Amateur Images Show Juno’s ‘Slingshot’ Around Earth Was a Success

The path of the Juno spacecraft imaged as it flies past Earth on October 9, 2013, using the iTelescope Observatory in Nerpio, Spain. Credit and copyright: Ernesto Guido, Nick Howes and Martino Nicolini/Remanzacco Observatory.

With the government shutdown, news out of NASA is sometimes sparse. But thankfully amateur astronomers can fill in some of the holes! While Juno’s project manager Rick Nybakken has confirmed that the spacecraft successfully completed its slingshot flyby of Earth yesterday, images taken by amateur astronomers around the world also conclusively confirm that Juno is now “bang on target!” tweeted Nick Howes of the Remanzacco Observatory team. This image from Howes, Ernesto Guido and Martino Nicolini shows the path of Juno across the sky, as seen from a remote telescope in Spain. “The spacecraft is trailed in the image due to its fast speed,” the team wrote on their website, and extrapolations of Juno’s orbit shows it is heading straight for Jupiter.

You can see a gallery of images of Juno’s flyby taken by amateurs on this SpaceWeather.com page.

Meanwhile, there are some concerns about the spacecraft going into safe mode immediately after the flyby. Our previous article by Ken Kremer reported that the mission teams are assessing the situation, and that the spacecraft is “power positive.”

One idea of why the spacecraft went into safe mode is that the battery was being depleted faster than anticipated, but the team is still working to confirm the reason.

Closest approach was at 12:21 PM PST (19:21 UTC, 3:21 PM EDT).

For more information about the flyby, check out this new video from Bill Nye the Science Guy — who has a new video series called “Why With Nye.”

Juno's flyby path, via Heaven's Above.
Juno’s flyby path, via Heaven’s Above.

A Crash Put Pluto’s Moons Into Odd Orbits: Study

Pluto's solar system in a 2012 artist's conception. P4 and P5 are now called Kerberos and Styx, respectively. Credit: NASA/John Hopkins University Applied Physics Laboratory

A smash-up that created Pluto’s largest moon, Charon, likely sprayed debris four billion years ago that formed the genesis of the other moons scientists are spotting today, a new study concludes.

The find could explain why the satellites Styx, Nix, Kereberos and Hydra have orbital periods that are, respectively, just about exactly 3, 4, 5 and 6 times longer than Charon’s, scientists said.

“Any initially surviving satellites would likely be destroyed in collisions, but these shattered moons wouldn’t be lost; rather, their remains would stay in the Pluto/Charon system and become the starting point for building new satellites,” stated the Southwest Research Institute (SWRI), which led the study.

Artist's impression of New Horizons' encounter with Pluto and Charon. Credit: NASA/Thierry Lombry
Artist’s impression of New Horizons’ encounter with Pluto and Charon. Credit: NASA/Thierry Lombry

“In modeling the destruction of the satellites, the SWRI study found that there may be a method for moving them, or their building blocks, outward, due to the competing effects of Charon’s gravitational kicks and collisions among the debris of the disrupted satellites.”

Given Charon’s large size relative to Pluto (it’s a tenth of the dwarf planet’s size, compared to the Earth-Moon 81: 1 ratio), its large mass could easily perturb these smaller moons if they got close. Also, collisions between the debris could alter the orbits “to keep things away from Charon”, the scientists said.

Hopefully we will learn more when the NASA New Horizons spacecraft arrives at Pluto in 2015.

The findings were presented yesterday (Oct. 9) at the American Astronomical Association’s division of planetary sciences meeting in Denver; information on whether the results are peer-reviewed was not immediately available.

Source: Southwest Research Institute

Tranquil Galaxy With Petals Shows Clues To A Violent Past

PGC 6240, a petal-like galaxy that probably was altered by a galactic merger. Credit: ESA/Hubble & NASA with acknowledgement to Judy Schmidt

Across the universe, some 350 million light-years away, lies a galaxy that looks like it has white rose petals. Don’t let the tranquil appearance of PGC 6240 fool you as to its past, however. This galaxy in Hydrus (The Water Snake) likely was dramatically altered by a galactic merger.

There’s a bunch of evidence pointing to this. There are “star shells” of globular clusters around the galaxy, but they’re distributed unevenly — some are close in, some are way out in the distant suburbs. Also, “several wisps of material have been thrown so far that they appear to be almost detached from the galaxy altogether,” stated the Hubble European Space Agency Information Centre.

“The most likely explanation for both the galaxy’s stacked shell structure and the unexpectedly young star clusters is that PGC 6240 merged with another galaxy at some point in the recent past,” the agency added.

“Such a merger would send ripples through the galaxy and disrupt its structure, forming the concentric shells of material seen here. It would also ignite a strong burst of star formation in the galaxy, which would then trigger similar activity in nearby space — leading to the creation of new, younger globular clusters around PGC 6240.”

Source: The Hubble European Space Agency Information Centre

Baby Free-Floating Planet Found Alone, Away From A Star

Artist's conception of PSO J318.5-22. Credit: MPIA/V. Ch. Quetz

The planetary world keeps getting stranger. Scientists have found free-floating planets — drifting alone, away from stars — before. But the “newborn” PSO J318.5-22 (only 12 million years old) shows properties similar to other young planets around young stars, even though there is no star nearby the planet.

“We have never before seen an object free-floating in space that that looks like this. It has all the characteristics of young planets found around other stars, but it is drifting out there all alone,” stated team leader Michael Liu, who is with the Institute for Astronomy at the University of Hawaii at Manoa. “I had often wondered if such solitary objects exist, and now we know they do.”

Image from the Pan-STARRS1 telescope of the free-floating planet PSO J318.5-22, in the constellation of Capricornus. Credit: N. Metcalfe & Pan-STARRS 1 Science Consortium
Image from the Pan-STARRS1 telescope of the free-floating planet PSO J318.5-22, in the constellation of Capricornus. Credit: N. Metcalfe & Pan-STARRS 1 Science Consortium

The planet is about 80 light-years from Earth, which is quite close, and is part of a star group named after Beta Pictoris that also came together about 12 million years ago. There is a planet in orbit around Beta Pictoris itself, but PSO J318.5-22 has a lower mass and likely had a different formation scenario, the researchers said.

Astronomers uncovered the planet, which is six times the mass of Jupiter, while looking for brown dwarfs or “failed stars.” PSO J318.5-22’s ultra-red color stood apart from the other objects in the survey, astronomers said.

The free-floating planet was identified in the Pan-STARRS 1 wide-field survey telescope in Maui. Follow-up observations were performed with several other Hawaii-based telescopes, including the NASA Infrared Telescope Facility, the Gemini North Telescope, and the Canada-France-Hawaii Telescope.

The discovery will soon be detailed in Astrophysical Letters, but for now you can read the prepublished verison on Arxiv.

Source: Institute for Astronomy at the University of Hawaii

Jupiter And Saturn May Be Rich In Diamonds

“Picture yourself in a boat on a river…” And make it a river of liquid hydrogen and helium deep within the atmospheres of Jupiter and Saturn. You might not find a girl with kaleidoscope eyes, but you may very well find diamonds. According to new research, there may be an abundance of these precious gemstones swirling about in the skies of our solar system’s giant planets.

Recent data compiled by planetary scientists Mona L. Delitsky of California Specialty Engineering in Pasadena, California, and Kevin H. Baines of the University of Wisconsin-Madison, has been combined with newly published pressure temperature diagrams of Jupiter and Saturn. These diagrams, known as adiabats, allow researchers to decipher at what interior level that diamond would become stable. They also allow for calculations at lower levels – regions where both temperature and pressure are so concentrated that diamond becomes a liquid. Imagine diamond rain… or rivulets of pure gemstone.

These adiabats of Saturn and Jupiter’s interior materials have been improved through new equations. Through the use of shockwave techniques, researchers at Sandia Laboratories and Lawrence Livermore National Laboratory have been provided with set boundaries for the various states of carbon. From these findings, you would be amazed at the chain of events at what might make diamonds occur. According to Delitsky and Baines, carbon could be generated as soot or graphite from a lightning strike. Since lightning is normal during Saturn’s many huge electrical storms, it stands to reason this elemental carbon would descend to a lower atmospheric level to be compressed into solid diamonds. It would then further descend towards the planet’s core to be eventually “pressure cooked” into a liquid state.

While the idea of diamonds at the heart of planets like Uranus and Neptune has been known for at least three decades, planetary scientists have been hesitant to include Jupiter and Saturn, concluding they were either too cool, too hot, or otherwise not suitable for the production of solid diamonds. Just as Jupiter and Saturn are much warmer at their cores, Uranus and Neptune are much too cold to sustain diamonds in a liquid state. However, thanks to the latest data, researchers are confident that deep inside Saturn there may be diamonds so large that they could be referred to as “diamondbergs”!

delitsky_alien_seas_diamondcruiseIs this the kind of stuff we dream of one day mining? You bet. In a book entitled “Alien Seas” (Springer 2013), Baines and Delitsky have devoted a chapter to the ringed planet entitled “The Seas of Saturn”. Here the duo elucidates on the new, accurate data and makes up a story about robotic mining missions delving deep into the interior of Saturn. Spooky robot hands reach out through the mist, gathering chunks of diamonds and ready them for return to Earth. Because of this new information, theorists Delitsky and Baines report that “diamonds are forever on Uranus and Neptune and not on Jupiter and Saturn.”

Ah, well… I’m still watching for Lucy in the sky.

This news release is based on DPS abstract #512.09 by M. L. Delitsky and K. H. Baines for their conference oral talk on Friday, 11 October 2013.

NASA’s Juno probe Gets Gravity Speed Boost during Earth Flyby But Enters ‘Safe Mode’

The first color reconstruction of the Moon by Adam Hurcewicz

Developing story – NASA’s Juno-bound Jupiter orbiter successfully blazed past Earth this afternoon (Oct. 9) and gained its huge and critical gravity assisted speed boost that’s absolutely essential to reach the Jovian system in 2016.

However, Juno’s project manager Rick Nybakken told me moments ago that the Juno spacecraft unexpectedly entered ‘safe mode’ during the fly by maneuver and the mission teams are assessing the situation.

But the very good news is “Juno is power positive at this time. And we have full command ability,” said Nybakken in an exclusive phone interview with me.

“After Juno passed the period of Earth flyby closest approach at 12:21 PM PST [3:21 PM EDT] and we established communications 25 minutes later, we were in safe mode,” Nybakken told me. Nybakken is the Juno mission project manager at NASA’s Jet Propulsion Lab in Pasadena, CA.

Furthermore, the Earth flyby did place the $1.1 Billion Juno spacecraft exactly on course for Jupiter as intended.

“We are on our way to Jupiter as planned!”

“None of this affected our trajectory or the gravity assist maneuver – which is what the Earth flyby is.”

Juno’s closest approach was over South Africa at about 500 kilometers (350 miles).

“Juno hit the target corridor within 2 km of the aim point,” Nybakken elaborated to Universe Today.

Juno needs the 16,330 mph velocity boost from the Earth swingby because the Atlas V launcher was not powerful enough to hurtle the 8000 pound (3267 kg) craft fast enough on a direct path to Jupiter.

And the team is in full radio contact with the probe. Safe mode is a designated protective state.

“Prior to the eclipse, which was a few minutes earlier than closest approach, the spacecraft was ‘nominal’. When we came out of the eclipse Juno was in safe mode,” Nybakken stated.

“We are going through safe mode diagnostics steps right now.”

“We have established full uplink and downlink. And we have full command ability of the spacecraft.”

First JunoCam image of the day! Taken at 11:07 UTC when Juno was 206,000 Kilometers from the Moon.
First JunoCam image of the day! Taken at 11:07 UTC when Juno was 206,000 Kilometers from the Moon.

Speed boosting slingshots have been used on numerous planetary missions in the past

The spacecraft’s power situation and health is as good as can be expected.

“Juno is power positive at this time and sun pointed and stable. So we are very pleased about that,” Nybakken explained.

I asked if Juno had ever entered ‘safe mode’ before?

“We have never been in safe mode before. We are in a safe, stable state.”

“We are investigating this,” said Nybakken.

Credit: NASA/JPL
Credit: NASA/JPL

Today’s (Oct. 9) Earth flyby is the only time the spacecraft experiences an eclipse period during Juno’s entire five year and 1.7 Billion mile (2.8 Billion km) trek to Jupiter, the largest planet in our solar system.

When it finally arrives at Jupiter on July 4, 2016, Juno will become the first polar orbiting spacecraft at the gas giant.

NASA’s Juno spacecraft blasted off atop an Atlas V rocket two years ago from Cape Canaveral Air Force Station, FL, on Aug. 5, 2011 on a journey to discover the genesis of Jupiter hidden deep inside the planet’s interior.

Juno soars skyward to Jupiter on Aug. 5, 2013 from launch pad 41 at Cape Canaveral Air Force Station at 12:25 p.m. EDT. View from the VAB roof. Credit: Ken Kremer/kenkremer.com
Juno soars skyward to Jupiter on Aug. 5, 2011 from launch pad 41 at Cape Canaveral Air Force Station at 12:25 p.m. EDT. View from the VAB roof. Credit: Ken Kremer/kenkremer.com
The science team had also hoped to use the on board JunoCam imager to make a cool and unprecedented movie of Earth as it approached from the sunlit side – showing the passage as though you were a visitor from outer space.

I had an inkling that something might be amiss this afternoon when no images of Earth appeared on the Juno mission website.

So I asked the status.

“We don’t know yet if any images of Earth were collected. We hope to know soon.”

Juno flew past the Moon before the gravity assist slingshot with Earth. And it did manage to successfully capture several lunar images. See the images herein.

Read more about Juno in my flyby preview story – here.

Note: Due to the continuing chaos resulting from the US government partial shutdown caused by gridlocked politico’s in Washington DC, NASA public affairs remains shut down and is issuing no official announcements on virtually anything related to NASA! This pertains to Juno’s flyby, LADEE’s lunar arrival on Oct. 6, MAVEN’s upcoming launch in November, Cygnus at the ISS, and more!

Stay tuned here for continuing Juno, LADEE, MAVEN and more up-to-date NASA news.

Ken Kremer

NASA’s Juno Jupiter-bound space probe will fly by Earth for essential speed boost on Oct 9, 2013. Credit: NASA/JPL
NASA’s Juno Jupiter-bound space probe will fly by Earth for essential speed boost on Oct 9, 2013. Credit: NASA/JPL

New Data: Will Comet ISON Survive its Close Perihelion Passage?

An analysis of the dust coma of comet ISON showing the evaporation of ice particles. (Credit: NASA/ESA J.-Y. Li (Planetary Science Institute and the Hubble ISON Imaging Science Team).

It’s the question on every astronomer’s mind this season, both backyard and professional: will Comet C/2012 S1 ISON survive perihelion?

Now, new studies released today at the American Astronomical Society’s 45th Annual Division for Planetary Sciences meeting being held this week in Denver suggests that ISON may have the “right stuff” to make it through its close perihelion passage near the Sun. This is good news, as Comet ISON is expected to be the most active and put on its best showing post-perihelion… if it survives.

Researchers Matthew Knight of the Lowell Observatory and Research Scientist Jian-Yang Li of the Planetary Science Institute both presented a compelling portrait of the characteristics and unique opportunities presented by the approach of comet ISON to the inner solar system.

Jian-Yang Li studied ISON earlier this year using Hubble before it passed behind the Sun from our Earthly vantage point. Li and researchers were able to infer the position and existence of a jet coming from the nucleus of the comet, which most likely marks the position of one of its rotational poles.

“We measured the rotational pole of the nucleus,” Li noted in a press release from the Planetary Science Institute. The pole indicates that only one side of the comet is being heating by the Sun on its way in until approximately one week before it reaches its closest point to the Sun.”

Could we be in for a “surge” of activity from ISON coming from around November 20th on?

Comet ISON as imaged from Aguadilla, (sp) Puerto Rico recently on october 6th. (Credit: Efrain Morales Rivera).
Comet ISON as imaged from Aguadilla, Puerto Rico recently on October 6th. (Credit: Efrain Morales Rivera).

Li also noted that the reddish color of the coma of ISON suggests an already active comet sublimating water ice grains as they move away from the nucleus. He also noted that time has been allocated to observe ISON using Hubble this week.

Next up, researcher Mathew Knight presented some encouraging news for ISON when it comes to surviving perihelion.

The findings were a result of numerical simulations carried out by Kevin Walsh and Knight, combined with a historical analysis of previous sun-grazing comets. Both suggest that comet nuclei smaller than 200 metres in diameter, with an average density or lower (for comets, that is) typically do not survive a close passage to the Sun.

Both researchers place the size of ISON’s nucleus in the range of 0.5 to 2 kilometres, comfortably above the 0.2 kilometre “shred limit” for its relative perihelion distance. ISON is not a technically Kreutz group sungrazer, though studies of the over 2,000 known Kreutz comets historically observed provide an interesting guideline for what might be in store for ISON. Four Kreutz comets, including C/2011 W3 Lovejoy and Comet C/1887 B1 partially survived perihelion to become “headless wonders,” while five, including Comet C/1965 S1 Ikeya-Seki — which ISON is often compared to — survived perihelion passage to become one of the great comets of the 20th century.

ISON will pass inside the Roche limit of the Sun, which is a distance of 2.4 million kilometres (for fluid bodies) and will be subject to temperatures approaching 5,000 degrees Fahrenheit on closest approach.

ISON is a first time visitor to the inner solar system. Discovered on September 21st, 2012 by Russian researchers Artyom Novichonok and Vitaly Nevsky participating in the International Scientific Optical Network, ISON will pass less than 1.2 million kilometres above the surface of the Sun on November 28th, 2013.

One interesting but little discussed factor highlighted in today’s press release was the retrograde versus prograde rotation of the cometary nucleus. A fast, prograde spin of an elongated nucleus may spell doom for ISON, as tidal forces will rip it apart. A retrograde rotator, however, is very likely to survive the encounter.

Thus far, there are no solid indications that ISON is indeed a retrograde rotator, although there are tantalizing hints that beg for further observations.

Li notes that it’s tough to infer a bias for comets like ISON to be retrograde over prograde rotators, as we’ve only got five historical comets to go by similar to ISON, and the breakdown is thus about 50/50 for and against.

ISON’s possible survival would validate both studies and their methods and give us more refined predictions for future comets.

“We’ve never discovered a sungrazer this far out,” Knight told Universe Today. “The rotation of ISON depends on the pole position (from Li’s study) and in theory, if we could get enough images, a proper morphology (for ISON) would emerge.”

Comet ISON imaged on October 5th from Long Beach, California. (Credit: Thad Szabo @AstroThad).
Comet ISON imaged on October 5th from Long Beach, California. (Credit: Thad Szabo @AstroThad).

The implications of this analysis is certainly good news for observers. If ISON survives perihelion, we would then have a brilliant dawn Christmas comet unfurling its tail off to the northeast in early December.

Of course, these findings are contrary to early cries of its demise, including the paper out of the Institute of Physics that has been circulating touting “The Impending Demise of ISON”. Read Universe Today editor Nancy Atkinson’s excellent synopsis on that, it’s a tale that just won’t seem to die.

And we’ve also done our skeptic’s duty of thoroughly debunking the mounting ISON lunacy, including its status as the harbinger for the “end of the world of the week,” as well as its inability to fulfill prophecy. But if we get a surge in ISON next month as researchers suggest, we fully expect the accompanying hype to crest as well.

The most recent observations put ISON at about +10th magnitude as it currently crosses the constellation Leo, near Mars and Regulus in the morning sky. We recently did an observing post tracking its plunge to perihelion in late November, and we’ve been diligently hunting for ISON with binoculars every morning pre-dawn.

We’re glad to have some positive science to report on for ISON. Things are looking up for a fine show come early December!

-Read the PSI press release on  JianYang Li’s findings as well as the original paper on ISON’s survival prospects by Matthew Knight.

Rocket Failures May Spur Change In Russian Federal Space Agency: Report

Archive picture of a Proton launch. Image credit: ILS

It appears that the Russian government wants to take action over the string of unmanned mission failures beleaguering Roscosmos, or the Russian Federal Space Agency. A recent example includes the loss in June of three GLONASS navigation/positioning satellites in a launch failure. In 2011, Roscosmos lost four major missions, including the Phobos-Grunt spacecraft that was bound for the Martian moon Phobos.

RIA Novosti reports that Dmitry Rogozin, Russia’s deputy prime minister, plans to create a new state entity to take over space manufacturing. The proposed United Rocket and Space Corporation, the report says, will reduce the reliance on imported parts to get missions off the ground, among other aims.

“A new state corporation will be created to take over manufacturing facilities from the Federal Space Agency, whose prestige has been severely dented in recent years by a string of failed rocket launches,” the report says. “The proposed United Rocket and Space Corporation will enable the trimming away of redundant departments replicated elsewhere in the space industry.”

As for Roscosmos itself, the report hints that other changes could be on the way. Its envisioned role is to “act as a federal executive body and contracting authority for programs to be implemented by the industry.” There are expected to be changes in management, among other measures.

The agency was formed after the breakup of the Soviet Union in 1991 and is responsible for most of Russia’s space activities. Russia’s heritage in space actually stretches back to the dawn of the space age in the 1950s and 1960s, when the country became the first nation to launch a satellite (Sputnik) and a human (Yuri Gagarin), among other milestones.

Read the whole report in Roscosmos.

How Could We Fix Gravity?

Gravity movie poster
Gravity movie poster

I finally caught up with the rest of the space journalist community and watched the new Gravity movie last night.

I absolutely loved it. It was by far the best movie I’ve seen this year, and I think one of the best space movies ever made.

The attention to detail on so many aspects of spaceflight was heartening: the cramped conditions of the space station, the perspective of the Earth, the lack of sound, the realistic physics (mostly).

WARNING – Spoilers Ahead

I believe that good art benefits from constraints. And in this case, director Alfonso Cuarón gave himself the constraint of a realistic portrayal of space, and it paid off in so many ways.

Except when he didn’t. There are a pile of unscientific moments that happen in the movie, that I think could have been easily fixed in the script stage.

It would have been amazing to hear Phil Plait or Neil deGrasse Tyson scratching their heads, unable to find a single scientific flaw.

So let’s fix Gravity

I’ll go first.

Remember I said spoilers? Here come the spoilers.

Stone can’t hold on to Kowalski and he’s forced to detach himself – As it was portrayed in the movie, and noted by Phil, he had no force pulling him away from Stone, so she should have been able to easily tug him back. But if the station was rotating quickly enough, there would be outward centripetal force.

People have speculated on the internet that it was rotating, and the background stars are shifting. But if that was the case, loose ropes and cables would be extending out from the station. And things wouldn’t have been floating so freely inside the station.

Solution:

As the astronauts are approaching the ISS, they noticed that the first Soyuz had already been used to abandon the station – what if they gave the station a kick as they departed in a rush? So maybe Kowalski could have noticed that the station was spinning. And the mess of parachute lines would have been taut, reflecting that.

That would have made hanging onto the lines more difficult, and would have been enough force to tear Kowalski away.

Your turn. What was a problem in the story, and how could it have been fixed without seriously ruining the movie?

I posted this topic over on Google+ and got some great suggestions for topics:

  • How could you get a debris cascade going so quickly?
  • Shouldn’t airlocks open inward?
  • Why did a fire start at the exact moment Stone gets on board ISS?
  • How could you get from Hubble to ISS to Tiangong? They’re on different orbital trajectories?
  • Why would communications satellites get taken out? They’re at a much higher altitude.
  • Why wasn’t Stone wearing traditional astronaut undergarments and, uh, a diaper?
  • Why didn’t Stone’s hair float in microgravity?

What scientific inconsistencies did you see, and how would you fix them?

Detecting the Magnetic Fields of Exoplanets May Help Determine Habitability

An artist's conception of two magnetic fields interacting in a bow shock. Image credit: NASA

Astronomers may soon be able to observe the shockwaves between the magnetic fields of exoplanets and the flow of particles from the stars they orbit.

Magnetic fields are crucial to a planet’s (and as it turns out a moon’s) habitability. They act as protective bubbles, preventing harmful space radiation from stripping away the object’s atmosphere entirely and even reaching the surface.

An extended magnetic field – known as a planetary magnetosphere – is created by the shock between the stellar wind and the intrinsic magnetic field of the planet. It has the potential to be huge. Within our own Solar System, Jupiter’s magnetosphere extends to distances up to 50 times the size of the planet itself, nearly reaching Saturn’s orbit.

When the wind of high-energy particles from the star hits the planetary magnetosphere, it interacts in a bow shock that diverts the wind and compresses the magnetosphere.

Recently a team of astronomers, led by PhD student Joe Llama of the University of St. Andrews, Scotland, have worked out how we might observe planetary magnetospheres and stellar winds via their bow shocks.

Llama took a careful look at the planet HD 189733b, located 63 light years away toward the constellation Vulpecula. From the Earth, the planet is seen to transit its host star every 2.2 days, causing a dip in the overall light from the system.

As a bright star, HD 189733b has been studied extensively by astronomers.  Data collected in July 2008 by the Canada-France-Hawaii telescope mapped the star’s magnetic field. While the magnetic field varied, it was on average 30 times greater than that of our Sun – meaning that the stellar wind is much higher than the solar wind.

This allowed the team to carry out extensive simulations of the stellar wind around HD 189733b – characterizing the bow shock created as the planet’s magnetosphere passes through the stellar wind.  With this information they were able to simulate the light curves that would result from the planet and the bow shock orbiting the star.

The bow shock leads the planet – causing the light to drop a little earlier than expected.  The amount of light blocked by the bow shock, however, will change as the planet moves through a variable stellar wind. If the stellar wind is particularly strong, the resulting bow shock will be strong, and the transit depth will be greater. If the stellar wind is weak, the resulting bow shock will be weak, and the transit depth will be less.

The video below shows the light curve of a bow shock and exoplanet.

“We found that the shockwave between the stellar and planetary magnetic fields will change drastically as activity on the star varies,” Llama told Universe Today. “As the planet passes through very dense regions of the stellar wind, so the shock will become denser, the material in it will block more light and therefore cause a larger dip in the transit making it more detectable.”

While there were no transit observations for this study, this theoretical outlook demonstrates that it will be possible to detect the bow shock, and therefore the magnetic field, of a distant exoplanet. Dr. Llama comments: “This will help us to better identify potentially habitable worlds.”

The paper has been accepted for publication in Monthly Notices of  The Royal Astronomical Society and is available for download here.