Extrasolar Planets Archives

June 20, 2017 by Matt Williams

NASA Announces 10, That’s Right 10! New Planets in Their Star’s Habitable Zone

Artist's impression of rocky exoplanets orbiting Gliese 832, a red dwarf star just 16 light-years from Earth. Credit: ESO/M. Kornmesser/N. Risinger (skysurvey.org).

The Kepler space telescope is surely the gift that keeps on giving. After being deployed in 2009, it went on to detect a total of 2,335 confirmed exoplanets and 582 multi-planet systems. Even after two of its reaction wheels failed, it carried on with its K2 mission, which has discovered an additional 520 candidates, 148 of which have been confirmed. And with yet another extension, which will last beyond 2018, it shows no signs of stopping!

In the most recent catalog to be released by the Kepler mission, an additional 219 new planet candidates have been added to its database. More significantly, 10 of these planets were found to be terrestrial (i.e. rocky), of comparable in size to Earth and orbited within their star’s habitable zone – the distance where surface temperatures would be warm enough to support liquid water.

These findings were presented at a news conference on Monday, June 19th, at NASA’s Ames Research Center. Of all the catalogs of Kepler candidates that have been released to date, this one is the most comprehensive and detailed. The eighth in a series of Kepler exoplanet catalogs, this one is based on data that was obtained from the first four years of the mission and is the final catalog that covers the spacecraft’s observations of the Cygnus constellation.

Since 2014, Kepler has ceased looking at a set starfield in the Cygnus constellation and has been collecting data on its second mission – observing fields on the plane of the ecliptic of the Milky Way Galaxy. With the release of this catalog, there are now 4,034 planet candidates that have been identified by Kepler – of which 2,335 have been verified.

An important aspect of this catalog were the methods that were used for producing it, which were the most sophisticated to date. As with all planets detected by Kepler, the latest finds were all made using the transit method. This consists of monitoring stars for occasional dips in brightness, which is used to confirm the presence of planets transiting between the star and the observer.

To ensure that the detections in this latest catalog were real, the team relied on two approaches to eliminate false positives. This consisted of introducing simulated transits into the dataset to make sure the dips that Kepler detected were consistent with planets. Then, they added false signals to see how often the analysis mistook these for planet transits. From this, they were able to tell which planets were overcounted and which were undercounted.

This led to another exciting find, which was the indication that for all of the smaller exoplanets discovered by Kepler, most fell within one of two distinct groupings. Essentially, half the planets that we know of in the galaxy are either rocky in nature and larger than Earth (i.e. Super-Earth’s), or are gas giants that are comparable in size to Neptune (i.e. smaller gas giants).

This conclusion was reached by a team of researchers who used the W.M. Keck Observatory to measure the sizes of 1,300 stars in the Kepler field of view. From this, they were able to determine the radii of 2,000 Kepler planets with extreme precision, and found that there was a clear division between rocky, Earth-sized planets and gaseous planets smaller than Neptune – with few in between.

As Benjamin Fulton, a doctoral candidate at the University of Hawaii in Manoa and the lead author of this study, explained:

“We like to think of this study as classifying planets in the same way that biologists identify new species of animals. Finding two distinct groups of exoplanets is like discovering mammals and lizards make up distinct branches of a family tree.”

These results are sure to have drastic implications when it comes to knowing the frequency of different types of planets in our galaxy, as well as the study of planet formation. For instance, they noted that most rocky planets discovered by Kepler are up to 75% larger than Earth. And for reasons that are not yet clear, about half of them take on hydrogen and helium, which swells their size to the point that they become almost Neptune-sized.

*Histogram shows the number of planets per 100 stars as a function of planet size relative to Earth. Credits: NASA/Ames Research Center/CalTech/University of Hawaii/B.J. Fulton*

These findings could similarly have significant implications in the search for habitable planets and extra-terrestrial life. As Mario Perez, Kepler program scientist in the Astrophysics Division of NASA’s Science Mission Directorate, said during the presentation:

“The Kepler data set is unique, as it is the only one containing a population of these near Earth-analogs – planets with roughly the same size and orbit as Earth. Understanding their frequency in the galaxy will help inform the design of future NASA missions to directly image another Earth.”

From this information, scientists will be able to know with a greater degree of certainty just how many “Earth-like” planets exist within our galaxy. The most recent estimates place the number of planets in the Milky Way at about 100 billion. And based on this data, it would seem that many of these are similar in composition to Earth, albeit larger.

Combined with a statistical models of how many of these can be found within a circumstellar habitable zone, we should have a better idea of just how many potentially-life-bearing worlds are out there. If nothing else, this should simplify some of the math in the Drake Equation!

In the meantime, the Kepler space telescope will continue to make observations of nearby star systems in order to learn more about their exoplanets. This includes the TRAPPIST-1 system and its seven Earth-sized, rocky planets. Its a safe bet that before it is finally retired after 2018, it will have some more surprises in store for us!

Further Reading: NASA, NASA Kepler and K2

June 7, 2017June 7, 2017 by Matt Williams

Even Calm Red Dwarf Stars Blast Their Planets with Mini-Flares, Destroying their Habitability

Artist's impression of a flaring red dwarf star, orbited by an exoplanet. Credit: NASA, ESA, and G. Bacon (STScI)

Thanks to some rather profound discoveries, red dwarf stars (aka. M-type stars) have been a popular target for exoplanet hunters lately. While small, cool, and relatively dim compared to our Sun, red dwarf star systems are where many of the most recent and promising exoplanet finds have been made. These include Proxima b, the seven rocky planets orbiting TRAPPIST-1, and the super-Earth discovered around LHS 1140b.

Unfortunately, red dwarf stars pose a bit of a problem when it comes to habitability. In addition to being variable in terms of the light they put out, they also known for being unstable. According to a new study by a team of scientists – which was presented the this week at the annual meeting of the American Astronomical Society – red dwarfs also experience mini-flares that could have a cumulative effect, thus rendering their orbiting planets uninhabitable.

For the sake of their study, titled “gPhoton: The GALEX Photon Data Archive“, the team relied on the ten years of ultraviolet observations made by the Galaxy Evolution Explorer (GALEX) spacecraft. During its mission, which ran from 2003 to 2013, GALEX monitored stars to detect rapid increases in brightness – i.e. signs of solar flare activity. These flares emit radiation across many wavelengths, but a significant amount is released in the UV band.

*Artist’s impression of the GALEX mission, which monitors ultraviolet throughout the Universe. Credit: NASA/JPL-Caltech*

Though not originally intended for exoplanet hunting, GALEX’s data proved very useful since red dwarfs are usually relatively dim in the ultraviolet band (a trait which makes flares particularly noticeable). Using this data, the team was able to measure events that were less intense than many previously detected flares. This was important, since red dwarf flares are known to be greater in frequency, but weaker in intensity.

It was also important from a habitability standpoint, since it is possible that frequent flaring could add up over time to create an inhospitable environment on orbiting planets. If planets like Proxima b are subject to radiation from smaller (but more frequent) flares, could there be a cumulative effect that could ultimately prevent life from emerging over time?

Such is the question that the team sought to address. To do this, they sorted through the ten years of GALEX data, which is held at the Mikulski Archive for Space Telescopes (MAST) at the Space Telescope Science Institute (STScI). Led by Chase Million of Million Concepts at State College in Pennsylvania, their efforts led to the creation of gPhoton – a 130 terabyte database with millisecond-timing resolution.

This database was then examined with custom software developed by Million and Clara Brasseur of the STScI, which enabled them to analyze the UV data at the photon level. As Million indicated, the results were quite interesting. “We have found dwarf star flares in the whole range that we expected GALEX to be sensitive to,” he said, “from itty bitty baby flares that last a few seconds, to monster flares that make a star hundreds of times brighter for a few minutes.”

While many of the flares that GALEX noticed were similar in strength to those generated by our Sun, the dynamics of red dwarf star systems are quite different. Since they are cooler and less bright, rocky planets need to orbit closer to red dwarfs in order to be warm enough to maintain liquid water on their surfaces (i.e. be habitable). This proximity means that they would be subject to more of the energy produced by these flares.

Such flares would be capable of stripping away a planet’s atmosphere, and could also prevent life from arising on the surface. And over time, smaller flares could poison an environment, making it impossible for organic life to thrive. At present, team members Brasseur and Rachel Osten (also from the STScI) are examining other stars observed by GALEX and also Kepler to look for similar flares.

The team expects to find examples of hundreds of thousands of these flares, which could help shed additional light on just what effect they could have on planetary habitability in red dwarf star systems. But for the time being, the case for red dwarf habitability appears to have been weakened. And once again, it has to do with the instability and radiation produced by these cool customers.

In the future, next-generation missions like the James Webb Space Telescope (which is scheduled to launch in 2018) are expected to reveal vital information on the atmospheres of nearby exoplanets. Most of these reside in red dwarf star systems, where questions about their composition and ability to support life are waiting to be resolved. In addition, the mission can also expected to shed light on these planet’s ability to retain atmospheres.

*Artist’s impression of the view from the most distant exoplanet discovered around the red dwarf star TRAPPIST-1. Credit: ESO/M. Kornmesser.*

On the plus side, this study has shown that archival data from missions that are no longer in operation can still be incredibly useful. As Don Neill, a research scientist at Caltech and a member of the GALEX collaboration, explained:

“These results show the value of a survey mission like GALEX, which was instigated to study the evolution of galaxies across cosmic time and is now having an impact on the study of nearby habitable planets. We did not anticipate that GALEX would be used for exoplanets when the mission was designed.”

These results were presented in a press conference at the American Astronomical Society, which will be taking place from June 4th to June 8th in Austin, Texas.

Further Reading: HubbleSite, The Astrophysical Journal

May 30, 2017May 31, 2017 by Matt Williams

Super-Earth Planet Found in the Habitable Zone of a Nearby Star

Artistic design of the super-Earth GJ 625 b and its star, GJ625 (Gliese 625). Credit: Gabriel Pérez/SMM (IAC)

M-type stars, also known as “red dwarfs”, have become a popular target for exoplanet hunters of late. This is understandable given the sheer number of terrestrial (i.e. rocky) planets that have been discovered orbiting around red dwarf stars in recent years. These discoveries include the closest exoplanet to our Solar System (Proxima b) and the seven planets discovered around TRAPPIST-1, three of which orbit within the star’s habitable zone.

The latest find comes from a team of international astronomers who discovered a planet around GJ 625, a red dwarf star located just 21 light years away from Earth. This terrestrial planet is roughly 2.82 times the mass of Earth (aka. a “super-Earth”) and orbits within the star’s habitable zone. Once again, news of this discovery is prompting questions about whether or not this world could indeed be habitable (and also inhabited).

The international team was led by Alejandro Mascareño of the Canary Islands Institute of Astrophysics (IAC), and includes members from the University of La Laguna and the University of Geneva. Their research was also supported by the Spanish National Research Council (CSIS), the Institute of Space Studies of Catalonia (IEEC), and the National Institute For Astrophysics (INAF).

*Diagram showing GJ 625’s habitable zone in comparison’s to the Sun’s. Credit: IAC*

The study which details their findings was recently accepted for publication by the journal Astronomy & Astrophysics, and appears online under the title “A super-Earth on the Inner Edge of the Habitable Zone of the Nearby M-dwarf GJ 625“. According to the study, the team used radial-velocity measurements of GJ 625 in order to determine the presence of a planet that has between two and three times the mass of Earth.

This discovery was part of the HArps-n red Dwarf Exoplanet Survey (HADES), which studies red dwarf stars to determine the presence of potentially habitable planets orbiting them. This survey relies on the High Accuracy Radial velocity Planet Searcher for the Northern hemisphere (HARPS-N) instrument – which is part of the 3.6-meter Galileo National Telescope (TNG) at the IAC’s Roque de Los Muchachos Observatory on the island of La Palma.

Using this instrument, the team collected high-resolution spectroscopic data of the GJ 625 system over the course of three years. Specifically, they measured small variations in the stars radial velocity, which are attributed to the gravitational pull of a planet. From a total of 151 spectra obtained, they were able to determine that the planet (GJ 625 b) was likely terrestrial and had a minimum mass of 2.82 ± 0.51 Earth masses.

Moreover, they obtained distance estimates that placed it roughly 0.078 AU from its star, and an orbital period estimate of 14.628 ± 0.013 days. At this distance, the planet’s orbit places it just within GJ 625’s habitable zone. Of course, this does not mean conclusively that the planet has conditions conducive to life on its surface, but it is an encouraging indication.

*Tjhe Observatorio del Roque de los Muchachos, located on the island of La Palma. Credit: IAC*

As Alejandro Suárez Mascareño explained in an IAC press release:

“As GJ 625 is a relatively cool star the planet is situated at the edge of its habitability zone, in which liquid water can exist on its surface. In fact, depending on the cloud cover of its atmosphere and on its rotation, it could potentially be habitable”.

This is not the first time that the HADES project detected an exoplanet around a red dwarf star. In fact, back in 2016, a team of international researchers used this project to discover 2 super-Earths orbiting GJ 3998, a red dwarf located about 58 ± 2.28 light years from Earth. Beyond HADES, this discovery is yet another in a long line of rocky exoplanets that have been discovered in the habitable zone of a nearby red dwarf star.

Such findings are very encouraging since red dwarfs are the most common type of star in the known Universe- accounting for an estimated 70% of stars in our galaxy alone. Combined with the fact that they can exist for up to 10 trillion years, red dwarf systems are considered a prime candidate in the search for habitable exoplanets.

But as with all other planets discovered around red dwarf stars, there are unresolved questions about how the star’s variability and stability could affect the planet. For starters, red dwarf stars are known to vary in brightness and periodically release gigantic flares. In addition, any planet close enough to be within the star’s habitable zone would likely be tidally-locked with it, meaning that one side would be exposed to a considerable amount of radiation.

As such, additional observations will need to be made of this exoplanet candidate using the time-tested transit method. According to Jonay Hernández – a professor from the University of La Laguna, a researcher with the IAC and one of the co-authors on the study – future studies using this method will not only be able to confirm the planet’s existence and characterize it, but also determine if there are any other planets in the system.

“In the future, new observing campaigns of photometric observations will be essential to try to detect the transit of this planet across its star, given its proximity to the Sun,” he said. “There is a possibility that there are more rocky planets around GJ 625 in orbits which are nearer to, or further away from the star, and within the habitability zone, which we will keep on combing”.

According to Rafael Rebolo – one of the study’s co-authors from the Univeristy of La Laguna, a research with the IAC, and a member of the CSIS – future surveys using the transit method will also allow astronomers to determine with a fair degree of certainty whether or not GJ 625 b has the all-important ingredient for habitability – i.e. an atmosphere:

“The detection of a transit will allow us to determine its radius and its density, and will allow us to characterize its atmosphere by the transmitted light observe using high resolution high stability spectrographs on the GTC or on telescopes of the next generation in the northern hemisphere, such as the Thirty Meter Telescope (TMT)”.

*Artist’s impression of a system of exoplanets orbiting a low mass, red dwarf star. Credit: NASA/JPL*

But what is perhaps most exciting about this latest find is how it adds to the population of extra-solar planets within our cosmic neighborhood. Given their proximity, each of these planets represent a major opportunity for research. And as Dr. Mascareño told Universe Today via email:

“While we have already found more than 3600 extra-solar planets, the exoplanet population in our near neighborhood is still somewhat unknown. At 21 ly from the Sun, GJ 625 is one of the 100 nearest stars, and right now GJ 625 b is one of the 30 nearest exoplanets detected and the 6th nearest potentially habitable exoplanet.”

Once again, ongoing surveys of nearby star systems is providing plenty of potential targets in the search for life beyond our Solar System. And with both ground-based and space-based next-generation telescopes joining the search, we can expect to find many, many more candidates in the coming years. In the meantime, be sure to check out this animation of GJ 625 b and its parent star:

Further Reading: arXiv, IAC

May 26, 2017May 26, 2017 by Ken Kremer

Trump Proposes $19.1 Billion 2018 NASA Budget, Cuts Earth Science and Education

NASA acting administrator Robert Lightfoot outlines NASA’s Fiscal Year 2018 budget proposal during a ‘State of NASA’ speech to agency employees held at NASA HQ on May 23, 2017. Credit: NASA TV/Ken Kremer

The Trump Administration has proposed a $19.1 Billion NASA budget request for Fiscal Year 2018, which amounts to a $0.5 Billion reduction compared to the recently enacted FY 2017 NASA Budget. Although it maintains many programs such as human spaceflight, planetary science and the Webb telescope, the budget also specifies significant cuts and terminations to NASA’s Earth Science and manned Asteroid redirect mission as well as the complete elimination of the Education Office.

Overall NASA’s FY 2018 budget is cut approximately 3%, or $560 million, for the upcoming fiscal year starting in October 2017 as part of the Trump Administration’s US Federal Budget proposal rolled out on May 23, and quite similar to the initial outline released in March.

The cuts to NASA are smaller compared to other Federal science agencies also absolutely vital to the health of US scientific research – such as the NIH, the NSF, the EPA, DOE and NIST which suffer unconscionable double digit slashes of 10 to 20% or more.

The highlights of NASA’s FY 2018 Budget were announced by NASA acting administrator Robert Lightfoot during a ‘State of NASA’ speech to agency employees held at NASA HQ, Washington, D.C. and broadcast to the public live on NASA TV.

Lightfoot’s message to NASA and space enthusiasts was upbeat overall.

“What this budget tells us to do is to keep going!” NASA acting administrator Robert Lightfoot said.

“Keep doing what we’ve been doing. It’s very important for us to maintain that course and move forward as an agency with all the great things we’re doing.”

“I want to reiterate how proud I am of all of you for your hard work – which is making a real difference around the world. NASA is leading the world in space exploration, and that is only possible through all of your efforts, every day.”

“We’re pleased by our top line number of $19.1 billion, which reflects the President’s confidence in our direction and the importance of everything we’ve been achieving.”

Lightfoot recalled the recent White House phone call from President Trump to NASA astronaut & ISS Station Commander Peggy Whitson marking her record breaking flight for the longest cumulative time in space by an American astronaut.

Thus Lightfoot’s vision for NASA has three great purposes – Discover, Explore, and Develop.

“NASA has a historic and enduring purpose. It can be summarized in three major strategic thrusts: Discover, Explore, and Develop. These correspond to our missions of scientific discovery, missions of exploration, and missions of new technology development in aeronautics and space systems.”

Lightfoot further recounted the outstanding scientific accomplishments of NASA’s Mars rover and orbiters paving the path for the agencies plans to send humans on a ‘Journey to Mars’ in the 2030s.

“We’ve had a horizon goal for some time now of reaching Mars, and this budget sustains that work and also provides the resources to keep exploring our solar system and look beyond it.”

Lightfoot also pointed to upcoming near term science missions- highlighting a pair of Mars landers – InSIGHT launching next year as well as the Mars 2020 rover. Also NASA’s next great astronomical observatory – the James Webb Space Telescope (JWST).

“In science, this budget supports approximately 100 missions: 40 missions currently preparing for launch & 60 operating missions.”

“The James Webb Space Telescope is built!” Lightfoot gleefully announced.

“It’s done testing at Goddard and now has moved to Johnson for tests to simulate the vacuum of space.”

JWST is the scientific successor to the Hubble Space Telescope and slated for launch in Oct. 2018. The budget maintains steady support for Webb.

The 18-segment gold coated primary mirror of NASA’s James Webb Space Telescope is raised into vertical alignment in the largest clean room at the agency’s Goddard Space Flight Center in Greenbelt, Maryland, on Nov. 2, 2016. The secondary mirror mount booms are folded down into stowed for launch configuration. Credit: Ken Kremer/kenkremer.com

The Planetary Sciences division receives excellent support with a $1.9 Billion budget request. It includes solid support for the two flagship missions – Mars 2020 and Europa Clipper as well as the two new Discovery class missions selected -Lucy and Psyche.

“The budget keeps us on track for the next selection for the New Frontiers program, and includes formulation of a mission to Jupiter’s moon Europa.”

“SLS and Orion are making great progress. They are far beyond concepts, and as I mentioned, components are being tested in multiple ways right now as we move toward the first flight of that integrated system.”

NASA is currently targeting the first integrated launch of SLS and Orion on the uncrewed Exploration Mission-1 (EM-1) for sometime in 2019.

Top NASA managers recently decided against adding a crew of two astronauts to the flight after conducting detailed agency wide studies at the request of the Trump Administration.

NASA would have needed an additional $600 to $900 to upgrade EM-1 with humans.

Unfortunately Trump’s FY 2018 NASA budget calls for a slight reduction in development funding for both SLS and Orion – thus making a crewed EM-1 flight fiscally unviable.

The newly assembled first liquid hydrogen tank, also called the qualification test article, for NASA’s new Space Launch System (SLS) heavy lift rocket lies horizontally beside the Vertical Assembly Center robotic weld machine (blue) on July 22, 2016. It was lifted out of the welder (top) after final welding was just completed at NASA’s Michoud Assembly Facility in New Orleans. Credit: Ken Kremer/kenkremer.com

The budget request does maintain full funding for both of NASA’s commercial crew vehicles planned to restore launching astronauts to low Earth orbit (LEO) and the ISS from US soil on US rockets – namely the crewed Dragon and CST-100 Starliner – currently under development by SpaceX and Boeing – thus ending our sole reliance on Russian Soyuz for manned launches.

“Working with commercial partners, NASA will fly astronauts from American soil on the first new crew transportation systems in a generation in the next couple of years.”

“We need commercial partners to succeed in low-Earth orbit, and we also need the SLS and Orion to take us deeper into space than ever before.”

Orion crew module pressure vessel for NASA’s Exploration Mission-1 (EM-1) is unveiled for the first time on Feb. 3, 2016 after arrival at the agency’s Kennedy Space Center (KSC) in Florida. It is secured for processing in a test stand called the birdcage in the high bay inside the Neil Armstrong Operations and Checkout (O&C) Building at KSC. Launch to the Moon is slated in 2018 atop the SLS rocket. Credit: Ken Kremer/kenkremer.com

However the Trump Administration has terminated NASA’s somewhat controversial plans for the Asteroid Redirect Mission (ARM) – initiated under the Obama Administration – to robotically retrieve a near Earth asteroid and redirect it to lunar orbit for a visit by a crewed Orion to gather unique asteroidal samples.

“While we are ending formulation of a mission to an asteroid, known as the Asteroid Redirect Mission, many of the central technologies in development for that mission will continue, as they constitute vital capabilities needed for future human deep space missions.”

Key among those vital capabilities to be retained and funded going forward is Solar Electric Propulsion (SEP).

“Solar electric propulsion (SEP) for our deep space missions is moving ahead as a key lynchpin.”

The Trump Administration’s well known dislike for Earth science and disdain of climate change has manifested itself in the form of the termination of 5 current and upcoming science missions.

NASA’s FY 2018 Earth Science budget suffers a $171 million cut to $1.8 Billion.

“While we are not proposing to move forward with Orbiting Carbon Observatory-3 (OCO-3), Plankton, Aerosol, Cloud, ocean Ecosystem (PACE), Climate Absolute Radiance and Refractivity Observatory Pathfinder (CLARREO PF), and the Radiation Budget Instrument (RBI), this budget still includes significant Earth Science efforts, including 18 Earth observing missions in space as well as airborne missions.”

The DSCOVR Earth-viewing instruments will also be shut down.

NASA’s Office of Education will also be terminated completely under the proposed FY 2018 budget and the $115 million of funding excised.

“While this budget no longer supports the formal Office of Education, NASA will continue to inspire the next generation through its missions and the many ways that our work excites and encourages discovery by learners and educators. Let me tell you, we are as committed to inspiring the next generation as ever.”

Congress will now have its say and a number of Senators, including Republicans says Trumps budget is DOA.

Stay tuned here for Ken’s continuing Earth and Planetary science and human spaceflight news.

Ken Kremer

May 23, 2017June 20, 2020 by Matt Williams

We Have More Details on the Outermost Trappist-1 Planet!

An artist’s conception shows the planet TRAPPIST-1h. (NASA / JPL-Caltech)

The announcement of a seven-planet system around the star TRAPPIST-1 earlier this year set off a flurry of scientific interest. Not only was this one of the largest batches of planets to be discovered around a single star, the fact that all seven were shown to be terrestrial (rocky) in nature was highly encouraging. Even more encouraging was the fact that three of these planets were found to be orbiting with the star’s habitable zone.

Since that time, astronomers have been seeking to learn all they can about this system of planets. Aside from whether or not they have atmospheres, astronomers are also looking to learn more about their orbits and surface conditions. Thanks to the efforts of a University of Washington-led international team of astronomers, we now have an accurate idea of what conditions might be like on its outermost planet – TRAPPIST-1h.

Continue reading “We Have More Details on the Outermost Trappist-1 Planet!”

May 23, 2017June 20, 2020 by Matt Williams

Here’s How We Can Detect Plants on Extrasolar Planets

Artist’s impression of the surface of the planet Proxima b orbiting the red dwarf star Proxima Centauri. The double star Alpha Centauri AB is visible to the upper right of Proxima itself. Credit: ESO

The past year has been an exciting time for those engaged in the hunt for extra-solar planets and potentially habitable worlds. In August of 2016, researchers from the European Southern Observatory (ESO) confirmed the existence of the closest exoplanet to Earth (Proxima b) yet discovered. This was followed a few months later (February of 2017) with the announcement of a seven-planet system around TRAPPIST-1.

The discovery of these and other extra-solar planets (and their potential to host life) was an overarching theme at this year’s Breakthrough Discuss conference. Taking place between April 20th and 21st, the conference was hosted by Stanford University’s Department of Physics and sponsored by the Harvard-Smithsonian Center for Astrophysics and Breakthrough Initiatives.

Continue reading “Here’s How We Can Detect Plants on Extrasolar Planets”

May 6, 2017May 7, 2017 by Matt Williams

Only 10 Light-Years Away, there’s a Baby Version of the Solar System

Artist's impression of the Epsilon Eridani system, showing Epsilon Eridani b (a Jupiter-mass planet) and a series of asteroid belts and comets. Credit: NASA/SOFIA/Lynette Cook.

Astronomers are understandanly fascinated with the Epsilon Eridani system. For one, this star system is in close proximity to our own, at a distance of about 10.5 light years from the Solar System. Second, it has been known for some time that it contains two asteroid belts and a large debris disk. And third, astronomers have suspected for many years that this star may also have a system of planets.

On top of all that, a new study by a team of astronomers has indicated that Epsilon Eridani may be what our own Solar System was like during its younger days. Relying on NASA’s Stratospheric Observatory for Infrared Astronomy (SOFIA) aircraft, the team conducted a detailed analysis of the system that showed how it has an architecture remarkably similar to what astronomer believe the Solar System once looked like.

Led by Kate Su – an Associate Astronomer with the Steward Observatory at the University of Arizona – the team includes researchers and astronomers from the Department of Physics & Astronomy of Iowa State University, the Astrophysical Institute and University Observatory at the University of Jena (Germany), and NASA’s Jet Propulsion Laboratory and Ames Research Center.

Artist’s diagram showing the similar structure of the Epsilon Eridani to the Solar System. Credit: NASA/JPL-Caltech

For the sake of their study – the results of which were published in The Astronomical Journal under the title “The Inner 25 AU Debris Distribution in the Epsilon Eri System” – the team relied on data obtained by a flight of SOFIA in January 2015. Combined with detailed computer modeling and research that went on for years, they were able to make new determinations about the structure of the debris disk.

As already noted, previous studies of Epsilon Eridani indicated that the system is surrounded by rings made up of materials that are basically leftovers from the process of planetary formation. Such rings consist of gas and dust, and are believed to contain many small rocky and icy bodies as well – like the Solar System’s own Kuiper Belt, which orbits our Sun beyond Neptune.

Careful measurements of the disk’s motion has also indicated that a planet with nearly the same mass as Jupiter circles the star at a distance comparable to Jupiter’s distance from the Sun. However, based on prior data obtained by the NASA’s Spitzer Space Telescope, scientists were unable to determine the position of warm material within the disk – i.e. the dust and gas – which gave rise to two models.

In one, warm material is concentrated into two narrow rings of debris that orbit the star at distances corresponding respectively to the Main Asteroid Belt and Uranus in our Solar System. According to this model, the largest planet in the system would likely be associated with an adjacent debris belt. In the other, warm material is in a broad disk, is not concentrated into asteroid belt-like rings, and is not associated with any planets in the inner region.

*NASA’s SOFIA aircraft before a 2015 flight to observe a nearby star. Credit: Massimo Marengo.*

Using the new SOFIA images, Su and her team were able to determine that the warm material around Epsilon Eridani is arranged like the first model suggests. In essence, it is in at least one narrow belt, rather than in a broad continuous disk. As Su explained in a NASA press release:

“The high spatial resolution of SOFIA combined with the unique wavelength coverage and impressive dynamic range of the FORCAST camera allowed us to resolve the warm emission around eps Eri, confirming the model that located the warm material near the Jovian planet’s orbit. Furthermore, a planetary mass object is needed to stop the sheet of dust from the outer zone, similar to Neptune’s role in our solar system. It really is impressive how eps Eri, a much younger version of our solar system, is put together like ours.”

These observations were made possible thanks to SOFIA’s on-board telescopes, which have a greater diameter than Spitzer – 2.5 meters (100 inches) compared to Spitzer’s 0.85 m (33.5 inches). This allowed for far greater resolution, which the team used to discern details within the Epsilon Eridani system that were three times smaller than what had been observed using the Spitzer data.

In addition, the team made use of SOFIA’s powerful mid-infrared camera – the Faint Object infraRed CAmera for the SOFIA Telescope (FORCAST). This instrument allowed the team to study the strongest infrared emissions coming from the warm material around the star which are otherwise undetectable by ground-based observatories – at wavelengths between 25-40 microns.

*This artist’s conception of the Epsilon Eridani system, the closest star system who’s structure resembles a young Solar System. Credit: NASA/JPL/Caltech*

These observations further indicate that the Epsilon Eridani system is much like our own, albeit in younger form. In addition to having asteroid belts and a debris disk that is similar to our Main Belt and Kuiper Belt, it appears that it likely has more planets waiting to be found within the spaces between. As such, the study of this system could help astronomers to learn things about the history of our own Solar System.

Massimo Marengo, one of he co-authors of the study, is an Associate Professor with the Department of Physics & Astronomy at Iowa State University. As he explained in a University of Iowa press release:

“This star hosts a planetary system currently undergoing the same cataclysmic processes that happened to the solar system in its youth, at the time in which the moon gained most of its craters, Earth acquired the water in its oceans, and the conditions favorable for life on our planet were set.”

At the moment, more studies will need to be conducted on this neighboring stars system in order to learn more about its structure and confirm the existence of more planets. And it is expected that the deployment of next-generation instruments – like the James Webb Space Telescope, scheduled for launch in October of 2018 – will be extremely helpful in that regard.

“The prize at the end of this road is to understand the true structure of Epsilon Eridani’s out-of-this-world disk, and its interactions with the cohort of planets likely inhabiting its system,” Marengo wrote in a newsletter about the project. “SOFIA, by its unique ability of capturing infrared light in the dry stratospheric sky, is the closest we have to a time machine, revealing a glimpse of Earth’s ancient past by observing the present of a nearby young sun.”

Further Reading: NASA, IAState, The Astronomical Journal

April 21, 2017April 28, 2017 by Evan Gough

Are Drylanders The Minority On Habitable Worlds?

Artist's depiction of a waterworld. A new study suggests that Earth is in a minority when it comes to planets, and that most habitable planets may be greater than 90% ocean. Credit: David A. Aguilar (CfA)

If we want to send spacecraft to exoplanets to search for life, we better get good at building submarines.

A new study by Dr. Fergus Simpson, of the Institute of Cosmos Sciences at the University of Barcelona, shows that our assumptions about exo-planets may be wrong. We kind of assume that exoplanets will have land masses, even though we don’t know that. Dr. Simpson’s study suggests that we can expect lots of oceans on the habitable worlds that we might discover. In fact, ocean coverage of 90% may be the norm.

At the heart of this study is something called ‘Bayesian Statistics’, or ‘Bayesian Probability.’

Normally, we give something a probability of occurring—in this case a habitable world with land masses—based on our data. And we’re more confident in our prediction if we have more data. So if we find 10 exoplanets, and 7 of them have significant land masses, we think there’s a 70% chance that future exoplanets will have significant land masses. If we find 100 exoplanets, and 70 of them have significant land masses, then we’re even more confident in our 70% prediction.

Is Earth in the range of normal when it comes to habitable planets? Or is it an outlier, with both large land masses, and large oceans? Image: Reto Stöckli, Nazmi El Saleous, and Marit Jentoft-Nilsen, NASA GSFC

But the problem is, even though we’ve discovered lots of exoplanets, we don’t know if they have land masses or not. We kind of assume they will, even though the masses of those planets is lower than we expect. This is where the Bayesian methods used in this study come in. They replace evidence with logic, sort of.

In Bayesian logic, probability is assigned to something based on the state of our knowledge and on reasonable expectations. In this case, is it reasonable to expect that habitable exoplanets will have significant landmasses in the same way that Earth does? Based on our current knowledge, it isn’t a reasonable expectation.

According to Dr. Simpson, the anthropic principle comes into play here. We just assume that Earth is some kind of standard for habitable worlds. But, as the study shows, that may not be the case.

“Based on the Earth’s ocean coverage of 71%, we find substantial evidence supporting the hypothesis that anthropic selection effects are at work.” – Dr. Fergus Simpson.

In fact, Earth may be a very finely balanced planet, where the amount of water is just right for there to be significant land masses. The size of the oceanic basins is in tune with the amount of water that Earth retains over time, which produces the continents that rise above the seas. Is there any reason to assume that other worlds will be as finely balanced?

Dr. Simpson says no, there isn’t. “A scenario in which the Earth holds less water than most other habitable planets would be consistent with results from simulations, and could help explain why some planets have been found to be a bit less dense than we expected.” says Simpson.

Simpson’s statistical model shows that oceans dominate other habitable worlds, with most of them being 90% water by surface area. In fact, Earth is very close to being a water world. The video shows what would happen to Earth’s continents if the amount of water increased. There is only a very narrow window in which Earth can have both large land masses, and large oceans.

Dr. Simpson suggests that the fine balance between land and water on Earth’s surface could be one reason we evolved here. This is based partly on his model, which shows that land masses will have larger deserts the smaller the oceans are. And deserts are not the most hospitable place for life, and neither are they biodiverse. Also, biodiversity on land is about 25 times greater than biodiversity in oceans, at least on Earth.

Simpson says that the fine balance between land mass and ocean coverage on Earth could be an important reason why we are here, and not somewhere else.

“Our understanding of the development of life may be far from complete, but it is not so dire that we must adhere to the conventional approximation that all habitable planets have an equal chance of hosting intelligent life,” Simpson concludes.

April 20, 2017April 21, 2017 by Matt Williams

Is This The Exoplanet Where Life Will First Be Found?

Using data obtained by Kepler and numerous observatories around the world, an international team has found a Super-Earth that orbits its orange dwarf star in just 14 hours. Credit: M. Weiss/CfA

It is good time to be an exoplanet hunter… or just an exoplanet enthusiast for that matter! Every few weeks, it seems, new discoveries are being announced which present more exciting opportunities for scientific research. But even more exciting is the fact that every new find increases the likelihood of locating a potentially habitable planet (and hence, life) outside of our Solar System.

And with the discovery of LHS 1140b – a super-Earth located approximately 39 light years from Earth – exoplanet hunters think they have found the most likely candidate for habitability to date. Not only does this terrestrial (i.e. rocky) planet orbit within its sun’s habitable zone, but examinations of the planet (using the transit method) have revealed that it appears to have a viable atmosphere.

Credit for the discovery goes to a team of international scientists who used the MEarth-South telescope array – a robotic observatory located on Cerro Tololo in Chile – to spot the planet. This project monitors the brightness of thousands of red dwarf stars with the goal of detecting transiting planets. After consulting data obtained by the array, the team noted characteristic dips in the star’s brightness that indicated that a planet was passing in front of it.

*The MEarth-South telescope array, located on Cerro Tololo in Chile, searches for planets by monitoring the brightness of nearby, small stars. Credit: Jonathan Irwin*

These findings were then followed up using the High Accuracy Radial velocity Planet Searcher (HARPS) instrument at the ESO’s La Silla Observatory, located on the outskirts of Chile’s Atacama Desert. According to the their study – which appeared in the April 20th, 2017, issue of the journal Nature – the team was able to make estimates of the planet’s age, size, mass, distance from its star, and orbital period.

They estimate that the planet is at least five billion years old – about 500 million years older than Earth. It is also slightly larger than Earth – 1.4 times Earth’s diameter – and is considerably more massive, weighing in at a hefty 6.6 Earth masses. Since they were able to view the planet almost edge-on, the team was also able to determine that it orbits its sun at a distance of about 0.1 AU (one-tenth the distance between Earth and the Sun) with a period of 25 days.

However, since its star is a red dwarf, this proximity places it in the middle of the system’s habitable zone. But what was most exciting was the fact that the team was able to look for evidence of an atmosphere since the planet was passing in front of its star – something that has not been possible with many exoplanets. Because of this, they were able to conduct transmission spectroscopy measurements that revealed the presence of an atmosphere.

As Jason Dittmann – of the Harvard-Smithsonian Center for Astrophysics (CfA) and the lead author of the study – said in a CfA press release:

“This is the most exciting exoplanet I’ve seen in the past decade. We could hardly hope for a better target to perform one of the biggest quests in science — searching for evidence of life beyond Earth.”

*This artist’s impression shows the exoplanet LHS 1140b, which orbits a red dwarf star 40 light-years from Earth. Credit: ESO/spaceengine.org*

Granted, this exoplanet is not as close as Proxima b, which orbits Proxima Centauri – just 4.243 light years away. And it certainly isn’t as robust a find as the TRAPPIST-1 system, with its seven rocky planets, three of which are located within its habitable zone. But compared to these candidates, the researchers were able to place solid constraints on the planet’s mass and density, not to mention the fact that they were able to observe an atmosphere.

The discovery of an exoplanet that orbits a red dwarf star and has an atmosphere is also encouraging in a wider context. Low-mass red dwarf stars are the most common star in the galaxy, accounting for 75% of stars in our cosmic neighborhood alone. They are also long-lived (up to 10 trillion years), and recent research indicates that they are capable of hosting large numbers of planets.

But given their variability and unstable nature, astronomers have expressed doubts as to whether or not planet orbiting them could retain their atmospheres for very long. Knowing that a terrestrial planet that orbits a red dwarf, is five billion years old, and still has an atmosphere is therefore a very good sign. But of course, simply knowing there is an atmosphere doesn’t mean that it is conducive to life as we know it.

“Right now we’re just making educated guesses about the content of this planet’s atmosphere,” said Dittman. “Future observations might enable us to detect the atmosphere of a potentially habitable planet for the first time. We plan to search for water, and ultimately molecular oxygen.”

This chart shows the location of the faint red star LHS 1140 in the faint constellation of Cetus (The Sea Monster). This star is orbited by a super-Earth exoplanet called LHS 1140b, which may be best place to look for signs of life beyond the Solar System. The star is too faint to be seen in a small telescope.

Hence, additional studies will be needed before this planet can claim the title of “best place to look for signs of life beyond the Solar System”. To that end, future space-based missions like the James Webb Space Telescope (which will launch in 2018), and ground-based instruments like the Giant Magellan Telescope and the ESO’s Extremely Large Telescope, will be especially well-suited!

In the meantime, the NASA/ESA Hubble Space Telescope will be conducting observations of the star system in the near future. These observations, it is hoped, will indicate exactly how much high-energy radiation LHS 1140b receives from its sun. This too will go a long way towards determining just how habitable the Super-Earth is.

And be sure to enjoy this video of the LHS 1140 star system, courtesy of the European Southern Observatory and spaceengine.org:

Further Reading: ESO, CfA

April 7, 2017April 28, 2017 by Matt Williams

Finally! A Low Mass Super-Earth With Some Funky Atmosphere

Artist's impression of the exoplanet GJ 1132 b, which orbits the red dwarf star GJ 1132. Astronomers have managed to detect the atmosphere of this Earth-like planet. Credit: MPIA

In 2015, astronomers discovered an intriguing extrasolar planet located in a star system some 39 light years from Earth. Despite orbiting very close to its parent star, this “Venus-like” planet – known as GJ 1138b – appeared to still be cool enough to have an atmosphere. In short order, a debate ensued as to what kind of atmosphere it might have, whether it was a “dry Venus” or a “wet Venus”.

And now, thanks to the efforts of an international team of researchers, the existence of an atmosphere has been confirmed around GJ 1138b. In addition to settling the debate about the nature of this planet, it also marks the first time that an atmosphere has been detected around a low-mass Super-Earth. On top of that, GJ 1138b is now the farthest Earth-like planet that is known to have an atmosphere.

Led by John Southworth (of Keele University) and Luigi Mancini (of the University of Rome Tor Vergata), the research team included members from the Max Planck Institute for Astronomy (MPIA), the National Institute for Astrophysics (INAF), the University of Cambridge and Stockholm University. Their study, titled “Detection of the atmosphere of the 1.6 Earth mass exoplanet GJ 1132b“, recently appeared in The Astrophysical Journal.

*Artist’s impression of the “Venus-like” exoplanet GJ 1132b. Credit: cfa.harvard.edu*

Using the GROND imager on the La Silla Observatory’s 2.2m ESO/MPG telescope, the team monitored GJ 1132b in different wavelengths as it transited in front of its parent star. Given the planet’s orbital period (1.6 days), these transits happen quite often, which presented plenty of opportunities to view it pass in front of its star. In so doing, they monitored the star for slight decreases in its brightness.

As Dr. Southworth explained to Universe via email, these observations confirmed the existence of an atmosphere:

“What we did was to measure the amount of dimming at 7 different wavelengths in optical and near-infrared light. At one of these wavelengths (IR) the planet seemed to be slightly bigger. This indicated that the planet has a large atmosphere around it which allows most of the starlight to pass through, but is opaque at one wavelength.”

The team members from the University of Cambridge and the MPIA then conducted simulations to see what this atmosphere’s composition could be. Ultimately, they concluded that it most likely has a thick atmosphere that is rich in water and/or methane – which contradicted recent theories that the planet had a thin and tenuous atmosphere (i.e. a “dry Venus”).

*The ESO’s Paranal Observatory, located in the Atacama Desert of Chile. Credit: ESO*

It was also the first time that an atmosphere has been confirmed around a planet that is not significantly greater in size and mass to Earth. In the past, astronomers have detected atmospheres around many other exoplanets. But in these cases, the planets were either gas giants or planets that were many times Earth’s size and mass (aka. “Super-Earths”). GJ 1132b, however, is 1.6 times as massive as Earth, and measures 1.4 Earth radii.

In addition, these findings are a significant step in the search for life beyond our Solar System. At present, astronomers seek to determine the chemical composition of a planet’s atmosphere to determine if it could be habitable. Where the right combination of chemical imbalances exist, the presence of living organisms is seen as a possible cause.

By being able to determine that a planet at lower end of the super-Earth scale has an atmosphere, we are one step closer to being able to determine exoplanet habitability. The detection of an atmosphere-bearing planet around an M-type (red dwarf) star is also good news in and of itself. Low-mass red dwarf stars are the most common star in the galaxy, and recent findings have indicated that they might be our best shot for finding habitable worlds.

Besides detecting several terrestrial planets around red dwarf stars in recent years – including seven around a single star (TRAPPIST-1) – there is also research that suggests that these stars are capable of hosting large numbers of planets. At the same time, there have been concerns about whether red dwarfs are too variable and unstable to support habitable worlds.

*Artist’s impression of Kepler-1649b, the “Venus-like” world orbiting an M-class star 219 light-years from Earth. Credit: Danielle Futselaar*

As Southworth explained, spotting an atmosphere around a planet that closely orbits a red dwarf could help bolster the case for red dwarf habitability:

“One of the big issues has been that very-low-mass stars typically have strong magnetic fields and thus throw out a lot of X-ray and ultraviolet light. These high-energy photons tend to destroy molecules in atmospheres, and might also evaporate them completely. The fact that we have detected an atmosphere around GJ 1132b means that this kind of planet is indeed capable of retaining an atmosphere for billions of years, even whilst being bombarded by the high-energy photons from their host stars.

In the future, GJ 1132b is expected to be a high-priority target for study with the Hubble Space Telescope, the Very Large Telescope (VLT) at the Paranal Observatory in Chile, and next-generation telescopes like the James Webb Space Telescope (scheduled for launch in 2018). Already, observations are being made, and the results are being eagerly anticipated.

I’m sure I’m not the only one who would like to hear what astronomers discover as they set their sights on this nearby star system and it’s Venus-like world! In the meantime, be sure to check out this video about GJ 1132b, courtesy of MIT news:

Further Reading: Max Planck Institute for Astronomy