Astronomy Archives

August 1, 2014December 23, 2015 by Ken Kremer

Rosetta Closing in on Comet 67P/Churyumov-Gerasimenko after Decade Long Chase

ESA’s Rosetta Spacecraft nears final approach to Comet 67P/Churyumov-Gerasimenko in late July 2014. This collage of imagery from Rosetta combines Navcam camera images at right taken nearing final approach from July 25 to July 31, 2014, with OSIRIS wide angle camera image at left of comet’s coma on July 25 from a distance of around 3000 km. On July 31 Rosetta had approached to within 1327 km. Images to scale and contrast enhanced to show further detail. Credit: ESA/Rosetta/NAVCAM/OSIRIS/MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA
Collage/Processing: Marco Di Lorenzo/Ken Kremer – kenkremer.com
Story updated[/caption]

The European Space Agency’s (ESA) Rosetta spacecraft is at last rapidly closing in on its target destination, Comet 67P/Churyumov-Gerasimenko, after a decade long chase of 6.4 billion kilometers through interplanetary space. See imagery above and below.

As of today, Friday, August 1, ESA reports that Rosetta has approached the ‘rubber ducky looking’ comet to within a distance of less than 1153 kilometers. That distance narrows with each passing moment as the speeding robotic probe moves closer and closer to the comet while looping around the sun at about 55,000 kilometers per hour (kph).

Rosetta is now just 5 days away from becoming Earth’s first probe ever to rendezvous and enter orbit around a comet.

See above our image collage of Rosetta nearing final approach with the spacecrafts most recent daily Navcam camera images, all taken within the past week starting on July 25 and including up to the most recently release image snapped on July 31. The navcam images are all to scale to give the sense of the spacecraft approaching the comet and revealing ever greater detail as it grows in apparent size in the cameras field of view. The navcam images were also taken at about the same time of day each day.

The highest resolution navcam image yet of the two lobed comet – merged at a bright band – was taken on July 31 from a distance of 1327 kilometers and published within the past few hours by ESA today, Aug 1. It shows the best view yet of the surface features of the mysterious bright necked wanderer composed of primordial ice, rock, dust and more.

The Navcam collage is combined with an OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) wide angle camera view of the comet and its asymmetric coma of ice and dust snapped on July 25 from a distance of around 3000 km, and with an exposure time of 300 seconds. The OSIRIS image covers an area of about 150 x 150 km (90 mi x 90 mi). The images have been contrast enhanced to bring out more detail.

Scientists speculate that the comets bright neck region could be caused by differences in material or grain size or topological effects.

Rosetta’s history making orbital feat is slated for Aug. 6 following the final short duration orbit insertion burns on Aug. 3 and Aug. 6 to place Rosetta into orbit at an altitude of about 100 kilometers (62 miles) where it will study and map the 4 kilometer wide comet for some 17 months.

The comet rotates around once every 12.4 hours.

Crop from the 31 July processed image of comet 67P/Churyumov-Gerasimenko, to focus on the comet nucleus. Credits: ESA/Rosetta/NAVCAM

“If any glitches in space or on ground had delayed the most recent burns, orbital mechanics dictate that we’d only have had a matter of a few days to fix the problem, re-plan the burn and carry it out, otherwise we run the risk of missing the comet,” says Trevor Morley, a flight dynamics specialist at ESOC.

In November 2014 the Rosetta mothership will deploy the Philae science lander for the first ever attempt to land on a comet’s nucleus using harpoons to anchor itself to the surface while the comet is rotating.

As Rosetta edges closer on its final lap, engineers at mission control at the European Space Operations Centre (ESOC), in Darmstadt, Germany have commanded the probes navigation camera (navcam) to capture daily images while the other science instruments also collect measurements analyzing the comets physical characteristics and chemical composition in detail.

ESA’s Rosetta Spacecraft nears final approach to Comet 67P/Churyumov-Gerasimenko in late July 2014. This image collage from Rosetta combines Navcam camera images taken nearing final approach from July 25 (3000 km distant) to July 31, 2014 (1327 km distant). Top row shows images as seen by spacecraft. Bottom row shows images rotated to same orientation. Images to scale and contrast enhanced to show further detail. Credit: ESA/Rosetta/NAVCAM. Collage/Processing: Marco Di Lorenzo/Ken Kremer

The probe has already discovered that the comet’s surface temperature is surprisingly warm at –70ºC, which is some 20–30ºC warmer than predicted. This indicates the surface is too hot to be covered in ice and must instead have a dark, dusty crust, says ESA.

Comet 67P/Churyumov-Gerasimenko is a short period comet some 555 million kilometres from the Sun at this time, about three times further away than Earth and located between the orbits of Jupiter and Mars.

You can watch the Aug. 6 orbital arrival live via a livestream transmission from ESA’s spacecraft operations centre in Darmstadt, Germany.

While you were reading this the gap between the comet and Rosetta closed to less than 1000 kilometers!

The coma of Rosetta's target comet as seen with the OSIRIS wide-angle camera. The image spans 150 km and was taken on 25 July 2014 with an exposure time of 330 seconds. The greyscale relates to the particle density in the coma, with highest density close to the nucleus, becoming more diffuse further away. The hazy circular structure on the right is an artefact. The nucleus is also overexposured. The specks and the streaks in the background are attributed to background stars and cosmic rays. Credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA — The coma of Rosetta’s target comet as seen with the OSIRIS wide-angle camera. The image spans 150 km and was taken on 25 July 2014 with an exposure time of 330 seconds. The greyscale relates to the particle density in the coma, with highest density close to the nucleus, becoming more diffuse further away. The hazy circular structure on the right is an artefact. The nucleus is also overexposured. The specks and the streaks in the background are attributed to background stars and cosmic rays. Credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

Stay tuned here for Ken’s continuing Curiosity, Opportunity, Orion, SpaceX, Boeing, Orbital Sciences, commercial space, MAVEN, MOM, Mars and more Earth and Planetary science and human spaceflight news.

Ken Kremer

Birthday cakes at @ESA_Rosetta Flight Dynamics are taking strange binary shapes these days... #ESOC. Credit: ESA — Birthday cakes at @ESA_Rosetta Flight Dynamics are taking strange binary shapes these days… #ESOC. Credit: ESA

August 1, 2014December 23, 2015 by Elizabeth Howell

Companion Planet Could Keep Alien Earths Warm In Old Age: Study

An artist's concept of a rocky world orbiting a red dwarf star. (Credit: NASA/D. Aguilar/Harvard-Smithsonian center for Astrophysics).

People are generally social creatures, and in the case of planets that generally is the case as well. Many of these alien worlds we have discovered are in groups of two or more around their parent star or stars. A new study, however, goes a step further and says that a companion planet could actually save another planet in its old age.

“Planets cool as they age. Over time their molten cores solidify and inner heat-generating activity dwindles, becoming less able to keep the world habitable by regulating carbon dioxide to prevent runaway heating or cooling,” the University of Washington stated.

“But astronomers … have found that for certain planets about the size of our own, the gravitational pull of an outer companion planet could generate enough heat — through a process called tidal heating — to effectively prevent that internal cooling, and extend the inner world’s chance at hosting life.”

The researchers ran computer models finding that tidal heating, which is known to happen on Jupiter’s moons Europa and Io, can also happen in planets the size of Earth that are in non-circular orbits around dwarf stars. An outer planet would keep the orbit from stabilizing in a circle, generating tidal heating and keeping conditions potentially warm enough for life.

The study, led by the University of Arizona’s Christa Van Laerhoven, will be available in the Monthly Notices of the Royal Astronomical Society and is available now in preprint version on Arxiv.

July 31, 2014December 23, 2015 by Shannon Hall

Hubble Spots Farthest Lensing Galaxy Yet

Credit: NASA, ESA, K.-V. Tran (Texas A&M University), and K. Wong (Academia Sinica Institute of Astronomy & Astrophysics)

Sometimes there’s a chance alignment — faraway in the universe, where objects are separated by unimaginable distances measured in billions of light-years — when a galaxy cluster in the foreground intersects light from an even more distant object. The conjunction plays visual tricks, where the galaxy cluster acts like a lens, appearing to magnify and bend the distant light.

The rare cosmic alignment can bring the distant universe into view. Now, astronomers have stumbled upon a surprise: they’ve detected the most distant cosmic magnifying glass yet.

Seen above as it looked 9.6 billion years ago, this monster elliptical galaxy breaks the previous record holder by 200 million light-years. It’s bending, distorting and magnifying the distant spiral galaxy, whose light has taken 10.7 billion years to reach Earth.

“When you look more than 9 billion years ago in the early universe, you don’t expect to find this type of galaxy-galaxy lensing at all,” said lead researcher Kim-Vy Tran from Texas A&M University in a Hubble press release.

“Imagine holding a magnifying glass close to you and then moving it much farther away. When you look through a magnifying glass held at arm’s length, the chances that you will see an enlarged object are high. But if you move the magnifying glass across the room, your chances of seeing the magnifying glass nearly perfectly aligned with another object beyond it diminishes.”

The team was studying star formation in data collected by the W. M. Keck Observatory in Hawai’i, when they came across a strong detection of hot hydrogen gas that appeared to arise form a massive, bright elliptical galaxy. It struck the team as odd. Hot hydrogen is a clear sign of star birth, but it was detected in a galaxy that looked far too old to be forming new stars.

“I was very surprised and worried,” Tran recalled. “I thought we had made a major mistake with our observations.”

So Tran dug through archived Hubble images, which revealed a smeared, blue object next to the larger elliptical. It was the clear signature of a gravitational lens.

“We discovered that light from the lensing galaxy and from the background galaxy were blended in the ground-based data, which was confusing us,” said coauthor Ivelina Momcheva of Yale University. “The Keck spectroscopic data hinted that something interesting was going on here, but only with Hubble’s high-resolution spectroscopy were we able to separate the lensing galaxy from the more distant background galaxy and determine that the two were at different distances. The Hubble data also revealed the telltale look of the system, with the foreground lens in the middle, flanked by a bright arc on one side and a faint smudge on the other — both distorted images of the background galaxy. We needed the combination of imaging and spectroscopy to solve the puzzle.”

By gauging the intensity of the background galaxy’s light, the team was able to measure the giant galaxy’s total mass. All in all it weighs 180 billion times more than our Sun. Although this may seem big, it actually weighs four times less than the Milky Way galaxy.

“There are hundreds of lens galaxies that we know about, but almost all of them are relatively nearby, in cosmic terms,” said lead author Kenneth Wong from the Academia Sinica Institute of Astronomy & Astrophysics. “To find a lens as far away as this one is a very special discovery because we can learn about the dark-matter content of galaxies in the distant past. By comparing our analysis of this lens galaxy to the more nearby lenses, we can start to understand how that dark-matter content has evolved over time.”

Interestingly, the lensing galaxy is underweight in terms of its dark-matter content. In the past, astronomers have assumed that dark matter and normal matter build up equally in a galaxy over time. But this galaxy, suggests this is not the case.

The team’s results appeared in the July 10 issue of The Astrophysical Journal Letters and is available online.

July 31, 2014December 23, 2015 by Shannon Hall

Surprise! Classical Novae Produce Gamma Rays

These images show Fermi data centered on each of the four gamma-ray novae observed by the LAT. Colors indicate the number of detected gamma rays with energies greater than 100 million electron volts (blue indicates lowest, yellow highest). Image Credit: NASA/DOE/Fermi LAT Collaboration

In a classical nova, a white dwarf siphons material off a companion star, building up a layer on its surface until the temperature and pressure are so high (a process which can take tens of thousands of years) that its hydrogen begins to undergo nuclear fusion, triggering a runaway reaction that detonates the accumulated gas.

The bright outburst, which releases up to 100,000 times the annual energy output of our Sun, can blaze for months. All the while, the white dwarf remains intact, with the potential of going nova again.

It’s a relatively straightforward picture — as far as complex astrophysics goes. But new observations with NASA’s Fermi Gamma-ray Space Telescope unexpectedly show that three classical novae — V959 Monocerotis 2012, V1324 Scorpii 2012, and V339 Delphini 2013 — and one rare nova, also produce gamma rays, the most energetic form of light.

“There’s a saying that one is a fluke, two is a coincidence, and three is a class, and we’re now at four novae and counting with Fermi,” said lead author Teddy Cheung from the Naval Research Laboratory in a press release.

The first nova detected in gamma rays was V407 Cygni — a rare star system in which a white dwarf interacts with a red giant — in March 2010.

One explanation for the gamma-ray emission is that the blast from the nova hits the hefty wind from the red giant, creating a shock wave that accelerates any charged particles to near the speed of light. These rapid particles, in turn, produce gamma rays.

But the gamma-ray peak follows the optical peak by a couple of days. This likely happens because the material the white dwarf ejects initially blocks the high-energy photons from escaping. So the gamma rays cannot escape until the material expands and thins.

But the later three novae are from systems that don’t have red giants and therefore their winds. There’s nothing for the blast wave to crash into.

“We initially thought of V407 Cygni as a special case because the red giant’s atmosphere is essentially leaking into space, producing a gaseous environment that interacts with the explosion’s blast wave,” said coauthor Steven Shore from the University of Pisa. “But this can’t explain more recent Fermi detections because none of those systems possess red giants.”

In a more typical system it’s likely that the blast creates multiple shock waves that expand into space at slightly different speeds. Faster shocks could blast into slower ones, creating the interaction necessary to produce gamma rays. Although, the team remains unsure if this is the case.

Astronomers estimate that between 20 and 50 novae occur each year in the Milky Way galaxy. Most go undetected, their visible light obscured by intervening dust, and their gamma rays dimmed by distance. Hopefully, future observations of nearby novae will shed light on the mysterious process producing gamma rays.

The results will appear in Science on August 1.

July 31, 2014December 23, 2015 by Shannon Hall

Numerous Jets Spied with New Sky Survey

Caption: The area shown here was part of the very first image taken for the UWISH2 survey. It shows on the top a region of massive star formation (called G35.2N) with two spectacular jets. On the bottom an intermediate mass young stellar cluster (Mercer14) can be seen. Several jets are visible in its vicinity, as well as a region of photo-ionized material surrounding a young massive star. Credit: University of Kent

Jets — narrow beams of matter spat out at a high speed — typically accompany the most enigmatic astronomical objects. We see them wherever gas accretes onto compact objects, such as newborn stars or black holes. But never before have astronomers detected so many at once.

This remarkable discovery is expected to prompt significant changes in our understanding of the planetary nebulae population in the Galaxy, as well as properties of jets ejected from young forming stars.

The results come from a five-year survey (officially dubbed UWISH2) covering approximately 180 degrees of the northern sky, or 1450 times the size of the full moon. The survey utilizes the 3.8-meter UK Infrared Telescope on Mauna Kea, Hawai’i.

Caption: This image shows a field that contains a newly discovered photogenic planetary nebulae. Internally dubbed by the research team as the "Jelly-Fish PN" it shows an almost circular ring of emission from molecular hydrogen with a variety of structure in the ring itself and inside. The central ionizing source responsible for the radiation is a white dwarf, which is too faint at the near infrared wavelengths to be visible in the image. Image Credit: University of Kent — This image shows a field that contains a newly discovered photogenic planetary nebulae, known as “Jelly-Fish PN.” It shows an almost circular ring of emission from molecular hydrogen with a variety of structure in the ring itself and inside. Image Credit: University of Kent

At these longer wavelengths, any cosmic dust becomes transparent, allowing us to see regions previously hidden from view. This includes jets from protostars and planetary nebulae, as well as supernova remnants, the illuminated edges of vast clouds of gas and dust, and the warm regions that envelope massive stars and their associated clusters of smaller stars.

Based on current estimates using these data, the project expects to identify about 1000 jets from young stars — at least 90 percent of which are new discoveries — as well as 300 planetary nebulae — at least 50 percent of which are also new.

“These discoveries are very exciting,” said lead author Dirk Froebrich from the University of Kent in a press release. “We will ultimately have much better statistics, meaning we will be able to investigate the physical mechanisms that determine the jet lengths, as well as their power. This will bring us much closer to answering some of the fundamental questions of star formation: How are these jets launched and how much energy, mass and momentum do they feed back into the surrounding interstellar medium.”

July 31, 2014December 30, 2015 by Elizabeth Howell

Stargazing Timelapse Plus Apollo 14 Launch Soundtrack Is Pure Magic

It feels like a real stargazing session watching this video. You head out at dusk, waiting for the first few stars to emerge. Then there’s a moment when — if you’re in the right spot — whammo. The Milky Way pops out. The sky turns into a three-dimensional playground.

Combine that feeling with the Apollo 14 launch audio from 1971, and this timelapse is a lot of fun.

Continue reading “Stargazing Timelapse Plus Apollo 14 Launch Soundtrack Is Pure Magic”

July 30, 2014December 23, 2015 by Shannon Hall

Early Tidal and Rotational Forces Helped Shape Moon

Using a precision formation-flying technique, the twin GRAIL spacecraft will map the moon's gravity field, as depicted in this artist's rendering. Radio signals traveling between the two spacecraft provide scientists the exact measurements required as well as flow of information not interrupted when the spacecraft are at the lunar farside, not seen from Earth. The result should be the most accurate gravity map of the moon ever made. The mission also will answer longstanding questions about Earth's moon, including the size of a possible inner core, and it should provide scientists with a better understanding of how Earth and other rocky planets in the solar system formed. GRAIL is a part of NASA's Discovery Program. Image credit: NASA/JPL-Caltech

The shape of the moon deviates from a simple sphere in a way that scientists have struggled to explain. But new research shows that tidal forces during the moon’s early history can explain most of its large-scale topography. As the moon cooled and solidified more than four billion years ago, the sculpting effects of tidal and rotational forces became frozen in place.

Astronomers think the moon formed when a rogue planet, larger than Mars, struck the Earth in a great, glancing blow. A cloud rose 13,700 miles (22,000 kilometers) above the Earth, where it condensed into innumerable solid particles that orbited the Earth. Over time these moonlets combined to form the moon.

So the moon was sculpted by Earth’s gravity from the get-go. Although scientists have long postulated that tidal forces helped shape the molten moon, the new study provides a much more detailed understanding of the additional forces at play.

Ian Garrick-Bethell from UCSC and colleagues studied topographic data gathered by NASA’s Lunar Reconnaissance Orbiter (LRO) and information about the moon’s gravity field collected by the agency’s twin GRAIL (Gravity Recovery and Interior Laboratory) spacecraft.

Not long after the moon’s formation, the crust was decoupled from the mantle below by an intervening ocean of magma. This caused immense tidal forces. At the poles, where the flexing and heating was greatest, the crust became thinner, while the thickest crust formed at the equators. Garrick-Bethel likened this to a lemon shape with the long axis of the lemon pointing at the Earth.

But this process does not explain why the bulge is now only found on the far side of the moon. You would expect to see it on both sides, because tides have a symmetrical effect.

“In 2010, we found one area that fits the tidal heating effect, but that study left open the rest of the moon and didn’t include the tidal-rotational deformation. In this paper we tried to bring all those considerations together,” said Garrick-Bethell in a press release.

Any rotational forces would cause the spinning moon to flatten slightly at the poles and bulge out near the equator. It would have had a similar effect on the moon’s shape as the tidal heating did — both of which left distinct signatures in the moon’s gravity field. Because the crust is lighter than the underlying mantle, gravity signals reveal variations in the moon’s internal structure, many of which may be due to previous forces.

Interestingly, Garrick-Bethell and colleagues discovered that the moon’s overall gravity field is no longer aligned with the topography. The long axis of the moon doesn’t point directly toward Earth as it likely did when the moon first formed; instead, it’s offset by about 30 degrees.

“The moon that faced us a long time ago has shifted, so we’re no longer looking at the primordial face of the moon,” said Garrick-Bethell. “Changes in the mass distribution shifted the orientation of the moon. The craters removed some mass, and there were also internal changes, probably related to when the moon became volcanically active.”

The details and timing of these processes are still uncertain, but the new analysis should help shed light on the tidal and rotational forces abundant throughout the Solar System and the Galaxy. These simple forces, after all, have helped shape our nearest neighbor and the most distant exoplanet.

The results have been published today in Nature.

July 30, 2014December 23, 2015 by Shannon Hall

Mysterious Molecules in Space Named?

The diffuse interstellar bands. Image Credit: P. Jenniskens, F. X. Desert

It’s a well-kept secret that the vacuum of space is not — technically speaking — a vacuum. Strong winds generated from supernova explosions push material into the interstellar medium, tainting space with the heavier elements generated by nuclear fusion. These lonely molecules account for a significant amount of all the hydrogen, carbon, silicon, and other atoms in the Universe.

Although these molecules remain mysterious, since we don’t know their exact chemical composition or atomic arrangements, they’re likely the cause of diffuse interstellar bands: unknown fingerprints within the spectra of distant astronomical objects.

New research, however, offers a tantalizing new possibility: these mysterious molecules may be silicon hydrocarbons.

Researchers on Earth should be able to identify the interstellar molecules easily. They simply have to demonstrate which molecules in the laboratory absorb light at the same wavelengths as the diffuse interstellar bands. But despite decades of effort, the identity of the molecules has remained a mystery.

“Not a single one has been definitively assigned to a specific molecule,” said coauthor Neil Reilly from the Harvard-Smithsonian Center for Astrophysics in a press release.

Now, Michael McCarthy from the Harvard-Smithsonian Center for Astrophysics, Reilly, and their colleagues are pointing to an unusual set of molecules — silicon-terminated carbon chain radicals such as SiC3H, SiC4H and SC5H — as potential twins to those found in interstellar space.

The researchers, however, were unable to create every spectral absorption line (over 400) responsible for the diffuse interstellar bands. But they think that longer molecules in this silicon-containing hydrocarbon family might cause the lines.

Absorption wavelength as a function of the number of carbon atoms in the silicon-terminated carbon chains SiC_(2n+1)H, for the extremely strong pi-pi electronic transitions. When the chain contains 13 or more carbon atoms - not significantly longer than carbon chains already known to exist in space - these strong transitions overlap with the spectral region occupied by the elusive diffuse interstellar bands (DIBs). CREDIT: D. Kokkin, ASU — Absorption wavelength as a function of the number of carbon atoms in the silicon-terminated carbon chains SiC_(2n+1)H. When the chain contains 13 or more carbon atoms — not significantly longer than carbon chains already known to exist in space — these strong transitions overlap with the spectral region occupied by the elusive diffuse interstellar bands. Image Credit: D. Kokkin, ASU

So the group remains cautious. History shows that while many possibilities have been proposed as the source of diffuse interstellar bands, none have been proven definitely. And they certainly need to conduct further research before they can say with certainty they’ve identified the mysterious interstellar molecules.

“The interstellar medium is a fascinating environment,” said McCarthy. “Many of the things that are quite abundant there are really unknown on Earth.”

July 30, 2014December 23, 2015 by Shannon Hall

ALMA Observes Binary Star System with Wacky Disks

ALMA data of HK Tau shown in a composite image with Hubble infrared and optical data. Credit: B. Saxton (NRAO/AUI/NSF); K. Stapelfeldt et al. (NASA/ESA Hubble)

When it comes to exoplanets, we’ve discovered an array of extremes — alien worlds that seem more like science fiction than reality. But there are few environments more extreme than a binary star system in which planet formation can occur. Powerful gravitational perturbations from the two stars can easily grind a planet to dust, let alone prevent it from forming in the first place.

A new study has uncovered a striking pair of wildly misaligned planet-forming disks in the young binary star system HK Tau. It’s the clearest picture ever of protoplanetary disks around a double star, shedding light on the birth and eventual orbit of the planets in a multiple star system.

The “Atacama Large Millimeter/submillimeter Array (ALMA) has given us an unprecedented view of a main star and its binary companion sporting mutually misaligned protoplanetary disks,” said Eric Jensen from Swarthmore College in a press release. “In fact, we may be seeing the formation of a solar system that may never settle down.”

The two stars in the system — located roughly 450 light-years away in the constellation Taurus — are less than four million years old and are separated by about 58 billion kilometers, or 13 times the distance of Neptune from the Sun.

ALMA’s high sensitivity and unprecedented resolution allowed Jensen and colleagues to fully resolve the rotation of HK Tau’s two protoplanetary disks.

“It’s easier to observe spread-out gas and dust because it has more surface area – just in the same way that it might be hard to see a small piece of chalk from a distance, but if you ground up the chalk and dispersed the cloud of chalk dust, you could see it from farther away,” Jensen told Universe Today.

The key velocity data taken with ALMA that helped the astronomers determine that the disks in HK Tau were misaligned. The red areas represent material moving away from Earth and the blue indicates material moving toward us. Credit: NASA/JPL-Caltech/R. Hurt (IPAC) — The key velocity data taken with ALMA. The red areas represent material moving away from Earth and the blue indicates material moving toward us. Image Credit: NASA / JPL-Caltech / R. Hurt (IPAC)

The carbon monoxide gas orbits both stars in two broad belts that are clearly rotating — the side spinning away from us is redshifted, while the side spinning toward us is blueshifted.

“What we find in this binary system is that the two orbiting disks are oriented very differently from each other, with about a 60 or 70 degree angle between their orbital planes,” Jensen told Universe Today. Because the disks are so misaligned it’s clear that at least one is also out of sync with the orbit of their host stars.

“This clear misalignment has given us a remarkable look at a young binary star system,” said coauthor Rachel Akeson from the NASA Exoplanet Science Institute at the California Institute of Technology. “Though there have been hints before that this type of misaligned system exists, this is the cleanest and most striking example.”

Stars and planets form out of vast clouds of dust and gas. Small pockets in these clouds collapse under the pull of gravity. But as the pocket shrinks, it spins rapidly, with the outer region flattening into a turbulent disk. Eventually the central pocket becomes so hot and dense that it ignites nuclear fusion — in the birth of a star — while the outer disk — now the protoplanetary disk — begins to form planets.

Despite forming from a flat, regular disk, planets can end up in highly eccentric orbits, and may be misaligned with the star’s equator. One likely explanation is that a binary companion star influences them — but only if its orbit is initially misaligned with the planets.

“Because these disks are misaligned with the binary orbit, then so too will be the orbits of any planets they form,” Jensen told Universe Today. “So in the long run, the binary companion will influence those planet orbits, causing them to oscillate and tend to come more into line with the binary orbit, and at the same time become more eccentric.”

Looking forward, the researchers want to determine if this type of system is typical or not. If it is, then tidal forces from companion stars may easily explain the orbital properties that make the present sample of exoplanets so unlike the planets of our own Solar System.

The results will appear in Nature on July 31, 2014.

July 29, 2014December 30, 2015 by Shannon Hall

GAIA is “Go” for Science After a few Minor Hiccups

Gaia Camera Array - Credit: Astrium / ESA

In astronomy we throw around the term “light-year” seemingly as fast as light itself travels. And yet actually measuring this distance is incredibly tricky. A star’s parallax — its tiny apparent shift once a year caused by our moving viewpoint on Earth — tells its distance more truly than any other method.

Accurate parallaxes of nearby stars form the base of the entire cosmic distance ladder out to the farthest galaxies. It’s a crucial science that’s about to take a giant leap forward. The European Space Agency’s long-awaited Gaia observatory — launched on Dec. 19, 2013 — is now ready to begin its science mission. Continue reading “GAIA is “Go” for Science After a few Minor Hiccups”