Pluto is What You Get When a Billion Comets Smash Together

Pluto is What You Get When a Billion Comets Smash Together:

Pluto has been the focus of a lot of attention for more than a decade now. This began shortly after the discovery of Eris in the Kuiper Belt, one of many Kuiper Belt Objects (KBOs) that led to the “Great Planetary Debate” and the 2006 IAU Resolution. Interest in Pluto also increased considerably thanks to the New Horizons mission, which conducted the first flyby of this “dwarf planet” in July of 2015.

The data this mission provided on Pluto is still proving to be a treasure trove for astronomers, allowing for new discoveries about Pluto’s surface, composition, atmosphere, and even formation. For instance, a new study produced by researchers from the Southwest Research Institute (and supported by NASA Rosetta funding) indicates that Pluto may have formed from a billion comets crashing together.

The study, titled “Primordial N₂ provides a cosmochemical explanation for the existence of Sputnik Planitia, Pluto“, recently appeared in the scientific journal Icarus. The study was authored by Dr. Christopher R. Glein – a researcher with the Southwest Research Institute’s Space Science and Engineering Division – and Dr. J. Hunter Waite Jr, an SwRI program director.

The first Kuiper Belt is home to more than 100,000 asteroids and comets there over 62 miles (100 km) across. Credit: JHUAPL

The origin of Pluto is something that astronomers have puzzled over for some time. An early hypothesis was that it was an escaped moon of Neptune that had been knocked out of orbit by Neptune’s current largest moon, Triton. However, this theory was disproven after dynamical studies showed that Pluto never approaches Neptune in its orbit. With the discovery of the Kuiper Belt in 1992, the true of origin of Pluto began to become clear.

Essentially, while Pluto is the largest object in the Kuiper Belt, it is similar in orbit and composition to the icy objects that surround it. On occasion, some of these objects are kicked out of the Kuiper Belt and become long-period comets in the Inner Solar System. To determine if Pluto formed from billions of KBOs, Dr. Glein and Dr. Waite Jr. examined data from the New Horizons mission on the nitrogen-rich ice in Sputnik Planitia.

This large glacier forms the left lobe of the bright Tombaugh Regio feature on Pluto’s surface (aka. Pluto’s “Heart”). They then compared this to data obtained by the NASA/ESA Rosetta mission, which studied the comet 67P/Churyumov–Gerasimenko (67P) between 2014 and 2016. As Dr. Glein explained:

“We’ve developed what we call ‘the giant comet’ cosmochemical model of Pluto formation. We found an intriguing consistency between the estimated amount of nitrogen inside the glacier and the amount that would be expected if Pluto was formed by the agglomeration of roughly a billion comets or other Kuiper Belt objects similar in chemical composition to 67P, the comet explored by Rosetta.”

New Horizon’s July 2015 flyby of Pluto captured this iconic image of the heart-shaped region called Tombaugh Regio. Credit: NASA/JHUAPL/SwRI

This research also comes up against a competing theory, known as the “solar model”. In this scenario, Pluto formed from the very cold ices that were part of the protoplanetary disk, and would therefore have a chemical composition that more closely matches that of the Sun. In order to determine which was more likely, scientists needed to understand not only how much nitrogen is present at Pluto now (in its atmosphere and glaciers), but how much could have leaked out into space over the course of eons.

They then needed to come up with an explanation for the current proportion of carbon monoxide to nitrogen. Ultimately, the low abundance of carbon monoxide at Pluto could only be explained by burial in surface ices or destruction from liquid water. In the end, Dr. Glein and Dr. Waite Jr.’s research suggests that Pluto’s initial chemical makeup, which was created by comets, was modified by liquid water, possibly in the form of a subsurface ocean.

“This research builds upon the fantastic successes of the New Horizons and Rosetta missions to expand our understanding of the origin and evolution of Pluto,” said Dr. Glein. “Using chemistry as a detective’s tool, we are able to trace certain features we see on Pluto today to formation processes from long ago. This leads to a new appreciation of the richness of Pluto’s ‘life story,’ which we are only starting to grasp.”

While the research certainly offers an interesting explanation for how Pluto formed, the solar model still satisfies some criteria. In the end, more research will be needed before scientists can conclude how Pluto formed. And if data from the New Horizons or Rosetta missions should prove insufficient, perhaps another to New Frontiers mission to Pluto will solve the mystery!

Further Reading: SwRI, Icarus

The post Pluto is What You Get When a Billion Comets Smash Together appeared first on Universe Today.

Astronomers Observe a Pulsar 6500 Light-Years From Earth and See Two Separate Flares Coming off its Surface

Astronomers Observe a Pulsar 6500 Light-Years From Earth and See Two Separate Flares Coming off its Surface:

Astronomy can be a tricky business, owing to the sheer distances involved. Luckily, astronomers have developed a number of tools and strategies over the years that help them to study distant objects in greater detail. In addition to ground-based and space-based telescopes, there’s also the technique known as gravitational lensing, where the gravity of an intervening object is used to magnify light coming from a more distant object.

Recently, a team of Canadian astronomers used this technique to observe an eclipsing binary millisecond pulsar located about 6500 light years away. According to a study produced by the team, they observed two intense regions of radiation around one star (a brown dwarf) to conduct observations of the other star (a pulsar) – which happened to be the highest resolution observations in astronomical history.

The study, titled “Pulsar emission amplified and resolved by plasma lensing in an eclipsing binary“, recently appeared in the journal Nature. The study was led by Robert Main, a PhD astronomy student at the University of Toronto’s Dunlap Institute for Astronomy & Astrophysics, and included members from the Canadian Institute for Theoretical Astrophysics, the Perimeter Institute for Theoretical Physics, and the Canadian Institute for Advanced Research.



The system they observed is known as the “Black Widow Pulsar”, a binary system that consists of a brown dwarf and a millisecond pulsar orbiting closely to each other. Because of their close proximity to one another, scientists have determined that the pulsar is actively siphoning material from its brown dwarf companion and will eventually consume it. Discovered in 1988, the name “Black Widow” has since come to be applied to other similar binaries.

The observations made by the Canadian team were made possible thanks to the rare geometry and characteristics of the binary – specifically, the “wake” or comet-like tail of gas that extends from the brown dwarf to the pulsar. As Robert Main, the lead author of the paper, explained in a Dunlap Institute press release:

“The gas is acting like a magnifying glass right in front of the pulsar. We are essentially looking at the pulsar through a naturally occurring magnifier which periodically allows us to see the two regions separately.”

Like all pulsars, the “Black Widow” is a rapidly rotating neutron star that spins at a rate of over 600 times a second. As it spins, it emits beams of radiation from its two polar hotspots, which have a strobing effect when observed from a distance. The brown dwarf, meanwhile, is about one third the diameter of the Sun, is located roughly two million km from the pulsar and orbits it once every 9 hours.

Image of the pulsar surrounded by its bow shock. White rays indicate particles of matter and antimatter being spewed from the star. Its companion star is too close to the pulsar to be visible at this scale. Credit: NASA/CXC/M.Weiss

Because they are so close together, the brown dwarf is tidally-locked to the pulsar and is blasted by strong radiation. This intense radiation heats one side of the relatively cool brown dwarf to temperatures of about 6000 °C (10,832 °F), the same temperature as our Sun. Because of the radiation and gases passing between them, the emissions coming from the pulsar interfere with each other, which makes them difficult to study.

However, astronomers have long understood that these same regions could be used as “interstellar lenses” that could localize pulsar emission regions, thus allowing for their study. In the past, astronomers have only been able to resolve emission components marginally. But thanks to the efforts of Main and his colleagues, they were able observing two intense radiation flares located 20 kilometers apart.

In addition to being an unprecedentedly high-resolution observation, the results of this study could provide insight into the nature of the mysterious phenomena known as Fast Radio Bursts (FRBs). As Main explained:

“Many observed properties of FRBs could be explained if they are being amplified by plasma lenses. The properties of the amplified pulses we detected in our study show a remarkable similarity to the bursts from the repeating FRB, suggesting that the repeating FRB may be lensed by plasma in its host galaxy.”

It is an exciting time for astronomers, where improved instruments and methods are not only allowing for more accurate observations, but also providing data that could resolve long-standing mysteries. It seems that every few days, fascinating new discoveries are being made!

Further Reading: University of Toronto, Nature

The post Astronomers Observe a Pulsar 6500 Light-Years From Earth and See Two Separate Flares Coming off its Surface appeared first on Universe Today.

Planets on Parade: Saturn at Opposition 2018

Planets on Parade: Saturn at Opposition 2018:

Saturn, Mars and Jupiter all beckon this summer. Image credit and copyright: Sharin Ahmad (@shahgazer).

We’re in the midst of a parade of planets crossing the evening sky. Jupiter reached opposition on May 9th, and sits high to the east at dusk. Mars heads towards a fine opposition on July 27th, nearly as favorable as the historic opposition of 2003. And Venus rules the dusk sky in the west after the setting Sun for most of 2018.

June is Saturn’s turn, as the planet reaches opposition this year on June 27th, rising opposite to the setting Sun at dusk.

In classical times, right up until just over two short centuries ago, Saturn represented the very outer limit of the solar system, the border lands where the realm of the planets came to an end. Sir William Herschel extended this view, when he spied Uranus—the first planet discovered in the telescopic era—slowly moving through the constellation Gemini just across the border of Taurus the Bull using a 7-foot reflector (in the olden days, telescopes specs were often quoted referring to their focal length versus aperture) while observing from his backyard garden in Bath, England on the night of March 13th, 1781.

Looking east tonight at sunset… note Vesta to the upper left. Credit: Stellarium.

Orbiting the Sun once every 29.5 years, Saturn is the slowest moving of the naked eye planets, fitting for a planet named after Father Time. Saturn slowly loops from one astronomical constellation along the zodiac to the next eastward, moving through one about every two years.

The path of Saturn through 2018. Image credit: Starry Night Education software.

2018 sees Saturn in the constellation Sagittarius the Archer, just above the ‘lid’ of the Teapot asterism, favoring the southern hemisphere for this apparition. Saturn won’t cross the celestial equator northward again until 2026. Not that that should discourage northern hemisphere viewers from going after this most glorious of planets. A low southerly declination also means that Saturn is also up in the evening in the summertime up north, a conducive time for observing. Taking 29-30 years to complete one lap around the ecliptic as seen from our Earthly vantage point, Saturn also makes a great timekeeper with respect to personal life milestones… where were you back in 1989, when Saturn occupied the same spot along the ecliptic?

Saturn also shows the least variation of all the planets in terms of brightness and size, owing to its immense distance 9.5 AU from the Sun, and consequently 8.5 to 10.5 AU from the Earth. Saturn actually just passed its most distant aphelion since 1959 on April 17^th, 2018 at 10.066 AU from the Sun.

Saturn’s in 2018 Dates with Destiny

Saturn sits just 1.6 degrees south of the waning gibbous Moon tonight. The Moon will lap it again one lunation later on June 28th. Note that the brightest of the asteroids, +5.7 magnitude 4 Vesta is nearby in northern Sagittarius, also reaching opposition on June 19^th. Can you spy Vesta with the naked eye from a dark sky site? 4 Vesta passes just 4 degrees from Saturn on September 23rd, and both flirt with the galactic plane and some famous deep sky targets, including the Trifid and Lagoon Nebulae.

Saturn reaches quadrature 90 degrees east of the Sun on September 25th, then ends its evening apparition when it reaches solar conjunction on New Year’s Day, 2019.

Saturn is well clear of the Moon’s path for most of this year, but stick around: starting on December 9^th, 2018, the slow-moving planet will make a great target for the Moon, which will begin occulting it for every lunation through the end of 2019.

It’s ironic: Saturn mostly hides its beauty to unaided eye. Presenting a slight saffron color in appearance, it never strays much from magnitude -0.2 to +1.4 in brightness. One naked eye observation to watch for is a sudden spurt in brightness known as the opposition surge or Seeliger Effect. This is a retro reflector type effect, caused by all those tiny iceball moonlets in the rings reaching 100% illumination at once. Think of how the Full Moon is actually 3 to 4 times brighter than the 50% illuminated Quarter Moon… all those little peaks, ridges and crater rims no longer casting shadows do indeed add up.

Saturn in all its glory (note the moons Enceladus and Tethys, too!). Image credit and copyright: Efrain Morales.

And this effect is more prominent in recent years for another reason: Saturn’s rings passed maximum tilt (26.7 degrees) with respect to our line of sight just last year, and are still relatively wide open in 2018. They’ll start slimming down again over the next few oppositions, reaching edge-on again in 2028.

Even using a pair of 7×50 hunting binoculars on Saturn, you can tell that something is amiss. You’re getting the same view that Galileo had through his spyglass, the pinnacle of early 17^th century technology. He could tell that something about the planet was awry, and drew sketches showing an oblong world with coffee cup handles on the side. Crank up the magnification using even a small 60 mm refractor, and the rings easily jump into view. This is what makes Saturn a star party staple, an eye candy feast capable of drawing the aim of all the telescopes down the row.

If seeing and atmospheric conditions allow, crank up the magnification up to 150x or higher, and the dark groove of the Cassini division snaps into view. Can you see the shadow of the disk of Saturn, cast back onto the plane of the rings? The shadow of the planet hides behind it near opposition, then becomes most prominent towards quadrature, when we get to peek around its edge. Can you spy the limb of the planet itself, through the Cassini Gap?

Though the disk of Saturn is often featureless, tiny swirls of white storms do occasionally pop up. Astrophotographer Damian Peach noted just one such short-lived storm on the ringed planet this past April 2018.

Saturn’s retinue of moons are also interesting to follow in there own right. The first one you’ll note is +8.5 magnitude smog-shrouded Titan. Larger in diameter than Mercury, Titan would easily be a planet in its own right, were it liberated from its primary’s domain.

Though Saturn has 62 known moons, only six in addition to Titan are in range of a modest backyard telescope: Enceladus, Rhea, Dione, Mimas, Tethys and Iapetus. Two-faced Iapetus is especially interesting to follow, as it varies two full magnitudes in brightness during its 79 day orbit. Arthur C. Clarke originally placed the final monolith in 2001: A Space Odyssey on this moon, its artificial coating a beacon to astronomers. Today, we know from flybys carried out by NASA’s Cassini spacecraft that the leading hemisphere of Iapetus is coated with dark in-falling material, originating from the dark Phoebe ring around Saturn.

Two-faced Iapetus as imaged by Cassini. Image credit: NASA/JPL/Space Science Institute.

Owners of large light bucket telescopes may also want to try from two fainter +15th magnitude moons: Hyperion and Phoebe.

Fun fact: Saturn’s moons can also cast shadows back on the planet itself, much like the Galilean moons do on Jupiter… the catch, however, is that these events only occur around equinox season in the years around when Saturn’s rings are edge-on. This next occurs starting in 2026.

Cassini finished up its thrilling 20 year mission just last year, with a dramatic plunge into Saturn itself. It will be a while before we return again, perhaps in the next decade if NASA selects a nuclear-powered helicopter to explore Titan. Until then, be sure to explore Saturn this summer, from your Earthbound backyard.

Love to observe the planets? Check out our new forthcoming book, The Universe Today Ultimate Guide to Viewing the Cosmos – out on October 23rd, now up for pre-order.

The post Planets on Parade: Saturn at Opposition 2018 appeared first on Universe Today.

This is What Happens When a Black Hole Gobbles up a Star

This is What Happens When a Black Hole Gobbles up a Star:

At the center of our galaxy resides a Supermassive Black Hole (SMBH) known as Sagittarius A. Based on ongoing observations, astronomers have determined that this SMBH measures 44 million km (27.34 million mi) in diameter and has an estimated mass of 4.31 million Solar Masses. On occasion, a star will wander too close to Sag A and be torn apart in a violent process known as a tidal disruption event (TDE).

These events cause the release of bright flares of radiation, which let astronomers know that a star has been consumed. Unfortunately, for decades, astronomers have been unable to distinguish these events from other galactic phenomena. But thanks to a new study from by an international team of astrophysicists, astronomers now have a unified model that explains recent observations of these extreme events.

The study – which recently appeared in the Astrophysical Journal Letters under the title “A Unified Model for Tidal Disruption Events” – was led by Dr. Jane Lixin Dai, a physicist with the Niels Bohr Institute’s Dark Cosmology Center. She was joined by members from University of Maryland’s Joint Space-Science Institute and the University of California Santa Cruz (UCSC).

Illustration of the supermassive black hole at the center of the Milky Way. Credit: NRAO/AUI/NSF

As Enrico Ramirez-Ruiz – the professor and chair of astronomy and astrophysics at UC Santa Cruz, the Niels Bohr Professor at the University of Copenhagen, and a co-author on the paper – explained in a UCSC press release:

“Only in the last decade or so have we been able to distinguish TDEs from other galactic phenomena, and the new model will provide us with the basic framework for understanding these rare events.”

In most galaxies, SMBHs do not actively consume any material and therefore do not emit any light, which distinguishes them from galaxies that have Active Galactic Nuclei (AGNs). Tidal disruption events are therefore rare, occurring only once about every 10,000 years in a typical galaxy. However, when a star does get torn apart, it results in the release of an intense amount of radiation. As Dr. Dai explained:

“It is interesting to see how materials get their way into the black hole under such extreme conditions. As the black hole is eating the stellar gas, a vast amount of radiation is emitted. The radiation is what we can observe, and using it we can understand the physics and calculate the black hole properties. This makes it extremely interesting to go hunting for tidal disruption events.”

Illustration of emissions from a tidal disruption event shows in cross section what happens when the material from a disrupted star is devoured by a black hole. Credit: Jane Lixin Dai

In the past few years, a few dozen candidates for tidal disruption events (TDEs) have been detected using wide-field optical and UV transient surveys as well as X-ray telescopes. While the physics are expected to be the same for all TDEs, astronomers have noted that a few distinct classes of TDEs appear to exist. While some emit mostly x-rays, others emit mostly visible and ultraviolet light.

As a result, theorists have struggled to understand the diverse properties observed and create a coherent model that can explain them all. For the sake of their model, Dr. Dai and her colleagues combined elements from general relativity, magnetic fields, radiation, and gas hydrodynamics. The team also relied on state-of-the-art computational tools and some recently-acquired large computer clusters funded by the Villum Foundation for Jens Hjorth (head of DARK Cosmology Center), the U.S. National Science Foundation and NASA.

Using the model that resulted, the team concluded that it is the viewing angle of the observer that accounts for the differences in observation.  Essentially, different galaxies are oriented randomly with respect to observers on Earth, who see different aspects of TDEs depending on their orientation. As Ramirez-Ruiz explained:

“It is like there is a veil that covers part of a beast. From some angles we see an exposed beast, but from other angles we see a covered beast. The beast is the same, but our perceptions are different.”

Artist’s impression of the Large Synoptic Survey Telescope. Credit: lsst.org

In the coming years, a number of planned survey projects are expected to provide much more data on TDEs, which will help expand the field of research into this phenomena. These include the Young Supernova Experiment (YSE) transient survey, which will be led by the DARK Cosmology Center at the Niels Bohr Institute and UC Santa Cruz, and the Large Synoptic Survey Telescopes (LSST) being built in Chile.

According to Dr. Dai, this new model shows what astronomers can expect to see when viewing TDEs from different angles and will allow them to fit different events into a coherent framework. “We will observe hundreds to thousands of tidal disruption events in a few years,” she said. “This will give us a lot of ‘laboratories’ to test our model and use it to understand more about black holes.”

This improved understanding of how black holes occasionally consume stars will also provide additional tests for general relativity, gravitational wave research, and help astronomers to learn more about the evolution of galaxies.

Further Reading: UCSC, Astrophysical Journal Letters

The post This is What Happens When a Black Hole Gobbles up a Star appeared first on Universe Today.

What are the Chances that the Next Generation LSST Could Find New Planets in the Solar System?

What are the Chances that the Next Generation LSST Could Find New Planets in the Solar System?:

In the past few decades, thanks to improvements in ground-based and space-based observatories, astronomers have discovered thousands of planets orbiting neighboring and distant stars (aka. extrasolar planets). Strangely enough, it is these same improvements, and during the same time period, that enabled the discovery of more astronomical bodies within the Solar System.

These include the “minor planets” of Eris, Sedna, Haumea, Makemake, and others, but also the hypothesized planetary-mass objects collectively known as Planet 9 (or Planet X). In a new study led by the Lowell Observatory, a team of researchers hypothesize that the Large Synoptic Survey Telescope (LSST) – a next-generation telescope that will go online in 2022 – has a good chance of finding this mysterious planet.

Their study, titled “On the detectability of Planet X with LSST“, recently appeared online. The study was led by David E. Trilling, an astrophysicist from the Northern Arizona University and the Lowell Observatory, and included Eric C. Bellm from the University of Washington and Renu Malhotra of the Lunar and Planetary Laboratory at The University of Arizona.

Artist’s impression of the Large Synoptic Survey Telescope (LSST). Credit: lsst.org

Located on the Cerro Pachón ridge in north-central Chile, the 8.4-meter LSST will conduct a 10-year survey of the sky that will deliver 200 petabytes worth of images and data that will address some of the most pressing questions about the structure and evolution of the Universe and the objects in it. In addition to surveying the early Universe in order to understand the nature of dark matter and dark energy, it will also conduct surveys of the remote areas of the Solar System.

Planet 9/X is one such object. In recent years, the existence of two planetary-mass bodies have been hypothesized to explain the orbital distribution of distant Kuiper Belt Objects. While neither planet is thought to be exceptionally faint, the sky locations of these planets are poorly constrained – making them difficult to pinpoint. As such, a wide area survey is needed to detect these possible planets.

In 2022, the LSST will carry out an unbiased, large and deep survey of the southern sky, which makes it an important tool when it comes to the search of these hypothesized planets. As they state in their study:

“The possibility of undiscovered planets in the solar system has long fascinated astronomers and the public alike. Recent studies of the orbital properties of very distant Kuiper belt objects (KBOs) have identified several anomalies that may be due to the gravitational influence of one or more undiscovered planetary mass objects orbiting the Sun at distances comparable to the distant KBOs.

Animated diagram showing the spacing of the Solar Systems planet’s, the unusually closely spaced orbits of six of the most distant KBOs, and the possible “Planet 9” (aka. “Planet X”). Credit: Caltech/nagualdesign

These studies include Trujillo & Sheppard’s 2014 study where they noticed similarities in the orbits of distant Trans-Neptunian Objects (TNOs) and postulated that a massive object was likely influencing them. This was followed by a 2016 study by Sheppard & Trujillo where they suggested that the high perihelion objects Sedna and 2012 VP113 were being influence by an unknown massive planet.

This was followed in 2016 by Konstantin Batygin and Michael E. Brown of Caltech suggesting that an undiscovered planet was the culprit. Finally, Malhotra et al. (2016) noted that the most distant KBOs have near-integer period ratios, which was suggestive of a dynamical resonance with a massive object in the outer Solar System. Between these studies, various mass and distance estimates were formed that became the basis of the search for this planet.

Overall, these estimates indicated that Planet 9/X was a super-Earth with anywhere between 5 to 20 Earth masses, and orbited the Sun at a distance of between 150 – 600 AU. Concurrently, these studies have also attempted to narrow down where this Super-Earth’s orbit will take it throughout the outer Solar System, as evidenced by the perturbations it has on KBOs.

Unfortunately, the predicted locations and brightness of the object are not yet sufficiently constrained for astronomers to simply look in the right place at the right time and pick it out. In this respect, a large area sky survey must be carried out using moderately large telescopes with a very wide field of view. As Dr. Trilling told Universe Today via email:

“The predicted Planet X candidates are not particularly faint, but the possible locations on the sky are not very well constrained at all. Therefore, what you really need to find Planet X is a medium-depth telescope that covers a huge amount of sky. This is exactly LSST. LSST’s sensitivity will be sufficient to find Planet X in almost all its (their) predicted configurations, and LSST will cover around half of the known sky to this depth. Furthermore, the cadence is well-matched to finding moving objects, and the data processing systems are very advanced. If you were going to design a tool to find Planet X, LSST is what you would design.”

The orbits of several KBOs provide indications about the possible existence of Planet 9. Credit: Caltech/R. Hurt (IPAC)

However, the team also acknowledges that within certain parameters, Planet 9/X may not be detectable by the LSST. For example, it is possible that that there is a very narrow slice of predicted Planet 9/X parameters where it might be slightly too faint to be easily detected in LSST data. In addition, there is also a small possibility that irregularities in the Planet 9/X cadence might lead to it being missed.

There is the even the unlikely ways in which Planet 9/X could go undetected in LSST data, which would come down to a simple case of bad luck. However, as Dr. Trilling indicated, the team is prepared for these possibilities and is hopeful they will find Planet 9/X, assuming there’s anything to find:

“The more likely conclusion if planet X is not detected in LSST data is that planet X doesn’t exist – or at least not the kind of planet X that has been predicted. In this case, we’ve got to work harder to understand how the Universe created this pattern of orbits in the outer Solar System that I described above. This is a really fun part of science: make a prediction and test it, and find that the result is rarely what is predicted. So now we’ve got to work harder to understand the universe. Hopefully this new understanding makes new predictions that we then can test, and we repeat the cycle.”

The existence of Planet 9/X has been one of the more burning questions for astronomers in recent years. If its existence can be confirmed, astronomers may finally have a complete picture of the Solar System and its dynamics. If it’s existence can be ruled out, this will raise a whole new series of questions about what is going on in the Outer Solar System!

Further Reading: arXiv

The post What are the Chances that the Next Generation LSST Could Find New Planets in the Solar System? appeared first on Universe Today.

Across The Universe - In the Heart of the Heart Nebula

In the Heart of the Heart Nebula:

Discover the cosmos!
Each day a different image or photograph of our fascinating universe is
featured, along with a brief explanation written by a professional astronomer.


2018 February 14

Explanation:
What's that inside the Heart Nebula?

First, the large emission nebula dubbed
IC 1805 looks, in whole, like a human heart.

It's shape perhaps fitting of the
Valentine's Day,
this heart glows brightly in red light
emitted by its most prominent element:
hydrogen.

The red glow and the larger shape are all created by a
small group of stars near the
nebula's center.

In the heart of the
Heart
Nebula are young stars from the open star cluster
Melotte 15 that are eroding away several picturesque
dust pillars with their energetic light and winds.

The open cluster of stars contains a few
bright stars nearly 50 times the mass of our Sun,
many dim stars only a fraction of the mass of our Sun, and an
absent microquasar
that was expelled millions of years ago.

The Heart Nebula is located about 7,500 light years away toward the
constellation
of the mythological Queen of Aethiopia (Cassiopeia).

Across The Universe - Jupiter in Infrared from Hubble

Jupiter in Infrared from Hubble:

Discover the cosmos!
Each day a different image or photograph of our fascinating universe is
featured, along with a brief explanation written by a professional astronomer.


2018 February 21

Jupiter in Infrared from Hubble

Image Credit:
NASA,
ESA,
Hubble;
Data:
Michael Wong
(UC Berkeley)
et al.;
Processing &
License:
Judy Schmidt


Explanation:
Jupiter looks a bit different in infrared light.

To better understand
Jupiter's cloud motions and to help NASA's robotic
Juno spacecraft understand the
planetary context of the small fields that it sees, the
Hubble Space Telescope is being directed to
regularly image the entire Jovian giant.

The colors of Jupiter
being monitored go beyond the normal human visual range to include both
ultraviolet and
infrared light.

Featured here in 2016, three bands of near-infrared light have been digitally reassigned into a mapped color image.

Jupiter appears
different in infrared
partly because the amount of sunlight reflected back is distinct,
giving differing cloud heights and latitudes discrepant brightnesses.

Nevertheless, many familiar features on
Jupiter remain, including the
light zones and dark belts that circle the planet near the equator, the
Great Red Spot on the lower left, and the
string-of-pearls storm systems south of the Great Red Spot.

The poles glow because high altitude haze there is energized by charged
particles from Jupiter's
magnetosphere.

Juno has now completed
10 of 12 planned science orbits of Jupiter and continues to record data that are helping humanity to
understand not only Jupiter's weather but
what lies beneath Jupiter's thick clouds.




Tomorrow's picture: roses aren't red

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Across The Universe - When Roses Aren t Red

When Roses Aren t Red:

Discover the cosmos!
Each day a different image or photograph of our fascinating universe is
featured, along with a brief explanation written by a professional astronomer.


2018 February 22

When Roses Aren't Red

Image Credit &
Copyright:

Eric Coles and
Mel Helm



Explanation:

Not all roses are red
of course,
but they can still be very pretty.

Likewise, the beautiful
Rosette
Nebula and other star forming regions are often shown in
astronomical images with a predominately red hue,
in part because the dominant emission in the nebula is
from hydrogen atoms.

Hydrogen's strongest optical emission line, known as H-alpha,
is in the red region of the spectrum, but the beauty of an
emission nebula need not be appreciated
in red light alone.

Other
atoms in the nebula are also excited by energetic
starlight and produce narrow emission lines as well.

In this gorgeous view of the Rosette Nebula,
narrowband images are combined to show
emission from sulfur atoms in red, hydrogen in blue, and
oxygen in green.

In fact, the
scheme of mapping these narrow atomic
emission lines into broader colors is adopted in
many Hubble images
of stellar nurseries.

The image spans about 100 light-years in
the constellation Monoceros, at the 3,000 light-year
estimated
distance of the
Rosette
Nebula.

To make the Rosette red, just follow
this link or
slide your cursor over the image.



Tomorrow's picture: the moon isn't blue

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Across The Universe - Facing NGC 6946

Facing NGC 6946:

Discover the cosmos!
Each day a different image or photograph of our fascinating universe is
featured, along with a brief explanation written by a professional astronomer.


2018 February 24

Facing NGC 6946

Composite Image Data -

Subaru Telescope
(NAOJ) and Robert Gendler;

Processing -

Robert Gendler



Explanation:

From our vantage point in the
Milky Way Galaxy, we see
NGC 6946
face-on.

The big, beautiful
spiral galaxy
is located just 20 million light-years away, behind a veil of
foreground dust and stars in the high and far-off
constellation of Cepheus.

From the core outward, the galaxy's colors change from the yellowish
light of old stars in the center to young blue star
clusters and reddish star forming regions along the loose, fragmented
spiral arms.

NGC 6946 is also bright in
infrared light and
rich in gas and dust, exhibiting a high star birth and
death rate.

In fact, since the early 20th century
ten
confirmed supernovae, the
death explosions
of massive stars, were
discovered in NGC 6946.

Nearly 40,000 light-years across, NGC 6946 is also known as the
Fireworks Galaxy.

This remarkable portrait of NGC 6946
is a composite that includes
image
data from the 8.2 meter Subaru Telescope
on Mauna Kea.



Tomorrow's picture: star fire

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NASA Official: Phillip Newman
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Across The Universe - NGC 613 in Dust, Stars, and a Supernova

NGC 613 in Dust, Stars, and a Supernova:

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Each day a different image or photograph of our fascinating universe is
featured, along with a brief explanation written by a professional astronomer.


2018 February 28

NGC 613 in Dust, Stars, and a Supernova

Image Credit:
NASA,
ESA,
Hubble,
S. Smartt
(QUB);
Acknowledgement:
Robert Gendler;
Insets: Victor Buso


Explanation:
Where did that spot come from?

Amateur astronomer Victor Buso was testing out a new camera on his telescope in 2016 when he noticed a curious spot of light appear -- and remain.

After reporting
this unusual observation,
this spot was determined to be light from a
supernova
just as it was becoming visible -- in an earlier stage
than had ever been photographed optically before.

The discovery before and after images, taken about an hour apart,
are shown in the inset of a
more detailed image
of the same spiral galaxy,
NGC 613,
taken by the Hubble Space Telescope.

Follow-up observations show that
SN 2016gkg was likely the explosion of a
supergiant star,
and Buso likely captured the stage where the outgoing
detonation wave
from the stellar core
broke through
the star's surface.

Since astronomers have spent years
monitoring galaxies for supernovas without seeing such a "break out" event,
the odds of Buso capturing this
have been compared to
winning a lottery.




Tomorrow's picture: the lunar 15

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Across The Universe - Arcs, Jets, and Shocks near NGC 1999

Arcs, Jets, and Shocks near NGC 1999:

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Each day a different image or photograph of our fascinating universe is
featured, along with a brief explanation written by a professional astronomer.


2018 March 7

Arcs, Jets, and Shocks near NGC 1999

Image Credit & Copyright:
Mark Hanson;
Annotation: Sakib Rasool
(StarSurfin)


Explanation:
This tantalizing array of nebulas and stars can be found
about two degrees south of the famous
star-forming Orion Nebula.

The
region abounds with energetic young stars producing jets and
outflows that push through the surrounding
material at speeds of hundreds of kilometers per second.

The interaction creates luminous shock
waves known as
Herbig-Haro (HH) objects.

For example, the graceful, flowing arc just right of center
is cataloged as
HH 222, also called the
Waterfall Nebula.

Seen below the Waterfall, HH 401 has a distinctive cone shape.

The bright bluish nebula below and left of center
is NGC 1999, a dusty cloud reflecting
light from an embedded variable star.

The entire cosmic vista spans over 30 light-years, near the edge of the
Orion Molecular Cloud
Complex
some 1,500 light-years distant.




Open Science:
Browse 1,600+ codes in the Astrophysics Source Code Library

Tomorrow's picture: open space

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Across The Universe - Horsehead: A Wider View

Horsehead: A Wider View:

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Each day a different image or photograph of our fascinating universe is
featured, along with a brief explanation written by a professional astronomer.


2018 March 9

Horsehead: A Wider View

Composition and Processing:
Robert Gendler


Image Data:
ESO,
VISTA,
HLA,
Hubble Heritage Team (STScI/AURA)



Explanation:

Combined image data from the massive,
ground-based
VISTA telescope and the
Hubble Space
Telescope was used to create
this
wide perspective
of the interstellar landscape surrounding
the famous Horsehead Nebula.

Captured at near-infrared wavelengths, the region's dusty
molecular cloud sprawls across the scene that covers
an angle about
two-thirds the size of the Full Moon on the sky.

Left to right the frame spans just over 10 light-years
at the Horsehead's estimated distance of 1,600 light-years.

Also known as
Barnard 33,
the still
recognizable Horsehead Nebula
stands at the upper right,
the near-infrared glow of a dusty pillar topped with newborn stars.

Below and left, the bright reflection nebula NGC 2023 is itself
the illuminated environs of a hot young star.

Obscuring
clouds
below the base of the Horsehead and on the outskirts of
NGC 2023 show the tell-tale far red emission of energetic jets,
known as Herbig-Haro objects,
also associated with newborn stars.



Tomorrow's picture: clair de lune

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Across The Universe - Dual Particle Beams in Herbig Haro 24

Dual Particle Beams in Herbig Haro 24:

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Each day a different image or photograph of our fascinating universe is
featured, along with a brief explanation written by a professional astronomer.


2018 March 11

Dual Particle Beams in Herbig-Haro 24

Image Credit:
NASA,
ESA,
Hubble Heritage
(STScI/AURA)/Hubble-Europe
Collaboration;

Acknowledgment:
D. Padgett (NASA's GSFC),
T. Megeath (U. Toledo),
B. Reipurth (U. Hawaii)


Explanation:
This might look like a double-bladed
lightsaber, but these two cosmic jets actually beam outward from
a
newborn star in a galaxy near you.

Constructed from Hubble Space Telescope image data, the stunning
scene spans about half a light-year across
Herbig-Haro 24 (HH 24), some 1,300 light-years away in the
stellar nurseries
of the Orion B molecular cloud complex.

Hidden from direct view,
HH 24's
central protostar is
surrounded by cold dust and gas flattened into a rotating
accretion disk.

As material from the disk falls toward the young stellar object it heats up.

Opposing jets are blasted out along the
system's rotation axis.

Cutting through the region's interstellar matter, the narrow,
energetic jets produce a series of glowing shock fronts
along their path.




Tomorrow's picture: flying over earth

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NASA Official: Phillip Newman
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Across The Universe - The Complete Galactic Plane: Up and Down

The Complete Galactic Plane: Up and Down:

Discover the cosmos!
Each day a different image or photograph of our fascinating universe is
featured, along with a brief explanation written by a professional astronomer.


2018 March 13

Explanation:
Is it possible to capture the entire plane of our galaxy in a single image?

Yes, but not in one exposure -- and it took some planning to do it in two.

The top part of the
featured image is the night sky above
Lebanon,
north of the equator, taken in 2017 June.

The image was taken at a time when the central band of the
Milky Way Galaxy passed directly overhead.

The bottom half was similarly captured six months later in
latitude-opposite
Chile, south of
Earth's equator.

Each image therefore captured the night sky in
exactly the opposite direction of the other, when fully half the Galactic plane was visible.

The southern half was then inverted -- car and all -- and digitally
appended
to the top half to show the entire central
band of our Galaxy, as a circle, in a single image.

Many stars and nebulas are visible, with the
Large Magellanic Cloud
being particularly notable inside the lower half of the complete galactic circle.

Across The Universe - Interstellar Asteroid ‘Oumuamua Had a Violent Past

Interstellar Asteroid ‘Oumuamua Had a Violent Past:

On October 19th, 2017, the Panoramic Survey Telescope and Rapid Response System-1 (Pan-STARRS-1) telescope in Hawaii announced the first-ever detection of an interstellar asteroid – I/2017 U1 (aka. ‘Oumuamua). Originally mistaken for a comet, follow-up observations conducted by the European Southern Observatory (ESO) and others confirmed that ‘Oumuamua was actually a rocky body that had originated outside of our Solar System.

Since that time, multiple investigations have been conducted to determine ‘Oumuamua’s structure, composition, and just how common such visitors are. At the same time, a considerable amount of attention has been dedicated to determining the asteroid’s origins. According to a new study by a team of international researchers, this asteroid had a chaotic past that causes it to tumble around chaotically.

The study, titled “The tumbling rotational state of 1I/‘Oumuamua“, recently appeared in the scientific journal Nature Astronomy. The study was led by Wesley C. Fraser, a research fellow at the University of Queens Belfast’s Astrophysics Research Center, and included members from the Academy of Sciences of the Czech Republic, the The Open University and the University of Belgrade.



As they indicate, the discovery of ‘Oumuamua has provided scientists with the first opportunity to study a planetesimal born in another planetary system. In much the same way that research into Near-Earth Asteroids, Main Belt Asteroids, or Jupiter’s Trojans can teach astronomers about the history and evolution of our Solar System, the study of a ‘Oumuamua would provide hints as to what was going on when and where it formed.

For the sake of their study, Dr. Fraser and his international team of colleagues have been measuring ‘Oumuamua brightness since it was first discovered. What they found was that ‘Oumuamua wasn’t spinning periodically (like most small asteroids and planetesimals in our Solar System), but chaotically. What this means is that the asteroid has likely been tumbling through space for billions of years, an indication of a violent past.

While it is unclear why this is, Dr. Fraser and his colleagues suspect that it might be due to an impact. In other words, when ‘Oumuamua was thrown from its own system and into interstellar space, it is possible it collided violently with another rock. As Dr. Fraser explained in a Queen’s University Belfast press release:

“Our modelling of this body suggests the tumbling will last for many billions of years to hundreds of billions of years before internal stresses cause it to rotate normally again. While we don’t know the cause of the tumbling, we predict that it was most likely sent tumbling by an impact with another planetesimal in its system, before it was ejected into interstellar space.”

These latest findings mirror what other studies have been able to determine about ‘Oumuamua based on its object changes in its brightness. For example, brightness measurements conducted by the Institute for Astronomy in Hawaii – and using data from the ESO’s Very Large Telescope (VLT) – confirmed that the asteroid was indeed interstellar in origin, and that its shape is highly elongated (i.e. very long and thin).

However, measurements of its color have produced little up until now other than confusion. This was due to the fact that the color appeared to vary between measurements. When the long face of the object is facing telescopes on Earth, it appears largely red, while the rest of the body has appeared neutral in color (like dirty snow). Based on their analysis, Dr. Fraser and his team resolved this mystery by indicating that the surface is “spotty”.

In essence, most of the surface reflects neutrally, but one of its long faces has a large red region – indicating the presence of tholins on its long surface. A common feature of bodies in the outer Solar System, tholins are organic compounds (i.e. methane and ethane) that have turned a deep shade of reddish-brown thanks to their exposure to ultra-violet radiation.

What this indicates, according to Dr. Fraser, is broad compositional variations on ‘Oumuamua, which is unusual for such a small body:

“We now know that beyond its unusual elongated shape, this space cucumber had origins around another star, has had a violent past, and tumbles chaotically because of it. Our results are really helping to paint a more complete picture of this strange interstellar interloper. It is quite unusual compared to most asteroids and comets we see in our own solar system,” comments Dr Fraser.

Oumuamua as it appeared using the William Herschel Telescope on the night of October 29. Queen’s University Belfast/William Herschel Telescope

To break it down succinctly, ‘Oumuamua may have originated closer to its parent star (hence its rocky composition) and was booted out by strong resonances. In the course of leaving its system, it collided with another asteroid, which sent it tumbling towards interstellar space. It’s current chaotic spin and its unusual color are both testaments to this turbulent past, and indicate that its home system and the Solar System have a few things in common.

Since its arrival in our system, ‘Oumuamua has set off a flurry of scientific research. All over the world, astronomers are hoping to get a glimpse of it before it leaves our Solar System, and there are even those who hope to mount a robotic mission to rendezvous with it before its beyond our reach (Project Lyra). In any event, we can expect that this interstellar visitor will be the basis of scientific revelations for years to come!

This study is the third to be published by their team, which has been monitoring ‘Oumuamua since it was first observed in October. All studies were conducted with support provided by the Science and Technology Facilities Council.

Further Reading: Queen’s University Belfast

The post Interstellar Asteroid ‘Oumuamua Had a Violent Past appeared first on Universe Today.