First Detection of Water Clouds Outside Our Solar System

Artist's conception of how WISE 0855 might appear if viewed close-up in infrared light. Artwork by Joy Pollard, Gemini Observatory/AURA.

Brown dwarfs – those not-quite-a-planet and not-quite-a-star objects – are intriguing oddities that are too low in mass to burn hydrogen, but are more massive than planets. They only emit a faint amount of light, so they are hard to detect, making scientists unsure of how many of them might be out there in our galaxy.

But astronomers have been keeping an eye one particular brown dwarf known called WISE 0855. Just 7.2 light-years from Earth, it is the coldest known object outside of our Solar System and is just barely visible at infrared wavelengths. But with some crafty spectroscopic observing techniques, astronomers have now determined this object has some exciting characteristics: its atmosphere is full of clouds of water vapor. This is the first time water clouds have been detected outside of our Solar System.

“It’s five times fainter than any other object detected with ground-based spectroscopy at this wavelength,” said Andrew Skemer, assistant professor of astronomy and astrophysics at UC Santa Cruz and the first author on a paper on WISE 0855 published in Astrophysical Journal Letters (paper is available on arXiv here). “Now that we have a spectrum, we can really start thinking about what’s going on in this object. Our spectrum shows that WISE 0855 is dominated by water vapor and clouds, with an overall appearance that is strikingly similar to Jupiter.”

This brown dwarf’s full name is WISE J085510.83-071442.5, but we’re among friends, so it’s W0855 for short. It has about five times the mass of Jupiter and is the coldest brown dwarf ever detected, with an average temperature of about 250 degrees Kelvin, or minus 10 degrees F, minus 20 C. That makes it nearly as cold as Jupiter, which is 130 degrees Kelvin.

“WISE 0855 is our first opportunity to study an extrasolar planetary-mass object that is nearly as cold as our own gas giants,” Skemer said.

Skemer and his team used the Gemini-North telescope in Hawaii and the Gemini Near Infrared Spectrograph to observe WISE 0855 over 13 nights for a total of about 14 hours. Skemer was part of a team that studied this object in 2014 found tentative indications of water clouds based on very limited photometric data. Skemer said obtaining a spectrum (which separates the light from an object into its component wavelengths) was the only way to detect this object’s molecular composition.

A video about the 2014 discovery and study of WISE 0855:

WISE 0855 is too faint for conventional spectroscopy at optical or near-infrared wavelengths, but the team took up a challenge and looked at the thermal emissions from the object at wavelengths in a narrow window around 5 microns.

“I think everyone on the research team really believed that we were dreaming to think we could obtain a spectrum of this brown dwarf because its thermal glow is so feeble,” said Skemer. WISE 0855, is so cool and faint that many astronomers thought it would be years before a spectrum could be obtained. “I thought we’d have to wait until the James Webb Space Telescope was operating to do this,” Skemer said.

This spectroscopic view provided a glimpse into the environment of WISE 0855’s atmosphere. With the data in hand, the researchers then developed atmospheric models of the equilibrium chemistry for a brown dwarf at 250 degrees Kelvin and calculated the resulting spectra under different assumptions, including cloudy and cloud-free models. The models predicted a spectrum dominated by features resulting from water vapor, and the cloudy model yielded the best fit to the features in the spectrum of WISE 0855.

While the spectra of this object are strikingly similar to Jupiter, WISE 0855 appears to have a less turbulent atmosphere.

“The spectrum allows us to investigate dynamical and chemical properties that have long been studied in Jupiter’s atmosphere, but this time on an extrasolar world,” Skemer said.

The scientists say WISE 0855 looks more similar to Jupiter than any exoplanet yet discovered, which is especially intriguing since the Juno mission has just begun its exploration at the giant world. Jupiter, along with the other gas planets in our Solar System, all have clouds and storms, although Jupiter’s clouds are mainly made of ammonia with lower level clouds perhaps containing water. One of Juno’s goals is to determine the global water abundance at Jupiter.

Sources: UC Santa Cruz, Gemini

New System Discovered with Five Planets

A new study announced the discovery of a system hosting five transiting planets (image credit: jhmart1/deviantart).
A new study announced the discovery of a new system hosting five transiting planets (image credit: jhmart1/deviantart).
A new study announced the discovery of a system hosting five transiting planets (image credit: jhmart1/deviantart).

NASA’s planet-discovering Kepler mission suffered a major mechanical failure in May 2013, but thanks to innovative techniques subsequently implemented by astronomers the satellite continues to uncover worlds beyond our Solar System (i.e., exoplanets).  Indeed, Andrew Vanderburg (CfA) and colleagues just published results highlighting a new system found to host five transiting planets, which include: two sub-Neptune sized planets, a Neptune sized planet, a sub-Saturn sized planet, and a Jupiter sized planet.

Continue reading “New System Discovered with Five Planets”

Webb Telescope Gets its Science Instruments Installed

In this rare view, the James Webb Space Telescope team crane lifted the science instrument package for installation into the telescope structure. Credits: NASA/Chris Gunn
In this rare view, the James Webb Space Telescope team crane lifted the science instrument package for installation into the telescope structure.  Credits: NASA/Chris Gunn
In this rare view, the James Webb Space Telescope team crane lifted the science instrument package for installation into the telescope structure. Credits: NASA/Chris Gunn

The package of powerful science instruments at the heart of NASA’s mammoth James Webb Space Telescope (JWST) have been successfully installed into the telescopes structure.

A team of two dozen engineers and technicians working with “surgical precision” inside the world’s largest clean room at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, meticulously guided the instrument package known as the ISIM (Integrated Science Instrument Module) into the telescope truss structure.

ISIM is located right behind the 6.5 meter diameter golden primary mirror – as seen in NASA’s and my photos herein.

The ISIM holds the observatory’s international quartet of state-of-the-art research instruments, funded, built and provided by research teams in the US, Canada and Europe.

“This is a tremendous accomplishment for our worldwide team,” said John Mather, James Webb Space Telescope Project Scientist and Nobel Laureate, in a statement.

“There are vital instruments in this package from Europe and Canada as well as the US and we are so proud that everything is working so beautifully, 20 years after we started designing our observatory.”

This side shot shows a glimpse inside a massive clean room at NASA's Goddard Space Flight Center in Greenbelt, Maryland where the James Webb Space Telescope team worked meticulously to complete the science instrument package installation.  Credits: NASA/Desiree Stover
This side shot shows a glimpse inside a massive clean room at NASA’s Goddard Space Flight Center in Greenbelt, Maryland where the James Webb Space Telescope team worked meticulously to complete the science instrument package installation. Credits: NASA/Desiree Stover

Just as with the mirrors installation and other assembly tasks, the technicians practiced the crucial ISIM installation procedure numerous times via test runs, computer modeling and a mock-up of the instrument package.

To accomplish the ISIM installation, the telescope structure had to be flipped over and placed into the giant work gantry in the clean room to enable access by the technicians.

“The telescope structure has to be turned over and put into the gantry system [in the clean room],” said John Durning, Webb Telescope Deputy Project Manager, in an exclusive interview with Universe Today at NASA’s Goddard Space Flight Center.

“Then we take ISIM and install in the back of the telescope.”

The team used an overhead crane to lift and maneuver the heavy ISIM science instrument package in the clean room. Then they lowered it into the enclosure behind the mirrors on the telescopes backside and secured it to the structure.

“Our personnel were navigating a very tight space with very valuable hardware,” said Jamie Dunn, ISIM Manager.

“We needed the room to be quiet so if someone said something we would be able to hear them. You listen not only for what other people say, but to hear if something doesn’t sound right.”

Up close view shows cone shaped Aft Optics Subsystem (AOS) standing at center of Webb telescopes 18 segment primary mirror at NASA's Goddard Space Flight Center in Greenbelt, Maryland on May 3, 2016.  ISIM science instrument module will be installed inside truss structure below.  Credit: Ken Kremer/kenkremer.com
Up close view shows cone shaped Aft Optics Subsystem (AOS) standing at center of Webb telescopes 18 segment primary mirror at NASA’s Goddard Space Flight Center in Greenbelt, Maryland on May 3, 2016. ISIM science instrument module will be installed inside truss structure below. Credit: Ken Kremer/kenkremer.com

The ISIM installation continues the excellently executed final assembly phase of Webb at Goddard this year. And comes just weeks after workers finished installing the entire mirror system.

This author has witnessed and reported on the assembly progress at Goddard on numerous occasions, including after the mirrors were recently uncovered and unveiled in all their golden glory.

“The entire mirror system is checked out. The system has been integrated and the alignment has been checked,” said John Durning, Webb Telescope Deputy Project Manager, in an exclusive interview with Universe Today at NASA’s Goddard Space Flight Center.

Up close side-view of newly exposed gold coated primary mirrors installed onto mirror backplane holding structure of  NASA’s James Webb Space Telescope inside the massive clean room at NASA's Goddard Space Flight Center in Greenbelt, Maryland on May 3, 2016.   Aft optics subsystem stands upright at center of 18 mirror segments between stowed secondary mirror mount booms.  Credit: Ken Kremer/kenkremer.com
Up close side-view of newly exposed gold coated primary mirrors installed onto mirror backplane holding structure of NASA’s James Webb Space Telescope inside the massive clean room at NASA’s Goddard Space Flight Center in Greenbelt, Maryland on May 3, 2016. Aft optics subsystem stands upright at center of 18 mirror segments between stowed secondary mirror mount booms. Credit: Ken Kremer/kenkremer.com

ISIM is a collection of cameras and spectrographs that will record the light collected by Webb’s giant golden primary mirror.

“It will take us a few months to install ISIM and align it and make sure everything is where it needs to be,” Durning told me.

The primary mirror is comprised of 18 hexagonal segments.

Each of the 18 hexagonal-shaped primary mirror segments measures just over 4.2 feet (1.3 meters) across and weighs approximately 88 pounds (40 kilograms). They are made of beryllium, gold coated and about the size of a coffee table.

Webb’s golden mirror structure was tilted up for a very brief period on May 4 as seen in this NASA time-lapse video:

The 18-segment primary mirror of NASA’s James Webb Space Telescope was raised into vertical alignment in the largest clean room at the agency’s Goddard Space Flight Center in Greenbelt, Maryland, on May 4, 2016. Credit: NASA

The gargantuan observatory will significantly exceed the light gathering power of NASA’s Hubble Space Telescope (HST) – currently the most powerful space telescope ever sent to space.

With the mirror structure complete, the next step was the ISIM science module installation.

To accomplish that installation, technicians carefully moved the Webb mirror structure into the clean room gantry structure.

As shown in this time-lapse video we created from Webbcam images, they tilted the structure vertically, flipped it around, lowered it back down horizontally and then transported it via an overhead crane into the work platform.

Time-lapse showing the uncovered 18-segment primary mirror of NASA’s James Webb Space Telescope being raised into vertical position, flipped and lowered upside down to horizontal position and then moved to processing gantry in the largest clean room at the agency’s Goddard Space Flight Center in Greenbelt, Maryland, on May 4/5, 2016. Images: NASA Webbcam. Time-lapse by Ken Kremer/kenkremer.com/Alex Polimeni

The telescope will launch on an Ariane V booster from the Guiana Space Center in Kourou, French Guiana in 2018.

The Webb Telescope is a joint international collaborative project between NASA, the European Space Agency (ESA) and the Canadian Space Agency (CSA).

Webb is designed to look at the first light of the Universe and will be able to peer back in time to when the first stars and first galaxies were forming. It will also study the history of our universe and the formation of our solar system as well as other solar systems and exoplanets, some of which may be capable of supporting life on planets similar to Earth.

All 18 gold coated primary mirrors of NASA’s James Webb Space Telescope are seen fully unveiled after removal of protective covers installed onto the backplane structure, as technicians work inside the massive clean room at NASA's Goddard Space Flight Center in Greenbelt, Maryland on May 3, 2016.  The secondary mirror mount booms are folded down into stowed for launch configuration. Credit: Ken Kremer/kenkremer.com
All 18 gold coated primary mirrors of NASA’s James Webb Space Telescope are seen fully unveiled after removal of protective covers installed onto the backplane structure, as technicians work inside the massive clean room at NASA’s Goddard Space Flight Center in Greenbelt, Maryland on May 3, 2016. The secondary mirror mount booms are folded down into stowed for launch configuration. Credit: Ken Kremer/kenkremer.com

More about ISIM and upcoming testing in the next story.

Watch this space for my ongoing reports on JWST mirrors, science, construction and testing.

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

Ken Kremer

Friendly Giants Have Cozy Habitable Zones Too

Artist's impression of a red giant star. If the star is in a binary pair, what happens to its sibling? Credit:NASA/ Walt Feimer

It is an well-known fact that all stars have a lifespan. This begins with their formation, then continues through their Main Sequence phase (which constitutes the majority of their life) before ending in death. In most cases, stars will swell up to several hundred times their normal size as they exit the Main Sequence phase of their life, during which time they will likely consume any planets that orbit closely to them.

However, for planets that orbit the star at greater distances (beyond the system’s “Frost Line“, essentially), conditions might actually become warm enough for them to support life. And according to new research which comes from the Carl Sagan Institute at Cornell University, this situation could last for some star systems into the billions of years, giving rise to entirely new forms of extra-terrestrial life!

In approximately 5.4 billion years from now, our Sun will exit its Main Sequence phase. Having exhausted the hydrogen fuel in its core, the inert helium ash that has built up there will become unstable and collapse under its own weight. This will cause the core to heat up and get denser, which in turn will cause the Sun to grow in size and enter what is known as the Red Giant-Branch (RGB) phase of its evolution.

The life cycle of a Sun-like star, from its birth on the left side of the frame to its evolution into a red giant on the right after billions of years. Credit: ESO/M. Kornmesser
The life cycle of a Sun-like star, from its birth on the left side of the frame to its evolution into a red giant on the right after billions of years. Credit: ESO/M. Kornmesser

This period will begin with our Sun becoming a subgiant, in which it will slowly double in size over the course of about half a billion years. It will then spend the next half a billion years expanding more rapidly, until it is 200 times its current size and several thousands times more luminous. It will then officially be a red giant star, eventually expanding to the point where it reaches beyond Mars’ orbit.

As we explored in a previous article, planet Earth will not survive our Sun becoming a Red Giant – nor will Mercury, Venus or Mars. But beyond the “Frost Line”, where it is cold enough that volatile compounds – such as water, ammonia, methane, carbon dioxide and carbon monoxide – remain in a frozen state, the remain gas giants, ice giants, and dwarf planets will survive. Not only that, but a massive thaw will set in.

In short, when the star expands, its “habitable zone” will likely do the same, encompassing the orbits of Jupiter and Saturn. When this happens, formerly uninhabitable places – like the Jovian and Cronian moons – could suddenly become inhabitable. The same holds true for many other stars in the Universe, all of which are fated to become Red Giants as they near the end of their lifespans.

However, when our Sun reaches its Red Giant Branch phase, it is only expected to have 120 million years of active life left. This is not quite enough time for new lifeforms to emerge, evolve and become truly complex (i.e. like humans and other species of mammals). But according to a recent research study that appeared in The Astrophysical Journal – titled “Habitable Zone of Post-Main Sequence Stars” – some planets may be able to remain habitable around other red giant stars in our Universe for much longer – up to 9 billion years or more in some cases!

Ramses Ramirez, left, and Lisa Kaltenegger hold a replica of our own habitable world, as they hunt for other places in the universe where life can thrive. Credit: Chris Kitchen/University Photo
Ramses Ramirez (left) and Lisa Kaltenegger are on the hunt for other places in the universe where life can thrive. Credit: Chris Kitchen/University Photo

To put that in perspective, nine billion years is close to twice the current age of Earth. So assuming that the worlds in question also have the right mix of elements, they will have ample time to give rise to new and complex forms of life. The study’s co-author, Professor Lisa Kaltennegeris, is also the director of the Carl Sagan Institute. As such, she is no stranger to searching for life in other parts of the Universe. As she explained to Universe Today via email:

“We found that planets – depending on how big their Sun is (the smaller the star, the longer the planet can stay habitable) – can stay nice and warm for up to 9 Billion years. That makes an old star an interesting place to look for life. It could have started sub-surface (e.g. in a frozen ocean) and then when the ice melts, the gases that life breaths in and out can escape into the atmosphere – what allows astronomers to pick them up as signatures of life. Or for the smallest stars, the time a formerly frozen planet can be nice and warm is up to 9 billion years. Thus life could potentially even get started in that time.”

Using existing models of stars and their evolution – i.e. one-dimensional radiative-convective climate and stellar evolutionary models – for their study, Kaltenegger and Ramirez were able to calculate the distances of the habitable zones (HZ) around a series of post-Main Sequence (post-MS) stars. Ramses M. Ramirez – a research associate at the Carl Sagan Institute and the lead author of the paper – explained the research process to Universe Today via email:

“We used stellar evolutionary models that tell us how stellar quantities, mainly the brightness, radius, and temperature all change with time as the star ages through the red giant phase. We also used a  climate model to then compute how much energy each star is outputting at the boundaries of the habitable zone. Knowing this and the stellar brightness mentioned above, we can compute the distances to these habitable zone boundaries.”

After several billions years, yellow suns (like ours) become Red Giants, expanding to several hundred times their normal size. Credit: Wendy Kenigsburg
After several billions years, yellow suns (like ours) become Red Giants, expanding to several hundred times their normal size. Credit: Wendy Kenigsburg

At the same time, they considered how this kind of stellar evolution could effect the atmosphere of the star’s planets. As a star expands, it loses mass and ejects it outward in the form of solar wind. For planets that orbit close to a star, or those that have low surface gravity, they may find some or all of their atmospheres blasted away. On the other hand, planets with sufficient mass (or positioned at a safe distance) could maintain most of their atmospheres.

“The stellar winds from this mass loss erodes planetary atmospheres, which we also compute as a function of time,” said Ramirez. “As the star loses mass, the solar system conserves angular momentum by moving outwards. So, we also take into account how the orbits move out with time.” By using models that incorporated the rate of stellar and atmospheric loss during the Red Giant Branch (RGB) and Asymptotic Giant Branch (AGB) phases of star, they were able to determine how this would play out for planets that ranged in size from super-Moons to super-Earths.

What they found was that a planet can stay in a post-HS HZ for eons or more, depending on how hot the star is, and figuring for metallicities that are similar to our Sun’s. As Ramirez explained:

“The main result is that the maximum time that a planet can remain in this red giant habitable zone of hot stars is 200 million years. For our coolest star (M1), the maximum time a planet can stay within this red giant habitable zone is 9 billion years. Those results assume metallicity levels similar to those of our Sun. A star with a higher percentage of metals takes longer to fuse the non-metals (H, He..etc) and so these maximum times can increase some more, up to about a factor of two.”

Europa's cracked, icy surface imaged by NASA's Galileo spacecraft in 1998. Credit: NASA/JPL-Caltech/SETI Institute.
Could Europa’s cracked, icy surface thaw and give rise to a new habitable world when our Sun becomes a Red Giant in a few billion years? Credit: NASA/JPL-Caltech/SETI Institute

Within the context of our Solar System, this could mean that in a few billion years, worlds like Europa and Enceladus (which are already suspected of having life beneath their icy surfaces) might get a shot at becoming full-fledged habitable worlds. As Ramirez summarized beautifully:

“This means that the post-main-sequence is another potentially interesting phase of stellar evolution from a habitability standpoint. Long after the inner system of planets have been turned into sizzling wastelands by the expanding, growing red giant star, there could be potentially habitable abodes farther away from the chaos. If they are frozen worlds, like Europa, the ice would melt, potentially unveiling any preexisting life. Such pre-existing life may be detectable by future missions/telescopes looking for atmospheric biosignatures.”

But perhaps the most exciting take-away from their research study was their conclusion that planets orbiting within their star’s post-MS habitable zones would be doing so at distances that would make them detectable using direct imaging techniques. So not only are the odds of finding life around older stars better than previously thought, we should have no trouble in spotting them using current exoplanet-hunting techniques!

It is also worth noting that Kaltenegger and Dr. Ramirez have submitted a second paper for publication, in which they provide a list of 23 red giant stars within 100 light-years of Earth. Knowing that these stars, all of which are in our stellar neighborhood, could have life-sustaining worlds within their habitable zones should provide additional opportunities for planet hunters in the coming years.

And be sure to check out this video from Cornellcast, where Prof. Kaltenegger shares what inspires her scientific curiosity and how Cornell’s scientists are working to find proof of extra-terrestrial life.

Further Reading: The Astrophysical Journal

Three New Earth-sized Planets Found Just 40 Light-Years Away

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).

Three more potentially Earthlike worlds have been discovered in our galactic backyard, announced online today by the European Southern Observatory. Researchers using the 60-cm TRAPPIST telescope at ESO’s La Silla observatory in Chile have identified three Earth-sized exoplanets orbiting a star just 40 light-years away.

The star, originally classified as 2MASS J23062928-0502285 but now known more conveniently as TRAPPIST-1, is a dim “ultracool” red dwarf star only .05% as bright as our Sun . Located in the constellation Aquarius, it’s now the 37th-farthest star known to host orbiting exoplanets.

The exoplanets were discovered via the transit method (TRAPPIST stands for Transiting Planets and Planetesimals Small Telescope) through which the light from a star is observed to dim slightly by planets passing in front of it from our point of view. This is the same method that NASA’s Kepler spacecraft has used to find over 1,000 confirmed exoplanets.

Location of TRAPPIST-1 in the constellation Aquarius. Credit: ESO/IAU and Sky & Telescope.
Location of TRAPPIST-1 in the constellation Aquarius. Credit: ESO/IAU and Sky & Telescope.

As an ultracool dwarf TRAPPIST-1 is a very small and dim and isn’t easily visible from Earth, but it’s its very dimness that has allowed its planets to be discovered with existing technology. Their subtle silhouettes may have been lost in the glare of larger, brighter stars.

Follow-up measurements of the three exoplanets indicated that they are all approximately Earth-sized and have temperatures ranging from Earthlike to Venuslike (which is, admittedly, a fairly large range.) They orbit their host star very closely with periods measured in Earth days, not years.

“With such short orbital periods, the planets are between 20 and 100 times closer to their star than the Earth to the Sun,” said Michael Gillon, lead author of the research paper. “The structure of this planetary system is much more similar in scale to the system of Jupiter’s moons than to that of the Solar System.”

Structure of the TRAPPIST-1 exosystem. The green is the star's habitable zone. Credit: PHL.
Structure of the TRAPPIST-1 exosystem. The green is the star’s habitable zone. Credit: PHL.

Although these three new exoplanets are Earth-sized they do not yet classify as “potentially habitable,” at least by the standards of the Planetary Habitability Laboratory (PHL) operated by the University of Puerto Rico at Arecibo. The planets fall outside PHL’s required habitable zone; two are too close to the host star and one is too far away.

In addition there are certain factors that planets orbiting ultracool dwarfs would have to contend with in order to be friendly to life, not the least of which is the exposure to energetic outbursts from solar flares.

This does not guarantee that the exoplanets are completely uninhabitable, though; it’s entirely possible that there are regions on or within them where life could exist, not unlike Mars or some of the moons in our own Solar System.

The exoplanets are all likely tidally locked in their orbits, so even though the closest two are too hot on their star-facing side and too cold on the other, there may be regions along the east or west terminators that maintain a climate conducive to life.

“Now we have to investigate if they’re habitable,” said co-author Julien de Wit at MIT in Cambridge, Mass. “We will investigate what kind of atmosphere they have, and then will search for biomarkers and signs of life.”

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

Discovering three planets orbiting such a small yet extremely common type of star hints that there are likely many, many more such worlds in our galaxy and the Universe as a whole.

“So far, the existence of such ‘red worlds’ orbiting ultra-cool dwarf stars was purely theoretical, but now we have not just one lonely planet around such a faint red star but a complete system of three planets,” said study co-author Emmanuel Jehin.

The team’s research was presented in a paper entitled “Temperate Earth-sized planets transiting a nearby ultracool dwarf star” and will be published in Nature.

Source: ESO, PHL, and MIT

________________

Note: the original version of this article described 2MASS J23062928-0502285 (TRAPPIST-1) as a brown dwarf based on its classification on the Simbad archive. But at M8V it is “definitely a star,” according to co-author Julien de Wit in an email, although at the very low end of the red dwarf line. Corrections have been made above.

Did the Sun Steal Planet Nine?

Artist's impression of Planet Nine, blocking out the Milky Way. The Sun is in the distance, with the orbit of Neptune shown as a ring. Credit: ESO/Tomruen/nagualdesign
Artist's impression of Planet Nine, blocking out the Milky Way. The Sun is in the distance, with the orbit of Neptune shown as a ring. Credit: ESO/Tomruen/nagualdesign

One of the biggest new mysteries in our Solar System is the purported presence of a large and distant “Planet Nine,” traveling around the Sun in a twenty-thousand-year orbit far beyond Pluto. Although this far-flung world’s existence has yet to actually be confirmed (or even directly detected) some scientists are suggesting it might have originally been an exoplanet around a neighboring star, pilfered by our Sun during its impudent adolescence.

Continue reading “Did the Sun Steal Planet Nine?”

ALMA Captures Never-Before-Seen Details of Protoplanetary Disk

ALMA’s best image of a protoplanetary disk to date. This picture of the nearby young star TW Hydrae reveals the classic rings and gaps that signify planets are in formation in this system. Credit: S. Andrews (Harvard-Smithsonian CfA); B. Saxton (NRAO/AUI/NSF); ALMA (ESO/NAOJ/NRAO)
ALMA’s best image of a protoplanetary disc to date. This picture of the nearby young star TW Hydrae reveals the classic rings and gaps that signify planets are in formation in this system.
ALMA’s best image of a protoplanetary disk to date. This picture of the nearby young star TW Hydrae reveals the classic rings and gaps that signify planets are in formation in this system. Credit: S. Andrews (Harvard-Smithsonian CfA); B. Saxton (NRAO/AUI/NSF); ALMA (ESO/NAOJ/NRAO)

TW Hydrae is a special star. Located 175 light years from Earth in the constellation Hydra the Water Snake, it sits at the center of a dense disk of gas and dust that astronomers think resembles our solar system when it was just 10 million years old. The disk is incredibly clear in images made using the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, which employs 66 radio telescopes sensitive to light just beyond that of infrared.  Spread across more than 9 miles (15 kilometers), the ALMA array acts as a gigantic single telescope that can make images 10 times sharper than even the Hubble Space Telescope.

This photo of the ALMA antennas on the Chajnantor Plateau in Chile, more than 16,000 feet (5000 meters) above sea level, was taken a few days before the start of ALMA Early Science and shows only one cluster of the 66 dishes. ALMA views the sky in "submillimeter" light, a slice of the spectrum invisible to the human eye that lies between infrared and radio waves. Credit: ALMA (ESO/NAOJ/NRAO)/W. Garnier (ALMA)
This photo of the ALMA antennas on the Chajnantor Plateau in Chile, more than 16,000 feet (5000 meters) above sea level, was taken a few days before the start of ALMA Early Science and shows only one cluster of the 66 dishes. ALMA views the sky in submillimeter light, a slice of the spectrum invisible to the human eye that lies between infrared and radio waves. Credit: ALMA (ESO/NAOJ/NRAO)/W. Garnier (ALMA)

Astronomers everywhere point their telescopes at TW Hydrae because it’s the closest infant star in the sky. With an age of between 5 and 10 million years, it’s not even running on hydrogen fusion yet, the process by which stars convert hydrogen into helium to produce energy. TW Hydrae shines from the energy released as it contracts through gravity. Fusion and official stardom won’t begin until it’s dense enough and hot enough for fusion to fire up in its belly.

ALMA image of the planet-forming disk around the young, sun-like star TW Hydrae. The inset image (upper right) zooms in on the gap nearest to the star, which is at the same distance as the Earth is from the sun, and may show an infant version of our home planet emerging from the dust and gas. The additional concentric light and dark features represent other planet-forming regions farther out in the disk. Credit: S. Andrews (Harvard-Smithsonian CfA), ALMA (ESO/NAOJ/NRAO)
ALMA image of the planet-forming disk around the young, sun-like star TW Hydrae. The inset image (upper right) zooms in on the gap nearest to the star, which is at the same distance as the Earth is from the sun, and may show an infant version of our home planet emerging from the dust and gas. The additional concentric light and dark features represent other planet-forming regions farther out in the disk. Credit: S. Andrews (Harvard-Smithsonian CfA), ALMA (ESO/NAOJ/NRAO)

We see most protoplanetary disks at various angles, but TW’s has a face-on orientation as seen from Earth, giving astronomers a rare, undistorted view of the complete disk around the star. The new images show amazing detail, revealing a series of concentric bright rings of dust separated by dark gaps. There’s even indications that a planet with an Earth-like orbit has begun clearing an orbit.

“Previous studies with optical and radio telescopes confirm that TW Hydrae hosts a prominent disk with features that strongly suggest planets are beginning to coalesce,” said Sean Andrews with the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, USA and lead author on a paper published today in the Astrophysical Journal Letters.

Blurry as it is, the detail here is staggering. It shows a gap about 93 million miles from the central starsuggesting that a planet with a similar orbit to Earth is forming there. Credit: S. Andrews (Harvard-Smithsonian CfA); B. Saxton (NRAO/AUI/NSF); ALMA (ESO/NAOJ/NRAO)
The model (at left) of a protoplanetary disk shows a newly forming star at the center of a saucer-shaped dust cloud. At right, a close up of TW Hydrae taken by ALMA shows a gap about 93 million miles from the central star, suggesting that a planet with a similar orbit to Earth is forming there. Credit: (Left: L. Calcada). Right: S. Andrews (Harvard-Smithsonian CfA); B. Saxton (NRAO/AUI/NSF); ALMA (ESO/NAOJ/NRAO)

Pronounced gaps that show up in the photos above are located at 1.9 and 3.7 billion miles (3-6 billion kilometers) from the central star, similar to the average distances from the sun to Uranus and Pluto in the solar system. They too are likely to be the results of particles that came together to form planets, which then swept their orbits clear of dust and gas to sculpt the remaining material into well-defined bands. ALMA picks up the faint emission of submillimeter light emitted by dust grains in the disk, revealing details as small as 93 million miles (150 million kilometers) or the distance of Earth from the sun

This image compares the size of the solar system with HL Tauri and its surrounding protoplanetary disc. Although the star is much smaller than the Sun, the disc around HL Tauri stretches out to almost three times as far from the star as Neptune is from the Sun. Credit:ALMA (ESO/NAOJ/NRAO)
This image compares the size of the solar system with HL Tauri and its surrounding protoplanetary disc. Although the star is much smaller than the Sun, the disc around HL Tauri stretches out to almost three times as far from the star as Neptune is from the Sun. Credit:ALMA (ESO/NAOJ/NRAO)

“This is the highest spatial resolution image ever of a protoplanetary disk from ALMA, and that won’t be easily beaten in the future!” said Andrews.

Earlier ALMA observations of another system, HL Tauri, show that even younger protoplanetary disks — a mere 1 million years old — look remarkably similar.  By studying the older TW Hydrae disk, astronomers hope to better understand the evolution of our own planet and the prospects for similar systems throughout the Milky Way.

First Super-Earth Atmosphere Detected

A new paper says that a Super-Earth may have formed in our Solar System and been swallowed by the Sun. Image Credit: ESA/Hubble, M. Kornmesser
A new paper says that a Super-Earth may have formed in our Solar System and been swallowed by the Sun. Image Credit: ESA/Hubble, M. Kornmesser

55 Cancri-e was once touted as one of the most exotic exo-planets ever discovered. Mass and radius modelling led some astronomers to speculate that its interior could be rich in carbon. And that much carbon crushed together under extreme pressure = diamonds. That’s how it got its nickname “Diamond Planet.”

But 55 Cancri-e—now named “Janssen” (Thank you International Astronomical Union!)—is even more exotic with the recent discovery of an atmosphere. A February 7th research paper in the Astrophysical Journal, by a team of European astronomers, reports that Janssen has an atmosphere rich in hydrogen. This makes Janssen the first exo-planet, that we know of, to have an atmosphere.

The team used the Wide Field Camera 3 (WDF3) on the Hubble Space Telescope, and a new scanning technique, to gain an understanding of Janssen’s atmosphere. Along with hydrogen, the team also found helium, and potentially, hydrogen cyanide.

Given Janssen’s surface temperature of 2000 K (1727 C), and its proximity to its host star, the existence of an atmosphere is surprising. The team suspects that the hydrogen-rich atmosphere is left over from the planet’s formation 8 billion years ago, and is a remnant of the nebula that the planet and star formed from.

“Our observations of 55 Cancri e’s atmosphere suggest that the planet has managed to cling on to a significant amount of hydrogen and helium from the nebula from which it formed,” said Angelos Tsiaras, a PhD student at UCL, who helped develop the new scanning technique. “This is a very exciting result because it’s the first time that we have been able to find the spectral fingerprints that show the gases present in the atmosphere of a super-Earth.”

Super-Earths are the most common type of planet in our galaxy, though none exist in our solar system. They are called super-Earths because they have more mass than Earth, but are smaller than the gas giants. A greater understanding of super-Earths should mean a greater understanding of the most common type of planet around.

“This result gives a first insight into the atmosphere of a super-Earth. We now have clues as to what the planet is currently like, how it might have formed and evolved, and this has important implications for 55 Cancri e and other super-Earths,” said Professor Giovanna Tinetti of UCL.

The existence of hydrogen cyanide in Janssen’s atmosphere is also significant. Its presence indicates a carbon-rich atmosphere. This supports the idea that Janssen is a diamond planet, though that conclusion is still far from certain. “If the presence of hydrogen cyanide and other molecules is confirmed in a few years time by the next generation of infrared telescopes, it would support the theory that this planet is indeed carbon rich and a very exotic place,” said Professor Jonathan Tennyson, UCL.

The team has used their new technique on 2 other super-Earths, but no atmosphere was found.

55-Cancri e is about 40 light years from Earth. Its host star is slightly smaller, cooler, and a little dimmer than our Sun, and its year is shorter than an Earth day.

 

 

Time-lapse Video Documents Assembly of Webb Telescope Primary Mirror

This overhead shot of the James Webb Space Telescope shows part of the installation of the 18 primary flight mirrors onto the telescope structure in a clean room at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. Credits: NASA’s Goddard Space Flight Center/Chris Gunn See time-lapse video below
This rare overhead shot of the James Webb Space Telescope shows the nine primary flight mirrors installed on the telescope structure in a clean room at NASA's Goddard Space Flight Center in Greenbelt, Maryland.  Credits: NASA's Goddard Space Flight Center/Chris Gunn
This overhead shot of the James Webb Space Telescope shows part of the installation of the 18 primary flight mirrors onto the telescope structure in a clean room at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. Credits: NASA’s Goddard Space Flight Center/Chris Gunn
See time-lapse video below

NASA GODDARD SPACE FLIGHT CENTER, MD – A time-lapse video newly released by NASA documents the painstakingly complex assembly of the primary mirror at the heart of the biggest space telescope ever conceived by humankind – NASA’s James Webb Space Telescope (JWST).

Although the video, seen here, is short, it actually compresses over two and a half months of carefully choreographed and very impressive mirror installation process into less than 90 seconds. Continue reading “Time-lapse Video Documents Assembly of Webb Telescope Primary Mirror”

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
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.