have temperatures of up to 1,000ºC/1,832ºF. Only one, a planet called EPIC 201238110.02, resides in the "habitable zone". "It's 1.87 Earth diameter in size, so it’s rather a super-Earth than an Earth twin," says Heller. The host star EPIC 201238110 is 522 light years from us, also between the constellations Leo and Virgo.

Can the new algorithm be used to find another Earth 2.0?

Given their discovery rate of 3.5% new planets in old data, the researchers think that their method will help them to find more than 100 other Earth-sized worlds in the Kepler data. “This new method is also particularly useful to prepare for the upcoming PLATO mission to be launched in 2026 by the European Space Agency,” says Professor Dr. Laurent Gizon, managing director at the MPS.

What is the PLATO mission?

Planned for launch by 2026, the PLATO (PLAnetary Transits and Oscillations of stars) mission will assemble the first-ever catalog of confirmed planets, including planets in the habitable zone of their host stars. It will study hundreds of rocky, icy and giant planets and accurately measure their radii, masses, and ages. It’s expected to revolutionize astronomers’ understanding of planet formation and the evolution of planetary systems. "Does a second Earth exist in the Universe? is one of the exciting questions in astrophysics today," says Johann-Dietrich Wörner, director general of ESA. "With our PLATO satellite, we are focusing on Earth-like planets orbiting up to the habitable zone around other stars which are similar to our Sun. This will be a major step towards finding another Earth." </s> Scientists have discovered 15 new planets, including a “super-Earth” that may have liquid water on its surface.

The planets are orbiting small, cool stars near our solar system that are known as “Red Dwarfs.”

One of the brightest Red Dwarfs, K2-155, has three “super-Earths,” one of which, K2-155d, could be within the star’s habitable zone. K2-155d, which has a radius 1.6 times that of Earth, may harbor liquid water, according to three-dimensional global climate simulations.

K2-155 is about 200 light years from Earth. A light year, which measures distance in space, equals 6 trillion miles.

The research also indicates that planets orbiting red dwarfs may be remarkably similar to planets orbiting stars that resemble the Sun, known as solar-type stars.

"It's important to note that the number of planets around red dwarfs is much smaller than the number around solar-type stars," said Teruyuki Hirano of Tokyo Institute of Technology's Department of Earth and Planetary Sciences, who led the research, in a statement. "Red dwarf systems, especially coolest red dwarfs, are just beginning to be investigated, so they are very exciting targets for future exoplanet research."

However, Hirano voiced caution about the conditions on K2-155d. "In our simulations, the atmosphere and the composition of the planet were assumed to be Earth-like, and there's no guarantee that this is the case,” he said.

ALIEN LIFE LOOMS? NEWLY DISCOVERED EXOPLANET MAY BE BEST CANDIDATE, EXPERTS SAY

More research on K2-155d’s temperature and radius is needed to confirm whether the planet is indeed habitable.

Scientists based their research on data from K2, the second mission of NASA’s Kepler spacecraft. Follow-up observations were made by the Subaru telescope in Hawaii and the Nordic Optical Telescope (NOT) in Spain.

The findings are published in two papers in The Astronomical Journal.

PLANETS IN GALAXIES BEYOND MILKY WAY SPOTTED FOR FIRST TIME

The find is the latest in a host of new planet discoveries. In February 2017, an international team of astronomers announced the discovery of 60 new planets orbiting stars close to Earth’s Solar System, including a rocky “super Earth.”

In the same month, NASA revealed the discovery of seven Earth-like planets orbiting the star TRAPPIST-1 40 light years from Earth. Three of the planets are in the “habitable zone” where liquid water can exist, according to scientists.

Two months later, in a separate research project, scientists reported that an exoplanet 40 light-years from Earth may be the best place to look for signs of life outside our solar system.

Earlier this year, for the first time, scientists announced the discovery of planets in galaxies beyond the Milky Way.

Using data from NASA’s Chandra X-ray observatory, a team of astrophysicists from the University of Oklahoma identified the extragalactic planets about 3.8 billion light years away. The space observatory helped scientists find about 2,000 objects with comparable mass to the Moon and Jupiter. </s> Scientists have announced the first planet found to be orbiting a brown dwarf. It’s a significant discovery and a fascinating window into the evolution of a type of substellar object we don’t know much about.

A brown dwarf — sometimes referred to as a failed star — is an object of near-Jupiter size, but substantially greater mass. Unlike a normal star, it is not massive enough to fuse hydrogen and does not emit much visible light. Brown dwarfs can fuse deuterium and lithium, but never reached the size required to sustain hydrogen fusion in their cores.

As you might imagine, there are questions regarding when a super-planet (a planet of greater than Jupiter mass) gathers enough material to qualify as a brown dwarf. Because they aren’t particularly luminous, they aren’t all that easy to spot. The researchers in question note: “Our galaxy could also be teeming with brown dwarfs, which cannot sustain hydrogen fusion and thus are very faint.”

Now, here’s the catch: We’ve actually found very large planets orbiting brown dwarfs before. As the researchers note, however:

[The] large mass ratios (q & 0.1) between the host and the companion would suggest that they are formed as binary systems either by the dynamical interaction in unstable molecular clouds (Bate 2009, 2012) or by the turbulent fragmentation of molecular cloud cores (Padoan & Nordlund 2004). This implies that the companions could be considered as substellar objects rather than planets (Chabrier et al. 2014). By contrast, the low mass ratio of this event (q ∼ 0.016), combined with recent reports of the massive disks (& MJ) around young brown dwarfs (Hervey et al. 2012; Andr´e et al. 2012; Palau et al. 2014), suggest that the planetary companion of the event may be formed by planet formation mechanisms.

In other words: In the past, we’ve found planets that appear to have formed around brown dwarfs very differently than how we believe our sun and solar system were created. This planet appears to have been formed in the more normal fashion, suggesting that brown dwarf systems may be able to host planets (or at least a planet) as well.

The chances of such planets hosting life, however, are pretty slim. Brown dwarfs are not thought to be capable of emitting significant amounts of heat, since they contain relatively low amounts of fusable material in the first place. Old brown dwarfs are cool enough to have an atmosphere, though it isn’t one you want to breathe (it can rain iron in the atmosphere of a brown dwarf). Still, a brown dwarf with a planet around it is a surprising find and could tell us more about how planets form, even around exceptionally low-mass, not-quite-stars. </s> When the majority of stars reach the end of their life, they make their own funeral pyre, throwing off most of their remaining gas in a glorious last display of their immense power and leaving behind a dense, cinderlike core known as a white dwarf. But what becomes of any planets orbiting such a star? This question has been difficult to answer, but now scientists say they have detected the suspected remnant of a white dwarf world, a first-of-its-kind discovery that could offer fascinating insights into planetary systems’ dying days across the universe.

In a paper published Friday in Science, a team led by Christopher Manser of the University of Warwick in England reports unprecedented observations of a white dwarf slightly larger than Earth but containing almost the mass of the sun. Called SDSS J1228+1040, the star is located about 410 light-years away, and it is more specifically known as a “polluted” white dwarf, owing to the heavy elements astronomers can detect raining down onto its surface. That material is believed to originate from a disk of gas that surrounds the object. And within that disk, the paper’s authors say, they have found a planet’s ghostly remains.

“It’s like the iron core left behind by a larger body that’s been ripped apart,” Manser says. “The crust and mantle have come off this body. We’re left with this iron core orbiting around that has a high internal strength holding it together, not just gravity.”

The white dwarf’s three-million-kilometer-wide debris disk was first discovered more than 15 years ago, making the star one of fewer than a dozen polluted white dwarfs known to be surrounded by disks. When a star of less than about eight solar masses exhausts its hydrogen fuel, it expels its outer layers, engulfing any close-in planets in the process. Some of these worlds, it is thought, might then be ripped apart, after which their shredded remains gather into such a disk. And although more than 4,000 exoplanets have been discovered to date, scientists have only once before seen smoking-gun evidence of this process: the remains of a planet in a disk around the white dwarf WD 1145+017, which was closely studied in 2015.

Whereas those planetary remnants orbit around WD 1145+017 in 4.5 hours, the heavy-metal core circling SDSS J1228+1040 completes a revolution in less than half of that time. The new study’s authors detected the star’s dense companion using the 10.4-meter Gran Telescopio Canarias (GTC) on the Canary Islands in two separating observing periods in April 2017 and in April and May 2018, respectively. By splitting up the white dwarf’s emitted light into its constituent wavelengths — much as a prism splits white light into a rainbow — the team detected the disk and recorded shifts in its color that corresponded to its orbital motion.

Generally, this method is used to observe systems such as SDSS J1228 over long periods of years, but by studying this white dwarf over the course of several hours, the team discerned a clump of material within the disk that exhibited a shift that was entirely its own. The shift’s strength suggested its source was a solid object some 600 kilometers across — a suspected planetary core, with a density between 7.7 and 39 grams per cubic meter, comparable to the pure iron found within Earth’s core. “The density of the piece of rock is consistent with what we think the cores of planets [are],” says Luca Fossati of the Austrian Academy of Sciences, who was not involved in the paper. “That’s a big thing. It essentially confirms the idea we have that these disks of dust and debris that orbit around some of the white dwarfs are [the remains of] ancient planets.”

The shift also indicated that the clump orbits at just a half-million kilometers from the star — an extremely close distance at which larger, less dense objects would be stretched and torn apart by the white dwarf’s intense gravitational field. This messy disassembly, which, at its most extreme, is dubbed “spaghettification” by astrophysicists, is the typical fate of anything falling into a black hole. But around the white dwarf, where gravity is not as extreme, a small, dense heavy-metal planetary core could survive. “If you have a small enough object, it’s easier to resist spaghettification,” says Andrew Vanderburg of the Harvard-Smithsonian Center for Astrophysics, who was also not involved in the paper. “What [the researchers] found here is that this planet is orbiting so close to its star that it must be held together by material strength.”

With a specific orbital period of 123 minutes, this core would set a new record for the fastest planetary object orbiting a star; the previous record was the exoplanet KOI 1843.03, which completes an orbit in 4.25 hours. The bizarre system also provides a one-of-a-kind scientific opportunity to scrutinize the exposed core of an exoplanet, even though astronomers presently lack any sufficiently large telescope to directly see the core.

Perhaps, however, similar objects await discovery around other white dwarfs. Whether studying them singly or in multitudes, such heavy-metal worlds may offer grim previews of our own solar system’s future, when our sun’s fuel runs out some five billion years hence. “It’s really exciting, because this is sort of the missing piece, if you like, [of white dwarf planetary systems],” says Sarah Casewell of the University of Leicester in England, who was not involved in the research. “We know big things can survive, and we know tiny things get destroyed. This is quite a sizable rocky object that has survived.”

This article is reproduced with permission from Scientific American. You can view the original story here. </s> Scientists have discovered 15 new planets – including one ‘super-Earth’ that could harbour liquid water – orbiting small, cool stars near our solar system. The stars, known as red dwarfs, are of interest for studies of planetary formation and evolution, said the team led by Teruyuki Hirano from the Tokyo Institute of Technology.

“Red dwarf systems, especially coolest red dwarfs, are just beginning to be investigated, so they are very exciting targets for future exoplanet research,” Hirano said. One of the brightest red dwarfs – K2-155 that is around 200 light years away from Earth – has three transiting ‘super-Earths’, which are slightly bigger than our own planet.

Of those three ‘super-Earths’, the outermost planet, K2-155d, with a radius 1.6 times that of Earth, could be within the host star’s habitable zone, the researchers noted in the study appeared in The Astronomical Journal. The team found that K2-155d could potentially have liquid water on its surface based on three-dimensional global climate simulations. To reach this conclusion, the team sifted through data from NASA Kepler spacecraft’s second mission, K2, and follow-up observations using ground-based telescopes, including the Subaru Telescope in Hawaii and the Nordic Optical Telescope (NOT) in Spain.

A more precise estimate of the radius and temperature of the K2-155 star would be needed to conclude definitively whether K2-155d is habitable. Achieving such precision would require further studies, for example, using interferometric techniques, the researchers said. The researchers also investigated the relationship between planet radius and metallicity of the host star.

“Large planets are only discovered around metal-rich stars and what we found was consistent with our predictions. The few planets with a radius about three times that of Earth were found orbiting the most metal-rich red dwarfs,” Hirano noted. With the planned launch of NASA’s Transiting Exoplanet Survey Satellite (TESS) in April this year, Hirano is hopeful that even more planets will be discovered. “TESS is expected to find many candidate planets around bright stars closer to Earth,” he said.

For all the latest Technology News, download Indian Express App </s> Dwarf Star –“Hosts First Nearby Super-Earth that Could Harbor Life”

“This is exciting, as this is humanity’s first nearby super-Earth that could harbor life – uncovered with help from TESS, our small, mighty mission with a huge reach.” said Lisa Kaltenegger, director of Cornell’s Carl Sagan Institute.

NASA’s Transiting Exoplanet Survey Satellite (TESS), a mission designed to comb the heavens for exoplanets, has discovered its first potentially habitable world outside of our own solar system – and an international team of astronomers has characterized the super-Earth, about 31 light-years away.

In a new paper in the The Astrophysical Journal Letters, a team led by Kaltenegger, associate professor of astronomy, models the conditions under which the planet — discovered in early 2019 — could sustain life.

As this super-Earth exoplanet is more massive than our own blue planet, Kaltenegger said this discovery will provide insight into Earth’s heavyweight planetary cousins. “With a thick atmosphere, the planet GJ 357 d could maintain liquid water on its surface like Earth and we could pick out signs of life with upcoming telescopes soon to be online,” she said.

Astronomers from the Institute of Astrophysics of the Canary Islands and the University of La Laguna, both of Spain, announced the discovery of the system July 31 in the journal Astronomy & Astrophysics. They showed that the distant solar system – with a diminutive M-type dwarf sun, about one-third the size of our own sun – harbors three planets, with one of those in that system’s habitable zone: GJ 357 d.

Last February, the TESS satellite observed that the dwarf sun GJ 357 dimmed very slightly every 3.9 days, evidence of a transiting planet moving across the star’s face. That planet was GJ 357 b, a so-called “hot Earth” about 22 percent larger than Earth, according to the NASA Goddard Space Flight Center, which guides TESS.

Follow up observations from the ground led to the discovery of two more exoplanetary siblings: GJ 357 c and GJ 357 d. The international team of scientists collected Earth-based telescopic data going back two decades – to reveal the newly found exoplanets’ tiny gravitational tugs on its host star, according to NASA.

Exoplanet GJ 357 c sizzles at 260 degrees Fahrenheit, and has at least 3.4 times Earth’s mass. However, the system’s outermost known sibling planet – GJ 357 d, a super-Earth – could provide conditions just like on Earth and orbits the dwarf star every 55.7 days at a distance about 20 percent of Earth’s distance from the Sun. It is not yet known if this planet transits its sun.

Kaltenegger, doctoral candidate Jack Madden and undergraduate student Zifan Lin simulated light fingerprints, climates and remotely detectable spectra for the planet, which could range from a rocky composition to a water world.

Madden explained that investigating new discoveries provides an opportunity to test theories and models. “We built the first models of what this new world could be like,” he said. “Just knowing that liquid water can exist on the surface of this planet motivates scientists to find ways of detecting signs of life.”
ArXiv publishes research that a gas giant may be orbiting a brown dwarf. The exoplanet, designated OGLE-2017-BLG-1522Lb, orbits its host at a distance of 0.59 AU and could be the first known gas giant to have formed inside the protoplanetary disk of a brown dwarf.