Thursday, January 29, 2015

Astronomers Catch A Quasar Shutting Off

Astronomers Catch A Quasar Shutting Off:

This artist's rending shows "before" and "after" images of a changing look quasar. Credit: Yale University.


This artist’s rending shows “before” and “after” images of a changing look quasar. Credit: Yale University.
Last week, astronomers at Yale University reported seeing something unusual: a seemingly stedfast beacon from the far reaches of the Universe went quiet. This relic light source, a quasar located in the region of our sky known as the celestial equator, unexpectedly became 6-7 times dimmer over the first decade of the 21st century. Thanks to this dramatic change in luminosity, astronomers now have an unprecedented opportunity to study both the life cycle of quasars and the galaxies that they once called home.

A quasar arises from a distant (and therefore, very old) galaxy that once contained a central, rotating supermassive black hole – what astronomers call an active galactic nucleus. This spinning beast ravenously swallowed up large amounts of ambient gas and dust, kicking up surrounding material and sending it streaming out of the galaxy at blistering speeds. Quasars shine because these ancient jets achieved tremendous energies, thereby giving rise to a torrent of light so powerful that astronomers are still able to detect it here on Earth, billions of years later.

In their hey-day, some active galactic nuclei were also energetic enough to excite electrons farther away from the central black hole. But even in the very early Universe, electrons couldn’t withstand that kind of excitement forever; the laws of physics don’t allow it. Eventually, each electron would drop back down to its rest state, releasing a photon of corresponding energy. This cycle of excitation happened over and over and over again, in regular and predictable patterns. Modern astronomers can visualize those transitions – and the energies that caused them – by examining a quasar’s optical spectrum for characteristic emission lines at certain wavelengths.

An example of an atomic spectrum, showing emission lines at particular wavelengths.


A simple example of an atomic spectrum, showing emission lines at particular wavelengths. Broad humps correspond to brighter emission lines, while lines that arise from narrow, lower-intensity emissions appear dimmer. Credit: NASA
Not all quasars are created equal, however. While the spectra of some quasars reveal many bright, broad emission lines at different energies, other quasars’ spectra consist of only the dim, narrow variety. Until now, some astronomers thought that these variations in emission lines among quasars were simply due to differences in their orientation as seen from Earth; that is, the more face-on a quasar was relative to us, the broader the emission lines astronomers would be able to see.

But all of that has now been thrown into question, thanks to our friend J015957.64+003310.5, the quasar revealed by the team of astronomers at Yale. Indeed, it is now plausible that a quasar’s pattern of emission lines simply changes over its lifetime. After gathering ten years of spectral observations from the quasar, the researchers observed its original change in brightness in 2010. In July 2014, they confirmed that it was still just as dim, disproving hypotheses that suggested the effect was simply due to intervening gas or dust. “We’ve looked at hundreds of thousands of quasars at this point, and now we’ve found one that has switched off,” explained C. Megan Urry, the study’s co-author.

How would that happen, you ask? After observing the comparable dearth of broad emission lines in its spectrum, Urry and her colleagues believe that long ago, the black hole at the heart of the quasar simply went on a diet. After all, an active galactic nucleus that consumed less material would generate less energy, giving rise to fainter particle jets and fewer excited atoms. “The power source just went dim,” said Stephanie LaMassa, the study’s principal investigator.

LaMassa continued, “Because the life cycle of a quasar is one of the big unknowns, catching one as it changes, within a human lifetime, is amazing.” And since the life cycle of quasars is dependent on the life cycle of supermassive black holes, this discovery may help astronomers to explain how those that lie at the center of most galaxies evolve over time – including Sagittarius A*, the supermassive black hole at the center of our own Milky Way.

“Even though astronomers have been studying quasars for more than 50 years, it’s exciting that someone like me, who has studied black holes for almost a decade, can find something completely new,” added LaMassa.

The team’s research will be published in an upcoming issue of The Astrophysical Journal. A pre-print of the paper is available here.



About 

Vanessa earned her bachelor's degree in Astronomy and Physics in 2009 from Wheaton College in Massachusetts. Her credits in astronomy include observing and analyzing eclipsing binary star systems and taking a walk on the theory side as a NSF REU intern, investigating the expansion of the Universe by analyzing its traces in observations of type 1a supernovae. In her spare time she enjoys writing about astrophysics, cosmology, biology, and medicine, making delicious vegetarian meals, taking adventures with her husband and/or Nikon D50, and saving the world.

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“Super Saturn” Has an Enormous Ring System and Maybe Even Exomoons

“Super Saturn” Has an Enormous Ring System and Maybe Even Exomoons:

Illustration by artist Ron Miller of the gigantic ring system around J1407b. (© Ron Miller)


Illustration by artist Ron Miller of the gigantic ring system around J1407b. (© Ron Miller. Used with permission.)
Astronomers watching the repeated and drawn-out dimming of a relatively nearby Sun-like star have interpreted their observations to indicate an eclipse by a gigantic exoplanet’s complex ring system, similar to Saturn’s except much, much bigger. What’s more, apparent gaps and varying densities of the rings imply the presence of at least one large exomoon, and perhaps even more in the process of formation!

J1407 is a main-sequence orange dwarf star about 434 light-years away*. Over the course of 57 days in spring of 2007 J1407 underwent a “complex series of deep eclipses,” which an international team of astronomers asserts is the result of a ring system around the massive orbiting exoplanet J1407b.

“This planet is much larger than Jupiter or Saturn, and its ring system is roughly 200 times larger than Saturn’s rings are today,” said Eric Mamajek, professor of physics and astronomy at the University of Rochester in New York. “You could think of it as kind of a super Saturn.”

The observations were made through the SuperWASP program, which uses ground-based telescopes to watch for the faint dimming of stars due to transiting exoplanets.

The first study of the eclipses and the likely presence of the ring system was published in 2012, led by Mamajek. Further analysis by the team estimates the number of main ring structures to be 37, with a large and clearly-defined gap located at about 0.4 AU (61 million km/37.9 million miles) out from the “super Saturn” that may harbor a satellite nearly as large as Earth, with an orbital period of two years.

Watch an animation of the team’s analysis of the J1407/J1407b eclipse below:

The entire expanse of J1407b’s surprisingly dense rings stretches for 180 million km (112 million miles), and could contain an Earth’s worth of mass.

“If we could replace Saturn’s rings with the rings around J1407b,” said Matthew Kenworthy from Leiden Observatory in the Netherlands and lead author of the new study, “they would be easily visible at night and be many times larger than the full Moon.”

Saturn's relatively thin main rings are about 250,000 km (156,000 miles) in diameter. (Image: NASA/JPL-Caltech/SSI/J. Major)


Saturn’s relatively thin main rings are about 250,000 km (156,000 miles) in diameter. (Image: NASA/JPL-Caltech/SSI/J. Major)
These observations could be akin to a look back in time to see what Saturn and Jupiter were like as their own system of moons were first forming.

“The planetary science community has theorized for decades that planets like Jupiter and Saturn would have had, at an early stage, disks around them that then led to the formation of satellites,” according to Mamajek. “However, until we discovered this object in 2012, no one had seen such a ring system. This is the first snapshot of satellite formation on million-kilometer scales around a substellar object.”

J1407b itself is estimated to contain 10-40 times the mass of Jupiter – technically, it might even be a brown dwarf.

Further observations will be required to observe another transit of J1407b and obtain more data on its rings and other physical characteristics as its orbit is about ten Earth-years long. (Luckily 2017 isn’t that far off!)

The team’s report has been accepted for publication in the Astrophysical Journal.

Source: University of Rochester. Image credit: Ron Miller.

Note: the originally published version of this article described J1407 at 116 light-years away. It’s actually 133 parsecs, which equates to about 434 light-years. Edited above. – JM



About 

A graphic designer in Rhode Island, Jason writes about space exploration on his blog Lights In The Dark, Discovery News, and, of course, here on Universe Today. Ad astra!

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Is The Moon A Planet?

Is The Moon A Planet?:

Composite picture of a dark red Moon during a total lunar eclipse. Credit: NASA/ Johannes Schedler (Panther Observatory)


Composite picture of a dark red Moon during a total lunar eclipse. Credit: NASA/ Johannes Schedler (Panther Observatory)
What makes a planet a planet? The Moon is so big compared to the Earth — roughly one-quarter our planet’s size — that occasionally you will hear our system being referred to as a “double planet”. Is this correct?

And we all remember how quickly the definition of a planet changed in 2006 when more worlds similar to Pluto were discovered. So can the Moon stay the Moon, or is the definition subject to change?

Defining a planet

First, it’s important to understand what the official definition of a “planet” is, at least according to the International Astronomical Union. In its own words, according to a vote in Prague in 2006, the union has this definition:

“A planet is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighborhood around its orbit.”

What this means is that a planet must move around the Sun (and not move around something else), that it’s massive enough to have a round shape due to gravity, and that it will swoop up any dust or debris in its orbit as it moves around the Sun.

But let’s be clear on something; the IAU definition of planet is not without controversy. There is still a strong contingent of people who say that Pluto is indeed a planet, including the principal investigator of a spacecraft (New Horizons) to examine the world: Alan Stern.

“It’s an awful definition; it’s sloppy science and it would never pass peer review,” he told the BBC in 2006. He said that the line between dwarf planets and planets is too artificial, and that the definition of a “cleared neighborhood” is muddy. The Earth alone has many asteroids that follow it — or approach or cross its orbit — not to mention the massive planet Jupiter.

UV observations from Hubble show the size of water vapor plumes coming from Europa's south pole (NASA, ESA, and M. Kornmesser)


UV observations from Hubble show the size of water vapor plumes coming from Europa’s south pole (NASA, ESA, and M. Kornmesser)
Definition of a ‘satellite’

The Moon is not a unique phenomenon in our Solar System, in the sense that there are other planets that have satellites around them. Jupiter and Saturn have many dozens! Referring again to the IAU, the union also said in 2006 that it does not consider Charon a dwarf planet despite its large relative size to Pluto.

But Charon’s status as a moon could change in future, the IAU acknowledged. That’s primarily because the center of gravity in the system is not inside of Pluto, but in “free space between Pluto and Charon”. This center is called the “barycenter”, technically — and in Jupiter and Saturn’s cases, for example, all the barycenters of the various moons reside “inside” the huge gas giants.

Another caution, however: the IAU says “there has been no official recognition that the location of the barycenter is involved with the definition of a satellite.” So for now, it doesn’t have any bearing. That said, one question to consider is if the Moon’s barycenter is inside the Earth?

This Cassini raw image shows a portion of Saturn's rings along with several moons. How many can you find? Credit: NASA/JPL/Space Science Institute


This Cassini raw image shows a portion of Saturn’s rings along with several moons. How many can you find? Credit: NASA/JPL/Space Science Institute
The answer right now is “yes”. But over time, that barycenter will move outside of Earth. That’s because the Moon is slowly receding from our planet at a rate of about 3.8 centimeters (1.5 inches) a year. It’ll take a long time, but eventually the center of our system’s mass will not be within our planet.

And if you read back to an IAU interview in 2006, you’ll see that at that time, the IAU defined a “double planet” as a system where both bodies meet the definition of a planet, and the barycenter is not inside either one of the objects. So for now, the Earth is a planet and the Moon a satellite — at least under IAU rules.

We have written many articles about the Moon for Universe Today. Here’s an article about how long it takes to get to the Moon, and here are some interesting facts about the Moon. We’ve also recorded an entire episode of Astronomy Cast all about the Moon. Listen here, Episode 113: The Moon, Part 1.



About 

Elizabeth Howell is the senior writer at Universe Today. She also works for Space.com, Space Exploration Network, the NASA Lunar Science Institute, NASA Astrobiology Magazine and LiveScience, among others. Career highlights include watching three shuttle launches, and going on a two-week simulated Mars expedition in rural Utah. You can follow her on Twitter @howellspace or contact her at her website.

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Oldest Planetary System Discovered, Improving the Chances for Intelligent Life Everywhere

Oldest Planetary System Discovered, Improving the Chances for Intelligent Life Everywhere:

An artist rendition of Kepler-444 planetary system, which hosts five planets, all smaller than Earth. Credit: Tiago Campante, University of Birmingham, UK.


An artist rendition of Kepler-444 planetary system, which hosts five planets, all smaller than Earth. Credit: Tiago Campante, University of Birmingham, UK.
Using data from the Kepler space telescope, an international group of astronomers has discovered the oldest known planetary system in the galaxy – an 11 billion-year-old system of five rocky planets that are all smaller than Earth. The team says this discovery suggests that Earth-size planets have formed throughout most of the Universe’s 13.8-billion-year history, increasing the possibility for the existence of ancient life – and potentially advanced intelligent life — in our galaxy.

“The fact that rocky planets were already forming in the galaxy 11 billion years ago suggests that habitable Earth-like planets have probably been around for a very long time, much longer than the age of our Solar System,” said Dr. Travis Metcalfe, Senior Research Scientist Space Science Institute, who was part of the team that used the unique method of asteroseismology to determine the age of the star.


The star, named Kepler-444, is about 25 percent smaller than our Sun and is 117 light-years from Earth. The system of five known planets is very compact, and all five planets orbit the parent star in less than 10 days, or within 0:08 AU, roughly one-fifth the size of Mercury’s orbit.

“The star is slightly cooler than the Sun (around 5000 K at the surface, compared to 5800 K),” Metcalfe told Universe Today, “but the planets in this system are still expected to be highly irradiated and inhospitable to life,” with little to no atmospheres.

The team wrote in their paper that the system’s habitable zone lies 0:47 AU from the parent star and so all planets orbit well interior to the inner edge of Kepler-444’s ‘Goldilocks zone.’

The team was led by Tiago Campante, a research fellow at the University of Birmingham in the UK.

The planets were found by analyzing four years of Kepler data, as the spacecraft had nearly continuous observations of Kepler-444 during Kepler’s active mission. The space telescope took high-precision measurements of changes in brightness in stars in its field of view. There are tiny changes in brightness when planets pass in front of their stars.

Transit signals indicated five planets orbiting Kepler-444, although this star has a binary companion, an M-dwarf, and it was a tedious process to tease out all the data to determine what were planets and not other stars, as well as which star the planets were orbiting.

An image of the Kepler-444 star system using the NIRC2 near-infrared imager on the Keck II telescope. Credit: Tiago Campante et al.


An image of the Kepler-444 star system using the NIRC2 near-infrared imager on the Keck II telescope. Credit: Tiago Campante et al.
Metcalfe said the the job of “validating” the planets by ruling out all of the other possible “false positive” scenarios is always a big challenge for Kepler targets.

But asteroseismology was used to directly measure the precise age of the star. Asteroseismology, or stellar seismology is basically listening to a star by measuring sound waves. The sound waves travel into the star and bring information back up to the surface. The waves cause oscillations that Kepler observes as a rapid flickering of the star’s brightness.

How can this help determine a star’s age?

“As a star ages, it converts hydrogen into helium in the core,” Metcalfe said via email. “This changes the mean density of the star over time, and asteroseismology provides a very precise measure of the mean density (from the regular spacing of the individual oscillation frequencies).”

Metcalfe said that in this case, the uncertainty on the age of the star (and thus the planets, which formed essentially at the same time) is only 9%, compared to a typical uncertainty of 30-50% from other methods based on rotation (gyrochronology) or other properties of the star.

The team also noted in their paper that this finding may also help to pinpoint the beginning of the era of planet formation.

“I think this system has a lot to teach us about planet formation and the long-term evolution of planetary systems,” said Darin Ragozzine, a professor at Florida Institute of Technology and a a member of the discovery team, who specializes in multi-transiting systems. “With an age of 11.2 billion years, it means that this system formed near the beginning of the age of the Universe.”

The team wrote that this finding implies that small, Earth-size, planets may have readily formed at early epochs in the Universe’s history, even when metals were more scarce.

“By the time Earth formed, this star and its planetary system were already older than our planet is today,” Ragozzine told Universe Today. “We don’t know for sure if this system has stayed the same the whole time, but it is amazing to think that the little inner planet has gone around the star about a trillion times!”

To find out more about asteroseismology, check out a website called the Pale Blue Dot Project. Metcalfe launched a non-profit organization to help raise research funds for the Kepler Asteroseismic Science Consortium. The Pale Blue Dot Project allows people to adopt a star to support asteroseismology, since there is no NASA funding for asteroseismology.

“Much of the expertise for this exists in Europe and not in the US, so as a cost saving measure NASA outsourced this particular research for the Kepler mission,” said Metcalfe, “and NASA can’t fund researchers in other countries.”

Metcalfe added that the “adopt a star” program supported the asteroseismic analysis of Kepler-444, “determining the precise age that makes this ancient planetary system so interesting… This private funding from citizens around the world has been an invaluable resource to facilitate our research and fuel amazing discoveries like this one.”

You can help this research by adopting one of the Kepler stars or planetary systems.
This research was published today in the Astrophysical Journal.

The team’s paper is titled, “An Ancient Extrasolar System with Five Sub-Earth-Size Planets.”

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Luna vs. the Hyades! The 1st of 13 Occultations of Aldebaran Set For January 29th

Luna vs. the Hyades! The 1st of 13 Occultations of Aldebaran Set For January 29th:

Credit:


Getting closer… the Moon and Aldebaran from May 2014. Credit and copyright: Ziad El-Zaatari.
The cosmos is continually in motion.

Be it atoms, stars or snowflakes from the latest nor’easter pounding the New England seaboard, anything worth studying involves movement. And as skies and snowbound roads clear, this Wednesday and Thursday evening will give us a reason to brave the January cold, as the waxing gibbous Moon pierces the Hyades star cluster to graze past the bright star Aldebaran.

During Thursday night’s passage, the Moon will be 78% illuminated. In a sort ‘cosmos mimics controversy’ irony, the gibbous Moon is doing its best to mimic a sky bound ‘deflategate’ football just in time for Superbowl XLIX this weekend.

Stellarium


The motion of the Moon this week across the Hyades. Credit: Stellarium.
But the January 29th event also marks the first occultation of Aldebaran for 2015.

Fun fact: At magnitude +0.8, Aldebaran is the only star brighter than +1st magnitude north of the celestial equator that the Moon can currently occult. Regulus, the runner up, shines at magnitude +1.4.  Two other second magnitude stars — Antares and Spica — lie along the Moon’s path on occasion, and up until the 2nd century BC, it was possible for the Moon to occult Pollux in the constellation Gemini as well.

There are 13 occultations of Aldebaran in 2015, and the Moon occults the star 49 times overall until the last event in the current cycle on September 3rd, 2018. Aldebaran is also occulted by the Moon more often in the current 2010-2020 decade than any other bright star. You can even spy Aldebaran near the daytime Moon with binoculars, as we did back in 1996 from North Pole, Alaska.

Credit: Occult


Maps for the 13 occultations of Aldebaran  by the Moon in 2015, click to enlarge. solid lines denote regions were the occultation occurs under dark skies. Credit: Occult 4.0.
Of course, the January 29th event is an occultation only for the high Arctic, with only a scattering of villages and distant early warning stations along the northern Nunavut coast welcoming the sequence of 2015 occultations of the bright star.

The rest of us will see a close photogenic pass, as the Moon makes an end run through the Hyades star cluster every 27.3 day sidereal lunar month in 2015. The Moon will thus occult several members of the Hyades on each pass. Our best bet for North America is the occultation of Aldebaran on November 26th, though the Moon will be just 13 hours past Full.

68 Tauri. Credit: Occult 4.0


The occultation of 68 Tauri (a member of the Hyades) for January 29th. Credit: Occult 4.0.
Why doesn’t the path of the Moon just stay put with respect to the sky? Because the orbit of our Moon is fixed at an inclination of 5.1 degrees not with respect to our equator, but to the plane of the ecliptic. This means that the Moon’s orbit is in motion as well, and can wander anywhere from declination 28.6 degrees north to south as it cycles from a shallow to steep path every 18.6 years. We’re actually in a shallow year in 2015 (known as a minor lunar standstill) after which the apparent path of the Moon through the sky begins to widen again until April 2025.

An occultation is celestial motion that you can see in real time as a star or planet is photobomb’d by the onrushing Moon like a January snowplow… but those background stars are in motion as well.



The Hyades themselves — along with our own solar system — are moving around the galactic center. The nearest open cluster to us at 153 light years distant, the Hyades provided a unique object of study for 19th century astronomers. Astronomer Lewis Boss of the Dudley observatory spent several decades studying the proper motion — the apparent motion that a star seems to be moving across the sky from our solar system-bound perspective, measured in arc seconds — of the Hyades, and found the entire group was converging on a point in the constellation Orion near 6 hours 7’ right ascension and +7 degrees declination.

Starry Night


The imaginary convergent point of the Hyades in the night sky. Credit: Starry Night Education software.
Of course, this motion is relative and demonstrates a changing perspective, as the Hyades recedes from our solar system like a defensive line rushing to sack a quarterback.

OK, enough with the sports similes. The Hyades are so close that the actual Hyades Stream — often referred to as the Hyades Moving Group — is actually strewn across the constellations Orion, Taurus and Aries and more.

Some stars, such as 20 Arietis in the adjacent constellation Aries and Iota Horologii in the southern hemisphere may actually members as well. There’s always a bit of ongoing controversy when it comes to actual moving group membership, which is usually pegged by determining proper motion, coupled with the age and metallicity of prospective stars. Growing up in the Milky Way galaxy, our Sun was once a member of some unnamed ancient open cluster that has since long dispersed, like the Hyades are in the process of doing now.

Photo by author


The asterism of the Hyades and the ‘eye of the Bull.’ Photo by author.
The Hyades contains hundreds of stars and ironically, Aldebaran is not a member of the cluster, but is merely 65 light years away from us in the foreground. The V-shaped asterism of the Hyades gives the Head of Taurus the Bull its distinctive shape. The Hyades are named after the rain nymph daughters of Atlas from Greek mythology, whose half daughters the Pleiades also adorn the nearby sky.

And as an added bonus, don’t miss comet C/2014 Q2 Lovejoy crossing the constellation Triangulum, also nearby. Q2 Lovejoy reaches perihelion this week on January 30th, and although it’s completing with the evening Moon, it’s still holding out at a respectable magnitude +4.5.

Credit:


Comet Q2 Lovejoy skirts by  the Hyades and the Pleiades. Credit and Copyright: John Chumack.
All reasons to get out these chilly January evenings and ponder a hurried universe continually in motion, both fast and slow.

-Check out Q2 Lovejoy on January 30th courtesy of the Virtual Telescope project.



About 

David Dickinson is an Earth science teacher, freelance science writer, retired USAF veteran & backyard astronomer. He currently writes and ponders the universe from Tampa Bay, Florida.

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Dawn Captures Best Images Ever of “Hipster Planet” Ceres

Dawn Captures Best Images Ever of “Hipster Planet” Ceres:

Animation of Ceres made from images acquired by Dawn on Jan. 25, 2015. (NASA/JPL-Caltech/UCLA/MPS/DLR/IDA)


Animation of Ceres made from images acquired by Dawn on Jan. 25, 2015. (NASA/JPL-Caltech/UCLA/MPS/DLR/IDA)
This is the second animation from Dawn this year showing Ceres rotating, and at 43 pixels across the images are officially the best ever obtained!

NASA’s Dawn spacecraft is now on final approach to the 950 km (590 mile) dwarf planet Ceres, the largest world in the main asteroid belt and the biggest object in the inner Solar System that has yet to be explored closely. And, based on what one Dawn mission scientist has said, Ceres could very well be called the Solar System’s “hipster planet.”

“Ceres is a ‘planet’ that you’ve probably never heard of,” said Robert Mase, Dawn project manager at NASA’s Jet Propulsion Laboratory in Pasadena, California. “We’re excited to learn all about it with Dawn and share our discoveries with the world.”

Originally classified as a planet, Ceres was later categorized as an asteroid and then reclassified as a dwarf planet in 2006 (controversially along with far-flung Pluto.) Ceres was first observed in 1801 by astronomer Giuseppe Piazzi who named the object after the Roman goddess of agriculture, grain crops, fertility and motherly relationships. (Its orbit would later be calculated by German mathematician Carl Gauss.)

“You may not realize that the word ‘cereal’ comes from the name Ceres,” said Marc Rayman, mission director and chief engineer of the Dawn mission at JPL. “Perhaps you already connected with the dwarf planet at breakfast today.”

Ceres: part of this nutritionally-balanced Solar System!

Comparison of HST and Dawn FC images of Ceres taken nearly 11 years apart. Credit: NASA.


Comparison of HST and Dawn FC images of Ceres taken nearly 11 years apart. Credit: NASA.
The animation above was made from images taken by Dawn framing camera on January 25, 2015 from a distance of about 237,000 km (147,000 miles). These are now the highest-resolution views to date of the dwarf planet, 30% more detailed than those obtained by Hubble in January 2004.

And there’s that northern white spot again too… seen in observations from earlier this month and in the 2003-04 HST images, scientists still aren’t quite sure what it is. A crater wall? An exposed ice deposit? Something else entirely? We will soon find out.

“We are already seeing areas and details on Ceres popping out that had not been seen before. For instance, there are several dark features in the southern hemisphere that might be craters within a region that is darker overall,” said Carol Raymond, Dawn deputy principal investigator at JPL.

Full-frame image from Dawn of Ceres on approach, acquired Jan. 25, 2015. (NASA/JPL-Caltech/UCLA/MPS/DLR/IDA)


Full-frame image from Dawn of Ceres on approach, acquired Jan. 25, 2015. (NASA/JPL-Caltech/UCLA/MPS/DLR/IDA)
From now on, every observation of Ceres by Dawn will be the best we’ve ever seen! This new chapter of the spacecraft’s adventure has only just begun.

Dawn is scheduled to arrive at Ceres on March 6. Follow the progress of the Dawn mission here.

Source: NASA/JPL

*(Does this mean that Ceres has now gone “mainstream?” Hmm… oh well, it’s still cool.)



About 

A graphic designer in Rhode Island, Jason writes about space exploration on his blog Lights In The Dark, Discovery News, and, of course, here on Universe Today. Ad astra!

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What Are The Orion’s Belt Stars?

What Are The Orion’s Belt Stars?:

The constellation Orion. Credit: Matthew Spinelli NASA/APOD


The constellation Orion. Credit: Matthew Spinelli NASA/APOD
Orion dominates the winter sky in the northern hemisphere. Its large size and  collection of bright stars — such as Betelgeuse at the shoulder, Rigel below the belt, and the three stars in the belt — make it easy to spot, even for beginning stargazers.

So how about those stars in the belt? They’re one of the most famous asterisms in Western culture, but beyond what we see with our eyes, what are their astronomical properties?

Introduction to Orion

First, a brief word about the constellation itself. In many mythologies, the shape is seen as a human figure — and in Greek mythology, it was named after a hunter, according to a web page from the Chandra X-Ray Observatory.

There are several “reasons” in mythology for why Orion ended up in the sky. One was because he was too boastful about how many animals he could kill — so he was put there to teach humility, since he and his dogs (Canis Major and Canis Minor) chase after animals in the sky but can’t catch them. Some say he died from a scorpion bite, and other legends say he was killed by his lover Artemis accidentally, when her brother Apollo tricked her to shooting an arrow at him.

Wide angle shot of Comet Lovejoy with the constellation Orion, showing rich fields of red nebula, star clouds and dark nebula with the bright green naked eye comet. Credit and copyright: Chris Schur.


Wide angle shot of Comet Lovejoy with the constellation Orion, showing rich fields of red nebula, star clouds and dark nebula with the bright green naked eye comet. Credit and copyright: Chris Schur.
Because Orion is on the celestial equator, Chandra adds, it is easy to see all over the world: “Ancient Indians saw the figure as a king who had been shot by an arrow (represented by the stars in Orion’s belt). Ancient Egyptians thought the stars in the belt represented the resting place of the soul of the god Osiris. The Arabs saw the constellation as the figure of a giant.”

The Orion’s belt stars

The three stars in the belt are Mintaka, Alnilam and Alnitak. According to an astronomer with the National Radio Astronomy Observatory, Ronald Maddlaena, these are the meanings of the three stars: Mintaka (on the west) means “belt”, Alnilam (in center) means “belt of pearls” and Altnitak (right) means “girdle.” The three range between 800 and 1,000 light-years from Earth.

The stars “probably formed at about the same time some ten million years ago from the molecular clouds astronomers have found in Orion,” wrote Maddalena.

In this image, the submillimetre-wavelength glow of the dust clouds is overlaid on a view of the region in the more familiar visible light, from the Digitized Sky Survey 2. The large bright cloud in the upper right of the image is the well-known Orion Nebula, also called Messier 42. Credit: ESO/Digitized Sky Survey 2


In this image, the submillimetre-wavelength glow of the dust clouds is overlaid on a view of the region in the more familiar visible light, from the Digitized Sky Survey 2. The large bright cloud in the upper right of the image is the well-known Orion Nebula, also called Messier 42. Credit: ESO/Digitized Sky Survey 2
Here are their properties compared to the Sun:

Mintaka: 20 times more massive and 7,000 times brighter. (Surface temperature 60,000 Fahrenheit.)

Alnilam: 20 times more massive and 18,000 times brigher. (Surface temperature 50,000 Fahrenheit.)

Alnitak: 20 times more massive and 10,000 times brighter. (Surface temperature 60,000 Fahrenheit).

To further blow your mind — these stars also have companion stars orbiting with them, so what you see from Earth with the naked eye isn’t necessarily what you always get.

We have written many articles about Orion for Universe Today. Here’s an article about the Orion Nebula, and another about the dust grains in the Orion Nebula. We’ve also done many episodes of Astronomy Cast about stars, such as this: Episode 12: Where Do Baby Stars Come From?



About 

Elizabeth Howell is the senior writer at Universe Today. She also works for Space.com, Space Exploration Network, the NASA Lunar Science Institute, NASA Astrobiology Magazine and LiveScience, among others. Career highlights include watching three shuttle launches, and going on a two-week simulated Mars expedition in rural Utah. You can follow her on Twitter @howellspace or contact her at her website.

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Astronomers See a Massive Black Hole Tear a Star Apart

Astronomers See a Massive Black Hole Tear a Star Apart:

When a star encounters a black hole, tidal forces stretch the star into an elongated blob before tearing it apart, as seen in these images from a computer simulation by James Guillochon of Harvard University.


When a star encounters a black hole, tidal forces stretch the star into an elongated blob before tearing it apart, as seen in these images from a computer simulation by James Guillochon of Harvard University.
A telescope peers into the blackness of deep space. Suddenly – a brilliant flash of light appears that wasn’t there before. What could it be? A supernova? Two massively dense stars fusing together? Perhaps a gamma ray burst?

Five years ago, researchers using the ROTSE IIIb telescope at McDonald Observatory noticed just such an event. But far from being your run-of-the-mill stellar explosion or neutron star merger, the astronomers believe that this tiny flare was, in fact, evidence of a supermassive black hole at the center of a distant galaxy, tearing a star to shreds.

Astronomers at McDonald had been using the telescope to scan the skies for such nascent flashes for years, as part of the ROTSE Supernova Verification Project (SNVP). And at first blush, the event seen in early 2009, which the researches nicknamed “Dougie,” looked just like many of the other supernovae they had discovered over the course of the project. With a blazing – 22.5-magnitude absolute brightness, the event fit squarely within the class of superluminous supernovae that the researchers were already familiar with.

But as time went on and more data on Dougie rolled in, the astronomers began to change their minds. X-ray observations made by the orbiting Swift satellite and optical spectra taken by McDonald’s Hobby-Eberly Telescope revealed an evolving light curve and chemical makeup that didn’t fit with computer simulations of superluminous supernovae. Likewise, Dougie didn’t appear to be a neutron star merger, which would have reached peak luminosity far more quickly than was observed, or a gamma ray burst, which, even at an angle, would have appeared far brighter in x-ray light.

That left only one option: a so-called “tidal disruption event,” or the carnage and spaghettification that occurs when a star wanders too close to a black hole’s horizon. J. Craig Wheeler, head of the supernova group at The University of Texas at Austin and a member of the team that discovered Dougie, explained that at short distances, a black hole’s gravity exerts a much stronger pull on the side of the star nearest to it than it does on the star’s opposite side. He explained, “These especially large tides can be strong enough that you pull the star out into a noodle.”

The team refined their models of the event and came to a surprising conclusion: having drawn in Dougie’s stellar material a bit faster than it could handle, the black hole was now “choking” on its latest meal. This is due to an astrophysical principle called the Eddington Limit, which states that a black hole of a given size can only handle so much infalling material. After this limit has been reached, any additional intake of matter exerts more outward pressure than the black hole’s gravity can compensate for. This pressure increase has a kind of rebound effect, throwing off material from the black hole’s accretion disk along with heat and light. Such a burst of energy accounts for at least part of Dougie’s brightness, but also indicates that the original dying star – a star not unlike our own Sun – wasn’t going down without a fight.

Combining these observations with the mathematics of the Eddington Limit, the researchers estimated the black hole’s size to be about 1 million solar masses – a rather small black hole, at the center of a rather small galaxy, three billion light years away. Discoveries like these not only allow astronomers to better understand the physics of black holes, but also properties of their often unassuming home galaxies. After all, mused Wheeler, “Who knew this little guy had a black hole?”

To get a simulated glimpse of Dougie for yourself, check out the amazing animation below, courtesy of team member James Guillochon:



The research is published in this month’s issue of The Astrophysical Journal. A pre-print of the paper is available here.



About 

Vanessa earned her bachelor's degree in Astronomy and Physics in 2009 from Wheaton College in Massachusetts. Her credits in astronomy include observing and analyzing eclipsing binary star systems and taking a walk on the theory side as a NSF REU intern, investigating the expansion of the Universe by analyzing its traces in observations of type 1a supernovae. In her spare time she enjoys writing about astrophysics, cosmology, biology, and medicine, making delicious vegetarian meals, taking adventures with her husband and/or Nikon D50, and saving the world.

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iPhone Astrophotography: How to Take Amazing Images of the Sky with Your Smartphone Tonight!

iPhone Astrophotography: How to Take Amazing Images of the Sky with Your Smartphone Tonight!:

All photos credit and copyright: Andrew Symes.


An Iphone portrait of the classical solar system. All photos credit and copyright: Andrew Symes.
Got a smartphone and a telescope?

It’s a sight now common at many star parties. Frequently, you see folks roaming through the darkness, illuminated smartphone aimed skyward. Certainly, the wealth of free planetarium apps has done lots to kindle a renewed interest in the night sky.

Inevitably, after peering through the eyepiece of a telescope, the question then arises:

“Can I get a picture of that with my phone?”

The short answer is yes, with a little skill and patience.

Now simply aiming a camera at the eyepiece of a telescope — known as afocal astrophotography — and shooting without removing the camera lens and physically coupling it to the telescope is a tricky balancing act. Back in the olden days, the Moon and perhaps the brighter planets were the only bright target within bounds of afocal film photographers, and only then after a lengthy set of estimations to hit the correct focal length. The advent of digital cameras and ‘live preview’ means that you can now simply aim, shoot, and throw away or delete anything off center or out of focus. Digital ‘film’ is cheap, and most folks simply use trial and error to get the ‘keepers’. The Moon is an especially bright and easy target for beginners to practice on.

Moon


A gibbous Moon, an easy first pic!
Of course, your typical smartphone, like a webcam, has an imaging chip much smaller than a DSLR. This is why astrophotographers are often tempted to take out a second mortgage (“we don’t really need that second car, do we?” is a common spousal refrain) in pursuit of excellence. Another drawback is that through a smartphone, a planet may look like an overexposed blob. A simple but effective way to get around this is to affix a light reducing filter to the eyepiece. In fact, I’ve used a variable polarizer during live broadcasts of the Virtual Star Party to great effect.  And as with webcam imaging, smartphone astrophotographers now often use automated stacking programs to clean up images and tease out detail. Being an old timer, my faves are still K3CCD Tools and Registax, though many young guns out there now use DeepSkyStacker as well.

Telescope


Andrew Symes’ imaging setup.
Now, I’ll admit, I’m an ‘Android guy,’ and I have put most of my efforts over the years into planetary imaging with a homemade webcam. We therefore sought out in-the-field expertise from someone on the forefront of iPhone astrophotography. Andrew Symes has been taking images of the solar system and beyond with his iPhone coupled to his Celestron NexStar 8” SE telescope for years. He also has one of the few handles on Twitter that we’re envious of, @FailedProtostar. He also ventures out into the chilly nights frequent to his native of Ottawa, Canada to practice his craft, as he observes in temperatures that would drop a Tauntaun.

We caught up with Andrew recently to ask him about some tips of the trade.

Sun


An ‘iPhone Sun’ shot in hydrogen alpha through a Coronado PST.
Universe Today: I know from doing webcam photography that acquiring, centering and focusing are often more than half the battle. Any tips for accomplishing these?

Andrew: Acquiring, centering, and focusing the objects I’m photographing is definitely the big challenge! To speed and simplify the process, I have a dedicated eyepiece that I use in association with my phone and adapter. Before even heading outside, I attach the adapter to this eyepiece, insert my phone, and hold the unit up to a light source to see if the camera lens is properly aligned with the eyepiece. It usually takes a bit of fiddling to get things set properly because if the adapter and eyepiece are not perfectly aligned, nothing will show up on the camera screen. It’s better to get that process out of the way in a lit environment than outside in the dark. I then set that unit aside, and use a separate “adapter-less” zoom eyepiece to locate and center the object in the telescope. Once I’ve acquired the object and am successfully tracking it, I remove my zoom eyepiece and drop in the eyepiece/adapter/phone combo. At that point, the object is usually visible on screen but out of focus since the focus required for the iPhone is different from what works for my eyes! To ensure proper focus, I display the object on my phone’s screen using a live video app called FiLMiC Pro and adjust the focus until it is sharp. I use that app because it has a digital zoom function that lets me get a closer look at the object than the standard iPhone video camera view. Only once I’m confident that I’ve achieved good focus and am tracking the object properly, will I start to record video or shoot individual frames.

A comparison


A comparison of the first image of the Orion Nebula (M42) shot in 1880 (left) with a modern iPhone image.
Universe Today: A question I always like to ask everyone… what was your biggest mistake? Are there any pitfalls to avoid?

Andrew: There are a few pitfalls to avoid when doing iPhone astrophotography. In the past, I would attach the adapter outside while the eyepiece was in the telescope but this caused a number of problems. Often, I would accidentally bump the object out of view while attaching and adjusting the adapter and have to align everything all over again. The weather is also often cold here, and it’s VERY difficult to attach the adapter properly with gloves on, so I would either get really cold hands or spend a lot of unnecessary time fumbling with the adapter with gloved hands. For those reasons, I now prepare the eyepiece/adapter/phone unit indoors in advance as described above. I also now make sure that my iPhone is fully charged before heading outdoors as I’ve found that the iPhone battery drains very quickly when the camera is running constantly — especially in cold weather. Even with an almost-full battery, there are times here in winter when the phone will simply shut down due to the low temperature so I make sure to only start capturing photos/videos once I’m completely confident in my setup.

Lovejoy


Yes, that’s Comet C/2014 Q2 Lovejoy shot with an iPhone!
Universe Today: You’re really pushing the envelope by doing deep sky astro-pics with an iPhone … anything else that you’re experimenting with or working on?

Andrew: My main focus is definitely still on iPhone astrophotography because I like the quick and “light” setup. I don’t need to bring a laptop outside and don’t need equipment that I wouldn’t normally have on me anyway (other than the adapter itself.) So, I want to keep pushing the envelope with what I can capture using the phone and my goal is now is to see how far I can go with deep-sky objects. I’d really like to add the Ring and Dumbbell Nebulae to my portfolio, for example, and see if it’s possible to grab even fainter ones. There are also some non-deep sky targets I’d like to try. I haven’t been successful at capturing a telescopic photo of the ISS, and would love to see if I can catch it transiting the Sun or Moon with my phone. I also still need to capture Uranus and Neptune to round out a solar system collage I put together in 2014!

Lastly, I’m continually experimenting with photo apps to see which are best at capturing and/or processing telescopic images, and have just started using both an iPhone 4S and iPhone 6 to take photos and video. Surprisingly, I still prefer the 4S for planetary imaging as I haven’t been able to properly capture the true colors of planets with the iPhone 6 yet. The 6 has better camera resolution but seems to be adjusting the exposure of small, faint objects like planets differently than the 4S, so I need to change my routine and techniques to compensate. The methods I’ve become accustomed to using with the 4S don’t seem to translate directly to the 6 so I have some learning yet to do!

M13


An iPhone capture of Messier 13.
Amazing stuff, for sure. And to think, we were all gas-hypering film and using absurdly long focal lengths to get blurry planetary images just a few decades ago!

-Check out more of Andrew’s images, as well as read more about how he does it.

-Got a pic, shot with a smartphone or otherwise? Send ‘em in to Universe Today!



About 

David Dickinson is an Earth science teacher, freelance science writer, retired USAF veteran & backyard astronomer. He currently writes and ponders the universe from Tampa Bay, Florida.

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How Are Planets Formed?

How Are Planets Formed?:

This artist's conception shows a newly formed star surrounded by a swirling protoplanetary disk of dust and gas. Credit: University of Copenhagen/Lars Buchhave


This artist’s conception shows a newly formed star surrounded by a swirling protoplanetary disk of dust and gas. Credit: University of Copenhagen/Lars Buchhave
How did the Solar System’s planets come to be? The leading theory is something known as the “protoplanet hypothesis”, which essentially says that very small objects stuck to each other and grew bigger and bigger — big enough to even form the gas giants, such as Jupiter.

But how the heck did that happen? More details below.

Birthing the Sun

About 4.6 billion years ago, as the theory goes, the location of today’s Solar System was nothing more than a loose collection of gas and dust — what we call a nebula. (Orion’s Nebula is one of the most famous examples you can see in the night sky.)

Astrophoto: The Orion Nebula by Vasco Soeiro


The Orion Nebula. Image Credit: Vasco Soeiro
Then something happened that triggered a pressure change in the center of the cloud, scientists say. Perhaps it was a supernova exploding nearby, or a passing star changing the gravity. Whatever the change, however, the cloud collapsed and created a disc of material, according to NASA.

The center of this disc saw a great increase in pressure that eventually was so powerful that hydrogen atoms loosely floating in the cloud began to come into contact. Eventually, they fused and produced helium, kickstarting the formation of the Sun.

The Sun was a hungry youngster — it ate up 99% of what was swirling around, NASA says — but this still left 1% of the disc available for other things. And this is where planet formation began.

These images are some of the first to be taken during Spitzer's warm mission -- a new phase that began after the telescope, which operated for more than five-and-a-half years, ran out of liquid coolant. They show a star formation region (DR22 in Cygnus),DR22, in the constellation Cygnus the Swan. Credit: NASA / JPL-Caltech


These images are some of the first to be taken during Spitzer’s warm mission — a new phase that began after the telescope, which operated for more than five-and-a-half years, ran out of liquid coolant. They show a star formation region (DR22 in Cygnus),DR22, in the constellation Cygnus the Swan. Credit: NASA / JPL-Caltech
Time of chaos

The Solar System was a really messy place at this time, with gas and dust and debris floating around. But planet formation appears to have happened relatively rapidly. Small bits of dust and gas began to clump together. The young Sun pushed much of the gas out to the outer Solar System and its heat evaporated any ice that was nearby.

Over time, this left rockier planets closer to the Sun and gas giants that were further away. But about four billion or so years ago, an event called the “late heavy bombardment” resulted in small bodies pelting the bigger members of the Solar System. We almost lost the Earth when a Mars-sized object crashed into it, as the theory goes.

What caused this is still under investigation, but some scientists believe it was because the gas giants were moving around and perturbing smaller bodies at the fringe of the Solar System. At any rate, in simple terms, the clumping together of protoplanets (planets in formation) eventually formed the planets.

Artist's impression of a Mars-sized object crashing into the Earth, starting the process that eventually created our Moon. Credit: Joe Tucciarone


Artist’s impression of a Mars-sized object crashing into the Earth, starting the process that eventually created our Moon. Credit: Joe Tucciarone
We can still see leftovers of this process everywhere in the Solar System. There is an asteroid belt between Mars and Jupiter that perhaps would have coalesced into a planet had Jupiter’s gravity not been so strong. And we also have comets and asteroids that are sometimes considered referred to as “building blocks” of our Solar System.

We’ve described in detail what happened in our own Solar System, but the important takeaway is that many of these processes are at work in other places. So when we speak about exoplanet systems — planets beyond our Solar System — it is believed that a similar sequence of events took place. But how similar is still being learned.

Making the case

One major challenge to this theory, of course, is no one (that we know of!) was recording the early history of the Solar System. That’s because the Earth wasn’t even formed yet, so it was impossible for any life — let alone intelligent life — to keep track of what was happening to the planets around us.

Artist's impression of the Solar Nebula. Image credit: NASA


Artist’s impression of the Solar Nebula. Image credit: NASA
There are two major ways astronomers get around this problem. The first is simple observation. Using powerful telescopes such as the Atacama Large Millimeter/submillimeter Array (ALMA), astronomers can actually observe dusty discs around young planets. So we have numerous examples of stars with planets being born around them.

The second is using modelling. To test their observational hypotheses, astronomers run computer modelling to see if (mathematically speaking) the ideas work out. Often they will try to use different conditions during the simulation, such as perhaps a passing star triggering changes in the dust cloud. If the model holds after many runs and under several conditions, it’s more likely to be true.

That said, there still are some complications. We can’t use modelling yet to exactly predict how the planets of the Solar System ended up where they were. Also, in fine detail our Solar System is kind of a messy place, with phenomena such as asteroids with moons.

This animation, created from individual radar images, clearly show the rough outline of 2004 BL86 and its newly-discovered moon. Credit: NASA/JPL-Caltech


This animation, created from individual radar images, clearly show the rough outline of 2004 BL86 and its newly-discovered moon. Credit: NASA/JPL-Caltech
And we need to have a better understanding of external factors that could affect planet formation, such as supernovae (explosions of old, massive stars.) But the protoplanet hypothesis is the best we’ve got — at least for now.

We have written many articles about the protoplanet hypothesis for Universe Today. Here’s an article about how the Solar System was formed, and here’s an article about protoplanets. We’ve also recorded a series of episodes of Astronomy Cast about every planet in the Solar System. Start here, Episode 49: Mercury.



About 

Elizabeth Howell is the senior writer at Universe Today. She also works for Space.com, Space Exploration Network, the NASA Lunar Science Institute, NASA Astrobiology Magazine and LiveScience, among others. Career highlights include watching three shuttle launches, and going on a two-week simulated Mars expedition in rural Utah. You can follow her on Twitter @howellspace or contact her at her website.

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What it Would Look Like if the Sun was Replaced with Other Stars?

What it Would Look Like if the Sun was Replaced with Other Stars?:



How would our horizon look if Earth orbited around another star, such as Alfa-Centauri, Sirius, or Polaris? Roscosmos TV has released two new videos that replace our familiar Sun and Moon with other stars and planets. While these are completely fantastical — as Earth would have evolved very differently or not evolved at all in orbit around a giant or binary star — the videos are very well done and they give a new appreciation for the accustomed and comforting views we have. The Sun video is above; the Moon below:


How our horizon might look if Earth orbited the star Artcurus. Credit: TV Roskosmos.


How our horizon might look if Earth orbited the star Artcurus. Credit: TV Roskosmos.


Check out Roscosmos TV You Tube page — they have a great collection of videos, from launches to science to fantastical videos like the ones we featured here.

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Found: Mars Orbiter Locates Beagle 2 Lander

Found: Mars Orbiter Locates Beagle 2 Lander:





The Beagle 2 Lander, built by the United Kingdom, has been thought lost on Mars since Dec. 25, 2003, but has now been found in images from NASA's Mars Reconnaissance Orbiter.





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Asteroid 2004 BL86 Has a Small Moon

Asteroid 2004 BL86 Has a Small Moon:





This movie of asteroid 2004 BL86 was generated from data collected by NASA's Deep Space Network antenna at Goldstone, California, on Jan. 26, 2015. Twenty individual images were used.





Original enclosures:
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Technical Origami

Technical Origami:





How do you develop the largest spinning antenna ever used on a NASA satellite? Testing, testing. . . .