Location chart for HD 162826, considered a sibling to the sun. Credit: Ivan Ramirez/Tim Jones/McDonald Observatory
Peer about 110 light-years away from our solar system, and you might catch a glimpse of how our own neighborhood came together. The recent discovery that HD 162826 — a star bright enough to be seen in binoculars — could be a “sibling” of our sun could shed more light on the solar system’s formation, astronomers said.
“We want to know where we were born,” stated Ivan Ramirez, an astronomer at the University of Texas at Austin who led the research. “If we can figure out in what part of the galaxy the sun formed, we can constrain conditions on the early solar system. That could help us understand why we are here.”
The star is called a “sibling” because it could have formed from the same gas and dust cloud in which our own solar system was formed, some 4.5 billion years ago. Since life is in our own solar system, a natural next question is whether HD 162826 could also have life-bearing planets. There is a tiny reason for “yes”, the astronomers said.
Basically, the argument goes that when the stars were first born and close together, chunks of matter could have been knocked off protoplanets and travelled between the two solar systems. There’s a small chance that this could have brought primitive life to Earth, although of course there’s a long way to go before that could even be proved.
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
That said, no planets have yet been found around HD 162826. (The star was known before, but just recently identified as a “sibling.”) Separate studies by the University of Texas and University of South Wales said there are likely no “hot Jupiters” (Jupiter-sized planets close to the star) nor Jupiter-sized planet in the solar system even further away. Smaller terrestrial planets, however, would have escaped the notice of this particular study.
The star is about 15 percent more massive than our sun and was selected from a list of 30 candidates based on its chemistry and orbit. There could also be more siblings out there to find, with one potential big help coming soon: the Gaia survey from the European Space Agency launched in December, which will chart the Milky Way in three dimensions.
Because Gaia will showcase the distance and motions of a billion stars, this will allow astronomers to look for these “solar siblings” as far in as the galaxy’s center, increasing the number of stars studied by a factor of 10,000. The exciting thing, the astronomers add, is with enough stars pinpointed as siblings to our sun, their orbits can then be traced back to the origin point — showing the location in the cosmos where the sun first came to be.
More information will be available in the June 1 issue of the Astrophysical Journal. A preprint version is available on Arxiv.
Mercury starts its best period of visibility in the evening sky for skywatchers at mid-northern latitudes this weekend. This map shows the sky facing northwest about 40 minutes after sundown. Bright Jupiter also provides a convenient sightline for locating Mercury. Stellarium
Don’t let furtive Mercury slip through your fingers this spring. The next two and a half weeks will be the best time this year for observers north of the tropics to spot the sun-hugging planet. If you’ve never seen Mercury, you might be surprised how bright it can be. This is especially true early in its apparition when the planet looks like a miniature ‘full moon’.
Mercury, like Venus, displays phases as it revolves around the sun as seen from Earth’s perspective outside Mercury’s orbit. Both Mercury and Venus appear largest when nearly lined up between Earth and sun at inferior conjunction. Planets not to scale and phases shown are approximate. Credit: Bob King
Both Venus and Mercury pass through phases identical to those of the moon. When between us and the sun, Mercury’s a thin crescent, when off to one side, a ‘half-moon’ and when on the far side of the sun, a full moon. This apparition of the planet is excellent because Mercury’s path it steeply tilted to the horizon in mid-spring.
We start the weekend with Mercury nearly full and brighter than the star Arcturus. Twilight tempers its radiance, but :
* Find a location with a wide open view to the northwest as far down to the horizon as possible.
* Click HERE to get your sunset time and begin looking for the planet about 30-40 minutes after sunset in the direction of the sunset afterglow.
* Reach your arm out to the northwestern horizon and look a little more than one vertically-held fist (10-12 degrees) above it for a singular, star-like object. Found it? Congratulations – that’s Mercury!
* No luck? Start with binoculars instead and sweep the bright sunset glow until you find Mercury. Once you know exactly where to look, lower the binoculars from your eyes and you should see the planet without optical aid. And before I forget – be sure to focus the binoculars on a distant object like a cloud or the moon before beginning your sweeps. I guarantee you won’t find Mercury if it’s out of focus.
Through a telescope, Mercury looks like a gibbous moon right now but its phase will lessen as it moves farther to the ‘left’ or east of the sun. Greatest eastern elongation happens on May 24. On and around that date the planet will be farthest from the sun, standing 12-14 degrees high 40 minutes after sundown from most mid-northern locales.
Mercury is even better placed on May 19 but fades and begins to drop back down toward the horizon late in the month. Stellarium
The planet fades in late May and become difficult to see by early June. Inferior conjunction, when Mercury passes between the Earth and sun, occurs on June 19. Unlike Venus, which remains brilliant right up through its crescent phase, Mercury loses so much reflective surface area as a crescent that it fades to magnitude +3. Its greater distance from Earth, lack of reflective clouds and smaller size can’t compete with closer, brighter and bigger Venus.
When a planet crosses the disk of the sun it’s called a transit. Mercury’s path across the solar disk is seen from the Solar and Heliospheric Observatory (SOHO) on November 8, 2006. Credit: NASA.
Mercury’s 7-degree inclined orbit means it typically glides well above or below the sun’s disk at inferior conjunction. But anywhere from 3 up to 13 years in either November or May the planet passes directly between the Earth and sun at inferior conjunction and we witness a transit. This last happened for U.S. observers on Nov. 8, 2006; the next transit occurs exactly two years from today on May 9, 2016. That event will be widely visible across the Americas, Western Europe and Africa. After having so much fun watching the June 2012 transit of VenusI can’t wait.
Inbound: the Hubble Space Telescope images Comet 2013 A1 Siding Spring with its Wide Field Camera 3. Credit: NASA.
It may be the chance of a lifetime for planetary science.
This October, a comet will brush past a planet, giving scientists a chance to study how it possibly interacts with a planetary atmosphere.
The comet is C/2013 A1 Siding Spring, and the planet in question Mars. And although an impact of the comet on the surface of the Red Planet has long been ruled out, a paper in the May 2014 issue of Icarus raises the interesting possibility of possible interactions of the coma of A1 Siding Spring and the tenuous atmosphere of Mars. The study comes out of the Department of Planetary Sciences at the University of Arizona, the Belgian Institute for Space Aeronomy, the Institut de Planétologie et d’Astrophysique de Grenoble at the Université J. Fourier in France, and the Cooperative Institute for Research in Environmental Sciences at the University of Colorado in Boulder.
For the study, researchers considered how active Comet A1 Siding Spring may be at the time of closest approach on October 19th, 2014.
Discovered early last year by Robert McNaught from the Siding Spring Observatory in Australia, Comet A1 Siding Spring created a stir in the astronomical community when it was found that it will passextremely close to Mars later this year. Further measurements of its orbit have since ruled this possibility out, but its passage will still be a close one, with a nominal passage of 138,000 kilometres from Mars. That’s about one third the distance from Earth to the Moon, and 17 times closer than the nearest recorded passage of a comet to the Earth, Comet D/1770 L1 Lexell in 1780. Mars’ outer moon Deimos has an orbital distance of about 23,500 kilometres.
The passage of Comet 2013 A1 Siding Spring through the inner solar system. Credit: NASA.
And although the nucleus will safely pass Mars, the brush with its extended atmosphere might just be detectable by the fleet of spacecraft and rovers in service around Mars. At a distance of 1.4 Astronomical Units (A.U.) from the Sun during the encounter, the vast coma is expected to be comprised primarily of H2O. At an input angle of about 60 degrees, penetration was calculated in the study to impinge down and altitude of 154 kilometres to the topside of the Martian ionosphere, in the middle of the thermosphere.
Such an effect should linger for just over 4 hours, well over the interaction period of Mars’ atmosphere with the coma of just over an hour, centered on 18:30 UT on October 19th, 2014.
What kind of views might missions like HiRISE and MSL get of the comet remains to be seen, although NEOWISE and Hubble are already monitoring the comet for enhanced activity. The Opportunity rover is also still functioning, and Mars Odyssey and ESA’s Mars Express are still in orbit around the Red Planet and sending back data. But perhaps the most interesting possibilities for observations of the event are still en route: India’s Mars Orbiter Mission and NASA’s MAVEN orbiter arrive just before the comet. MAVEN was designed to study the upper atmosphere of Mars, and carries an ion-neutral mass spectrometer (NGIMS) which could yield information on the interaction of the coma with the Martian upper atmosphere and ionosphere. The NGIMS cover is slated for release just two days before the comet encounter. All spacecraft orbiting Mars may feel the increased drag effects of the encounter.
A simulation of Mars as seen from Comet A1 Siding Spring on closest approach. Created by the author using Starry Night Software.
Proposals for using Earth-based assets for further observations of the comet prior to the event in October are still pending. Amateur observers will be able to follow the approach telescopically, as Comet A1 Siding Spring is expected to reach +8th magnitude in October and pass 7’ from Mars in the constellation Ophiuchus as seen from the Earth. Mars just passed opposition last month, but both will be low to the south west at dusk for northern hemisphere observers in October.
It’s also interesting to consider the potential for interactions of the coma with the surfaces of the moons of Mars as well, though the net amount of water vapor expected to be deposited will not be large.
UPDATE: Check out this nifty interactive simulator which includes Comet A1 Siding Springs courtesy of the Solar System Scope:
The H2O coma of A1 Siding Spring is expected to have a radius of 150,000 kilometres when it passes Mars, just a shade over the nominal flyby distance.
“There is a more extended coma made up of H2O dissociation products (such as hydrogen and hydroxide) that extends for ~1,000,000 kilometres,” researcher at the Department of Planetary Sciences at the University of Arizona and lead author on the paper Roger Yelle told Universe Today.
“Essentially, Mars is in the outer reaches of the coma. The main ion tail misses Mars but there will be some ions from the comet that do reach Mars. The dust tail just misses Mars, which is fortunate.”
The paper also notes that significant perturbations of the upper atmosphere of Mars will occur if the cometary production rate is 10^28 s-1 or larger, which corresponds to about 300 kilograms per second.
“The MAVEN spacecraft will make very interesting observations,” Roger Yelle also told Universe Today. “The comet will perturb primarily the upper atmosphere of Mars and MAVEN was designed to study the upper atmosphere of Mars. Also, it’s just such an incredible coincidence that the comet arrives at Mars less than one month after MAVEN does. MAVEN is nominally in its checkout phase then, and the main science phase of the mission was not scheduled to start until November 1st. However, we are reassessing our plans to see what observations we can make. It’s all quite exciting, and we have to balance safety and the desire to make the best science measurements.”
It’s an unprecedented opportunity, that’s for sure… all eyes will be on the planet Mars and Comet A1 Siding Spring on October the 19th!
A 45-minute time exposure of the southern sky taken in early May shows trailed stars. The fat, bright streak is the planet Mars. Credit: Bob King
A week ago I made a 45-minute time exposure of the southern sky featuring the planet Mars. As the Earth rotated on its axis, the stars trailed across the sky. But take a closer look at the photo and you’ll see something interesting going on.
The trails across the diagonal (upper right to lower left) are straight, those in the top third arc upward or north while those in the bottom third curve downward or south.
I’ve drawn part of the imaginary great circle in the sky called the celestial equator. Residents of cities on or near the Earth’s equator see the celestial equator pass directly overhead. From mid-northern latitudes, it’s about halfway up in the southern sky. From mid-southern latitudes, it’s halfway up in the northern sky. Credit: Bob King
I suspect you know what’s happening here. Mars happens to lie near the celestial equator, an extension of Earth’s equator into the sky. The celestial equator traces a great circle around the celestial sphere much as the equator completely encircles the Earth.
On Earth, cities north of the equator are located in the northern hemisphere, south of the equator in the southern hemisphere. The same is true of the stars. Depending on their location with respect to the celestial equator they belong either to the northern or southern halves of the sky.
Earth’s axis points north to Polaris, the northern hemisphere’s North Star, and south to dim Sigma Octantis. Illustration: Bob King
Next, let’s take a look at Earth’s axis and where each end points. If you live in the northern hemisphere, you know that the axis points north to the North Star or Polaris. As the Earth spins, Polaris appears fixed in the north while all the stars in the northern half of the sky describe a circle around it every 24 hours (one Earth spin). The closer a star is to Polaris, the tighter the circle it describes.
Time exposure centered on Polaris, the North Star. Notice that the closer stars are to Polaris, the smaller the circles they describe. Stars at the edge of the frame make much larger circles. Credit: Bob King
Likewise, from the southern hemisphere, all the southern stars circle about the south pole star, an obscure star named Sigma in the constellation of Octans, a type of navigational instrument. Again, as with Polaris, the closer a star lies to Sigma Octantis, the smaller its circle.
Stars trail around the dim southern pole star Sigma Octantis as seen from the southern hemisphere. The two smudges are the Large and Small Magellanic Clouds, companion galaxies of the Milky Way. Credit: Ted Dobosz
But what about stars on or near the celestial equator? These gems are the maximum distance of 90 degrees from either pole star just as Earth’s equator is 90 degrees from the north and south poles. They “tread the line” between both hemispheres and make circles so wide they appear not as arcs – as the other stars do in the photo – but as straight lines. And that’s why stars appear to be heading in three separate directions in the photograph.
A view of the entire sky as seen from Quito, Ecuador on the equator this evening. The celestial equator crosses directly overhead while each pole star lies 90 degrees away on opposite horizons. Stellarium
In so many ways, we see aspects of our own planet in the stars above.
Comet C/2013 UQ4, once thought to be an asteroid, now shows characteristics of a comet including a coma. This photo was made on May 7, 2014. Credit: Artyom Novichonok and Taras Prystavski
On October 23, 2013, astronomers with the Catalina Sky Survey picked up a very faint asteroid with an unusual orbit more like a that of a comet than an asteroid. At the time 2013 UQ4 was little more than a stellar point with no evidence of a hazy coma or tail that would tag it as a comet. But when it recently reappeared in the morning sky after a late January conjunction with the sun, amateur astronomers got a surprise.
On May 7, Comet ISON co-discoverer Artyom Novichonok, and Taras Prystavski used a remote telescope located in Siding Spring, Australia to take photos of 2013 UQ4 shortly before dawn in the constellation Cetus. Surprise, surprise. The asteroid had grown a little fuzz, making the move to comethood. No longer a starlike object, 2013 UQ4 now displays a substantial coma or atmosphere about 1.5 arc minutes across with a more compact inner coma measuring 25 arc seconds in diameter. No tail is visible yet, and while its overall magnitude of +13.5 won’t make you break out the bottle of champagne, it’s still bright enough to see in a 12-inch telescope under dark skies.
Wide field map showing the comet’s movement from Cetus through Pisces and into Cepheus in July when it becomes circumpolar for skywatchers at mid-northern latitudes. It should reach a peak brightness of 7th magnitude in early July. Click to enlarge. Created with Chris Marriott’s SkyMap program
The best is yet to come. Assuming the now renamed C/2013 UQ4 continues to spout dust and water vapor, it should brighten to magnitude +11 by month’s end as it moves northward across Pisces and into a dark morning sky. Perihelion occurs on June 5 with the comet reaching magnitude +8-9 by month’s end. Peak brightness of 7th magnitude is expected during its close approach of Earth on July 10 at 29 million miles (46.7 million km).
This should be a great summer comet, plainly visible in binoculars from a dark sky as it speeds across Cepheus and Draco during convenient viewing hours at the rate of some 7 degrees per night! That’s 1/3 of a degree per hour or fast enough to see movement through a telescope in a matter of minutes when the comet is nearest Earth.
Light curve showing C/2013 UQ4 brightening to a sharp peak in early July and then quickly fading. Created by Artyom Novichonok and Taras Prystavski
Come August, C/2013 UQ4 rapidly fades to magnitude +10 and then goes the way of so many comets – a return to a more sedentary lifestyle in the cold bones of deep space.
C/2013 UQ4 belongs to a special category of asteroids called damocloids (named for asteroid 5335 Damocles) that have orbits resembling the Halley-family comets with long periods, fairly steep inclinations and highly eccentric orbits (elongated shapes). Some, like Comet Halley itself, even travel backwards as they orbit the sun, an orbit astronomers describe as ‘retrograde’.
Evolution of a comet as it orbits the sun. Credit: Laboratory for Atmospheric and Space Sciences/ NASA
Damocloids are thought to be comets that have lost all their fizz. With their volatile ices spent from previous trips around the sun, they stop growing comas and tails and appear identical to asteroids. Occasionally, one comes back to life. It’s happened in at least four other cases and appears to be happening with C/2013 UQ4 as well.
Studies of the comet/asteroid’s light indicate that UQ4 is a very dark but rather large object some 4-9 miles (7-15 km) across. It’s estimated that C/2013 UQ4 takes at least 500 years to make one spin around the sun. Count yourself lucky this damocloid decided to spend its summer vacation in Earth’s skies. We’ll have more detailed maps and updates as the comet becomes more easily visible next month. Stay tuned.
An artist’s conception of a KBO encounter by New Horizons. Credit: JHUAPL/SwRI.
Are you ready for the summer of 2015? A showdown of epic proportions is in the making, as NASA’s New Horizons spacecraft is set to pass within 12,500 kilometres of Pluto — roughly a third of the distance of the ring of geosynchronous satellites orbiting the Earth — a little over a year from now on July 14th, 2015.
But another question is already being raised, one that’s assuming center stage even before we explore Pluto and its retinue of moons: will New Horizons have another target available to study for its post-Pluto encounter out in the Kuiper Belt? Researchers say time is of the essence to find it.
To be sure, it’s a big solar system out there, and it’s not that researchers haven’t been looking. New Horizons was launched from Cape Canaveral Air Force Station on January 19th, 2006 atop an Atlas V rocket flying in a 551 configuration in one of the fastest departures from Earth ever: it took New Horizons just nine hours to pass Earth’s moon after launch.
New Horizons spends its last days on Earth pre-encapsulation. (Credit: NASA/KSC).
The idea has always been out there to send New Horizons onward to explore and object beyond Pluto in the Kuiper Belt, but thus far, searches for a potential target have turned up naught.
A recent joint statement from NASA’s Small Bodies and Outer Planets Assessment Groups (SBAG and OPAG) has emphasized the scientific priority needed for identifying a possible Kuiper Belt Object (KBO) for the New Horizons mission post-Pluto encounter. The assessment notes that such a chance to check out a KBO up close may only come once in our lifetimes: even though it’s currently moving at a heliocentric velocity of just under 15 kilometres a second, it will have taken New Horizons almost a decade to traverse the 32 A.U. distance to Pluto.
The report also highlights the fact that KBOs are expected to dynamically different from Pluto as well and worthy of study. The statement also notes that the window may be closing to find such a favorable target after 2014, as the upcoming observational apparition of Pluto as seen from Earth — and the direction New Horizons is headed afterwards — reaches opposition this summer on July 4th.
But time is of the essence, as it will allow researchers to plan for a burn and trajectory change for New Horizons shortly after its encounter with Pluto and Charon using what little fuel it has left. Then there’s the issue of debris in the Pluto system that may require fine-tuning its trajectory pre-encounter as well. New Horizons will begin long range operations later this year in November, switching on permanently for two years of operations pre-, during and post- encounter with Pluto.
And there currently isn’t a short-list of “next best thing” targets for New Horizons post-Pluto encounter. One object, dubbed VNH0004, may be available for distant observations in January of next year, but even this object will only pass 75 million kilometres — about 0.5 A.U. — from New Horizons at its closest.
Ground based assets such as the Keck, Subaru and Gemini observatories have been repeatedly employed in the search over the past three years. The best hopes lie with the Hubble Space Telescope, which can go deeper and spy fainter targets.
Nor could New Horizons carry out a search for new targets on its own. Its eight inch (20 cm in diameter) LORRI instrument has a limiting magnitude of about +18, which is not even close to what would be required for such a discovery.
New Horizons currently has 130 metres/sec of hydrazine fuel available to send it onwards to a possible KBO encounter, limiting its range and maneuverability into a narrow cone straight ahead of the spacecraft. This restricts the parameters for a potential encounter to 0.35 A.U. off of its nominal path for a target candidate be to still be viable objective. New Horizons will exit the Kuiper Belt at around 55 A.U. from the Sun, and will probably end its days joining the Voyager missions probing the outer solar system environment. Like Pioneers 10 and 11, Voyagers 1 and 2 and the upper stage boosters that deployed them, New Horizons will escape our solar system and orbit the Milky Way galaxy for millions of years. We recently proposed a fun thought experiment concerning just how much extraterrestrial “space junk” might be out there, littering the galactic disk.
And while the crowd-sourced Ice Hunters project generated lots of public engagement, a suitable target wasn’t found. There is talk of a follow up Ice Investigators project, though it’s still in the pending stages.
Another issue compounding the problem is the fact that Pluto is currently crossing the star rich region of the Milky Way in the constellation Sagittarius. Telescopes looking in this direction must contend with the thousands of background stars nestled towards the galactic center, making the detection of a faint moving KBO difficult. Still, if any telescope is up to the task, it’s Hubble, which just entered its 25th year of operations last month.
The path of Pluto through the constellation Sagittarius through August 2015. Credit: Starry Night.
Shining at +14th magnitude, Pluto will be very near the 3.5th magnitude star Xi2 Sagittarii during the July 2015 encounter.
New Horizons is currently 1.5 degrees from Pluto — about 3 times the angular size of a Full Moon —as seen from our Earthly vantage point, and although neither can be seen with the naked eye, you can wave in their general direction this month on May 18th, using the nearby daytime Moon as a guide.
The waning crescent Moon lies in the direction of New Horizons and Pluto on May 18th… note the ESA’s Rosetta spacecraft (lower left) and Pioneer 11 (upper center) are also ‘nearby!’ Credit: Starry Night
July 2015 will be an exciting and historic time in solar system exploration. Does Pluto have more undiscovered moons? A ring system of its own? Does it resemble Neptune’s moon Triton, or will it turn out looking entirely different ?
If nothing else, exploration of Pluto will finally give us science writers some new images to illustrate articles on the distant world, rather than recycling the half a dozen-odd photos and artist’s conceptions that are currently available. An abundance of surface features will then require naming as well. It would be great to see Pluto’s discoverer Clyde Tombaugh and Venetia Burney — the girl who named Pluto — get their due. We’ll even assume our space pundit’s hat and predict a resurgence of the “is it a planet?” debate once again in the coming year as the encounter nears…
Construction on the new observatory on the summit of the Haleakala Crater on Maui, Hawaii this February. Credit: National Solar Observatory
Rising 10,000 feet above the sunburned faces of 2.2 million tourists a year, the largest solar telescope on the planet is under construction atop Haleakala Crater in Maui, Hawaii. Never mind all those admonitions about never staring at the sun. Astronomers can’t wait for the chance.
Named for the late Senator Daniel Inouye, the Daniel K. Inouye Solar Telescope or DKIST will be the world’s premier ground-based solar observatory in the world. With its 4-meter (157.5-inch) primary mirror, DKIST is capable of distinguishing features down to 0.03 arc seconds or just 20-70 km (12-44 miles) wide at the sun’s surface. To achieve such fantastic resolutions the telescope will employ the latest adaptive optics technology to cancel the blurring effects of the atmosphere using a computer-controlled deformable mirror.
Extreme closeup of a sunspot showing the dark, central umbra (top) feathery penumbra and individual granules or hot gas. DKIST will capture the evolution of sunspot fine structure and finally understand its physical origin. Credit: NSO Dunn Solar Telescope, courtesy of Thomas Rimmele
Consider that the smallest features visible in large amateur telescopes are solar granules, columns of hot gas rising up from the sun’s interior. Each spans about 930 miles (1,500 km) and together give the sun’s surface the texture of finely-etched glass. DKIST will resolve features more than 60 times smaller. The current largest sun-dedicated telescope is the McMath-Pierce Solar Telescope , which has kept a steady eye on the home star with its 63-inch (1.6-meter) mirror since 1962 from Kitt Peak, Arizona.
Observatory cutaway showing light entering the top of the dome and gathered by the primary mirror, which is reflected to a secondary mirror and from there through a series of smaller mirrors to the science gallery below. Inset shows the light path in greater detail including the deformable mirror that will cancel the blurring effects of atmospheric turbulence. Notice that the secondary mirror is offset with no obstructions between it and the primary mirror that would otherwise lessen the telescope’s ability to resolve fine detail. Credit: L. Phelps with enhancements by the author
DKIST will focus on three key areas: What is the nature of solar magnetism; how does that magnetism control our star; and how can we model and predict its changing outputs that affect the Earth? Astronomers hope to clearly resolve solar flux tubes – magnetic field concentrations near the sun’s surface – thought to be the building blocks of magnetic structures in the atmosphere.
We still lack a complete understanding of how energy in the sun’s turbulent, churning interior is transferred to magnetic fields. Earth’s magnetic field is about 0.5 gauss at the surface. Fields within sunspots can range from 1,500 to 3,000 gauss – about the strength of a bar magnet but across a region several times larger than Earth.
A test of the DKIST Visible Broadband Imager interference filter in 2012 shows material flowing from a sunspot’s outer penumbra into the surrounding solar gases. Credit: NSO
A better understanding of small scale magnetic structures, too tiny to be resolved with current telescopes, will help make sense of broader phenomena like sunspot formation, the heating of the solar corona and why the sun’s energy output varies. The solar constant, the amount of radiation we receive from the sun, increases with an increase in solar activity like spots and flares. Since the smallest magnetic elements are the biggest contributors to this increase, DKIST will be the first telescope able to image and study these structures directly, helping astronomers understand how variations in the sun’s output can lead to climate changes.
Left – Solar photosphere showing bright structures between granules associated with magnetic fields bubbling up from below. Right – Computer model of a magnetic flux tube rising from the convective zone into the photosphere. Flux tubes are believed to be an important conduit for energy flowing from the solar interior to the hot outer atmosphere but are below the limit of resolution in current telescopes. Credit: Paxman, Seldin, Keller / O. Steiner
DKIST will do its work on rapid times scales, taking images once every 3 seconds. For comparison, NASA’s orbiting Solar Dynamics Observatory takes pictures in 8 different wavelengths every 10 seconds, STEREO one image every 3 minutes and SOHO (Solar Heliospheric Observatory) once every 12 minutes. The speedy shooting ability will help DKIST resolve rapidly evolving structures on the sun’s surface and lower atmosphere in a multitude of wavelengths of light from near-ultraviolet to deep infrared thanks to the the extraordinarily clean and dry air afforded by its high altitude digs.
DKIST is under construction in the observatory complex on Haleakala Crater in Maui, Hawaii. The Maui Space Surveillance Complex is the large structure right of center. Photo take Oct. 2013. Credit: Bob King
The new solar telescope will be in excellent company not far from the current Mees Solar Observatory and a stone’s throw from the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) telescope, the 79-inch (2-meter) Faulkes Telescope North and Maui Space Surveillance Complexwhich keeps an eye on man-made orbital debris. Tourists to Mt. Haleakala, a popular destination for tourists, can watch it take shape in the next few years while enjoying a hike in the cool air for which Haleakala is famous.
On August 31, 2012 a long filament of solar material erupted out into space as a coronal mass ejection, or CME, traveling at over 900 miles per second. By probing solar gases at high resolution and rapid time scales using DKIST’s high power optics and spectrographs, astronomers hope to better understand the first stirrings of these huge outbursts of solar energy. Credit: NASA
I first heard about the DKIST telescope from a burly stranger with fierce-looking tattoos. My wife and I vacationed in Maui last fall. One afternoon, while watching surfers ride the waves near the beach town of Paia, this big guy overheard us mention Duluth (Minn.), our hometown. He said he’d lived in Duluth for a time before moving to Hawaii and offered us a beer. We got to talking and learned he worked safety inspection at at the “biggest solar telescope in the world”, making the hour-long drive up the mountain 5 days a week. I checked it out and he was absolutely right.
The Daniel K. Inouye Solar Telescope (formerly the Advanced Technology Solar Telescope) is being developed by a consortium led by the National Solar Observatory and comprising the University of Chicago, the New Jersey Institute of Technology, University of Hawaii, the High Altitude Observatory, NASA, the U.S. Air Force and others. For more details on the project, click HERE.
There’s poetry in building a large solar observatory on an island known for its sunny, warm climate. While vacationers flop out on Kaanapali Beach to vanquish the mid-winter chills, astronomers 50 miles away and 10,000 feet up will be at work coaxing secrets from the fiery ball of light that illuminates surf and scope alike.
Artist's impression of a gamma-ray burst, showing the two intense beams of relativistic matter emitted by the black hole. To be visible from Earth, the beams must be pointing directly towards us. Credit : NASA/Swift/Mary Pat Hrybyk-Keith and John Jones
Roughly once a day the sky is lit up by a mysterious torrent of energy. These events — known as gamma-ray bursts — represent the most powerful explosions in the cosmos, sending out as much energy in a fraction of a second as our Sun will give off during its entire lifespan.
Yet no one has ever witnessed a gamma-ray burst directly. Instead astronomers are left to study their fading light.
New research from an international team of astronomers has discovered a puzzling feature within one Gamma-ray burst, suggesting that these objects may behave differently than previously thought.
These powerful explosions are thought to be triggered when dying stars collapse into jet-spewing black holes. While this stage only lasts a few minutes, its afterglow — slowly fading emission that can be seen at all wavelengths (including visible light) — will last for a few days to weeks. It is from this afterglow that astronomers meticulously try to understand these enigmatic explosions.
The afterglow emission is formed when the jets collide with the material surrounding the dying star. They cause a shockwave, moving at high velocities, in which electrons are being accelerated to tremendous energies. However, this acceleration process is still poorly understood. The key is in detecting the afterglow’s polarization — the fraction of light waves that move with a preferred plane of vibration.
“Different theories for electron acceleration and light emission within the afterglow all predict different levels of linear polarization, but theories all agreed that there should be no circular polarization in visible light,” said lead author Klaas Wiersema in a press release.
“This is where we came in: we decided to test this by carefully measuring both the linear and circular polarization of one afterglow, of GRB 121024A, detected by the Swift satellite.”
Gamma-ray burst 121024A, as seen on the day of the burst by ESO’s Very Large Telescope in Chile. Only a week later the source had faded completely. Image Credit: Dr Klaas Wiersema, University of Leicester, UK and Dr Peter Curran, ICRAR.
And to their surprise, the team detected circular polarization, meaning that the light waves are moving together in a uniform, spiral motion as they travel. The gamma-ray burst was 1000 times more polarized than expected. “It is a very nice example of observations ruling out most of the existing theoretical predictions,” said Wiersema.
The detection shows that current theories need to be re-examined. Scientists expected any circular polarization to be washed out. The radiation of so many electrons travelings billions of light-years would erase any signal. But the new discovery suggests that there could be some sort of order in the way these electrons travel.
Of course the possibility remains that this particular afterglow was simply an oddball and not all afterglows behave like this.
Nonetheless “extreme shocks like the ones in GRB afterglows are great natural laboratories to push our understanding of physics beyond the ranges that can be explored in laboratories,” said Wiersema.
The 'Block Island' meteorite reproduced in plastic at NASA’s Jet Propulsion Laboratory. Credit: NASA/JPL-Caltech
Captain Picard orders tea
“Tea, Earl Grey, hot.” Who doesn’t remember that famous command by Captain Picard’s of TV’s “Star Trek: The Next Generation”? While no one’s yet invented a replicator that can brew a cup of tea out of thin air, scientists have taken in step in that direction by creating an amazing replica of a Martian meteorite using a 3D printer.
Without the fuss and expense of a sample retrieving mission to Mars, NASA scientists now have a realistic, true to life facsimile of the ‘Block Island’ meteorite discovered by the Opportunity Rover in 2009. Block Island, an iron-nickel meteorite similar to those found at Meteor Crater in Arizona, is the largest meteorite found on the Red Planet.
The real Block Island, the largest meteorite yet found on Mars, photographed by Opportunity’s panoramic camera.Credit: NASA/JPL-Caltech/Cornell
Measuring about two feet (60 cm) across, it’s about the size of picnic cooler and weighs an estimated 1,000 pounds. The replica’s made of plastic – you could tote it around like a … picnic cooler.
Analysis of Block Island’s composition using the rover’s alpha particle X-ray spectrometer confirmed that it’s rich in iron and nickel. Scientists based the design of the plastic meteorite on detailed measurements and stereo images taken by Opportunity’s panoramic camera.
Get out your red-blue plastic glasses to get a look at Block Island in stereo. Credit: NASA/JPL-Caltech
The rover made a 360-degree study of the meteorite five years ago taking measurements and many stereo images. But because Opportunity couldn’t see every square inch of the rock, the missing data created holes in the computer model, making it a poor candidate for 3D printing.
Last summer, scientists got around that problem by filling in the missing data and building small scale models of Block Island. To build the life-sized rock, they created depth meshes of the meteorite’s surface from six positions, then combined them into a three-dimensional digital model, according to researcher Kris Capraro of NASA’s Jet Propulsion Laboratory.
Researcher Kris Capraro (second from left) adds the finishing touches of realistic color to a model of the “Block Island” meteorite.Credit: NASA/JPL-Caltech
The printer built the meteorite from ABS plastic, the same material used in Lego bricks, with cord the width of the plastic line in your weed-whacker. One small problem remained before the replica could be executed – it was too big to fit in the printer’s building space. So researchers broke up the computer model of the meteorite into 11 sections. Printing took 305 hours and 36 minutes.
Researchers created each of 11 pieces in the 3D printer and glued them together to build the true-size model. Credit: NASA/JPL-Caltech
The sections were assembled and then painted to match the real rock. Said Capraro: “it’s the next best thing to bringing back real Martian rock samples back to Earth.”
Scientists hope someday to use 3D printing to not only replicate more Mars rocks but terrains across the solar system.
Comparison of Lyman alpha blob observed with Cosmic Web Imager and a simulation of the cosmic web based on theoretical predictions.
Credit: Christopher Martin, Robert Hurt
- See more at: http://www.caltech.edu/content/intergalactic-medium-unveiled-caltechs-cosmic-web-imager-directly-observes-dim-matter#sthash.3bs0Xl3d.dpuf
An international team of astronomers has taken unprecedented images of intergalactic space — the diffuse and often invisible gas that connects and feeds galaxies throughout the Universe.
Until now, the structure of intergalactic space has mostly been a matter for theoretical speculation. Advanced computer simulations predict that primordial gas from the Big Bang is distributed in a vast cosmic web — a network of filaments that span galaxies and flow between them.
This vast network is impossible to see alone. In the past astronomers have looked at distant quasars — supermassive black holes at the centers of galaxies which are rapidly accreting material and shining brightly — to indicate the otherwise invisible matter along their lines of sight.
While distant quasars may reveal the otherwise invisible gas, there’s no information about how that gas is distributed across space. New images, however, from the Cosmic Web Imager are revealing the webs’ filaments directly, allowing them to be seen across space.
The first filaments observed by the Cosmic Web Imager are in the vicinity of two ancient but bright objects: the quasar QSO 1549+19 and a so-called Lyman alpha blob (yes, this is a technical term for a huge concentration of hydrogen gas) in the emerging galaxy cluster SSA22. These objects are bright, lighting up the intervening galactic space and boosting the detectable signal.
Image of quasar (QSO 1549+19) taken with Caltech’s Cosmic Web Imager, showing surrounding gas (in blue) and direction of filamentary gas inflow. Image Credit: Christopher Martin, Robert Hurt
Both objects date back to two billion years after the Big Bang, in a time of rapid star formation in galaxies. Observations show a narrow filament, about one million light-years across flowing into the quasar, which is likely fueling the growth of the host galaxy.
There are three filaments flowing into the Lyman alpha blob. “I think we’re looking at a giant protogalactic disk,” said lead author Christopher Martin from the California Institute of Technology in a press release. “It’s almost 300,000 light-years in diameter, three times the size of the Milky Way.”
The Cosmic Web Imager on board the Hale 200 inch telescope is a spectrographic imager, taking pictures at many different wavelengths simultaneously. This allows astronomers to learn about objects’ composition, mass and velocity.
“The gaseous filaments and structures we see around the quasar and the Lyman alpha blob are unusually bright,” said Martin. “Our goal is to eventually be able to see the average intergalactic medium everywhere. It’s harder, but we’ll get there.”
