The Aquarius Constellation

Welcome back to Constellation Friday! Today, we will be dealing with one of the best-known constellations, that “watery” asterism and section of the sky known as Aquarius. Cue the soundtrack from Hair!

In the 2nd century CE, Greek-Egyptian astronomer Claudius Ptolemaeus (aka. Ptolemy) compiled a list of all the-then known constellations. This work (known as the Almagest) would remain the definitive guide to astronomy and astrology for over a thousand years. Among the 48 constellations listed in this book was Aquarius, a constellation of the zodiac that stretches from the celestial equator to the southern hemisphere.

Also known as the “Water Carrier”, Aquarius is bordered by Pegasus, Equuleus and Delphinus at the north, Aquila to the west, Capricornus to the south-west, Piscis Austrinus and Sculptor to the south, Cetus to the east and Pisces to the north-east. Today, it is one of the 88 constellations recognized by the International Astronomical Union (IAU), and is perhaps the most referenced and recognized of all the constellation.

Continue reading “The Aquarius Constellation”

Why Do Red Giants Expand?

We know that the Sun will last another 5 billion years and then expand us a red giant. What will actually make this process happen?

One of the handy things about the Universe, apart from the fact that it exists, is that it lets us see crazy different configurations of everything, including planets, stars and galaxies.

We see stars like our Sun and dramatically unlike our Sun. Tiny, cool red dwarf stars with a fraction of the mass of our own, sipping away at their hydrogen juice boxes for billions and even trillions of years. Stars with way more mass than our own, blasting out enormous amounts of radiation, only lasting a few million years before they detonate as supernovae.

There are ones younger than the Sun; just now clearing out the gas and dust in their solar nebula with intense ultraviolet radiation. Stars much older than ours, bloated up into enormous sizes, nearing the end of their lives before they fade into their golden years as white dwarfs.

The Sun is a main sequence star, converting hydrogen into helium at its core, like it’s been doing for more than 4.5 billion years, and will continue to do so for another 5 or so. At the end of its life, it’s going to bloat up as a red giant, so large that it consumes Mercury and Venus, and maybe even Earth.

What’s the process going on inside the Sun that makes this happen? Let’s peel away the Sun and take a look at the core. After we’re done screaming about the burning burning hands, we’ll see that the Sun is this enormous sphere of hydrogen and helium, 1.4 million kilometers across, the actual business of fusion is happening down in the core, a region that’s a delicious bubblegum center a tiny 280,000 kilometers across.

The core is less than one percent of the entire volume, but because the density of hydrogen in the chewy center is 150 times more than liquid water, it accounts for a freakishly huge 35% of its mass.

It’s thanks to the mass of the entire star, 2 x 10^30 kg, bearing down on the core thanks to gravity. Down here in the core, temperatures are more than 15 million degrees Celsius. It’s the perfect spot for nuclear fusion picnic.

There are a few paths fusion can take, but the main one is where hydrogen atoms are mushed into helium. This process releases enough gamma radiation to make you a planet full of Hulks.

Proton-proton fusion in a sun-like star. Credit: Borb
Proton-proton fusion in a sun-like star. Credit: Borb

While the Sun has been performing hydrogen fusion, all this helium has been piling up at its core, like nuclear waste. Terrifyingly, it’s still fuel, but our little Sun just doesn’t have the temperature or pressure at its core to be able to use it.

Eventually, the fusion at the core of the Sun shuts down, choked off by all this helium and in a last gasp of high pitched mickey mouse voice terror the helium core begins to contract and heat up. At this point, an amazing thing happens. It’s now hot enough for a layer of hydrogen just around the core to heat up and begin fusion again. The Sun now gets a second chance at life.

As this outer layer contains a bigger volume than the original core of the Sun, it heats up significantly, releasing far more energy. This increase in light pressure from the core pushes much harder against gravity, and expands the volume of the Sun.

Even this isn’t the end of the star’s life. Dammit, Harkness, just stay down. Helium continues to build up, and even this extra shell around the core isn’t hot and dense enough to support fusion. So the core dies again. The star begins to contract, the gravitational energy heats up again, allowing another shell of hydrogen to have the pressure and temperature for fusion, and then we’re back in business!

Red giant. Credit:NASA/ Walt Feimer
Red giant. Credit:NASA/ Walt Feimer

Our Sun will likely go through this process multiple times, each phase taking a few years to complete as it expands and contracts, heats and cools. Our Sun becomes a variable star.

Eventually, we run out of usable hydrogen, but fortunately, it’s able to switch over to using helium as fuel, generating carbon and oxygen as byproducts. This doesn’t last long, and when it’s gone, the Sun gets swollen to hundreds of times its size, releasing thousands of times more energy.

This is when the Sun becomes that familiar red giant, gobbling up the tasty planets, including, quite possibly the Earth.The remaining atmosphere puffs out from the Sun, and drifts off into space creating a beautiful planetary nebula that future alien astronomers will enjoy for thousands of years. What’s left is a carbon oxygen core, a white dwarf.

The Sun is completely out of tricks to make fusion happen any more, and it’ll now cool down to the background temperature of the Universe. Our Sun will die in a dramatic way, billions of years from now when it bloats up 500 times its original volume.

What do you think future alien astronomers will call the planetary nebula left behind by the Sun? Give it a name in the comments below.

Two Stars On A Death Spiral Set To Detonate As A Supernova

Two white dwarfs circle around one other, locked in a fatal tango. With an intimate orbit and a hefty combined mass, the pair is ultimately destined to collide, merge, and erupt in a titanic explosion: a Type Ia supernova.

Or so goes the theory behind the infamous “standard candles” of cosmology.

Now, in a paper published in today’s issue of Nature, a team of astronomers have announced observational support for such an arrangement – two massive white dwarf stars that appear to be on track for a very explosive demise.

The astronomers were originally studying variations in planetary nebulae, the glowing clouds of gas that red giant stars throw off as they fizzle into white dwarfs. One of their targets was the planetary nebula Henize 2-428, an oddly lopsided specimen that, the team believed, owed its shape to the existence of two central stars, rather than one. After observing the nebula with the ESO’s Very Large Telescope, the astronomers concluded that they were correct – Henize 2-428 did, in fact, have a binary star system at its heart.

This image of the unusual planetary nebula was obtained using ESO’s Very Large Telescope at the Paranal Observatory in Chile. In the heart of this colourful nebula lies a unique object consisting of two white dwarf stars, each with a mass a little less than that of the Sun. These stars are expected to slowly draw closer to each other and merge in around 700 million years. This event will create a dazzling supernova of Type Ia and destroy both stars. Credit: ESO
This image of the unusual planetary nebula was obtained using ESO’s Very Large Telescope at the Paranal Observatory in Chile. In the heart of this colourful nebula lies a unique object consisting of two white dwarf stars, each with a mass a little less than that of the Sun. These stars are expected to slowly draw closer to each other and merge in around 700 million years. This event will create a dazzling supernova of Type Ia and destroy both stars. Credit: ESO

“Further observations made with telescopes in the Canary Islands allowed us to determine the orbit of the two stars and deduce both the masses of the two stars and their separation,” said Romano Corradi, a member of the team.

And that is where things get juicy.

In fact, the two stars are whipping around each other once every 4.2 hours, implying a narrow separation that is shrinking with each orbit. Moreover, the system has a combined heft of 1.76 solar masses – larger, by any count, than the restrictive Chandrasekhar limit, the maximum ~1.4 solar masses that a white dwarf can withstand before it detonates. Based on the team’s calculations, Henize 2-428 is likely to be the site of a type Ia supernova within the next 700 million years.

“Until now, the formation of supernovae Type Ia by the merging of two white dwarfs was purely theoretical,” explained David Jones, another of the paper’s coauthors. “The pair of stars in Henize 2-428 is the real thing!”

Check out this simulation, courtesy of the ESO, for a closer look at the fate of the dynamic duo:


Astronomers should be able to use the stars of Henize 2-428 to test and refine their models of type Ia supernovae – essential tools that, as lead author Miguel Santander-García emphasized, “are widely used to measure astronomical distances and were key to the discovery that the expansion of the Universe is accelerating due to dark energy.” This system may also enhance scientists’ understanding of the precursors of other irregular planetary nebulae and supernova remnants.

The team’s work was published in the February 9 issue of Nature. A copy of the paper is available here.

Behold: 100 Planetary Nebulas

If you like planetary nebulas, you’re in luck. Multimedia artist Judy Schmidt has put together an amazing collection of 100 of these colorful glowing shells of gas and plasma, all at apparent size relative to one another. There’s even a giant-sized 10,000 pixel-wide version available on Flickr.

How many of these planetary nebulae can you identify?

Judy explained her inspiration for putting together this wonderful ‘poster’:

Inspired by insect illustration posters, this is a large collage of planetary nebulas I put together bit by bit as I processed them. All are presented north up and at apparent size relative to one another–I did not rotate or resize them in order to satisfy compositional aesthetics (if you spot any errors, let me know). Colors are aesthetic choices, especially since most planetary nebulas are imaged with narrowband filters.

Planetary nebulae are formed by certain types of stars at the end of their lives, and actually have nothing to do with planets. They were given the confusing name 300 years ago by William Herschel because in early, rudimentary telescopes, the puffed out balls of gas looked like planets.

Our own Sun will likely undergo a similar process, but not for another 5 billion years or so.

You can see more of Judy’s work at her website “Geckzilla” or Flickr page.

What Is The Future Of Our Sun?

Who knows what the future holds for our Sun? Dr. Mark Morris, a professor of astronomy at UCLA sure knows. Professor Morris sat down with us to let us know what we’re in for over the next few billions years.

“Hi, I’m Professor Mark Morris. I’m teaching at UCLA where I also carry out my research. I work on the center of the galaxy and what’s going on there – in this fabulous arena there, and on dying stars – stars that have reached the end of their lifetime and are putting on a display for us as they do so.”

What is the future of our sun?

“Well, there’s every expectation that in about 5 billion more years, that our sun will swell up to become a red giant. And then, as it gets larger and larger, it will eventually become what’s called an asymptotic giant branch star – a star whose radius is just under the distance between the sun and the Earth – one astronomical unit in size. So the Earth will be literally skimming the surface of the red giant sun when it’s an asymptotic giant branch star.”

“A star that big is also cool because they’re cold – red hot versus blue hot or yellow hot like our sun. Because it’s cold, a red giant star at its surface layers can keep all of its elements in the gas phase. So some of the heavier elements – the metals and the silicates – condense out as small dust grains, and when these elements condense out as solids, then radiation pressure from this very luminous giant star pushes the dust grains out. That may seem like a minor issue, but in fact these dust grains carry the gas with them. And so the star literally expels its atmosphere, and goes from a red giant star to a white dwarf, when finally the core of the star is exposed. Now, as it’s doing this, that hot core of the star is still very luminous and lights up through a fluorescent process, this out-flowing envelope, this atmosphere that was once a star, and that’s what produces these beautiful displays that are called planetary nebulae.”

“Now, planetary nebulae can be these beautiful round, spherical objects, or they can be bipolar, which is one of the mysteries that we’re working here is trying to understand why, at some stage, a star suddenly becomes axisymmetric – in other words, is sending out is’s atmosphere in two diametrically opposed directions predominantly, rather than continuing to lose mass spherically.”

Planetary Nebula
Planetary Nebula M2-9 (Credit: Bruce Balick (University of Washington), Vincent Icke (Leiden University, The Netherlands), Garrelt Mellema (Stockholm University), and NASA)

“We can’t invoke rotation of the star – that would be one way to get a preferred axis, but stars don’t rotate fast enough. If you take the sun and let it expand to become a red giant, then by the conservation of angular momentum, it literally won’t be spinning at all. It’ll be spinning so slowly that it’ll literally have no effect. So we can’t invoke spin, so there must be something going on deep down inside the star, that when you finally expose some rapidly spinning core, it can have an effect.”

“Or, all of the stars that we see as planetary nebula can have binary companions, that could be massive planets or relatively low mass stars that themselves can impose an angular momentum orientation on the system. This is in fact an idea that I’ve been championing for decades now, and it has some traction. There’s a lot of planetary nebula nuclei, the white dwarves, that seem to have companions near them that are suspect for having been responsible for helping strip the atmosphere of the mass-losing red giant star but also providing a preferred axis along which the ejected matter can flow.”

ALMA Warms Up the View of the Coldest Place In the Universe

Where is the coldest place in the Universe? Right now, astronomers consider the “Boomerang Nebula” to have the honors. Located about 5,000 light-years away in the constellation Centaurus, this pre-planetary nebula carries a temperature of about one Kelvin – or a brisk, minus 458 degrees Fahrenheit. That makes it even colder than the natural background temperature of space! What makes it more frigid than the elusive afterglow of the Big Bang? Astronomers are employing the powers of the Atacama Large Millimeter/submillimeter Array (ALMA) telescope to tell us more about its chilly properties and unusual shape.

The “Boomerang” is different all the way around. It is not yet a planetary nebula. The fueling light source – the central star – just isn’t hot enough yet to emit the massive amounts of ultra-violet radiation which lights up the structure. Right now it is illuminated by starlight shining off its surrounding dust grains. When it was first observed in optical light by our terrestrial telescopes, the nebula appeared to be shifted to one side and that’s how it got its fanciful name. Subsequent observations with the Hubble Space Telescope revealed an hour-glass structure. Now, enter ALMA. With these new observations, we can see the Hubble images only show part of what’s happening and the dual lobes seen in the older data were probably only a “trick of the light” as presented by optical wavelengths.

“This ultra-cold object is extremely intriguing and we’re learning much more about its true nature with ALMA,” said Raghvendra Sahai, a researcher and principal scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California, and lead author of a paper published in the Astrophysical Journal. “What seemed like a double lobe, or ‘boomerang’ shape, from Earth-based optical telescopes, is actually a much broader structure that is expanding rapidly into space.”

So what is going on out there that makes the Boomerang such a cool customer? It’s the outflow, baby. The central star is expanding at a frenzied pace and it is lowering its own temperature in the process. A prime example of this is an air conditioner. It uses expanding gas to create a colder core and as the breeze blows over it – or in this case, the expanding shell – the environment around it is cooled. Astronomers were able to determine just how cool the gas in the nebula is by noting how it absorbed the constant of the cosmic microwave background radiation: a perfect 2.8 degrees Kelvin (minus 455 degrees Fahrenheit).

Credit: NASA/ESA
Credit: NASA/ESA
“When astronomers looked at this object in 2003 with Hubble, they saw a very classic ‘hourglass’ shape,” commented Sahai. “Many planetary nebulae have this same double-lobe appearance, which is the result of streams of high-speed gas being jettisoned from the star. The jets then excavate holes in a surrounding cloud of gas that was ejected by the star even earlier in its lifetime as a red giant.”

However, the single-dish millimeter wavelength telescopes didn’t see things the same as Hubble. Rather than a skinny waist, they found a fuller figure – a “nearly spherical outflow of material”. According to the news release, ALMA’s unprecedented resolution permitted researchers to determine why there was such a difference in overall appearance. The dual-lobe structure was evident when they focused on the distribution of carbon monoxide molecules as seen at millimeter wavelengths, but only toward the inside of the nebula. The outside was a different story, though. ALMA revealed a stretched, cold gas cloud that was relatively rounded. What’s more, the researchers also pinpointed a thick corridor of millimeter-sized dust grains enveloping the progenitor star – the reason the outer cloud took on the appearance of a bowtie in visible light! These dust grains shielded a portion of the star’s light, allowing just a glimpse in optical wavelengths coming from opposite ends of the cloud.

“This is important for the understanding of how stars die and become planetary nebulae,” said Sahai. “Using ALMA, we were quite literally and figuratively able to shed new light on the death throes of a Sun-like star.”

There’s even more to these new findings. Even though the perimeter of the nebula is beginning to warm up, it’s still just a bit colder than the cosmic microwave background. What could be responsible? Just ask Einstein. He called it the “photoelectric effect”.

Original Story Source: NRAO News Release.

This Planetary Nebula Comes With a Twist

From the Cat’s Eye to the Eskimo, planetary nebulae are arguably among the most dazzling objects in the Universe. These misnamed stellar remnants are created when the outer layers of a dying star blows off and expands into space. However, they can look radically different from one another, revealing complicated histories and structures.

But recently, astronomers have argued that some of the most exotic shapes are the result of not one, but two stars at the center. It is the interaction between the progenitor star and a binary companion that shapes the resulting planetary nebula.

The archetypal planetary nebula is spherical. Most planetary nebulae, however, have been shown to be non-spherical, complex structures.

“LoTr 1 is one such planetary nebula, but with a twist,” Amy Tyndall – a graduate student at the University of Manchester and lead author on the study – told Universe Today. It has not one star at its center but two. The binary central star system consists of a faint, hot white dwarf and a cool companion – a rapidly rotating giant.

LoTr 1 with a binary central star system and two slightly elongated shells, with ages of 17 and 35 thousand years.
LoTr 1 with a binary central star system and two slightly elongated shells, with ages of 17 and 35 thousand years. Credit: Tyndal et al.

LoTr 1 was first discovered by astronomers using the 1.2 meter telescope at the Royal Observatory in Edinburgh, Scotland. At the time it seemed that LoTr 1 was similar to a particular group of 4 planetary nebulae (Abell 35, Abell 70, WeBo 1 and LoTr 5), all of which had a central binary star system.

Another common factor amongst this particular group is that in most cases the companion star seemed to be a barium star – a cool giant that shows relatively large amounts of barium. Before the planetary nebula forms, the progenitor star dredges up an excess amount of Barium on its surface. It then releases a Barium-enriched stellar wind, which falls on its companion star.

“After the stellar envelope is ejected to form the surrounding nebula, the giant star evolves into a white dwarf, while the contaminated star retains the barium from the wind as it continues to evolve to form a Barium star,” explains Tyndall.

Tyndall and her collaborates set out to see if the companion star within LoTr 1 was in fact a Barium star. They acquired data from telescopes in both Chile and Australia and compared their results to the two other elusive planetary nebulae in the group: Abell 70 and WeBo 1.

“If barium is indeed present, it would be a good step further towards our understanding of how mass is transferred between stars in a binary system, and how that subsequently affects the formation and morphology of planetary nebulae,” says Tyndall.

While the results show that LoTr 1 does consist of binary star system, the companion star is not a Barium star. But a null result is still a result. “LoTr 1 remains an interesting object to us as it shows that we still have huge gaps in our knowledge as to how these stunning objects form,” Tyndall told Universe Today.

Without the presence of Barium, it would appear at first that little mass was transferred to the companion star. However, the companion star is rotating rapidly, which is a direct consequence of mass transfer. The most plausible explanation is that the mass was transferred before the barium could be dredged up to the stellar surface.

If the stellar evolution was cut short this way then there will be detectable evidence in the properties of the white dwarf. The next step will be to take another look at this odd planetary nebula in hopes of better understanding the complexities of this system.

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

Endings and Beginnings – Magnetic Jets Shape Stellar Transformation

The incredible visual appearance of planetary nebulae are some of the most studied and observed of deep space objects. However, these enigmatic clouds of gas have defied explanation as to their shapes and astronomers are seeking answers. Thanks to a new discovery made by an international team of scientists from Sweden, Germany and Austria, we have now observed a jet of high-energy particles in the process of being ejected from an expiring star.

When a sun-like star reaches the end of its life, it begins to shed itself of its outer layers. These layers blossom into space at speeds of a few kilometers per second, forming a variety of shapes and sizes – yet we know little about what causes their ultimate appearance. Now astronomers are taking a close look at a rather normal star that has reached the end of its life and is beginning to form a planetary nebula. Cataloged as IRAS 15445-5449, this stellar study resides 230,000 light years away in the constellation of Triangulum Australe (the Southern Triangle). Through the use of the CSIRO Australia Telescope Compact Array, a compliment of six 22-meter radio telescopes in New South Wales, Australia, researchers have found what may be the answer to this mystery… high-speed magnetic jets.

“In our data we found the clear signature of a narrow and extremely energetic jet of a type which has never been seen before in an old, Sun-like star,” says Andrés Pérez Sánchez, graduate student in astronomy at Bonn University, who led the study.

How does a radio telescope aid researchers in an optical study? In this case the radio waves emitted by the dying star are compatible with the trademark high-energy particles they are expected to produce. These “spouts” of particles travel at nearly the speed of light and coincident jets are also known to emanate from other astronomical objects that range from newborn stars to supermassive black holes.

“What we’re seeing is a powerful jet of particles spiraling through a strong magnetic field,” says Wouter Vlemmings, astronomer at Onsala Space Observatory, Chalmers. “Its brightness indicates that it’s in the process of creating a symmetric nebula around the star.”

Will these high-energy particles contained within the jet eventually craft the planetary nebula into an ethereal beauty? According to the astronomers, the current state of IRAS 15445-5449 is probably a short-lived phenomenon and nothing more than an intense and dramatic phase in its life… One we’re lucky to have observed.

“The radio signal from the jet varies in a way that means that it may only last a few decades. Over the course of just a few hundred years the jet can determine how the nebula will look when it finally gets lit up by the star,” says team member Jessica Chapman, astronomer at CSIRO in Sydney, Australia.

Will our Sun also follow suit? Right now the answer is unclear. There may be more to this radio picture than meets the ear. However, rest assured that this new information is being heard and might well become the target of additional radio studies. Considering the life of a planetary nebula is generally expected to last few tens of thousands of years, this is a unique opportunity for astronomers to observe what might be a transient occurrence.

“The star may have an unseen companion – another star or large planet — that helps create the jet. With the help of other front-line radio telescopes, like ALMA, and future facilities like the Square Kilometre Array (SKA), we’ll be able to find out just which stars create jets like this one, and how they do it,” says Andrés Pérez Sánchez.

Original Story Source: Royal Astronomical Society News Release.

Hubble and NTT Capture Strange Alignment of Planetary Nebulae

While taking a look at more than a hundred planetary nebulae in our galaxy’s central bulge, astronomers using the NASA/ESA Hubble Space Telescope and ESO’s New Technology Telescope have found something rather incredible. It would appear that butterfly-shaped planetary nebulae – despite their differences – are somehow mysteriously aligned!

We know that stars similar to our Sun end their lives shedding their outer layers into space. Like a reptile’s intact skin casing, this stellar material forms a huge variety of shapes known as planetary nebulae. One of the more common forms is bipolar – which creates a bowtie or butterfly shape around the progenitor star.

Like snowflakes, no two planetary nebulae are exactly alike. They are created in different places, under different circumstances and have very different characteristics. There is no way that any of these nebulae, nor the responsible stars that formed them, could have interacted with other planetary nebulae. However, according to a new study done by astronomers from the University of Manchester, UK, there seems to be a rather incredible coincidence… A surprising number of these stellar shells are lining up the same way from our galactic point of view.

“This really is a surprising find and, if it holds true, a very important one,” explains Bryan Rees of the University of Manchester, one of the paper’s two authors. “Many of these ghostly butterflies appear to have their long axes aligned along the plane of our galaxy. By using images from both Hubble and the NTT we could get a really good view of these objects, so we could study them in great detail.”

According to the news release, the astronomers observed 130 planetary nebulae in the Milky Way’s central bulge. They identified three different types, and closely examined their characteristics and appearance.

“While two of these populations were completely randomly aligned in the sky, as expected, we found that the third — the bipolar nebulae — showed a surprising preference for a particular alignment,” says the paper’s second author Albert Zijlstra, also of the University of Manchester. “While any alignment at all is a surprise, to have it in the crowded central region of the galaxy is even more unexpected.”

What causes a planetary nebula to take on a particular shape? For some time, astronomers figured their appearance may have been affected by the rotation of the star system in which they form. Many factors could contribute, such as whether or not the spawning star is a binary, or if it has a planetary system. Both of these factors could help mold the eventual outcome of the shed stellar material. However, bipolar planetary nebulae are the most extreme. Astronomers theorize their shapes are the product of jets blowing mass from the binary system perpendicular to the orbit.

“The alignment we’re seeing for these bipolar nebulae indicates something bizarre about star systems within the central bulge,” explains Rees. “For them to line up in the way we see, the star systems that formed these nebulae would have to be rotating perpendicular to the interstellar clouds from which they formed, which is very strange.”

We accept the fact that the properties of the parent stars are the biggest contributor to a planetary nebula’s shape, but this new information gives an enigmatic edge to the final outcome. Not only is each unique, but the Milky Way itself adds even more complexity. The entire central bulge rotates around the galactic center, and this bulge may have considerably more influence than we expected… the influence of its magnetic fields. The researchers suggest this “orderly behavior of the planetary nebulae” may have occurred because a strong magnetic field was present when the bulge formed. Since planetary nebulae nearer to us don’t line up in the same orderly fashion, it would be logical to assume these magnetic fields were much stronger when our galaxy first formed.

“We can learn a lot from studying these objects,” concludes Zijlstra. “If they really behave in this unexpected way, it has consequences for not just the past of individual stars, but for the past of our whole galaxy.”

Original Story Source: ESO News Release.

Looking Into The Green Eye Of Planetary Nebula IC 1295

Located on Cerro Paranal in the Atacama Desert of northern Chile, the ESO’s Very Large Telescope was busy using the FORS instrument (FOcal Reducer Spectrograph) to achieve one of the most detailed observations ever taken off a lonely, green planetary nebula – IC 1295. Exposures taken through three different filters which enhanced blue light, visible green light, and red light were melded together to make this 3300 light year distant object come alive.

Located in the constellation of Scutum, this jewel in the “Shield” is a miniscule star that’s at the end of its life. Much like our Sun will eventually become, this white dwarf star is softly shedding its outer layers, like an unfolding flower in space. It will continue this process for a few tens of thousands of years, before it ends, but until then IC 1295 will remain something of an enigma.

“The range of shapes observed up to today has been reproduced by many theoretical works using arguments such as density enhancements, magnetic fields, and binary central systems. Despite this, no complete agreement between models and properties of a given morphological group has been achieved. One of the main reasons for this is selection criteria and completeness of studied samples.” say researchers at Georgia State University. “The samples are usually limited by available images in few bands such as Ha, [NII] and [OIII]. Of course they are also limited by distance, since the further away the object is, the harder it is to resolve its structure. Even with the modern telescopes, obtaining a truly complete sample is far from being achieved.”

Why is this common deep space object like IC 1295 such a mystery? Blame it on its structure. It is comprised of multiple shells.- gaseous layers which once were the star’s atmosphere. As the star aged, its core became unstable and it erupted in unexpected releases of energy – like expansive blisters breaking open. These waves of gas are then illuminated by the ancient star’s ultraviolet radiation, causing it to glow. Each chemical acts as a pigment, resulting in different colors. In the case of IC 1295, the verdant shades are the product of ionised oxygen.

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This video sequence starts with a broad panorama of the Milky Way and closes in on the small constellation of Scutum (The Shield), home to many star clusters. The final detailed view shows the strange green planetary nebula IC 1295 in a new image from ESO’s Very Large Telescope. This faint object lies close to the brighter globular star cluster NGC 6712. Credit: ESO/Nick Risinger ( Kimball. Music: movetwo

However, green isn’t the only color you see here. At the heart of this planetary nebula beats a bright, blue-white stellar core. Over the course of billions of years, it will gently cool – becoming a very faint, white dwarf. It’s just all part of the process. Stars similar to the Sun, and up to eight times as large, are all theorized to form planetary nebulae as they extinguish. How long does a planetary nebula last? According to astronomers, it’s a process that could be around 8 to 10 thousand years.

“Athough planetary nebulae (PNe) have been discovered for over 200 years, it was not until 30 years ago that we arrived at a basic understanding of their origin and evolution.” says Sun Kwok of the Institute of Astronomy and Astrophysics. “Even today, with observations covering the entire electromagnetic spectrum from radio to X-ray, there are still many unanswered questions on their structure and morphology.”

Original Story Source: ESO Photo Release.