Kepler Archives

March 22, 2016April 12, 2016 by Evan Gough

Kepler Catches Early Flash Of An Exploding Star

“Life exists because of supernovae,” said Steve Howell, project scientist for NASA’s Kepler and K2 missions at NASA’s Ames Research Center. “All heavy elements in the universe come from supernova explosions. For example, all the silver, nickel, and copper in the earth and even in our bodies came from the explosive death throes of stars.”

So a glimpse of a supernova explosion is of intense interest to astronomers. It’s a chance to study the creation and dispersal of the life-enabling elements themselves. A greater understanding of supernovae will lead to a greater understanding of the origins of life.

Stars are balancing acts. They are a struggle between the pressure to expand, created by the fusion in the star, and the gravitational urge to collapse, caused by their own enormous mass. When the core of a star runs out of fuel, the star collapses in on itself. Then there is a massive explosion, which we call a supernova. And only very large stars can become supernovae.

The brilliant flashes that accompany supernovae are called shock breakouts. These events last only about 20 minutes, an infinitesimal amount of time for an object that can shine for billions of years. But when Kepler captured two of these events in 2011, it was more than just luck.

Peter Garnavich is an astrophysics professor at the University of Notre Dame. He led an international team that analyzed the light from 500 galaxies, captured every 30 minutes over a period of 3 years by Kepler. They searched about 50 trillion stars, trying to catch one as it died as a supernova. Only a fraction of stars are large enough to explode as supernovae, so the team had their work cut out for them.

“In order to see something that happens on timescales of minutes, like a shock breakout, you want to have a camera continuously monitoring the sky,” said Garnavich. “You don’t know when a supernova is going to go off, and Kepler’s vigilance allowed us to be a witness as the explosion began.”

An artist's concept of a shock breakout. Image: NASA Ames/STScl/G. Bacon — An artist’s concept of a shock breakout. Image: NASA Ames/STScl/G. Bacon

In 2011 Kepler caught two gigantic stars as they died their supernova death. Called KSN 2011a, and KSN 2011d, the two red super-giants were 300 times and 500 times the size of our Sun respectively. 2011a was 700 million light years from Earth, and 2011d was 1.2 billion light years away.

The intriguing part of the two supernovae is the difference between them; one had a visible shock breakout and one did not. This was puzzling, since in other respects, both supernovae behaved much like theory predicted they would. The team thinks that the smaller of the two, KSN 2011a, may have been surrounded by enough gas to mask the shock breakout.

The Kepler spacecraft is well-known for searching for and discovering extrasolar planets. But when some components on board Kepler failed in 2013, the mission was re-cast as the K2 Mission. “While Kepler cracked the door open on observing the development of these spectacular events, K2 will push it wide open, observing dozens more supernovae,” said Tom Barclay, senior research scientist and director of the Kepler and K2 guest observer office at Ames. “These results are a tantalizing preamble to what’s to come from K2!”

(For a brilliant and detailed look at the life-cycle of stars, I recommend “The Life and Death of Stars” by Kenneth R. Lang.)

February 10, 2016March 18, 2016 by Evan Gough

Largest Rocky World Found

An illustration of a large, rocky planet similar to the recently discovered BD+20594b. Image: JPL-Caltech/NASA

We thought we understood how big rocky planets can get. But most of our understanding of planetary formation and solar system development has come from direct observation of our own Solar System. We simply couldn’t see any others, and we had no way of knowing how typical—or how strange—our own Solar System might be.

But thanks to the Kepler Spacecraft, and it’s ability to observe and collect data from other, distant, solar systems, we’ve found a rocky planet that’s bigger than we thought one could be. The planet, called BD+20594b, is half the diameter of Neptune, and composed entirely of rock.

The planet, whose existence was reported on January 28 at arXiv.org by astrophysicist Nestor Espinoza and his colleagues at the Pontifical Catholic University of Chile in Santiago, is over 500 light years away, in the constellation Aries.

BD+20594b is about 16 times as massive as Earth and half the diameter of Neptune. Its density is about 8 grams per cubic centimeter. It was first discovered in 2015 as it passed in between Kepler and its host star. Like a lot of discoveries, a little luck was involved. BD+20594b’s host star is exceptionally bright, which allowed more detailed observations than most exoplanets.

The discovery of BD+20594b is important for a couple of reasons: First, it shows us that there’s more going on in planetary formation than we thought. There’s more variety in planetary composition than we could’ve known from looking at our own Solar System. Second, comparing BD+20594b to other similar planets, like Kepler 10c—a previous candidate for largest rocky planet—gives astrophysicists an excellent laboratory for testing out our planet formation theories.

It also highlights the continuing importance of the Kepler mission, which started off just confirming the existence of exoplanets, and showing us how common they are. But with discoveries like this, Kepler is flexing its muscle, and starting to show us how our understanding of planetary formation is not as complete as we may have thought.

January 11, 2016February 4, 2016 by Matt Williams

What Is The Geocentric Model Of The Universe?

The Geocentric View of the Solar System — An illustration of the Ptolemaic geocentric system by Portuguese cosmographer and cartographer Bartolomeu Velho, 1568 (Bibliothèque Nationale, Paris)

During the many thousand years that human beings have been looking up at the stars, our concept of what the Universe looks like has changed dramatically. At one time, the magi and sages of the world believed that the Universe consisted of a flat Earth (or a square one, a zigarrut, etc.) surrounded by the Sun, the Moon, and the stars. Over time, ancient astronomers became aware that some stars did not move like the rest, and began to understand that these too were planets.

In time, we also began to understand that the Earth was indeed round, and came up with rationalized explanations for the behavior of other celestial bodies. And by classical antiquity, scientists had formulated ideas on how the motion of the planets occurred, and how all the heavenly orbs fit together. This gave rise to the Geocentric model of the universe, a now-defunct model that explained how the Sun, Moon, and firmament circled around our planet.

Continue reading “What Is The Geocentric Model Of The Universe?”

November 25, 2015December 23, 2015 by Bob King

Do Comets Explain Mystery Star’s Bizarre Behavior?

A new study indicates that in about a million years, a star will pass close to our Solar System, sending comets towards Earth and the other planets. Credit: NASA/JPL-Caltech

The story of KIC 8462852 appears far from over. You’ll recall NASA’s Kepler mission had monitored the star for four years, observing two unusual incidents, in 2011 and 2013, when its light dimmed in dramatic, never-before-seen ways. Models to explain its erratic behavior were so lacking that some considered the possibility that alien megastructures built to capture sunlight around the host star (think Dyson Spheres) might be the cause.

But a search using the SETI Institute’s Allen Telescope Array for two weeks in October detected no significant radio signals or other signs of intelligent life emanating from the star’s vicinity. Something had passed in front of the star and blocked its light, but what?

The Spitzer Space Telescope observatory trails behind Earth as it orbits the Sun. Credit: NASA/JPL-Caltech

Shattered comets and asteroids were also suggested as possible explanations — dust and ground-up rock would be at the right temperature to glow in the infrared — but Kepler could only observe in visible light where any debris would be invisible or swamped by the light of the star. So researchers looked through older observations made in 2010 by the Wide Field Infrared Survey Explorer (WISE) space telescope. Unfortunately, WISE observed the star before the strange variations were seen and therefore before any putative dust-busting collisions.

Not to be stymied, astronomers next checked out the data from NASA’s Spitzer Space Telescope, which like WISE, is optimized for infrared light. Spitzer just happened to observe KIC 8462852 much more recently in 2015.

“Spitzer has observed all of the hundreds of thousands of stars where Kepler hunted for planets, in the hope of finding infrared emission from circumstellar dust,” said Michael Werner, the Spitzer project scientist and the lead investigator of that particular Spitzer/Kepler observing program.

Comet Siding Spring (C/2007 Q3) as imaged in the infrared by the WISE space telescope. The images was taken January 10, 2010 when the comet was 2.5AU from the Sun. Credit: NASA/JPL-Caltech/UCLA — Comet Siding Spring (C/2007 Q3) imaged in the infrared by the WISE space telescope in January 2010. Credit: NASA/JPL-Caltech/UCLA

I’d love to report that Spitzer tracked down glowing dust but no, it also came up empty-handed. This makes the idea of an asteroidal smash-up very unlikely, but not one involving comets according to Massimo Marengo of Iowa State University (Ames) who led the new study. Marengo proposes that cold comets are responsible. Picture a family of comets traveling on a very long, eccentric orbit around the star with a very large comet at the head of the pack responsible for the big fading seen by Kepler in 2011. Later, in 2013, the rest of the comet family, a band of various-sized fragments lagging behind, would have passed in front of the star and again blocked its light. By 2015, the comets would have moved even farther away on their long orbital journey, leaving no detectable infrared excess.

“This is a very strange star,” said Marengo. “It reminds me of when we first discovered pulsars. They were emitting odd signals nobody had ever seen before, and the first one discovered was named LGM-1 after ‘Little Green Men.'”

Clearly, more long-term observations are needed. And frankly, I’m still puzzled why cold or less active comets might still not be detected by their glowing dust. But let’s assume for a moment the the comet idea is correct. If so, we should expect to see similar dips in KIC 8462852’s light as the comet swarm swings around again.

October 21, 2015December 23, 2015 by Bob King

SETI Institute Undertakes Search for Alien Signal from Kepler Star KIC 8462852

One of the 42 dishes in the Allen Telescope Array that searches for signals from space. Credit: Seth Shostak / SETI Institute.

“We either caught something shortly after an event like two planets crashing together or alien intelligence,” said Dr. Gerald Harp, senior scientist at the SETI Institute in Mountain View, California, referring to the baffling light variations seen by the Kepler Observatory in the star KIC 8462852 .

And he and a team from the Institute are working hard at this moment to determine which of the two it is.

Gerald Harp of the SETI Institute is involved in gathering and studying data from the mysterious KIC Credit: SETI Institute — Gerald Harp of the SETI Institute is involved in gathering and studying data from the mysterious Kepler star. Credit: SETI Institute

Beginning last Friday (Oct. 16), the Institute’s Allen Telescope Array (ATA) was taken off its normal survey schedule and instead focused on KIC 8462852, one of the 150,000-plus stars studied by NASA’s Kepler Mission to detect Earth-sized exoplanets orbiting distant stars.. The array of 42 dishes comprises a fully automated system that can run day and night, alerting staff whenever an unusual or interesting signal has been detected.

A swarm of comets has been proposed to explain the erratic and non-repeating light variations seen in the star located nearly 1,500 light years from Earth in the constellation Cygnus the Swan. But no one really seems satisfied with the explanation, and the chances that we’d catch a huge event like a comet breakup or planetary collision in the short time the star has been under observation seems unlikely. Collisions also generate dust. Warmed by the star, that dust would glow in infrared light, but none beyond what’s expected has been detected.

The Allen Telescope Array (ATA) is a “Large Number of Small Dishes” (LNSD) array designed to be highly effective for simultaneous surveys undertaken for SETI projects (Search for Extraterrestrial Intelligence) at centimeter wavelengths. Credit: Seth Shostak / SETI Institute

The ATA picks up radio frequencies in the microwave range from 1-10 gigahertz. For comparison, your kitchen microwave oven produces microwaves at around 2 gigahertz. Although Harp couldn’t reveal the team’s results yet — that will come soon when a paper is submitted in few weeks in a science journal — he did share the excitement of a the hunt in a phone interview Tuesday.

The array normally looks for a very narrow wave or specific frequency when hunting for potential “ET” signals. But not this time.

“This is a special target,” said Harp. “We’re using the scope to look at transmissions that would produce excess power over a range of wavelengths.” Perhaps from a potential alien power source? Maybe. Harp believes the star’s peculiar, a-periodic light variations seen by Kepler are “probably natural and definitely worth looking at” but considers an intelligent source a possibility, however remote.

This artist concept illustrates how two large, planet-sized objects could collide to create clumps of material in orbit around a star. The only problem is that they'd also create a lot of dust, which would glow in infrared light, something not seen around the Kepler star. Credit: NASA/JPL-Caltech/T. Pyle (SSC) — This artist concept illustrates how two large, planet-sized objects could collide to create clumps of material in orbit around a star. They’d also create a lot of dust, which would glow in infrared light, something *not* seen around the Kepler star. Credit: NASA/JPL-Caltech/T. Pyle (SSC)

During our conversation, he emphasized how special the light variations from the star were, adding how the “big gob” of material orbiting KIC (stands for Kepler Input Catalog) 8462852 is unusual in that it’s “clumped”. “We expect it to spread into a ring,” he said.

AAVSO chart of KIC 8462852. Click to go to the website to make your own customized version. Credit: AAVSO — AAVSO chart of KIC 8462852. Click to enlarge or go to the **website** to make your own customized version. Credit: AAVSO

Meanwhile, the American Association of Variable Star Observers (AAVSO) published an Alert Notice this week requesting amateurs and professional astronomers around the world to immediately begin observing KIC 8462852 now through the end of the current observing season. To locate the star, you can either use the charts provided in our previous story or go to the AAVSO site and type in KIC 8462852 in the “Pick a Star” box to create a chart of your own.

I’m a variable star observer, so naturally I thought of variables with irregular fluctuations in light when I first heard about this stellar mystery. Time to talk to an expert. According to Elizabeth Waagen, senior technical assistant for science operations at the AAVSO, KIC 8462852 is different.

“Based on the information so far, it doesn’t seem to fit the criteria for an irregular variable,” said Waagen in a phone interview this morning. “It’s doesn’t add up.”

She encouraged an open mind. “It’s a big puzzle, so we sent out the notice,” referring to the alert described above.

All quite exciting, and I’m as eager as you to see the published results on the signals, which Harp said would appear or link from the SETI website soon. Stay tuned …

June 18, 2015February 27, 2017 by Fraser Cain

When Will We Find Another Earth?

We hear about discoveries of exoplanets every day. So how long will it take us to find another planet like Earth?

Back in the olden days, astronomers could only guess if there were planets orbiting other stars.

These were the days when we had to wait at the bank to pay our bills, nobody carried computers in their pockets and those computers gave direct connections to everyone else’s pockets because pocket connectivity is highly important, school was uphill both ways, the number 6 was brand new, we recorded images on thin sheets of transparent plastic, 5 bees were worth a quarter and I had an onion tied to my belt, as was the style at the time.

With the discovery of a mega Jupiter-sized world orbiting the star 51 Pegasi in 1995, the floodgates opened up. In the years that followed, dozens more planets were discovered. Then hundreds, and now, we know about thousands orbiting other stars.

The bad news is we can’t get to any of them. The good news is most of these worlds suck. You don’t want any part of them. For starters their wifi is terrible.

Consider Kepler-70b. This world orbits its star 4 times in a 24 hour period. This means it’s super close, and a great place to really quickly win all the human torch cosplay competitions. The surface temperature is a completely unreasonable 7200 Kelvin, hotter than the surface temperature of the Sun.

There’s the planets orbiting pulsar PSR B1257+12, a millisecond pulsar in the constellation of Virgo. As they whip around their exotic host, they’re bathed in intense radiation. Which is generally considered bad for creatures who need functioning organs.

Perhaps HD 106906 b, orbiting its star 650 times more distantly than we orbit the Sun. You’d spend every second of your short life on that planet inventing new words for cold. And then you’d die. Cold.

Imagine a world that orbits a star like our Sun. A world made of about an Earth’s worth of rocky material that you could stand on, at just the right distance from its star that water can exist as a liquid.

This is what astronomers search for, the tri-wizard cup of extrasolar planetary research. Earth 2? Terra Nova? The Gaia part le deux.

Here’s the exciting part. Astronomers have found each of these characteristics in a planet, but never all together. They’ve found plenty of stars similar to our Sun, with planets orbiting them. In fact, the star HD 10180 is incredibly similar to the Sun, and astronomers have discovered 9 planets orbiting it so far. Which does have a familiar ring to it. No word so far on which ones are about to be demoted to dwarf planets.

Sizes and temperatures of Kepler discoveries compared to Earth and Jupiter

They’ve found planets roughly the same mass as the Earth. Kepler-89, with 98% the mass of the Earth. So close! Sadly, it’s way too close to its parent hydrogen furnace to be habitable.

They’ve found planets in the habitable zone. Here on Earth, the global average temperature is -18 degrees C. Sounds cold, but the wintery nights in Antarctica absolutely wreck our GPA.

The closest analog discovered is Kepler-22b, with a global average temperature of -11C. So, it should feel downright balmy. Except, it’s about 2.4 times bigger than Earth and orbits a nasty red dwarf star.

Astronomers have even matched up two criteria at the same time. Earth-sized world orbiting around a Sun-like star, but it’s hellishly hot. Wrong flavor star but with the right temperature and size, it’s a veritable tic tac toe board of near wins.

So far, there hasn’t been a single extrasolar planet discovered that meets all three criteria. An Earth-sized world, orbiting a Sun-like star inside the habitable zone where liquid water could be present.

Astronomers were hoping that NASA’s Kepler spacecraft would have been the first to discover Earth 2.0. It had already turned up thousands of planets, including many of the ones I’ve already mentioned.

Artist's conception of the Kepler Space Telescope. Credit: NASA/JPL-Caltech — Artist’s conception of the Kepler Space Telescope. Credit: NASA/JPL-Caltech

Sadly, just a few years into the mission, it lost too many reaction wheels, which allow the spacecraft to change direction. It wasn’t able to make enough observations to help confirm a true Earth 2.0. Kepler is still searching for planets, but with a reduced ability to point, it’s only looking at red dwarf stars.

Don’t worry, NASA’s Transiting Exoplanet Survey Satellite will launch in 2017, and will survey a region of the sky 400 times larger than Kepler did. It should turn up thousands of planets, Earth-sized and larger.

Once we actually find New Terra, things get really interesting. Astronomers will search those planets for life. I know it sounds almost impossible to see life from this distance, but astronomers know that if they can analyze the atmosphere of these worlds, they can detect life flourishing there.

They might even be able to detect the pollution from their alien cars and heavy industry, contributing to their CO2 levels, and learn we’re not so different after all. Even if they’re icky bug people.

At the time I’m recording this video, no analog Earth planet has been discovered so far. But it’s just a matter of time. In the next few decades astronomers are going to find that first Earth 2.0, and then dozens, then hundreds, and even figure out which ones have life on them.

It’s a great time to be alive. Place your bets. Predict the date astronomers announce that we’ll find Earth 2.0. Put your guess into the comments below.

February 16, 2015March 11, 2016 by Nancy Atkinson

Everything About Kepler-432b is Extreme, Especially the Way it’s Going to Die

Illustration of the orbit of Kepler-432b (inner, red) in comparison to the orbit of Mercury around the Sun (outer, orange). Credit: Dr. Sabine Reffert.

Astronomers are calling Kepler-432b a ‘maverick’ planet because everything about this newly found exoplanet is an extreme, and is unlike anything we’ve found before. This is a giant, dense planet orbiting a red giant star, and the planet has enormous temperature swings throughout its year. In addition to all these extremes, there’s another reason you wouldn’t want to live on Kepler 432b: its days are numbered.

“In less than 200 million years, Kepler-432b will be swallowed by its continually expanding host star,” said Mauricio Ortiz, a PhD student at Heidelberg University who led one of the two studies of the planet. “This might be the reason why we do not find other planets like Kepler-432b – astronomically speaking, their lives are extremely short.”

Kepler-432b is one of the densest and massive planets ever found. The planet has six times the mass of Jupiter, but is about the same size. The shape and the size of its orbit are also unusual, as the orbit is very small (52 Earth days) and highly elongated. The elliptical orbit brings Kepler-432b both incredibly close and very far away from its host star.

“During the winter season, the temperature on Kepler-432b is roughly 500 degrees Celsius,” said Dr. Sabine Reffert from the Königstuhl observatory, which is part of the Centre for Astronomy. “In the short summer season, it can increase to nearly 1,000 degrees Celsius.”

Dr. Davide Gandolfi, also from the Königstuhl observatory, said that the star Kepler-432b is orbiting has already exhausted the nuclear fuel in its core and is gradually expanding. Its radius is already four times that of our Sun and it will get even larger in the future.

While Kepler-432b was previously identified as a transiting planet candidate by the NASA Kepler satellite mission, two research groups of Heidelberg astronomers independently made further observations of this rare planet, acquiring the high-precision measurements needed to determine the planet’s mass. Both groups of researchers used the 2.2-metre telescope at Calar Alto Observatory in Andalucía, Spain to collect data. The group from the state observatory also observed Kepler-432b with the Nordic Optical Telescope on La Palma (Canary Islands).

The results of this research were published in Astronomy & Astrophysics.

Source: University of Heidelberg

February 11, 2015December 23, 2015 by Nancy Atkinson

250 Years of Planetary Detection in 60 Seconds

An animated history of planetary detection, from 1750 to 2015. It shows the period (x-axis), mass (y-axis), radius (circle size) and detection method (color) of the 1800 plus planets now known. Credit and copyright: Hugh Osborn.

Early astronomers realized some of the “stars” in the sky were planets in our Solar System, and really, only then did we realize Earth is a planet too. Now, we’re finding planets around other stars, and thanks to the Kepler Space Telescope, we’re able to find planets that are even smaller than Earth.

This great new graphic of the history of planetary detection was put together by Hugh Osborn, a PhD student at the University of Warwick, who works with data from the WASP (Wide Angle Search for Planets) and NGTS (Next Generation Transit Survey) telescope surveys to discover exoplanets. It starts with the first real “discovery’ of a planet — Uranus in 1781 by William and Caroline Herschel.

“The idea of this plot is to compare our own Solar System (with planets plotted in dark blue) against the newly-discovered extrasolar worlds,” wrote Osborn on his website. “Think of this plot as a projection of all 1873 worlds onto our own solar system, with the Sun (and all other stars) at the far left. As you move out to the right, the orbital period of the planets increases, and correspondingly (thanks to Kepler’s Third Law), so does the distance from the star. Moving upwards means the mass of the worlds increase, from Moon-sized at the base to 10,000 times that of Earth at the top (30 Jupiter Masses).”

You’ll notice a few “clusters” as time moves along. The circles in dark blue are the planets in our Solar System; light blue are planets found by radial velocity. Then in maroon are planets found by direct imaging, followed by orange for microlensing and green for transits.

The first batch of exoplanets were the massive ‘Hot Jupiters’, which were the first exoplanets found “simply because they are easiest to find,” using the radial velocity method. Then you’ll see clusters found by the other methods ending with the big batch found by Kepler.

“This clustering shows that there are more Earth and super-Earth sized planets than any other,” said Osborn. “Hopefully we can begin to probe below it’s limit and into the Earth-like regime, where thousands more worlds should await!”

On reddit, Osborn also provided great, short explanations of the various methods used to detect planets, which we’ll include below:

Radial Velocity

Planets orbit thanks to gravitational attraction from their star’s mass. But the mass of the planet also has an effect on the star – pulling it around in a tiny circle once every orbit. Astronomers can split the light from a star up into it’s colours, which have an atomic barcode of absorption lines in. These lines shift position as the star moves – the light is effectively compressed to bluer colours when moving towards and pulled to redder colours when moving away.

So, by measuring this to-and-fro (radial) velocity, and finding periodic signals, astronomers can detect the tug of distant exoplanets.

Direct Imaging

This is easier to get your head around – point a big telescope at a star and directly image a planet around it. This only work for the biggest young planets as these are warmest, so glow brightest in the infra-red (like a red-hot piece of Iron). To find the planet in the glare of it’s star, the starlight needs to be suppressed. This is done by either blocking it out with a starshade, or digitally combining the images in such a way to remove the central star, revealing new exoplanets.

Microlensing

Einstein’s general theory of relativity shows that mass bends space time. This means that light can be bent by massive objects, and even act like a lens. Occasionally a star with a planetary system passes in front of a distant star. The light from the distant star is bent and lensed by both the star and the planet, giving two sharp increases in brightness over a few days – one for the star and one for the planet. The amount of lensing gives the mass of the planets, and the time between the events gives us the distance from their star. More info

Transits

When a planet crosses in front of it’s star, it blocks out a small portion of sunlight depending on it’s size. We only see the star as a single point, but we can infer the presence of a planet from the dip in light. When this repeats, we get a period. This is how we have found more than 1000 of the current crop of ~1800 exoplanets!

Thanks to Hugh Osborn for sharing his expertise with Universe Today!

January 27, 2015December 23, 2015 by Nancy Atkinson

Oldest Planetary System Discovered, Improving the Chances for Intelligent Life Everywhere

An artist rendition of Kepler-444 planetary system, which hosts five planets, all smaller than Earth. Credit: Tiago Campante, University of Birmingham, UK.

Using data from the Kepler space telescope, an international group of astronomers has discovered the oldest known planetary system in the galaxy – an 11 billion-year-old system of five rocky planets that are all smaller than Earth. The team says this discovery suggests that Earth-size planets have formed throughout most of the Universe’s 13.8-billion-year history, increasing the possibility for the existence of ancient life – and potentially advanced intelligent life — in our galaxy.

“The fact that rocky planets were already forming in the galaxy 11 billion years ago suggests that habitable Earth-like planets have probably been around for a very long time, much longer than the age of our Solar System,” said Dr. Travis Metcalfe, Senior Research Scientist Space Science Institute, who was part of the team that used the unique method of asteroseismology to determine the age of the star.

The star, named Kepler-444, is about 25 percent smaller than our Sun and is 117 light-years from Earth. The system of five known planets is very compact, and all five planets orbit the parent star in less than 10 days, or within 0:08 AU, roughly one-fifth the size of Mercury’s orbit.

“The star is slightly cooler than the Sun (around 5000 K at the surface, compared to 5800 K),” Metcalfe told Universe Today, “but the planets in this system are still expected to be highly irradiated and inhospitable to life,” with little to no atmospheres.

The team wrote in their paper that the system’s habitable zone lies 0:47 AU from the parent star and so all planets orbit well interior to the inner edge of Kepler-444’s ‘Goldilocks zone.’

The team was led by Tiago Campante, a research fellow at the University of Birmingham in the UK.

The planets were found by analyzing four years of Kepler data, as the spacecraft had nearly continuous observations of Kepler-444 during Kepler’s active mission. The space telescope took high-precision measurements of changes in brightness in stars in its field of view. There are tiny changes in brightness when planets pass in front of their stars.

Transit signals indicated five planets orbiting Kepler-444, although this star has a binary companion, an M-dwarf, and it was a tedious process to tease out all the data to determine what were planets and not other stars, as well as which star the planets were orbiting.

An image of the Kepler-444 star system using the NIRC2 near-infrared imager on the Keck II telescope. Credit: Tiago Campante et al.

Metcalfe said the the job of “validating” the planets by ruling out all of the other possible “false positive” scenarios is always a big challenge for Kepler targets.

But asteroseismology was used to directly measure the precise age of the star. Asteroseismology, or stellar seismology is basically listening to a star by measuring sound waves. The sound waves travel into the star and bring information back up to the surface. The waves cause oscillations that Kepler observes as a rapid flickering of the star’s brightness.

How can this help determine a star’s age?

“As a star ages, it converts hydrogen into helium in the core,” Metcalfe said via email. “This changes the mean density of the star over time, and asteroseismology provides a very precise measure of the mean density (from the regular spacing of the individual oscillation frequencies).”

Metcalfe said that in this case, the uncertainty on the age of the star (and thus the planets, which formed essentially at the same time) is only 9%, compared to a typical uncertainty of 30-50% from other methods based on rotation (gyrochronology) or other properties of the star.

The team also noted in their paper that this finding may also help to pinpoint the beginning of the era of planet formation.

“I think this system has a lot to teach us about planet formation and the long-term evolution of planetary systems,” said Darin Ragozzine, a professor at Florida Institute of Technology and a a member of the discovery team, who specializes in multi-transiting systems. “With an age of 11.2 billion years, it means that this system formed near the beginning of the age of the Universe.”

The team wrote that this finding implies that small, Earth-size, planets may have readily formed at early epochs in the Universe’s history, even when metals were more scarce.

“By the time Earth formed, this star and its planetary system were already older than our planet is today,” Ragozzine told Universe Today. “We don’t know for sure if this system has stayed the same the whole time, but it is amazing to think that the little inner planet has gone around the star about a trillion times!”

To find out more about asteroseismology, check out a website called the Pale Blue Dot Project. Metcalfe launched a non-profit organization to help raise research funds for the Kepler Asteroseismic Science Consortium. The Pale Blue Dot Project allows people to adopt a star to support asteroseismology, since there is no NASA funding for asteroseismology.

“Much of the expertise for this exists in Europe and not in the US, so as a cost saving measure NASA outsourced this particular research for the Kepler mission,” said Metcalfe, “and NASA can’t fund researchers in other countries.”

Metcalfe added that the “adopt a star” program supported the asteroseismic analysis of Kepler-444, “determining the precise age that makes this ancient planetary system so interesting… This private funding from citizens around the world has been an invaluable resource to facilitate our research and fuel amazing discoveries like this one.”

You can help this research by adopting one of the Kepler stars or planetary systems.

This research was published today in the Astrophysical Journal.

The team’s paper is titled, “An Ancient Extrasolar System with Five Sub-Earth-Size Planets.”

January 9, 2015February 9, 2021 by Fraser Cain

Weekly Space Hangout – Jan 9, 2015: Andy Weir of “The Martian”

Host: Fraser Cain (@fcain)
Special Guest: Andy Weir , author of “The Martian”
Andy was first hired as a programmer for a national laboratory at age fifteen and has been working as a software engineer ever since. He is also a lifelong space nerd and a devoted hobbyist of subjects like relativistic physics, orbital mechanics, and the history of manned spaceflight. “The Martian” is his first novel.

Guests:
Morgan Rehnberg (cosmicchatter.org / @cosmic_chatter)
Ramin Skibba (@raminskibba)
Brian Koberlein (@briankoberlein)
Dave Dickinson (@astroguyz / www.astroguyz.com)
Nicole Gugliucci (cosmoquest.org / @noisyastronomer)
Continue reading “Weekly Space Hangout – Jan 9, 2015: Andy Weir of “The Martian””