Astronomy Archives

May 29, 2018 by Matt Williams

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

Artist’s impression of the pulsar PSR B1957+20 (seen in the background) through the cloud of gas enveloping its brown dwarf star companion. Credit: Dr. Mark A. Garlick; Dunlap Institute for Astronomy & Astrophysics, University of Toronto

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

May 25, 2018May 25, 2018 by Matt Williams

Two Spacecraft Will Get Closer to the Sun Than Ever Before

ESA's Solar Orbiter will capture the very first images of the Sun’s polar regions, where magnetic tension builds up and releases in a lively dance. Credits: Spacecraft: ESA/ATG medialab; Sun: NASA/SDO/P. Testa (CfA)

Our understanding of distant stars has increased dramatically in recent decades. Thanks to improved instruments, scientists are able to see farther and clearer, thus learning more about star systems and the planets that orbit them (aka. extra-solar planets). Unfortunately, it will be some time before we develop the necessary technology to explore these stars up close.

But in the meantime, NASA and the ESA are developing missions that will allow us to explore our own Sun like never before. These missions, NASA’s Parker Solar Probe and the ESA’s (the European Space Agency) Solar Orbiter, will explore closer to the Sun than any previous mission. In so doing, it is hoped that they will resolve decades-old questions about the inner workings of the Sun.

These missions – which will launch in 2018 and 2020, respectively – will also have significant implications for life here on Earth. Not only is sunlight essential to life as we know it, solar flares can pose a major hazard for technology that humanity is becoming increasingly dependent on. This includes radio communications, satellites, power grids and human spaceflight.

And in the coming decades, Low-Earth Orbit (LEO) is expected to become increasingly crowded as commercial space stations and even space tourism become a reality. By improving our understanding of the processes that drive solar flares, we will therefore be able to better predict when they will occur and how they will impact Earth, spacecraft, and infrastructure in LEO.

As Chris St. Cyr, the Solar Orbiter project scientist at NASA’s Goddard Space Flight Center, explained in a recent NASA press release:

“Our goal is to understand how the Sun works and how it affects the space environment to the point of predictability. This is really a curiosity-driven science.”

Both missions will focus on the Sun’s dynamic outer atmosphere, otherwise known as the corona. At present, much of the behavior of this layer of the Sun is unpredictable and not well understood. For instance, there’s the so-called “coronal heating problem”, where the corona of the Sun is so much hotter than the solar surface. Then there is the question of what drives the constant outpouring of solar material (aka. solar wind) to such high speeds.

As Eric Christian, a research scientist on the Parker Solar Probe mission at NASA Goddard, explained:

“Parker Solar Probe and Solar Orbiter employ different sorts of technology, but — as missions — they’ll be complementary. They’ll be taking pictures of the Sun’s corona at the same time, and they’ll be seeing some of the same structures — what’s happening at the poles of the Sun and what those same structures look like at the equator.”

*Illustration of the Parker Solar Probe spacecraft approaching the Sun. Credits: Johns Hopkins University Applied Physics Laboratory*

For its mission, the Parker Solar Probe will get closer to the Sun than any spacecraft in history – as close as 6 million km (3.8 million mi) from the surface. This will replace the previous record of 43.432 million km (~27 million mi), which was established by the Helios B probe in 1976. From this position, the Parker Solar Probe will use its four suites of scientific instruments to image the solar wind and study the Sun’s magnetic fields, plasma and energetic particles.

In so doing, the probe will help clarify the true anatomy of the Sun’s outer atmosphere, which will help us to understand why the corona is hotter than the Sun’s surface. Basically, while temperatures in the corona can reach as high as a few million degrees, the solar surface (aka. photosphere), experiences temperatures of around 5538 °C (10,000 °F).

Meanwhile, the Solar Orbiter will come to a distance of about 42 million km (26 million mi) from the Sun, and will assume a highly-tilted orbit that can provide the first-ever direct images of the Sun’s poles. This is another area of the Sun that scientists don’t yet understand very well, and the study of it could provide valuable clues as to what drives the Sun’s constant activity and eruptions.

Both missions will also study solar wind, which is the Sun’s most pervasive influence on the solar system. This steam of magnetized gas fills the inner Solar System, interacting with magnetic fields, atmospheres and even the surfaces of planets. Here on Earth, it is what is responsible for the Aurora Borealis and Australis, and can also play havoc with satellites and electrical systems at times.

*Artist’s impression of a solar flare erupting from the Sun’s surface. Credit: NASA Goddard Space Flight Center*

Previous missions have led scientists to believe that the corona contributes to the process that accelerates solar wind to such high speeds. As these charged particles leave the Sun and pass through the corona, their speed effectively triples. By the time the solar wind reaches the spacecraft responsible for measuring it – 148 million km (92 million mi) from the Sun – it has plenty of time to mix with other particles from space and lose some of its defining features.

By being parked so close to the Sun, the Parker Solar Probe will able to measure the solar wind just as it forms and leaves the corona, thus providing the most accurate measurements of solar wind ever recorded. From its perspective above the Sun’s poles, the Solar Orbiter will complement the Parker Solar Probe’s study of the solar wind by seeing how the structure and behavior of solar wind varies at different latitudes.

This unique orbit will also allow the Solar Orbiter to study the Sun’s magnetic fields, since some of the Sun’s most interesting magnetic activity is concentrated at the poles. This magnetic field is far-reaching largely because of solar wind, which reaches outwards to create a magnetic bubble known as the heliosphere. Within the heliosphere, solar wind has a profound effect on planetary atmospheres and its presence protects the inner planets from galactic radiation.

In spite of this, it is still not entirely clear how the Sun’s magnetic field is generated or structured deep inside the Sun. But given its position, the Solar Orbiter will be able to study phenomena that could lead to a better understanding of how the Sun’s magnetic field is generated. These include solar flares and coronal mass ejections, which are due to variability caused by the magnetic fields around the poles.

In this way, the Parker Solar Probe and Solar Orbiter are complimentary missions, studying the Sun from different vantage points to help refine our knowledge of the Sun and heliosphere. In the process, they will provide valuable data that could help scientists to tackle long-standing questions about our Sun. This could help expand our knowledge of other star systems and perhaps even answer questions about the origins of life.

As Adam Szabo, a mission scientist for Parker Solar Probe at NASA Goddard, explained:

“There are questions that have been bugging us for a long time. We are trying to decipher what happens near the Sun, and the obvious solution is to just go there. We cannot wait — not just me, but the whole community.”

In time, and with the development of the necessary advanced materials, we might even be able to send probes into the Sun. But until that time, these missions represent the most ambitious and daring efforts to study the Sun to date. As with many other bold initiatives to study our Solar System, their arrival cannot come soon enough!

Further Reading: NASA

May 23, 2018May 23, 2018 by Matt Williams

Oumuamua was Just the Beginning. Astronomers Find an Interstellar Asteroid Orbiting Retrograde near Jupiter.

Artist’s impression of the first interstellar asteroid/comet, "Oumuamua". This unique object was discovered on 19 October 2017 by the Pan-STARRS 1 telescope in Hawaii. Credit: ESO/M. Kornmesser

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.

News of this interstellar asteroids, the first to ever be detected by astronomers, raised a lot of excitement. And according to a new study by an international pair of astronomers, ‘Oumuamua was not the Solar System’s first interstellar visitor. Whereas ‘Oumuamua was an interloper on its way to another star system, this latest object – known as Asteroid (514107) 2015 BZ509 – appears to be a long-term resident.

The study, titled “An interstellar origin for Jupiter’s retrograde co-orbital asteroid“, recently appeared in the Monthly Notices of Royal Astronomical Society: Letters. The study team consisted of Fathi Namouni, a researcher at Université Côte d’Azur and the Observatoire de la Côte d’Azur; and Maria Helena Moreira Morais, a researcher from the Instituto de Geociências e Ciências Exatas at the Universidade Estadual Paulista (UNESP).

Images of 2015 BZ509 obtained at the Large Binocular Telescope Observatory (LBTO) that established its retrograde co-orbital nature (click on the image to see the animation). Credit: C. Veillet / Large Binocular Telescope Observatory.

After locating this asteroid, the team noticed something very interesting about it. All planets in our Solar System, and the vast majority of objects as well, orbit the Sun in the same direction. However, upon observing 2015 BZ509, the team concluded that it had a retrograde orbit – i.e. it rotated in the opposite direction as the other planets and objects. As Dr. Fathi Namouni, the lead author of the study, explained:

“How the asteroid came to move in this way while sharing Jupiter’s orbit has until now been a mystery. If 2015 BZ509 were a native of our system, it should have had the same original direction as all of the other planets and asteroids, inherited from the cloud of gas and dust that formed them.”

Using a high-resolution statistical search for stable orbits, the team found that 2015 BZ509 has been in its current orbital state since the formation of the Solar System – ca. 4.5 billion years ago. From this, they determined that the asteroid could not be indigenous to the Solar System since it would not have been able to assume its current large-inclination orbit – not when the nearby planets had early coplanar orbits and interacted with coplanar debris.

The only conclusion they could reach from these results was that this asteroid was captured from the interstellar medium 4.5 billion years ago. As Dr. Maria Helena Moreira Morais, the second author on the paper, added:

“Asteroid immigration from other star systems occurs because the Sun initially formed in a tightly-packed star cluster, where every star had its own system of planets and asteroids. The close proximity of the stars, aided by the gravitational forces of the planets, help these systems attract, remove and capture asteroids from one another.”

*Based on their study, the team determined that 2015 BZ509 was acquired by our Solar System early in its history. Credit: NASA*

The discovery of the first interstellar asteroid was certainly excited and led to multiple proposals for sending a mission to study it up close. The discovery of an interstellar asteroid that became a permanent resident in our system, however, has important implications for the study of planet formation, the evolution of the Solar System, and maybe even the origin of life itself – all of which remain open questions at this point.

Looking ahead, Dr. Namouni and Dr. Moraiswant hope to obtain more information on 2015 BZ509 so they might be able to determine exactly when it how it settled in the Solar System. In so doing, they will be able to provide clues about the Sun’s original star nursery, and about how our Early Solar System might have been enriched with components necessary for the appearance of life on Earth.

And who knows? We may soon discovery many more asteroid interlopers and long-term residents in the future. The study of these could provide even more information on the early history of our Solar System, how it interacted with neighboring systems, and how the basic ingredients for life (as we know it) came to be distributed. Perhaps the Rama enthusiasts had a point when they reminded us that the Ramans “do everything in threes”!

Further Reading: RAS, MNRAS

May 23, 2018 by Matt Williams

The Ant Nebula Actually has Intense Laser Emissions Coming From its Core

From ground-based telescopes, the so-called "ant nebula" (Menzel 3, or Mz 3) resembles the head and thorax of a garden-variety ant. This dramatic NASA/ESA Hubble Space Telescope image, showing 10 times more detail, reveals the "ant's" body as a pair of fiery lobes protruding from a dying, Sun-like star. Credit: NASA/ESA/Hubble Heritage Team (STScI/AURA)

When low- to middleweight stars like our Sun approach the end of their life cycles they eventually cast off their outer layers, leaving behind a dense, white dwarf star. These outer layers became a massive cloud of dust and gas, which is characterized by bright colors and intricate patterns, known as a planetary nebula. Someday, our Sun will turn into such a nebula, one which could be viewed from light-years away.

This process, where a dying star gives rise to a massive cloud of dust, was already known to be incredibly beautiful and inspiring thanks to many images taken by Hubble. However, after viewing the famous Ant Nebula with the European Space Agency’s (ESA) Herschel Space Observatory, a team of astronomers discovered an unusual laser emission that suggests that there is a double star system at the center of the nebula.

The study, titled “Herschel Planetary Nebula Survey (HerPlaNS): hydrogen recombination laser lines in Mz 3“, recently appeared in the Monthly Notices of the Royal Astronomical Society. The study was led by Isabel Aleman of the University of São Paulo and the Leiden Observatory, and included members from the Herschel Science Center, the Smithsonian Astrophysical Observatory, the Institute of Astronomy and Astrophysics, the Royal Observatory of Belgium and multiple universities.

*The life cycle of a Sun-like star, from its birth on the left side of the frame to its evolution into a red giant on the right after billions of years. Credit: ESO/M. Kornmesser*

The Ant Nebula (aka. Mz 3) is a young bipolar planetary nebula located in the constellation Norma, and takes its name from the twin lobes of gas and dust that resemble the head and body of an ant. In the past, this nebula’s beautiful and intricate nature was imaged by the NASA/ESA Hubble Space Telescope. The new data obtained by Herschel also indicates that the Ant Nebula beams intense laser emissions from its core.

In space, infrared laser emissions are detected at very different wavelengths and only under certain conditions, and only a few of these space lasers are known. Interestingly enough, it was astronomer Donald Menzel – who first observed and classified the Ant Nebula in 1920 (hence why it is officially known as Menzel 3 after him) – who was one of the first to suggest that lasers could occur in nebula.

According to Menzel, under certain conditions natural “light amplification by the stimulated emissions of radiation” (aka. where we get the term laser from) would occur in space. This was long before the discovery of lasers in laboratories, an occasion that is celebrated annually on May 16th, known as UNESCO’s International Day of Light. As such, it was highly appropriate that this paper was also published on May 16th, celebrating the development of the laser and its discoverer, Theodore Maiman.

As Isabel Aleman, the lead author of a paper, described the results:

“When we observe Menzel 3, we see an amazingly intricate structure made up of ionized gas, but we cannot see the object in its center producing this pattern. Thanks to the sensitivity and wide wavelength range of the Herschel observatory, we detected a very rare type of emission called hydrogen recombination line laser emission, which provided a way to reveal the nebula’s structure and physical conditions.”

Artist's impression of the Herschel Space Telescope. Credit: ESA/AOES Medialab/NASA/ESA/STScI — *Artist’s impression of the Herschel Space Telescope. Credit: ESA/AOES Medialab/NASA/ESA/STScI*

“Such emission has only been identified in a handful of objects before and it is a happy coincidence that we detected the kind of emission that Menzel suggested, in one of the planetary nebulae that he discovered,” she added.

The kind of laser emission they observed needs very dense gas close to the star. By comparing observations from the Herschel observatory to models of planetary nebula, the team found that the density of the gas emitting the lasers was about ten thousand times denser than the gas seen in typical planetary nebulae, and in the lobes of the Ant Nebula itself.

Normally, the region close to the dead star – in this case, roughly the distance between Saturn and the Sun – is quite empty because its material was ejected outwards after the star went supernova. Any lingering gas would soon fall back onto it. But as Professor Albert Zijlstra, from the Jodrell Bank Center for Astrophysics and a co-author on the study, put it:

“The only way to keep such dense gas close to the star is if it is orbiting around it in a disc. In this nebula, we have actually observed a dense disc in the very center that is seen approximately edge-on. This orientation helps to amplify the laser signal. The disc suggests there is a binary companion, because it is hard to get the ejected gas to go into orbit unless a companion star deflects it in the right direction. The laser gives us a unique way to probe the disc around the dying star, deep inside the planetary nebula.”

*The planetary nebula Abell 39. According to a new study, our Sun will similarly become a luminous planetary nebula by the end of its life cycle. Credit: WIYN/NOAO/NSF*

While astronomers have not yet seen the expected second star, they are hopeful that future surveys will be able to locate it, thus revealing the origin of the Ant Nebula’s mysterious lasers. In so doing, they will be able to connect two discoveries (i.e. planetary nebula and laser) made by the same astronomer over a century ago. As Göran Pilbratt, ESA’s Herschel project scientist, added:

“This study suggests that the distinctive Ant Nebula as we see it today was created by the complex nature of a binary star system, which influences the shape, chemical properties, and evolution in these final stages of a star’s life. Herschel offered the perfect observing capabilities to detect this extraordinary laser in the Ant Nebula. The findings will help constrain the conditions under which this phenomenon occurs, and help us to refine our models of stellar evolution. It is also a happy conclusion that the Herschel mission was able to connect together Menzel’s two discoveries from almost a century ago.”

Next-generation space telescopes that could tell us more about planetary nebula and the life-cycles of stars include the James Webb Space Telescope (JWST). Once this telescope takes to space in 2020, it will use its advanced infrared capabilities to see objects that are otherwise obscured by gas and dust. These studies could reveal much about the interior structures of nebulae, and perhaps shed light on why they periodically shoot out “space lasers”.

Further Reading: University of Manchester, ESA, MNRAS

May 22, 2018 by David Dickinson

Are We Headed Towards Another Deep Solar Minimum?

Solar SDO — A (nearly) naked Sol... more the norm than the exception these days. Credit: NASA/SDO AIA 512/1600 imager.

Have you been keeping an eye on Sol lately? One of the top astronomy stories for 2018 may be what’s not happening, and how inactive our host star has become.

The strange tale of Solar Cycle #24 is ending with an expected whimper: as of May 8^th, the Earthward face of the Sun had been spotless for 73 out of 128 days thus far for 2018, or more than 57% of the time. This wasn’t entirely unexpected, as the solar minimum between solar cycle #23 and #24 saw 260 spotless days in 2009 – the most recorded in a single year since 1913. Cycle #24 got off to a late and sputtering start, and though it produced some whopper sunspots reminiscent of the Sol we knew and loved on 20^th century cycles past, it was a chronic under-performer overall. Mid-2018 may see the end of cycle #24 and the start of Cycle #25… or will it?

solar minimum — The story thus far… and the curious drama that is solar cycle #24. Credit: David Hathaway/NASA Marshall Spaceflight Center.

One nice surprise during Cycle #24 was the appearance of massive sunspot AR 2192, which popped up just in time for the partial solar eclipse of October 23^rd, 2014. Several times the size of the Earth, the spot complex was actually the largest seen in a quarter century. But just as “one swallow does not a Summer make,” one large sunspot group couldn’t save Solar Cycle #24.

The Sun goes through an 11-year sunspot cycle, marked by the appearance of new spots at mid- solar latitudes, which then slowly progress to make subsequent appearances closer towards the solar equator, in a pattern governed by what’s known as Spörer’s Law. The hallmark of a new solar cycle is the appearance of those high latitude spots. The Sun actually flips overall polarity every cycle, so a proper Hale Cycle for the Sun is actually 11 x 2 = 22 years long.

A big gaseous fusion bomb, the Sun actually rotates once every 25 days near its equator, and 34 days at the poles. The Sun’s rotational axis is also tipped 7.25 degrees relative to the ecliptic, with the northern rotational pole tipped towards us in early September, while the southern pole nods towards us in early March.

An animation of massive susnpot AR 2192 crossing the Earthward face of Sol from October 17th to October 29th, 2014. Credit: NASA/SDO.

What’s is store for Cycle #25? One thing’s for certain: if the current trend continues, with spotless days more the rule than the exception, we could be in for a deep profound solar minimum through the 2018 to 2020 season, the likes of which would be unprecedented in modern astronomy.

Fun fact: a similar dearth of sunspots was documented during the 1645-1715 period referred to as the Maunder Minimum. During this time, crops failed and the Thames River in London froze, making “frost fairs” along its frozen shores possible. Ironically, the Maunder Minimum also began just a few decades after the dawn of the age of telescopic astronomy. During this time, the idea of “spots on the Sun” was regulated to a controversial, and almost mythical status in mainstream astronomy.

Keeping Vigil on a Tempestuous (?) Star

We’ve managed to study the last two solar cycles with unprecedented scrutiny. NASA’s STEREO-A and -B spacecraft (Only A is currently active) monitors the farside of the Sun from different vantage points. The Solar Dynamics Observatory (NASA SDO) keeps watch on the Sun across the electromagnetic spectrum. And our favorite mission, the joint NASA/European Space Agency’s SOHO spacecraft, has monitored the Sun from its sunward L1 Lagrange vantage point since it launched in 1995—nearly through one complete 22 year Hale Cycle by mid- 2020s. Not only has SOHO kept a near-continuous eye on Sol, but it’s also discovered an amazing 3,398 sungrazing comets as of September 1^st, 2017… mostly due to the efforts of diligent online amateur astronomers.

A guide to features on the Sun. The left view in Calcium-K shows the photosphere and is similar to a standard whitelight view, and the right view shows features in the chromosphere in hydrogen-alpha. Credit: Paul Stewart Instagram: @Upsidedownastronomer/annotations by Dave Dickinson

…and did you know: we can actually model the solar farside currently out of view from the Earth to a high degree of fidelity thanks to the advent of powerful computational methods used in the nascent field of solar helioseismology.

Unfortunately, this low ebb in the solar cycle will also make for lackluster aurora in the years to come. It’s a shame, really… the relatively powerful cycles of the 1970s and 80s hosted some magnificent aurorae seen from mid-latitudes (and more than a few resulting blackouts). We’re still getting some minor outbursts, but you’ll have to venture “North/South of the 60” to really see the aurorae in all of its splendor over the next few years.

But don’t take our word for it: get out there and observe the Sun for yourself. Don’t let this discourage you when it comes to observing the Sun. Even near its minimum, the Sun is a fascinating target of study… and unlike most astronomical objects, the face of the Sun can change very quickly, sometimes erupting with activity from one hour to the next.

We like to use a Coronado Personal Solar Telescope to monitor the Sun in hydrogen-alpha for prominences and filaments: such a scope can be kept at the ready to pop outside at lunch time daily for a quick look. For observing sunspots and the solar photosphere in white-light, you’ll need an approved glass filter which fits snugly over the aperture end of your telescope or camera, or you can make a safe solar filter with Baader Safety Film.

Solar scopes — Safe ways to observe the Sun: a homemade whitelight filter (left) and a Coronado PST solar telescope (right). Images by author.

Does the sunspot cycle tell the whole picture? Certainly, the Sun most likely has longer, as yet undiscovered cycles. For about a century now, astronomers have used the Wolf Sunspot Number as calculated mean average to describe the current state of activity seen on the Sun. An interesting study calls this method into question, and notes that the direction and orientation of the heliospheric current sheet surrounding the Sun seems to provide a better overall depiction of solar activity.

Other mysteries of the Sun include: just why does the solar cycle seem baked in at 11 years? Why don’t we ever see spots at the poles? And what’s in store for the future? We do know that solar output is increasing to the tune of 1% every 100 million years… and a billion years from now, Earth will be a toasty place, probably too warm to sustain liquid water on its surface…

Which brings us to the final point: what role does the solar cycle play versus albedo, global dimming and climate? This is a complex game to play: Folks have literally gone broke trying to link the solar cycle with terrestrial human affairs and everything from wheat crops to stock market fluctuations. Many a climate change-denier will at least concede that the current climate of the Earth is indeed changing, though they’ll question human activity’s role in it. The rather ominous fact is, taking only current solar activity into account, we should be in a cooling trend right now, a signal in the data that anthropogenic climate change is working hard against.

See for yourself. You can keep track of Sol’s daily activity online: our favorite sites are SpaceWeather, NOAA’s space weather/aurora activity page, and the SOHO and SDO websites.

Be sure to keep tabs of Sol, as the next solar minimum approaches and we ask the question: will Cycle #25 occur at all?

Well, we’re finally emerging from our self-imposed monastic exile that is editing to mention we’ve got a book coming out later this year: The Universe Today Ultimate Guide to Viewing the Cosmos: Everything You Need to Know to Become an Amateur Astronomer, and yes, there’s a whole chapter dedicated to solar observing and aurora. The book is up for pre-order now, and comes out on October 23^rd, 2018!

May 17, 2018August 7, 2018 by Matt Williams

Are Mysterious Fast Radio Bursts Coming From the Collapse of Strange Star Crusts?

According to a new study, the strongest material in the Universe is the "nuclear pasta" found inside neutron stars. Credit: NASA/Goddard Space Flight Center

Fast Radio Bursts (FRBs) have fascinated astronomers ever since the first one was detected in 2007. This event was named the “Lorimer Burst” after it discoverer, Duncan Lorimer from West Virginia University. In radio astronomy, this phenomenon refers to transient radio pulses coming from distant cosmological sources, which typically last a few milliseconds on average.

Over two dozen events have been discovered since 2007 and scientists are still not sure what causes them – though theories range from exploding stars and black holes to pulsars and magnetars. However, according to a new study by a team of Chinese astronomers, FRBs may be linked to crusts forming around “strange stars”. According to a model they created, it is the collapse of these crusts that lead to high-energy bursts that can be seen light-years away.

The study, titled “Fast Radio Bursts from the collapse of Strange Star Crusts“, recently appeared in The Astrophysical Journal. The team was led by Yue Zhang of the School of Astronomy and Space Science (SASC) at Nanjing University and included Jin-Jun Geng and Yong-Feng Huang – a postdoc and professor from the SASC and the Key Laboratory of Modern Astronomy and Astrophysics (also at Nanjing University), respectively.

As they state in their study, all previous attempts to explain FRBs have been unable to resolve where these strange phenomena come from. What’s more, no counterparts in other wavebands have been detected for non-repeating FRBs so far and research into their origins has been confounded by the study of repeating FRBs. This is due to the fact that the former are often attributed to catastrophic events, which are incapable of repeating.

In the case of the FRBs, these catastrophic events include “magnetar giant flares, the collapses of magnetized supramassive rotating neutron stars, binary neutron star mergers, binary white dwarf mergers, collisions between neutron stars and asteroids/comets, collisions between neutron stars and white dwarfs, and evaporation of primordial black holes.”

Alternately, in the case of the repeating FRBs, various models suggest that these could be caused by “highly magnetized pulsars traveling through asteroid belts, neutron star-white dwarf binary mass transfer, and star quakes of pulsars.” For the sake of their study, the team proposed a new model whereby the build up and collapse of matter on certain types of neutron stars (aka. “strange stars”) could explain the behavior of FRBs. As they explain:

“It has been conjectured that strange quark matter (SQM), a kind of dense material composed of approximately equal numbers of up, down, and strange quarks, may have a lower energy per baryon than ordinary nuclear matter (such as 56 Fe) so that it may be the true ground state of hadronic matter. If this hypothesis is correct, then neutron stars (NSs) may actually be ‘strange stars'”.

*This artist’s impression of the cosmic web, the filamentary structure that fills the entire Universe, showing radio sources associated with FRBs. Credit: M. Weiss/CfA*

According to this model, strange stars build up a layer of hadronic (aka. “normal”) matter on their surface over time. As these SQM stars accrete matter from their environment, their crusts becomes heavier and heavier. Eventually, this leads the crust to collapse, leaving a hot and bare strange star that becomes a powerful source of electrons and positron pairs.

These pairs would then be released along with large amounts of magnetic energy over a very short timescale. The team further hypothesized that during a collapse, a fraction of magnetic energy would be transferred to the polar cap region of the SQM stars, where the magnetic field energy is released. This would cause the electrons and positrons to be accelerated to ultra-relativistic speeds, which would then expand along magnetic field lines to form a shell.

Beyond a certain distance from the star, coherent emission in radio bands will be produced, giving birth to an FRB event. They also theorize that this same phenomenon could give to rise to repeating FRBs. One possibility is that the crust of an SQM star could be reconstructed over time, thus allowing for repeated events. A second is that only small sections of crust collapse at any given time, thus resulting in repeated events.

As they conclude, further studies will be needed before this can be said either way:

Owing to this long reconstruction timescale, multiple FRB events from the same source seem not likely to happen in our scenario. Our model thus is more suitable for explaining the non- repeating FRBs… However, we should also note that during the collapse process, if only a small portion (in the polar cap region) of the crust falls onto the SQM core while the other portion of the crust remains stable, then the rebuilt timescale for the crust can be markedly reduced and repeating FRBs would still be possible.

*The CHIME telescope, a massive radio telescope located in Penticton, British Columbia. Credit: CHIME/DRAO*

Another thing that they claim will require further investigation is whether or not the collapse of a strange star’s crust could result in electromagnetic radiation other than radio waves. At present, any emissions in the X-ray and Gamma-ray bands would be too faint for current detectors to observe. For these reasons, further investigations of FRB sources with more sensitive instruments are needed.

These include the Canadian Hydrogen Intensity Mapping Experiment (CHIME) telescope – located in Penticton, British Columbia – and the Square Kilometer Array (SQA) currently under construction in South Africa and Australia. These facilities, which are optimized for radio astronomy, are expected to reveal a great deal more about FRBs and other mysterious cosmic phenomena.

Further Reading: arXiv

May 17, 2018 by Matt Williams

There was Evidence for Europa’s Geysers Hiding in Plain Sight in Old Spacecraft Data From 1997

Artist’s illustration of Jupiter and Europa (in the foreground) with the Galileo spacecraft after its pass through a plume erupting from Europa’s surface. Credits: NASA/JPL-Caltech/Univ. of Michigan

Jupiter’s moon Europa continues to fascinate and amaze! In 1979, the Voyager missions provided the first indications that an interior ocean might exist beneath it’s icy surface. Between 1995 and 2003, the Galileo spaceprobe provided the most detailed information to date on Jupiter’s moons to date. This information bolstered theories about how life could exist in a warm water ocean located at the core-mantle boundary.

Even though the Galileo mission ended when the probe crashed into Jupiter’s atmosphere, the spaceprobe is still providing vital information on Europa. After analyzing old data from the mission, NASA scientists have found independent evidence that Europa’s interior ocean is venting plumes of water vapor from its surface. This is good news for future mission to Europa, which will attempt to search these plumes for signs of life.

The study which describes their findings, titled “Evidence of a plume on Europa from Galileo magnetic and plasma wave signatures“, recently appeared in the journal Nature Astronomy. The study was led by Xianzhe Jia, a space physicist from the Department of Climate and Space Sciences and Engineering at the University of Michigan, and included members from UCLA and the University of Iowa.

*Artist’s concept of the Galileo space probe passing through the Jupiter system. Credit: NASA*

The data was collected in 1997 by Galileo during a flyby of Europa that brought it to within 200 km (124 mi) of the moon’s surface. At the time, its Magnetometer (MAG) sensor detected a brief, localized bend in Jupiter’s magnetic field, which remained unexplained until now. After running the data through new and advanced computer models, the team was able to create a simulation that showed that this was caused by interaction between the magnetic field and one of the Europa’s plumes.

This analysis confirmed ultraviolet observations made by NASA’s Hubble Space Telescope in 2012, which suggested the presence of water plumes on the moon’s surface. However, this new analysis used data collected much closer to the source, which indicated how Europa’s plumes interact with the ambient flow of plasma contained within Jupiter’s powerful magnetic field.

In addition to being the lead author on this study, Jia is also the co-investigator for two instruments that will travel aboard the Europa Clipper mission – which may launch as soon as 2022 to explore the moon’s potential habitability. Jia’s and his colleagues were inspired to reexamine data from the Galileo mission thanks to Melissa McGrath, a member of the SETI Institute and also a member of the Europa Clipper science team.

During a presentation to her fellow team scientists, McGrath highlighted other Hubble observations of Europa. As Jiang explained in a recent NASA press release:

“The data were there, but we needed sophisticated modeling to make sense of the observation. One of the locations she mentioned rang a bell. Galileo actually did a flyby of that location, and it was the closest one we ever had. We realized we had to go back. We needed to see whether there was anything in the data that could tell us whether or not there was a plume.”

*Artist’s impression of a water vapor plume on Europa. Credit: NASA/ESA/K. Retherford/SWRI*

When they first examined the information 21 years ago, the high-resolution data obtained by the MAG instrument showed something strange. But it was thanks to the lessons provided by the Cassini mission, which explored the plumes on Saturn’s moon Enceladus, that the team knew what to look for. This included material from the plumes which became ionized by the gas giant’s magnetosphere, leaving a characteristic blip in the magnetic field.

After reexamining the data, they found that the same characteristic bend (localized and brief) in the magnetic field was present around Europa. Jia’s team also consulted data from Galileo’s Plasma Wave Spectrometer (PWS) instrument to measure plasma waves caused by charged particles in gases around Europa’s atmosphere, which also appeared to back the theory of a plume.

This magnetometry data and plasma wave signatures were then layered into new 3D modeling developed by the team at the University of Michigan (which simulated the interactions of plasma with Solar system bodies). Last, they added the data obtained from Hubble in 2012 that suggested the dimensions of the potential plumes. The end result was a simulated plume that matched the magnetic field and plasma signatures they saw in the Galileo data.

As Robert Pappalardo, a Europa Clipper project scientist at NASA’s Jet Propulsion Laboratory (JPL), indicated:

“There now seem to be too many lines of evidence to dismiss plumes at Europa. This result makes the plumes seem to be much more real and, for me, is a tipping point. These are no longer uncertain blips on a faraway image.”

*Artist’s concept of a Europa Clipper mission, which will study Europa in 2022-2025 to search for signs of life. Credit: NASA/JPL*

The findings are certainly good news for the Europa Clipper mission, which is expected to make the journey to Jupiter between 2022 and 2025. When this probe arrives in the Jovian system, it will establish an orbit around Jupiter and conduct rapid, low-altitude flybys of Europa. Assuming that plume activity does take place on the surface of the moon, the Europa Clipper will sample the frozen liquid and dust particles for signs of life.

“If plumes exist, and we can directly sample what’s coming from the interior of Europa, then we can more easily get at whether Europa has the ingredients for life,” Pappalardo said. “That’s what the mission is after. That’s the big picture.”

At present, the mission team is busy looking at potential orbital paths for the Europa Clipper mission. With this new research in hand, the team will choose a path that will take the spaceprobe above the plume locations so that it is in an ideal position to search them for signs of life. If all goes as planned, the Europa Clipper could be the first of several probes that finally proves that there is life beyond Earth.

And be sure to check out this video of the Europa Clipper mission, courtesy of NASA:

Further Reading: NASA, Nature

May 16, 2018 by Matt Williams

Gaia Turns Up 13,928 White Dwarfs Nearby the Sun, Including Several Formed Through Mergers

Using information from Gaia's second data release, a team of scientists have made refined estimates of the Milky Way's mass. Credit: ESA/Gaia/DPAC

In 2013, the European Space Agency (ESA) deployed the Gaia mission, a space observatory designed to measure the positions of movements of celestial bodies. For the past four years, Gaia has been studying distant stars, planets, comets, asteroids, quasars and other astronomical objects, and the data it has acquired will be used to construct the largest and most precise 3D space catalog ever made, totaling 1 billion objects.

The second release of Gaia data, which took place on April 25th, 2018, has already resulted in a number of impressive discoveries. The latest was made by an international team of scientists who identified 13,928 white dwarfs within 100 parsecs (326 light-years) of the Sun, many of which were formed through mergers. This is the first time that white dwarf stars have been directly detected within the Solar neighborhood.

The study which describes their findings, “Gaia Reveals Evidence for Merged White Dwarfs“, recently appeared online and is being considered for publication in the Monthly Notices of the Royal Astronomical Society. The study was led by Dr. Mukremin Kilic, an associate professor at the University of Oklahoma, and included members from the Institute for Astronomy at the University of Edinburgh and the University of Montreal.

*Artist impression of colliding white dwarfs. Credit: CfA*

Basically, white dwarfs are what become of the majority of stars (with masses less than 8 Solar masses) once they exit the main sequence phase of their lives. This consists of a star exhausting its hydrogen fuel and expanding to several times its size (entering its Red Giant Branch Phase). These stars then blow off their external layers (a supernova) and leaving behind a white dwarf remnant.

By studying them, astronomers can learn far more about the life cycle of stars and how they evolve. As Dr. Kilic explained to Universe Today via email:

“[W]e’re basically doing Galactic archaeology when we study nearby white dwarfs. They tell us about the ages and star formation histories of the Galactic disk and halo. More importantly, white dwarfs explode as a Type Ia supernova when they reach 1.4 times the mass of the Sun. We use these supernovae to study the shape of the Universe and conclude that the expansion of the universe is accelerating. However, we have not yet found the progenitor systems of these supernovae. One of the channels to form Type Ia supernovae is through mergers of white dwarfs. Hence, the direct detection of merged white dwarfs is important for understanding the frequency of these white dwarf mergers.”

However, until recently only a few hundred white stars have been found within the local galactic neighborhood (500 within a 40 parsec radius). In addition, astronomers were only able to obtain accurate parallax (distance) measurements for about half of these. But thanks to the Gaia data, the number of white dwarfs systems that astronomers are able to study has increased exponentially.

*Artist’s impression of a white dwarf star in orbit around Sirius (a white supergiant). Credit: NASA, ESA and G. Bacon (STScI)*

“Gaia provided distance measurements,” said Kilic. “We can now create complete samples of white dwarfs within a given volume. For example, prior to Gaia, we only knew about 100 white dwarfs within 20 parsecs of the Sun. With Gaia Data Release 2, we identified more than 13,000 white dwarfs within 100 parsecs of the Sun. The difference in numbers is amazing!”

The Gaia data was also helpful in determining the nature of these white dwarf systems and how they formed. As they indicate in their study, previous research has shown that the majority of white dwarf stars in our local galaxy (roughly 56%) are the product of single-star evolution, whereas 7 to 23% were the product of mergers between binaries. The remainder were white dwarf binaries, or binaries with one white dwarf and a main sequence star.

Using the Gaia data – which included the color and distribution data of thousands of white dwarf stars within ~326 light-years of the Sun – the team was able to determine how massive these stars are. This, in turn, provided vital clues as to how they formed, which indicated that mergers were far more common than previous studies suggested. As Kilic explained:

“Massive white dwarfs tend to be smaller, which means that they are also fainter (since they have a smaller surface area). Since Gaia gave us a complete sample of white dwarfs within 100 parsecs of the Sun, for the first time, we were able to derive the magnitude distribution (hence the mass distribution) of thousands of white dwarfs and find a large fraction of massive white dwarfs. We see that the number of massive white dwarfs is significantly higher than expected from single star evolution. Therefore, we concluded that many of these massive white dwarfs actually formed through mergers in previously binary systems.”

*Artist’s impression of white dwarf binary pair CSS 41177. Credit: Andrew Taylor.*

From this, the team was able to assemble the first reliable Hertzsprung-Russell Diagram for nearby field white dwarf stars, as well as estimates on how often white dwarf binaries merge. As Kilic indicated, this could have significant implications for other areas of astronomical study.

“Based on the frequency of these single white dwarfs that formed through mergers, we can estimate how many white dwarf mergers occur on average and with what mass distribution,” he said. “We can then infer the rate of Type Ia supernovae from these mergers and see if it’s enough to explain part or all of the Ia supernova explosions. This is an ongoing area of research and I’m sure we will some results on these very soon.”

These findings are yet another gem to come from the second Gaia data release, which has proven to be a treasure trove for astronomers. The third release of Gaia data is scheduled to take place in late 2020, with the final catalog being published in the 2020s. Meanwhile, an extension has already been approved for the Gaia mission, which will now remain in operation until the end of 2020 (to be confirmed at the end of this year).

Further Reading: arXiv

May 15, 2018February 8, 2023 by Matt Williams

If There is a Multiverse, Can There be Life There Too?

*Could our Universe be part of a wider Multiverse? And could these other Universes support life? Credit: Jaime Salcido/EAGLE Collaboration*

The Multiverse Theory, which states that there may be multiple or even an infinite number of Universes, is a time-honored concept in cosmology and theoretical physics. While the term goes back to the late 19th century, the scientific basis of this theory arose from quantum physics and the study of cosmological forces like black holes, singularities, and problems arising out of the Big Bang Theory.

One of the most burning questions when it comes to this theory is whether or not life could exist in multiple Universes. If indeed the laws of physics change from one Universe to the next, what could this mean for life itself? According to a new series of studies by a team of international researchers, it is possible that life could be common throughout the Multiverse (if it actually exists).

Continue reading “If There is a Multiverse, Can There be Life There Too?”

May 14, 2018May 15, 2018 by David Dickinson

Recovered Asteroid 2010 WC9 Set to Buzz the Earth Tomorrow

The orbit of asteroid 2010 WC9. Credit: NASA/JPL

Incoming: The Earth-Moon system has company tonight.

The Asteroid: Near Earth Asteroid 2010 WC9 is back. Discovered by the Catalina Sky Survey outside Tucson, Arizona on November 30^th, 2010, this asteroid was lost after a brief 10 day observation window and was not recovered until just earlier this month. About 71 meters in size, 2010 WC9 is one of the largest asteroids to pass us closer than the Earth-Moon distance.

A closeup of the passage of asteroid 2010 WC9 through the Earth-Moon system on May 15th. Credit: NASA-JPL

2010 WC9 poses no threat to the Earth. About the size of the Statue of Liberty from the ground level to her crown, the asteroid is over three times bigger than the one that exploded over Chelyabinsk, Russia on the morning of February 15th, 2013.

The view from asteroid 2010 WC9 on closest approach. Credit: Starry Night

The Pass: 2010 WC9 passes just 0.5 times the Earth-Moon distance (126,500 miles or 203,500 kilometers) on Tuesday, May 15^th at 22:05 UT/6:05 PM EDT. That’s only roughly five times the distance of satellites in geosynchronous orbit. The asteroid is also a relative fast mover, whizzing by at over 12 kilometers per second. An Apollo-type asteroid, 2010 WC9 orbits the Sun once every 409 days, ranging from a perihelion of 0.78 astronomical units (AU) outside the orbit of Venus out to 1.38 AU, just inside the orbit of Mars. This is the closest passage of the asteroid by the Earth for this century.

The passage of asteroid 2010 WC9 through the constellation Ophiuchus on May 15th from 00:00 to 16:00 UT. Credit Starry Night.

Observing: This one grabbed our attention when it cropped up on the Space Weather page for close asteroid passes this past weekend: a large, fast mover passing close to the Earth is a true rarity. At closest approach, 2010 WC9 will be moving at 0.22 degrees (that’s 13 arcminutes, about half the span of a Full Moon) per minute through the constellation Pavo the Peacock shining at magnitude +10, making it a good telescopic object for observers based in South Africa as it heads over the South Pole.

The southern hemisphere passage of asteroid 2010 WC9 on May 15th from 19:00 to 23:00 UT.

North American and European observers get their best look at the asteroid tonight into early tomorrow morning while it’s still twice the distance of the Moon, shining at 13th magnitude and moving southward through the constellation Ophiuchus and across the ecliptic plane.

The best strategy to ambush the space rock is to simply aim a low power field of view at the right coordinates at the right time (see below), and watch. You should be able to see the asteroid moving slowly against the starry background, in real time.

Asteroid 2010 WC9 (non-streaking dot in the center) on May 15th while it was still 730,000 km out. Credit: Gianluca Masi/Virtual Telescope Project 2.0.

Keep in mind, the charts we made here are geocentric, assuming you’re observing from the center of the Earth. Parallax comes into play on a close asteroid pass, and the Earth’s gravity will deflect 2010 WC9’s orbit considerably. Your best bet for generating a refined track for the asteroid is to use NASA JPL’s Horizons web interface to generate Right Ascension/Declination coordinates for the 2010 WC9 for your location.

How do you ‘lose an asteroid?” Often, an initial observation arc for a distant asteroid is too short to pin down a refined orbit. We have a blind spot sunward, for example, and fast moving asteroids can also be difficult to track across rich star fields and movement from one celestial hemisphere to the next. Recovery of 2010 WC9 earlier this month now gives us a solid seven year observation arc to peg its orbit down to a high accuracy.

Clouded out, or live in the wrong hemisphere? Slooh will carry an observing session for 2010 WC9 starting tonight at 24:00 UT/ 8:00 PM EDT. The Northholt Branch Observatories in London, England will also stream the pass live via Facebook tonight. Check their page for a start time.

Go, little asteroid… the speedy passage of 2010 WC9. Credit: Northolt Branch Observatories.

There’s no word yet if Arecibo radar plans to ping 2010 WC9 over the coming days, but if they do, so expect to see an animation soon.

Don’t miss tonight’s passage of 2010 WC9 near the Earth, either in person or online.