Universe Today

July 12, 2016April 8, 2018 by Evan Gough

ESA Prepares Revolutionary Air Breathing Rocket Engine

The SABRE (Synergistic Air-Breathing Rocket Engine) could revolutionize access to space. Image: Reaction Engines

If new rocket engines being developed by the European Space Agency (ESA) are successful, they could revolutionize rocket technology and change the way we get to space. The engine, called the Synergistic Air-Breathing Rocket Engine (SABRE), is designed to use atmospheric air in the early flight stages, before switching to conventional rocket mode for the final ascent to space. If all goes well, this new air-breathing rocket could be ready for test firings in about four years.

Conventional rockets have to carry an on-board oxidizer such as liquid oxygen, which is combined with fuel in the rocket’s combustion chamber. This means rockets can require in excess of 250 tons of liquid oxygen in order to function. Once this oxygen is consumed in the first stages, these used up stages are discarded, creating massive waste and expense. (Companies like SpaceX and Blue Origin are developing re-usable rockets to help circumvent this problem, but they’re still conventional rockets.)

Conventional rockets carry their own oxygen because its temperature and pressure can be controlled. This guarantees the performance of the rocket, but requires complicated systems to do so. SABRE will eliminate the need for carrying most on-board oxygen, but this is not easy to do.

SABRE’s challenge is to compress the atmospheric oxygen to about 140 atmospheres before introducing it into the engine’s combustion chambers. But compressing the oxygen to that degree raises its temperature so much that it would melt the engines. The solution to that is to cool the air with a pre-cooling heat exchanger, to the point where it’s almost a liquid. At that point, a turbine based on standard jet engine technology can compress the air to the required operating temperature.

This means that while SABRE is in Earth’s atmosphere, it uses air to burn its hydrogen fuel, rather than liquid oxygen. This gives it an 8 x improvement in propellant consumption. Once SABRE has reached about 25 km in altitude, where the air is thinner, it switches modes and operates as a standard rocket. By the time it switches modes, it’s already about 20% of the way into Earth orbit.

Like a lot of engineering challenges, understanding what needs to be done is not the hard part. Actually developing these technologies is extremely difficult, even though many people just assume engineers will be successful. The key for Reaction Engines Ltd, the company developing SABRE, is to develop the light weight heat exchangers at the heart of the engine.

Heat exchangers are common in industry, but these heat exchangers have to cool incoming air from 1000 Celsius to -150 Celsius in less than 1/100th of a second, and they have to do it while preventing frost from forming. They are extremely light, at about 100 times lighter than current technology, which will allow them to be used in aerospace for the first time. Some of the lightness factor of these new heat exchanges stems from the wall thickness of the tubing, which is less than 30 microns. That’s less than the thickness of a human hair.

Reaction Engines Limited says that these heat exchangers will have the same impact on aerospace propulsion systems that silicone chips had on computing.

A new funding agreement with the ESA will provide Reaction Engines with 10 million Euros for continued development of SABRE. This will add to the 50 million Pounds that the UK Space Agency has already contributed. That 50 million Pound investment was the result of a favorable viability review of SABRE that the ESA performed in 2010.

In 2012 the pre-cooler, a vital component of SABRE, was successfully tested at Reaction Engines facility in Oxfordshire, UK. Image: ESA/Reaction Engines

IN 2012, the pre-cooler and the heat exchangers were tested. After that came more R&D, including the development of altitude-compensating rocket nozzles, thrust chamber cooling, and air intakes.

Now that the feasibility of SABRE has been strengthened, Reaction Engines wants to build a ground demonstrator engine by 2020. If the continued development of SABRE goes well, and if testing by 2020 is successful, then these Air Breathing rocket engines will be in a position to truly revolutionize access to space.

In ESA’s words, “ESA are confident that a ground test of a sub-scale engine can be successfully performed to demonstrate the flight regime and cycle and will be a critical milestone in the development of this program and a major breakthrough in propulsion worldwide.”

Bring it on.

July 12, 2016September 20, 2016 by Matt Williams

ESA Discovers Where All The Missing Socks Have Been Going

earth's atmosphere has an ozone hole (not seen here) — Earth’s atmosphere seen from space. The top layer of the stratosphere is the ozone layer, which protects us from harmful solar UV. Scientists are tracking the ozone hole over the Antarctic. Credit: NASA

We here at Earth are fortunate that we have a viable atmosphere, one that is protected by Earth’s magnetosphere. Without this protective envelope, life on the surface would be bombarded by harmful radiation emanating from the Sun. However, Earth’s upper atmosphere is still slowly leaking, with about 90 tonnes of material a day escaping from the upper atmosphere and streaming into space.

And although astronomers have been investigating this leakage for some time, there are still many unanswered questions. For example, how much material is being lost to space, what kinds, and how does this interact with solar wind to influence our magnetic environment? Such has been the purpose of the European Space Agency’s Cluster project, a series of four identical spacecraft that have been measuring Earth’s magnetic environment for the past 15 years.

Understanding our atmosphere’s interaction with solar wind first requires that we understand how Earth’s magnetic field works. For starters, it extends from the interior of our planet (and is believed to be the result of a dynamo effect in the core), and reaches all the way out into space. This region of space, which our magnetic field exerts influence over, is known as the magnetosphere.

The four Cluster spacecraft crossing the northern cusp of Earth's magnetosphere. Credit: ESA/AOES Medialab — *The four Cluster spacecraft crossing the northern cusp of Earth’s magnetosphere. Credit: ESA/AOES Medialab*

The inner portion of this magnetosphere is called the plasmasphere, a donut-shaped region which extends to a distance of about 20,000 km from the Earth and co-rotates with it. The magnetosphere is also flooded with charged particles and ions that get trapped inside, and then are sent bouncing back and forth along the region’s field lines.

At its forward, Sun-facing edge, the magnetosphere meets the solar wind – a stream of charged particles flowing from the Sun into space. The spot where they make contact is known as the “Bow Shock”, which is so-named because its magnetic field lines force solar wind to take on the shape of a bow as they pass over and around us.

As the solar wind passes over Earth’s magnetosphere, it comes together again behind our planet to form a magnetotail – an elongated tube which contains trapped sheets of plasma and interacting field lines. Without this protective envelope, Earth’s atmosphere would have been slowly stripped away billions of years ago, a fate that is now believed to have befallen Mars.

That being said, Earth’s magnetic field is not exactly hermetically sealed. For example, at our planet’s poles, the field lines are open, which allows solar particles to enter and fill our magnetosphere with energetic particles. This process is what is responsible for Aurora Borealis and Aurora Australis (aka. the Northern and Southern Lights).

*An illustration showing the natural barrier Earth gives us against solar radiation. Credit: NASA.*

At the same time, particles from Earth’s upper atmosphere (the ionosphere) can escape the same way, traveling up through the poles and being lost to space. Despite learning much about Earth’s magnetic fields and how plasma is formed through its interaction with various particles, much about the whole process has been unclear until quite recently.

As Arnaud Masson, ESA’s Deputy Project Scientist for the Cluster mission stated in an ESA press release:

“The question of plasma transport and atmospheric loss is relevant for both planets and stars, and is an incredibly fascinating and important topic. Understanding how atmospheric matter escapes is crucial to understanding how life can develop on a planet. The interaction between incoming and outgoing material in Earth’s magnetosphere is a hot topic at the moment; where exactly is this stuff coming from? How did it enter our patch of space?“

Given that our atmosphere contains 5 quadrillion tons of matter (that’s 5 x 10¹⁵, or 5,000,000 billion tons), a loss of 90 tons a day doesn’t amount to much. However, this number does not include the mass of “cold ions” that are regularly being added. This term is typically used to described the hydrogen ions that we now know are being lost to the magnetosphere on a regular basis (along with oxygen and helium ions).

Since hydrogen requires less energy to escape our atmosphere, the ions that are created once this hydrogen becomes part of the plasmasphere also have low energy. As a result, they have been very difficult to detect in the past. What’s more, scientists have only known about this flow of oxygen, hydrogen and helium ions – which come from the Earth’s polar regions and replenish plasma in the magnetosphere – for a few decades.

Illustration of ions flowing out from the polar cap towards the magnetotail. Credit: ESA - C. Carreau — *Illustration of ions flowing out from the polar cap towards the magnetotail. Credit: ESA – C. Carreau*

Prior to this, scientists believed that solar particles alone were responsible for plasma in Earth’s magnetosphere. But in more recent years, they have come to understand that two other sources contribute to the plasmasphere. The first are sporadic “plumes” of plasma that grow within the plasmasphere and travel outwards towards the edge of the magnetosphere, where they interact with solar wind plasma coming the other way.

The other source? The aforementioned atmospheric leakage. Whereas this consists of abundant oxygen, helium and hydrogen ions, the cold hydrogen ions appear to play the most important role. Not only do they constitute a significant amount of matter lost to space, and may play a key role in shaping our magnetic environment. What’s more, most of the satellites currently orbiting Earth are unable to detect the cold ions being added to the mix, something which Cluster is able to do.

In 2009 and in 2013, the Cluster probes were able to characterize their strength, as well as that of other sources of plasma being added to the Earth’s magnetosphere. When only the cold ions are considered, the amount of atmosphere being lost o space amounts to several thousand tons per year. In short, its like losing socks. Not a big deal, but you’d like to know where they are going, right?

This has been another area of focus for the Cluster mission, which for the last decade and a half has been attempting to explore how these ions are lost, where they come from, and the like. As Philippe Escoubet, ESA’s Project Scientist for the Cluster mission, put it:

“In essence, we need to figure out how cold plasma ends up at the magnetopause. There are a few different aspects to this; we need to know the processes involved in transporting it there, how these processes depend on the dynamic solar wind and the conditions of the magnetosphere, and where plasma is coming from in the first place – does it originate in the ionosphere, the plasmasphere, or somewhere else?“

*Color illustration showing the scale of planets in our solar system, focusing on Jupiter and Saturn. Credit: NASA*

The reasons for understanding this are clear. High energy particles, usually in the form of solar flares, can pose a threat to space-based technology. In addition, understanding how our atmosphere interacts with solar wind is also useful when it comes to space exploration in general. Consider our current efforts to locate life beyond our own planet in the Solar System. If there is one thing that decades of missions to nearby planets has taught us, it is that a planet’s atmosphere and magnetic environment are crucial in determining habitability.

Within close proximity to Earth, there are two examples of this: Mars, which has a thin atmosphere and is too cold; and Venus, who’s atmosphere is too dense and far too hot. In the outer Solar System, Saturn’s moon Titan continues to intrigue us, mainly because of the unusual atmosphere. As the only body with a nitrogen-rich atmosphere besides Earth, it is also the only known planet where liquid transfer takes place between the surface and the atmosphere – albeit with petrochemicals instead of water.

Moreover, NASA’s Juno mission will spend the next two years exploring Jupiter’s own magnetic field and atmosphere. This information will tell us much about the Solar System’s largest planet, but it is also hoped to shed some light on the history planetary formation in the Solar System.

In the past fifteen years, Cluster has been able to tell astronomers a great deal about how Earth’s atmosphere interacts with solar wind, and has helped to explore magnetic field phenomena that we have only begun to understand. And while there is much more to be learned, scientists agree that what has been uncovered so far would have been impossible without a mission like Cluster.

Further Reading: ESA

July 11, 2016February 22, 2017 by Fraser Cain

How Fast Can Stars Spin?

Everything in the Universe is spinning. Spinning planets and their spinning moons orbit around spinning stars, which orbit spinning galaxies. It’s spinning all the way down.

Consider that fiery ball in the sky, the Sun. Like all stars, our Sun rotates on its axis. You can’t tell because staring at the Sun long enough will permanently damage your eyeballs. Instead you can use a special purpose solar telescope to observe sunspots and other features on the surface of the Sun. And if you track their movements, you’ll see that the Sun’s equator takes 24.47 days to turn once on its axis. Unlike its slower poles which take 26.24 days to turn.

The Sun isn’t a solid ball of rock, it’s a sphere of hot plasma, so the different regions can complete their rotation at different rates. But it rotates so slowly that it’s an almost perfect sphere.

If you were standing on the surface of the Sun, which you can’t, of course, you would be whipping around at 7,000 km/h. That sounds fast, but just you wait.

How does that compare to other stars, and what’s the fastest that a star can spin?

Achenar is located at the lower right of the constellation Eridanus. — Achenar rotates much faster than our Sun. It is located at the lower right of the constellation Eridanus.

A much faster spinning star is Achenar, the tenth brightest star in the sky, located 139 light-years away in the constellation of Eridanus. It has about 7 times the mass of the Sun, but it spins once on its axis every 2 days. If you could see Achenar up close, it would look like a flattened ball. If you measured it from pole to pole, it would be 7.6 Suns across, but if you measured across the equator, it would be 11.6 Suns across.

If you were standing on the surface of Achenar, you’d be hurtling through space at 900,000 km/h.

The very fastest spinning star we know of is the 25 solar mass VFTS 102, located about 160,000 light-years away in the Large Magellanic Cloud’s Tarantula Nebula – a factory for massive stars.

If you were standing on the surface of VFTS 102, you’d be moving at 2 million km/h.

In fact, VFTS 102 is spinning so quickly, it can just barely keep itself together. Any faster, and the outward centripetal force would overcome the gravity holding its guts in, and it would tear itself apart. Perhaps that’s why we don’t see any spinning faster; because they couldn’t handle the speed. It appears that this is the fastest that stars can spin.

This is an artist's concept of the fastest rotating star found to date. The massive, bright young star, called VFTS 102, rotates at a million miles per hour, or 100 times faster than our Sun does. Centrifugal forces from this dizzying spin rate have flattened the star into an oblate shape and spun off a disk of hot plasma, seen edge on in this view from a hypothetical planet. The star may have "spun up" by accreting material from a binary companion star. The rapidly evolving companion later exploded as a supernova. The whirling star lies 160,000 light-years away in the Large Magellanic Cloud, a satellite galaxy of our Milky Way. Credit: NASA, ESA, and G. Bacon (STScI) — This is an artist’s concept of VFTS 102, the fastest rotating star found to date. Credit: NASA, ESA, and G. Bacon (STScI)

One other interesting note about VFTS 102 is that it’s also hurtling through space much faster than the stars around it. Astronomers think it was once in a binary system with a partner that detonated as a supernova, releasing it into space like a catapult.

Not only stars can spin. Dead stars can spin too, and they take this to a whole other level.

Neutron stars are what you get when a star with much more mass than the Sun detonates as a supernova. Suddenly you’ve got a stellar remnant with twice the mass of the Sun compressed down into a tiny ball about 20 km across. All that angular momentum of the star is retained, and so the neutron star spins at an enormous speed.

The fastest neutron star ever recorded spins around 700 times a second. We know it’s turning this quickly because it’s blasting out beams of radiation that sweep towards us like an insane lighthouse. This, of course, is a pulsar, and we did a whole episode on them.

A regular star would be torn apart, but neutron stars have such intense gravity, they can rotate this quickly. Over time, the radiation streaming from the neutron star strips away its angular momentum, and it slows down.

A black hole with an accretion disk. Credit: (NASA/Dana Berry/SkyWorks Digital)

Black holes can spin even faster than that. In fact, when a black hole is actively feeding from a binary companion, or a supermassive black hole is gobbling up stars, it can rotate at nearly the speed of light. The laws of physics prevent anything in the Universe spinning faster than the speed of light, and black holes go right up to the edge of the law without breaking it.

Astronomers recently found a supermassive black hole spinning up to 87% the maximum speed permitted by relativity.

If you were hoping there are antimatter lurking out there, hoarding all that precious future energy, I’m sorry to say, but astronomers have looked and they haven’t found it. Just like the socks in your dryer, we may never discover where it all went.

July 11, 2016September 20, 2016 by Evan Gough

New Dwarf Planet Discovered Beyond Neptune

2015 RR245's orbit takes it 120 times further from the Sun than the Earth is. Image: OSSOS/Alex Parker

A new dwarf planet has been discovered beyond Neptune, in the disk of small icy worlds that resides there. The planet was discovered by an international team of astronomers as part of the Outer Solar Systems Origins Survey (OSSOS). The instrument that found it was the Canada-France Hawaii Telescope at Maunakea, Hawaii.

The planet is about 700 km in size, and has been given the name 2015 RR245. It was first sighted by Dr. JJ Kavelaars, of the National Research Council of Canada, in images taken in 2015. Dwarf planets are notoriously difficult to spot, but they’re important pieces of the puzzle in tracing the evolution of our Solar System.

Dr. Michele Bannister, of the University of Victoria in British Columbia, describes the moment when the planet was discovered: “There it was on the screen— this dot of light moving so slowly that it had to be at least twice as far as Neptune from the Sun.”

These images show 3 hours of RR245's movement. Image: OSSOS — These images show 3 hours of RR245’s movement. Image: OSSOS

“The icy worlds beyond Neptune trace how the giant planets formed and then moved out from the Sun. They let us piece together the history of our Solar System. But almost all of these icy worlds are painfully small and faint: it’s really exciting to find one that’s large and bright enough that we can study it in detail.” said Bannister.

As the New Horizons mission has shown us, these far-flung, cold bodies can have exotic features in their geological landscapes. Where once Pluto, king of the dwarf planets, was thought to be a frozen body locked in time, New Horizons revealed it to be a much more dynamic place. The same may be true of RR245, but for now, not much is known about it.

The 700 km size number is really just a guess at this point. More measurements will need to be taken of its surface properties to verify its size. “It’s either small and shiny, or large and dull.” said Bannister.

As our Solar System evolved, most dwarf planets like RR245 were destroyed in collisions, or else flung out into deep space by gravitational interactions as the gas giants migrated to their current positions. RR245 is one of the few that have survived. It now spends its time the same way other dwarf planets like Pluto and Eris do, among the tens of thousands of small bodies that orbit the sun beyond Neptune.

RR245 has not been observed for long, so much of what’s known about its orbit will be refined by further observation. But at this point it appears to have a 700 year orbit around the Sun. And it looks like for at least the last 100 million years it has travelled its current, highly elliptical orbit. For hundreds of years, it has been further than 12 billion km (80 AU)from the Sun, but by 2096 it should come within 5 billion km (34 AU) of the Sun.

The discovery of RR 245 came as a bit of a surprise to the OSSOS team, as that’s not their primary role. “OSSOS was designed to map the orbital structure of the outer Solar System to decipher its history,” said Prof. Brett Gladman of the University of British Columbia in Vancouver. “While not designed to efficiently detect dwarf planets, we’re delighted to have found one on such an interesting orbit”.

OSSOS has discovered over 500 hundred trans-Neptunian objects, but this is the first dwarf planet it’s found. “OSSOS is only possible due to the exceptional observing capabilities of the Canada-France-Hawaii Telescope. CFHT is located at one of the best optical observing locations on Earth, is equipped with an enormous wide-field imager, and can quickly adapt its observing each night to new discoveries we make. This facility is truly world leading.” said Gladman.

If RR 245's diameter is conclusively measured as 700 km, it will be smaller than the dwarf planet Ceres, which is 945 km in diameter. Image courtesy of NASA. — If RR 245’s diameter is conclusively measured as 700 km, it will be smaller than the dwarf planet Ceres, which is 945 km in diameter. Image courtesy of NASA.

A lot of work has been done to find dwarf planets in the far reaches of our Solar System. It may be that RR 245 is the last one we find. If there are any more out there, they may have to wait until larger and more powerful telescopes become available. In the mid-2020’s, the Large Synoptic Survey Telescope (LSST) will come on-line in Chile. That ‘scope features a 3200 megapixel camera, and each image it captures will be the size of 40 full Moons. It’ll be hard for any remaining dwarf planets to hide from that kind of imaging power.

As for RR 245’s rather uninspiring name, it will have to do for a while. But as the discoverers of the new dwarf planet, the OSSOS team will get to submit their preferred name for the planet. After that, it’s up the International Astronomical Union (IAU) to settle on one.

What do you think? If this is indeed the last dwarf planet to be found in our Solar System what should we call it?

July 11, 2016July 11, 2016 by Tammy Plotner

Messier 18 (M18) – The NGC 6613 Star Cluster

Messier 18, shown in proximity to M17 (Omega Nebula), and Messier 24 (Sagittarius Star Cloud). Credit: Wikisky

Welcome back to Messier Monday! In our ongoing tribute to the great Tammy Plotner, we take a look at the Messier 18 open star cluster. Enjoy!

In the 18th century, while searching the night sky for comets, French astronomer Charles Messier began noticing a series of “nebulous objects” in the night sky. Hoping to ensure that other astronomers did not make the same mistake, he began compiling a list of these objects,. Known to posterity as the Messier Catalog, this list has come to be one of the most important milestones in the research of Deep Sky objects.

One of these objects was Messier 18 (aka. NGC 6613), a relatively dim open star cluster located in the constellation Sagittarius. Located in close proximity to Messier 17 (the Omega Nebula), it is possible that these two clusters formed together.

Description:

Located about 4,900 light years from Earth, and spread over an expanse measuring 17 light-years across, this group of around 20 stars is only about 32 million years old. Its hottest members are spectral type B3, yet you will also see many yellow and orange stars as well. But as already noted, M18 may not be alone in space.

According to research done by R. and C. R. de la Fuente Marcos, M18 may very well be a binary cluster, paired with the open cluster – NGC 6618 – which is harbored inside M17:

“We have shown that binary open clusters appear to constitute a statistically significant sample and that the fraction of possible binary clusters in the Galactic disk is comparable to that in the Magellanic Clouds. The spatial proximity of two almost coeval open clusters, compared to the large distances which typically separate these objects, suggests that both objects were formed together. In starforming complexes, one star cluster might capture another to form a bound state in the presence of a third body or of energy dissipation. This mechanism may also be at work within orbital resonances for non-coeval clusters.”

Messier 18 location. Image: IAU and Sky & Telescope magazine (Roger Sinnott & Rick Fienberg) — *The location of Messier 18 in the Sagittarius constellation. Credit: IAU/Sky & Telescope magazine (Roger Sinnott & Rick Fienberg)*

History of Observation:

M18 was one of Charles Messier’s original discoveries, which took place in 1764. As he wrote in his notes upon observing the cluster:

“In the same night [June 3 to 4, 1764], I have discovered a bit below the nebula reported here above, a cluster of small stars, environed in a thin nebulosity; its extension may be 5 minutes of arc: its appearances are less sensible in an ordinary refractor of 3 feet and a half [FL] than that of the two preceding [M16 and M17]: with a modest refractor, this star cluster appears in the form of a nebula; but when employing a good instrument, as I have done, one sees well many of the small stars: after my observations I have determined its position: its right ascension is 271d 34′ 3″, and its declination 17d 13′ 14″ south.”

In this circumstance, we must give Messier great credit considering his observations were performd long before the nature of open clusters and stellar movement were understood. While Messier seems to have spotted some nebulosity around the cluster (which may have belonged to M17), he takes a later historic cut from Smyth:

“A neat double star, in a long and straggling assemblage of stars,below the Polish shield. A 9 and B 11 [mag], both blueish. This cluster was discovered by Messier in 1764, and registered as a mass of small stars appearing like a nebula in a 3 1/2-foot telescope; which affords another instance that the means of that very zealous observer did not quadrate with his diligence.”

What a shame Smyth wasn’t around to later know that M18 could be paired with its nebulous neighbor!

Credit: Two Micron All Sky Survey (2MASS), a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation. — *The open cluster Messier 18 (NGC 6613), as observed by the Two Micron All Sky Survey (2MASS). Credit: University of Massachusetts/IPAC/Caltech/NASA/NSF*

Locating Messier 18:

Because Messier 18 is nothing more than a small collection of stars which are slightly brighter than the background Milky Way stars, it isn’t easy to distinguish it using binoculars or a finderscope if you’ve never seen it before. One of the most sure ways of locating it is to become familiar with Messier 17 and simply aim a couple of degrees (about a field of view) south.

While it won’t strike you as a grand object, you will notice that the stars are compressed in this area and that there are several dozen of them which appear brighter than the rest. In a telescope, use your lowest magnification. Since this is a very well spread cluster, it is easily resolved in even modest instruments.

And here are the quick facts on M18 to get you started:

Object Name: Messier 18
Alternative Designations: M18, NGC 6613
Object Type: Open Star Cluster
Constellation: Sagittarius
Right Ascension: 18 : 19.9 (h:m)
Declination: -17 : 08 (deg:m)
Distance: 4.9 (kly)
Visual Brightness: 7.5 (mag)
Apparent Dimension: 9.0 (arc min)

We have written many interesting articles about Messier Objects here at Universe Today. Here’s Tammy Plotner’s Introduction to the Messier Objects, , M1 – The Crab Nebula, M8 – The Lagoon Nebula, and David Dickison’s articles on the 2013 and 2014 Messier Marathons.

Be to sure to check out our complete Messier Catalog. And for more information, check out the SEDS Messier Database.

July 11, 2016September 20, 2016 by Matt Williams

A Planet With A 27,000 Year Orbit & That’s Just Where The Strangeness Begins

The star system CVSO 30, which was found to have two exoplanets with extreme orbital periods. If you look closely, you can see 30c to the upper left of the star. Credit: ESO

Every planet in the Solar System has its own peculiar orbit, and these vary considerably. Whereas planet Earth takes 365.25 days to complete a single orbit about our Sun, Mars takes almost twice as long – 686.971 days. Then you have Jupiter and the other gas giants, which take between 11.86 and 164.8 years to orbit our Sun. But even with these serving as examples, astronomers were not prepared for what they found when they looked at CVSO 30.

This star system, which lies some 1200 light years from Earth, has been found in recent years to have two candidate exoplanets. These planets, which are many times the mass of Jupiter, were discovered by an international team of astronomers using both the Transit Method and Direct Imaging. And what they found was very interesting: one planet has an orbital period of less than 11 days while the other takes a whopping 27,000 years to orbit its parent star!

In addition to being a big surprise, the detection of these two planets using different methods was an historic achievement. Up until now, the vast majority of the over 2,000 exoplanets discovered have been detected thanks to indirect methods. These include the aforementioned Transit Method, which detects planets by measuring the dimming effect they cause when crossing their parent star’s path, and the Radial Velocity Method, which measures the gravitational effect planets have on their parent star.

In 2012, astronomers used the Transit Method to detect CVSO 30b, a planet with 5 to 6 times the mass of Jupiter, and which orbits its star at a distance of only 1.2 million kilometers (by comparison, Mercury orbits our Sun at a distance of 58 million kilometers). From these characteristics, CVSO 30b can be described as a particularly “hot-Jupiter”.

In contrast, Direct Imaging has been used to spot only a few dozen exoplanets. The reason for this is because it is typically quite difficult to detect the light reflected by a planet’s atmosphere due it being drowned out by the light of its parent star. It can also be quite demanding when it comes to the instrument involved. Still, compared to indirect methods, it can be more effective when it comes to exploring the remote regions of a star.

Thanks to the efforts of an international team of astronomers, who combined the use of the Keck Observatory in Hawaii, the ESO’s Very Large Telescope in Chile, and the Spanish National Research Council’s (CSIC) Calar Alto Observatory, CVSO 30c was spotted in remote regions around its parent star, orbiting at a distance of around 666 AU.

The details of the discovery were published in a paper titled “Direct Imaging discovery of a second planet candidate around the possibly transiting planet host CVSO 30“. In it, the researchers – who hail from such prestigious institutions as the Cerro Tololo Inter-American Observatory, the Jena Observatory, the European Space Agency and the Max Planck Institute for Astronomy – explained the methods used to find the exoplanet, and the significance of its discovery.

*The star CVSO30, showing the two detection methods that revealed its exoplanet candidates. Credit: Keck Observatory/ESO/VLT/NACO*

As Tobias Schmidt – of the University of Hamburg, the Astrophysical Institute and University Observatory Jena, and the lead author of the paper – told Universe Today via email:

“[30b and 30c] are both unusual on their own. CVSO 30b is the first transiting planet around a star as young as 2.5 million years. Published in 2012, all previously detected transiting planets were older than few hundred million years… It has been a surprise to find a planetary mass companion at 662 AU, or 662 times the distance from Earth to the Sun, from a primary star having only about 0.4 solar masses. According to the standard model, planets form in disks around the star. But none of the observed disks around such low-mass stars is large enough to form such an object.”

In other words, it is surprising to find two exoplanet candidates with several times the mass of Jupiter (aka. Super-Jupiters) orbiting a star as small as CVSO 30. But to find two exoplanets with such a disparity in terms of their respective distance from their star (despite being similar in mass) was particularly surprising.

Relying on high-contrast photometric and spectroscopic observations from the Very Large Telescope, the Keck telescopes and the Calar Alto observatory, the international team was able to spot 30c using a technique known as lucky imaging. This process, which is used by ground-based telescopes, involves many high-speed, quick exposure photos being taken to minimize atmospheric interference.

An artist's conception of a T-type brown dwarf. (Credit: Tyrogthekreeper under a Wikimedia Commons Attribution-Share Alike 3.0 Unported license). — *An artist’s conception of a T-type brown dwarf. Credit: Tyrogthekreeper/Wikimedia Commons.*

What they found was an exoplanet with a wide orbit that was between 4 and 5 Jupiter masses, and was also very young – less than 10 million years old. What’s more, the spectroscopic data indicated that it is unusually blue for a planet, as most other planet candidates of its kind are very red. The researchers concluded from this that it is likely that 30c is the first young planet of its kind to be directly imaged.

They further concluded that 30 c is also likely the first “L-T transition object” younger than 10 million years to be found orbiting a star. L-T transition objects are a type of brown dwarf – objects that are too large to be considered planets, but too small to be considered stars. Typically they are found embedded in large clouds of gas and dust, or on their own in space.

Paired with its companion – 30 b, which is impossibly close to its parent star – 30 c is not believed to have formed at its current position, and is likely not stable in the long-term. At least, not where current models of planetary formation and orbit are concerned. However, as Prof. Schmidt indicated, this offers a potential explanation for the odd nature of these exoplanets.

“We do think this is a very good hint,” he said, “that the two objects might have formed regularly around the star at a separation comparable to Jupiter or Saturn’s separation from the Sun, then interacted gravitationally and were scattered to their current orbits. However this is still speculation, further investigations will try to prove this. Both have about the same mass of few Jupiter masses, the inner one might be even lower.”

The Very Large Telescoping Interferometer firing it's adaptive optics laser. Credit: ESO/G. Hüdepohl — *The Very Large Telescoping Interferometer firing it’s adaptive optics laser. Credit: ESO/G. Hüdepohl*

The discovery is also significant since it was the first time that these two detection methods – Transit and Direct Imaging – were used to confirm exoplanet candidates around the same star. In this case, the methods were quite complimentary, and present opportunities to learn more about exoplanets. As Professor Schmidt explained:

“Both Transit method and radial velocity method have problems finding planets around young stars, as the activity of young stars is disturbing the search for them. CVSO 30 b was the first very young planet found with these methods, currently a hand full of candidates exist. Direct imaging, on the other hand, is working best for young planets as they still contract and are thus self-luminous. It is therefore great luck that a far out planet was found around the very first young star hosting a inner planet…

“However, the real advantage of transit and direct imaging methods is that the two objects can now be investigated in greater detail. While we can use the direct light from the imaging for spectroscopy, i.e. split the light according to its wavelength, we hope to achieve the same for the inner planet candidate. This is possible as the light passes through the atmosphere of the planet during transits and some of the elements are absorbed by the composition material of the atmosphere. So we do hope to learn a lot about planet formation, thus also formation of the early Solar System and about young planets in particular from the CVSO 30 system.”

Since astronomers first began began to find exoplanet candidates in distant star systems, we have come to learn just how diverse our Universe really is. Many of the discoveries have challenged our notions about where planets can form around their parent star, while others have showed us that planets can take many different forms.

As time goes on and our exploration of the local Universe advances, we will be challenged to find explanations for how it all fits together. And from that, new and more comprehensive models will no doubt emerge.

Further Reading: IAA, arXiv

July 10, 2016 by Ken Kremer

Flawless Shakedown Mission from Modified Soyuz Delivers Multinational Crew to Space Station

Three newly arrived crew of Expedition 48 in Soyuz MS-01 open the hatch and enter the International Space Station after docking on July 9, 2016. Credit: NASA TV

A flawless shakedown mission from Russia’s newly modified Soyuz capsule successfully delivered a new multinational crew to the Space Station early Saturday, July 9 after a two day orbital chase.

The upgraded Soyuz MS-01 spacecraft launching on its maiden flight successfully docked to the International Space Station at 12:06 a.m. EDT Saturday, July 9, while soaring 254 statute miles over the South Pacific.

“Docking confirmed,” said a commentator from Russian mission control at Korolev outside Moscow. “Contact and capture complete.”

The Soyuz was ferrying the new multinational trio of astronauts and cosmonauts comprising Kate Rubins of NASA, Soyuz Commander Anatoly Ivanishin of the Russian space agency Roscosmos and Takuya Onishi of the Japan Aerospace Exploration Agency on the Expedition 48/49 mission.

The three person crew of two men and one woman had launched flawlessly into picture perfect skies two days earlier from the Baikonur Cosmodrome in Kazakhstan at 9:36 p.m. EDT Wednesday, July 6 (7:36 a.m. Baikonur time, July 7), in the brand new version of the Russian Soyuz capsule that has been significantly upgraded and modified.

NASA’s Kate Rubins was strapped into the right seat, Ivanishin in the center and Onishi on the left.

The Soyuz MS-01 spacecraft, carrying three Expedition 48-49 crew members, launches from the Baikonur Cosmodrome in Kazakhstan at 9:36 p.m. EDT Wednesday, July 6, 2016 (7:36 a.m. Baikonur time, July 7). Credits: NASA/Bill Ingalls

It was a textbook approach on the shakedown mission that culminated in a flawless docking at the Earth-facing Russian Rassvet module on the Russian side of the massive orbiting outpost.

NASA TV carried the whole operation live with beautiful color video imagery streaming from the ISS showing the Soyuz approach and black and white video streaming from the Soyuz.

The Soyuz MS-01 spacecraft is viewed from the International Space Station as it approaches the Rassvet module docking port. Credit: NASA TV

The Soyuz performed magnificently. All of the upgraded and modified systems checked out perfectly on this maiden flight of the new version of Russias venerable Soyuz, said NASA commentator Rob Navias.

“All new systems functioning perfectly,” said Navias. “This has been a perfect shakedown mission for the new Soyuz crew docking at the ISS.”

The Soyuz had slowed to an approach velocity of just 0.1 m/s at docking with the forward docking probe extended.

The approach was fully automated under Russian mission control as Ivanishin carefully monitored all spacecraft systems with steady update calls back to ground control.

The fully automated approached utilized the upgraded KURS NA automated rendezvous radar system.

During final approach, the Soyuz conducted a fly around maneuver starting at a distance of 400 meters. It moved 57 degress around the station while closing in to about 250 meters.

After station keeping for about 2 minutes while ground controllers conducted a final evaluation and no issues were detected, Russian mission control at last gave the GO for final approach and the GO command for docking was given.

The Soyuz made contact and completed a perfect docking at Rassvet. The hook and latches were then closed in for a tight grasp onto the station.

The crews then conducted a series of leak and pressurization checks.

After everything checked out, the hatches were finally opened about two and a half hours later at 2:26 a.m. EDT.

The new crew members of Expedition 48 officially floated aboard the International Space Station at about 2:50 a.m. EDT, July 9 with the hatches opened between their Soyuz MS-01 and the space station and after a live video transmission link had been established to show the festivities.

The new six-member Expedition 48 crew join each other for well wishes and congratulations from family, friends and mission officials. In front, from left, are the new crew members Kate Rubins, Anatoly Ivanishin and Takuya Onishi. In the back row are Flight Engineers Oleg Skripochka and Alexey Ovchinin and Commander Jeff Williams. Credit: NASA TV

They were welcomed aboard with hugs and joined the Expedition 48 Commander Jeff Williams of NASA and Flight Engineers Oleg Skripochka and Alexey Ovchinin of Roscosmos.

With the arrival of Rubins, Ivanishin and Onishi, the stations resident crew is beefed up to its normal six person crew complement.

They soon held the traditional video telecon for well wishes and congratulations from family, friends and mission officials.

The new trio will spend at least four months at the orbiting lab complex conducting more than 250 science investigations in fields such as biology, Earth science, human research, physical sciences, and technology development.

Rubins is on her rookie space mission. She holds a bachelor’s degree in molecular biology and a doctorate in cancer biology which will be a big focus of her space station research activities.

The new trio will join Expedition 48 Commander Jeff Williams of NASA and Flight Engineers Oleg Skripochka and Alexey Ovchinin of Roscosmos.

“The approximately 250 research investigations and technology demonstrations – not possible on Earth – will advance scientific knowledge of Earth, space, physical, and biological sciences. Science conducted on the space station continues to yield benefits for humanity and will enable future long-duration human and robotic exploration into deep space, including the agency’s Journey to Mars,” says NASA.
The newly upgraded Soyuz offers increased reliability and enhanced performance.

Many changes were instituted including enhanced structural performance to minimize chances of micrometeoroid penetration. Engineers also added a fifth battery for more power and storage capacity. The solar arrays are also about one square meter larger and the efficiency of the solar cells increased about 2 percent.

Also a more modern command and telemetry system to interact with a new series of new Russian communications satellites that will offer greatly increased the coverage by ground control. This was previously only about 20 minutes per orbit while over Russian ground stations and will now increase up to 45 to 90% of orbital coverage via the Russian comsat system.

A phased array antenna was also added with increased UHF radio capability in the Soyuz descent module that now also include a GPS system to improve search and rescue possibilities.

The newly upgraded KURS rendezvous radar system will weigh less, use less power and overall will be less complicated. For example it doesn’t have to be moved out of the way before docking. Weighs less and uses less power.

New approach and attitude control thrusters were installed. The new configuration uses 28 thrusters with a redundant thruster for each one – thus two fully redundant manifolds of 28 thrusters each.
All of these modification were tested out on the last two progress vehicles.

Multiple unmanned cargo ships carrying tons of essential supplies and science experiments are also scheduled to arrive from Russia, the US and Japan over the next few months.

A SpaceX Dragon is scheduled to launch as soon as July 18 and an Orbital ATK Cygnus should follow in August.
The SpaceX Dragon CRS-9 mission is slated to deliver the station’s first International docking adapter (IDA) to accommodate the future arrival of U.S. commercial crew spacecraft, including the Boeing built Starliner and SpaceX built Crew Dragon.

A Japanese HTV cargo craft will carry lithium ion batteries to replace the nickel-hydrogen batteries currently used on station to store electrical energy generated by the station’s huge rotating solar arrays.

Two Russian Progress craft with many tons of supplies are also scheduled to arrive.

The Soyuz MS-01 spacecraft launches from the Baikonur Cosmodrome with Expedition 48-49 crewmembers Kate Rubins of NASA, Anatoly Ivanishin of Roscosmos and Takuya Onishi of the Japan Aerospace Exploration Agency (JAXA) onboard, Thursday, July 7, 2016 , Kazakh time (July 6 Eastern time), Baikonur, Kazakhstan. Photo Credit: NASA/Bill Ingalls

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

Ken Kremer

July 8, 2016July 9, 2016 by Nancy Atkinson

A ‘Cosmic Miracle’: Indications Of Early Forming ‘Direct Collapse’ Black Hole Seen

An image based on a supercomputer simulation of the cosmological environment where primordial gas undergoes the direct collapse to a black hole. Credit: Aaron Smith/TACC/UT-Austin. — An image based on a supercomputer simulation of the cosmological environment where primordial gas undergoes the direct collapse to create black holes. Credit: Aaron Smith/TACC/UT-Austin.

Astronomers have been finding some extremely old supermassive black holes, ones that formed when the Universe was quite young. But they were puzzled at how a black hole could grow to such tremendous size when the Universe itself was just a toddler.

Astronomers have now found a unique set of conditions were present half a billion years after the Big Bang that allowed these monster black holes to form. An unusual source of intense radiation created what are called “direct-collapse black holes.”

“It’s a cosmic miracle,” said Volker Bromm of The University of Texas at Austin, who worked with several astronomers on the finding. “It’s the only time in the history of the universe when conditions are just right for them to form.”

The conventional understanding of how black holes form is called the accretion theory, where an extremely massive star collapses and black hole “seeds” are built from the collapse by pulling in gas from their surroundings and by mergers of smaller black holes. But that process takes a long time, much longer than the time these quickly forming black holes were around. Plus, the early universe didn’t have the quantities of gas and dust needed for supermassive black holes to grow to their gigantic size.

The new findings suggest instead that some of the first black holes formed directly when a cloud of gas collapsed, bypassing any other intermediate phases, such as the formation and subsequent destruction of a massive star.

This artist's illustration depicts a possible "seed" for the formation of a supermassive black hole, that is an object that contains millions or even billions of times the mass of the Sun. In the artist's illustration, the gas cloud is shown as the wispy blue material, while the orange and red disk is showing material being funneled toward the growing black hole through its gravitational pull. Credit: X-ray: NASA/CXC/Scuola Normale Superiore/Pacucci, F. et al, Optical: NASA/STScI; Illustration: NASA/CXC/M.Weiss. — This artist’s illustration depicts a possible “seed” for the formation of a supermassive black hole, that is an object that contains millions or even billions of times the mass of the Sun. In the artist’s illustration, the gas cloud is shown as the wispy blue material, while the orange and red disk is showing material being funneled toward the growing black hole through its gravitational pull. Credit: X-ray: NASA/CXC/Scuola Normale Superiore/Pacucci, F. et al, Optical: NASA/STScI; Illustration: NASA/CXC/M.Weiss.

Of course, like any black hole, these “direct collapse” black holes can’t be seen. But there was strong evidence for their existence, as they are needed to power the highly luminous quasars detected in the young universe. A quasar’s great brightness comes from matter spiraling into a supermassive black hole, heating to millions of degrees, creating jets that shine like beacons across the Universe. But since the accretion theory doesn’t explain supermassive black holes in extremely distant — and therefore young — universe, astronomers couldn’t explain the quasars either. This has been called “the quasar seed problem.”

“The quasars observed in the early universe resemble giant babies in a delivery room full of normal infants,” said Avi Loeb from the Harvard-Smithsonian Center for Astrophysics, who worked with Bromm. “One is left wondering: what is special about the environment that nurtured these giant babies? Typically the cold gas reservoir in nearby galaxies like the Milky Way is consumed mostly by star formation.”

But In 2003, Bromm and Loeb came up with a theoretical idea to get an early galaxy to form a supermassive seed black hole, by suppressing the otherwise prohibitive energy input from star formation. They called the process “direct collapse.”

“Begin with a “primordial cloud of hydrogen and helium, suffused in a sea of ultraviolet radiation,” Bromm said. “You crunch this cloud in the gravitational field of a dark-matter halo. Normally, the cloud would be able to cool, and fragment to form stars. However, the ultraviolet photons keep the gas hot, thus suppressing any star formation. These are the desired, near-miraculous conditions: collapse without fragmentation! As the gas gets more and more compact, eventually you have the conditions for a massive black hole.”

This set of cosmic conditions appears to have only existed in the very early universe, and this process does not happen in galaxies today.

To test their theory, Bromm, Loeb and their colleague Aaron Smith started studying a galaxy called CR7, identified by a Hubble Space Telescope survey called COSMOS as being around at less than 1 billion years after the Big Bang.

David Sobral of the University of Lisbon had made follow-up observations of CR7 with some of the world’s largest ground-based telescopes, including Keck and the VLT. These uncovered some extremely unusual features in the light signature coming from CR7. Specifically, the Lyman-alpha hydrogen line was several times brighter than expected. Remarkably, the spectrum also showed an unusually bright helium line.

“Whatever is driving this source is very hot — hot enough to ionize helium,” Smith said, about 100,000 degrees Celsius.

These and other unusual features in the spectrum meant that it could either be a cluster of primordial stars or a supermassive black hole likely formed by direct collapse.

Smith ran simulations for both scenarios and while the star cluster scenario “spectacularly failed,” Smith said, the direct collapse black hole model performed well.

Also, earlier this year, researchers using combined data from the Chandra X-ray Observatory, Hubble Space Telescope, and Spitzer Space Telescope to identify these possible black hole seeds. They found two objects, both of these matched the theoretical profile in the infrared data. (read their paper here.)

It seems astronomers are “converging on this model,” Smith said, for solving the quasar seed problem and the early black hole conundrum.

Stay tuned.

Bromm, Loeb and Smith’s work is published in the journal Monthly Notices of the Royal Astronomical Society.

Sources:
RAS, Harvard-Smithsonian CfA, Press release for NASA’s detection of direct collapse black holes earlier this year.

July 8, 2016February 22, 2017 by Fraser Cain

What if Earth Stopped Orbiting the Sun?

In a previous article I investigated what would happen if the Earth stopped turning entirely, either locking to the Sun or the background stars.

If it happened quickly, then results would be catastrophic, turning the whole planet into a blended slurry of mountains, oceans and trees, hurting past a hundreds of kilometers per hour. And if it happened slowly, it would still be unpleasant, as we stopped having a proper day/night cycle. But it wouldn’t be immediately lethal.

But would happen if the Earth somehow just stopped in its tracks as it was orbiting the Sun, as if it ran into an invisible wall? As with the Earth turning question, it’s completely and totally impossible; it’s not going to happen. And with the unspun Earth, it would be totally devastating and super interesting to imagine.

A view of Earth on October 24, 2014 from the Chinese Chang’e-5 T1 spacecraft. Credit: Xinhua News, via UnmannedSpaceflight.com. — Credit: Xinhua News, via UnmannedSpaceflight.com.

Before we begin to imagine the horrifying consequences of a total loss of orbital velocity, let’s examine the physics involved.

The Earth is traveling around the Sun with an orbital velocity of 30 kilometers per second. This is exactly the speed it needs to be going to counteract the force of gravity from the Sun pulling it inward. If the Sun were to suddenly disappear, Earth would travel in a perfectly straight line at 30 km/s. This is how orbits work.

If the Earth’s orbital velocity sped up, then it would go into a higher orbit to compensate. And if the Earth’s orbital velocity slowed down, then it fall into a lower orbit to compensate. And if the Earth’s orbital velocity was slowed all the way down to zero? Now we’re cooking, literally.

First, let’s imagine what would happen if the Earth just suddenly stopped.

As I mentioned above, the Earth’s orbital velocity is 30 km/s, which means that if it suddenly stopped, everything on it would still have 30 km/s worth of inertia. The escape velocity of the Earth is about 11 km/s.

In other words, anything on the Earth’s leading side would fly off into space, continuing along the Earth’s orbital path around the Sun. Anything on the trailing side would be pulverized against the Earth. It would be a horrible, gooey mess.

But even if the Earth slowed gently to a stop, it would still be a horrible mess. Without the outward centripetal force to counteract the inward pull of gravity, the Earth would begin falling towards the Sun.

How long would it take? My integral calculus is a little rusty, so I’ll draw upon the calculations of Dave Rothstein from Cornell’s Ask an Astronomer. According to Dr. Rothstein, the whole journey would take about 65 days. It would take 41 days to cross the orbit of Venus, and on day 57, we’d cross the orbit of Mercury.

As they days went by, the Earth would get hotter and hotter as it got closer to the Sun. Aatish Bhatia over at WIRED did some further calculations to figure out the temperature. A month into the freefall, and the average temperature on Earth would have risen to 50 degrees C. 50 days in and we’d be about 125 C. On the final day, we’d get up to 3,000 C… and then, that would be that.

Of course, this is completely and totally impossible. There’s no force that could just stop the Earth in its tracks like that. There is, however, a plausible scenario that might drag the Earth into the Sun.

In the far future, the Sun will turn into a red giant and expand outward, engulfing the orbits of Mercury and Venus. There’s still an argument among astronomers on whether it’s going to gobble up Earth as well.

Illustration of the red supergiant Betelgeuse, as seen from a fictional orbiting world. © Digital Drew. — Poor Earth. © Digital Drew.

Let’s say it does. In that case, the Earth will be inside the atmosphere of the Sun, and experience a friction from the solar material as it orbits around, and spiral inward. Of course, at this point you’re orbiting inside the Sun, so falling into the Sun already happened.

There you go. If the Earth happened to stop dead in its orbit, it would take about 65 days to plunge down into the Sun, disappearing in a puff of plasma.

July 8, 2016September 20, 2016 by Bob King

Astronomers Discover Exoplanet With Triple Sunrises and Sunsets

This graphic shows the orbit of the planet in the HD 131399 system (red line) and the orbits of the stars (blue lines). The planet orbits the brightest star in the system, HD 131399A. Credit: ESO

In the famous scene from the Star Wars movie “A New Hope” we recall young Luke Skywalker contemplating his future in the light of a binary sunset on the planet Tatooine. Not so many years later in 2011, astronomers using the Kepler Space Telescope discovered Kepler-16b, the first Tatooine-like planet known to orbit two suns in a binary system. Now astronomers have found a planet in a triple star system where an observer would either experience constant daylight or enjoy triple sunrises and sunsets each day, depending on the seasons, which last longer than human lifetimes.

They used the SPHERE instrument on the European Southern Observatory’s Very Large Telescope to directly image the planet, the first ever found inside a triple-star system. The three stars are named HD 131399A, HD 131399B and HD 131399C in order of decreasing brightness; the planet orbits the brightest and goes by the chunky moniker HD 131399Ab.

This annotated composite image shows the newly discovered exoplanet HD 131399Ab in the triple-star system HD 131399. The image of the planet was obtained with the SPHERE imager on the ESO Very Large Telescope in Chile. This is the first exoplanet to be discovered by SPHERE and one of very few directly-imaged planets. With a temperature of around 580 degrees Celsius and an estimated mass of four Jupiter masses, it is also one of the coldest and least massive directly-imaged exoplanets. This picture was created from two separate SPHERE observations: one to image the three stars and one to detect the faint planet. The planet appears vastly brighter in this image than in would in reality in comparison to the stars. Credit: ESO/K. Wagner et al. — This composite image shows the newly discovered exoplanet HD 131399Ab in the triple-star system HD 131399. The image of the planet was obtained with the SPHERE imager. This is the first exoplanet to be discovered by SPHERE and one of very few directly-imaged planets. This picture was created from two separate SPHERE observations: one of the three stars and one to detect the faint planet. The planet appears vastly brighter in this image than in would in reality in comparison to the stars. Credit: ESO/K. Wagner et al.

Located about 320 light-years from Earth in the constellation of Centaurus the Centaur HD 131399Ab is about 16 million years old, making it also one of the youngest exoplanets discovered to date, and one for which we have a direct image. With a temperature of around 1,075° F (580° C) and the mass about four times that of Jupiter, it’s also one of the coldest and least massive directly-imaged exoplanets.

This infrared image of Saturn’s largest moon, Titan, was one of the first produced by the SPHERE instrument soon after it was installed on ESO’s Very Large Telescope in May 2014. This picture shows how effective the adaptive optics system is at revealing fine detail on this tiny disc (just 0.8 arc seconds across). Credit: ESO/J.-L. Beuzit et al./SPHERE Consortium

To pry it loose from the glare of its host suns, a team of astronomers led by the University of Arizona used a state of the art adaptive optics system to give razor-sharp images coupled with SPHERE, an instrument that blocks the light from the central star(s) similar to the way a coronagraph blocks the brilliant solar disk and allows study of the Sun’s corona. Finally, the region around the star is photographed in infrared polarized light to make any putative planets stand out more clearly against the remaining glare.

The planet, HD 131399Ab, is unlike any other known world — its orbit around the brightest of the three stars is by far the widest known within a multi-star system. It was once thought that planets orbiting a multi-star system would be unstable because of the changing gravitational tugs on the planet from the other two stars. Yet this planet remains in orbit instead of getting booted out of the system, leading astronomers to think that planets orbiting multiple stars might be more common that previously thought.

This artist's impression shows a view of the triple star system HD 131399 from close to the giant planet orbiting in the system. The planet is known as HD 131399Ab and appears at the lower-left of the picture. Credit: ESO / L. Calcada — This artist’s impression shows a view of the triple star system HD 131399 from close to the giant planet orbiting in the system. The planet is known appears at the lower-left of the picture. Credit: ESO / L. Calcada

HD 131399Ab orbits HD 131399A, estimated to be 80% more massive than the Sun. Its double-star companions orbit about 300 times the Earth-Sun distance away. For much of the planet’s 550 year orbit, all three stars would appear close together in the sky and set one after the other in unique triple sunsets and sunrises each day. But when the planet reached the other side of its orbit around its host sun, that star and the pair would lie in opposite parts of the sky. As the pair set, the host would rise, bathing HD 131399Ab in near-constant daytime for about one-quarter of its orbit, or roughly 140 Earth-years.

Click to see a wonderful simulation showing how the planet orbits within the trinary system

Planets in multi-star systems are of special interest to astronomers and planetary scientists because they provide an example of how the mechanism of planetary formation functions in these more extreme scenarios. Since multi-star systems are just as common as single stars, so planets may be too.

How would our perspective of the cosmos change I wonder if Earth orbited triple suns instead of a single star? Would the sight deepen our desire for adventure like the fictional Skywalker? Or would we suffer the unlucky accident of being born at the start of a multi-decade long stretch of constant daylight? Wonderful musings for the next clear night under the stars.