How Far Can You See in the Universe?

When you look into the night sky, you’re seeing tremendous distances away, even with your bare eyeball. But what’s the most distant object you can see with the unaided eye? And what if you get help with a pair of binoculars, a telescope, or even with the Hubble Space Telescope.

Standing at sea level, your head is at an altitude of 2 meters, and the horizon appears to be about 3 miles, or 5 km away. We’re able to see more distant objects if they’re taller, like buildings or mountains, or when we’re higher up in the air. If you get to an altitude of 20 meters, the horizon stretches out to about 11 km. But we can see objects in space which are even more distant with the naked eye. The Moon is 385,000 km away and the Sun is a whopping 150 million km. Visible all the way down here on Earth, the most distant object in the solar system we can see, without a telescope, is Saturn at 1.5 billion km away.

In the very darkest conditions, the human eye can see stars at magnitude 6.5 or greater. Which works about to about 9,000 individual stars. Sirius, the brightest star in the sky, is 8.6 light years. The most distant bright star, Deneb, is about 1500 light years away from Earth. If someone was looking back at us, right now, they could be seeing the election of the 52nd pope, St. Hormidas, in the 6th Century.
There are even a couple of really bright stars in the 8000 light year range, that we might just barely be able to see without a telescope. If a star detonates, we can see it much further away. The famous 1006 supernova was the brightest in history, recorded in China, Japan and the Middle East.

It was a total of 7,200 light years away and was visible in the daytime. There’s even large structures we can see. Outside the galaxy, the Large Magellanic Cloud is 160,000 light years and the Small Magellanic Cloud is almost 200,000 light years away. Unfortunately for us up North, these are only visible from Southern Hemisphere.The most distant thing we can see with our bare eyeballs is Andromeda at 2.6 million light years, which in dark skies looks like a fuzzy blob.

If we cheat and get a little help, say with binoculars – you can see magnitude 10 – fainter stars and galaxies at more than 10 million light-years away. With a telescope you can see much, much further. A regular 8-inch telescope would let you see the brightest quasars, more than 2 billion light years away. Using gravitational lensing the amazing Hubble space telescope can see galaxies, incredibly far out, where the light had left them just hundreds of millions of years after the Big Bang.

If you could see in other wavelengths, you could see different distances. Fortunately for our precious radiation sensitive organs, Gamma and X rays are blocked by our atmosphere. But if you could see in that spectrum, you could see objects exploding billions of light years away. And if you could see in the radio spectrum, you’d be able to see the cosmic microwave background radiation, surrounding us in all directions and marking the edge of the observable universe.

Wouldn’t that be cool? Well, maybe we can… just a little. Turn on your television, some of the static on the screen is this very background radiation, the afterglow of the Big Bang.

What do you think? If you could see far out in the Universe what would you like a close up view of? Tell us in the comments below.

Keeping An Eye On Gaia

Gaia, ESA’s long-anticipated mission to map the stars of our galaxy (as well as do a slew of other cool science things) is now tucked comfortably in its position in orbit around Earth-Moon L2, a gravitationally stable spot in space 1.5 million km (932,000 miles) away.

Once its mission begins in earnest, Gaia will watch about a billion stars an average of 70 times each over a five-year span… that’s 40 million observations every day. It will measure the position and key physical properties of each star, including its brightness, temperature and chemical composition, and help astronomers create the most detailed 3D map of the Milky Way ever.

But before Gaia can do this, its own position must be precisely determined. And so several of the world’s most high-powered telescopes are trained on Gaia, keeping track daily of exactly where it is up to an accuracy of 150 meters… which, with the ten-meter-wide spacecraft one and a half million kilometers away, isn’t too shabby.

Called GBOT, for Ground Based Orbit Tracking, the campaign to monitor Gaia’s position was first set up in 2008 — long before the mission launched. This allowed participating observatories to practice targeting on other existing spacecraft, like NASA’s WMAP and ESA’s Planck space telescopes.

The image above shows an image of Gaia (circled) as seen by the European Southern Observatory’s Very Large Telescope Survey Telescope (VST) atop Cerro Paranal in Chile, one of the supporting observatories in the GBOT campaign. The images were taken with the 2.6-meter Survey Telescope’s 268-megapixel OmegaCAM on Jan. 23, 6.5 minutes apart. With just the reflected sunlight off its circular sunshield, the distant spacecraft is about a million times fainter than what your eyes could see unaided.

Gaia mapping the stars of the Milky Way. (ESA/ATG medialab; background: ESO/S. Brunier)
Gaia mapping the stars of the Milky Way. (ESA/ATG medialab; background: ESO/S. Brunier)

It’s also one the closest objects ever imaged by the VST.

Currently Gaia is still undergoing calibration for its survey mission. Some problems have been encountered with stray sunlight reaching its detectors, and this may be due to the angle of the sunshield being a few degrees too high relative to the Sun. It could take a few weeks to implement an orientation correction; read more on the Gaia blog here.

Read more: Ghostly Cat’s Eye Nebula Shines In Space Telescope Calibration Image

Of the billion stars Gaia will observe, 99% have never had their distances accurately measured. Gaia will also observe 500,000 distant quasars, search for brown dwarfs and exoplanets, and will conduct experiments testing Einstein’s General Theory of Relativity. Find out more facts about the mission here.

Gaia launched on December 19, 2013, aboard a Soyuz VS06 from ESA’s spaceport in Kourou, French Guiana. Watch the launch here.

Source: ESA

How Spitzer’s Focus Changed To Strange New Worlds

After 10 years in space — looking at so many galaxies and stars and other astronomy features — the Spitzer Space Telescope is being deployed for new work: searching for alien worlds.

The telescope is designed to peer in infrared light (see these examples!), the wavelength in which heat is visible. When looking at infrared light from exoplanets, Spitzer can figure out more about their atmospheric conditions. Over time, it can even detect brightness differences as the planet orbits its sun, or measure the temperature by looking at how much the brightness declines when the planet goes behind its star. Neat stuff overall.

“When Spitzer launched back in 2003, the idea that we would use it to study exoplanets was so crazy that no one considered it,” stated Sean Carey of NASA’s Spitzer Science Center, which is at the California Institute of Technology. “But now the exoplanet science work has become a cornerstone of what we do with the telescope.”

Of course, the telescope wasn’t designed to do this. But to paraphrase the movie Apollo 13, NASA was interested in what the telescope could do while it’s in space — especially because the planet-seeking Kepler space telescope has been sidelined by a reaction wheel problem. Redesigning Spitzer, in a sense, took three steps.

Classifying Galaxies
An example of Spitzer’s past work: This image from NASA’s Spitzer Space Telescope shows infrared light from the Sunflower galaxy, otherwise known as Messier 63. Spitzer’s view highlights the galaxy’s dusty spiral arms. Image credit: NASA/JPL-Caltech

Fixing the wobble: Spitzer is steady, but not so steady that it could easily pick out the small bit of light that an exoplanet emits. Engineers determined that the telescope actually wobbled regularly and would wobble for an hour. Looking into the problem further, they discovered it’s because a heater turns on to keep the telescope battery’s temperature regulated.

“The heater caused a strut between the star trackers and telescope to flex a bit, making the position of the telescope wobble compared to the stars being tracked,” NASA stated. In October 2010, NASA decided to cut the heating back to 30 minutes because the battery only needs about 50 per cent of the heat previously thought. Half the wobble and more exoplanets was more the recipe they were looking for.

The Spitzer Space Telescope.  Credit:  NASA
The Spitzer Space Telescope. Credit: NASA

Repurposing a camera: Spitzer has a pointing control reference sensor “peak-up” camera on board, which originally gathered up infrared light to funnel to a spectrometer. It also calibrated the telescope’s star-tracker pointing devices. The same principle was applied to infrared camera observations, putting stars in the center of camera pixels and allowing a better view.

Remapping a camera pixel: The scientists charted the variations in a single pixel of the camera that showed them which were the most stable areas for observations. For context, about 90% of Spitzer’s exoplanet observations are about a 1/4 of a pixel wide.

That’s pretty neat stuff considering that Spitzer’s original mission was just 2.5 years, when it had coolant on board to allow three temperature-sensitive science instruments to function. Since then, engineers have set up a passive cooling system that lets one set of infrared cameras keep working.

Source: NASA

Double Vision: Scientists Spot An Elder ‘Twin’ To the Sun

If you want a picture of how you’ll look in 30 years, youngsters are told, look at your parents. The same principle is true of astronomy, where scientists compare similar stars in different age groups to see how they progress.

We have a special interest in learning how the Sun will look in a few billion years because, you know, it’s the main source of energy and life on Earth. Newly discovered HIP 102152 could give us some clues. The star is four billion years older than the sun, but so close in composition that researchers consider it almost like a twin.

Telescopes have only been around for a few centuries, making it hard to project what happens during the billions upon billions of years for a star’s lifetime. We have about 400 years of observations on the sun, for example, which is a minute fraction of its 4.6 billion-year-old lifespan so far.

The Sun in H-Alpha, on 01-07-2013, using a Lunt Solar LS60Scope/LS50 Hydrogen Alpha Solar filter. Credit: John Chumack
Today, we take telescopic observations of the Sun for granted, but the technology only became available about 400 years ago. This picture shows the Sun in H-Alpha, on 01-07-2013, using a Lunt Solar LS60Scope/LS50 Hydrogen Alpha Solar filter. Credit: John Chumack

“It is very hard to study the history and future evolution of our star, but we can do this by hunting for rare stars that are almost exactly like our own, but at different stages of their lives,” stated the European Southern Observatory.

ESO’s Very Large Telescope — guided by a team led by the University of Sao Paulo’s Jorge Melendez — examined HIP 102152 with a spectrograph that broke up the light into various colors, revealing properties such as chemical composition. Around the same time, they scrutinized 18 Scorpii, also considered to be a twin but one that is younger than the sun (2.9 billion years old)

So what can we predict about the Sun’s future? One thing puzzling scientists has been the amount of lithium in our closest stellar companion. Although the Big Bang (the beginning of the universe) created hydrogen, helium and lithium, only the first two elements are abundant in the Sun.

Periodic Table of Elements
Periodic Table of Elements

HIP 102152, it turns out, also has low levels of lithium. Why isn’t clear yet, ESO notes, although “several processes have been proposed to transport lithium from the surface of a star into its deeper layers, where it is then destroyed.” Previous observations of young Sun-like stars also show higher levels of lithium, implying something changes between youth and middle age.

The elder twin to our Sun may host another discovery: there could be Earth-sized planets circling the star. Chemical properties of HIP 102152 show that it has few elements that you see in meteorites and rocky planets, implying the elements are “locked up” in bodies close to the star. “This is a strong hint that HIP 102152 may host terrestrial rocky planets,” ESO stated.

Better yet, separate observations showed that there are no giant planets close to the star — leaving room for Earth-sized planets to flourish.

The research is available in a recent edition of Astrophysical Letters.

Source: European Southern Observatory

An Amazing Anniversary Image from the VLT

This Saturday will mark 15 years that the European Southern Observatory’s Very Large Telescope (VLT) first opened its eyes on the Universe, and ESO is celebrating its first-light anniversary with a beautiful and intriguing new image of the stellar nursery IC 2944, full of bright young stars and ink-black clouds of cold interstellar dust.

This is the clearest ground-based image yet of IC 2944, located 6,500 light-years away in the southern constellation Centaurus.

Emission nebulae like IC 2944 are composed mostly of hydrogen gas that glows in a distinctive shade of red, due to the intense radiation from the many brilliant newborn stars. Clearly revealed against this bright backdrop are mysterious dark clots of opaque dust, cold clouds known as Bok globules. They are named after Dutch-American astronomer Bart Bok, who first drew attention to them in the 1940s as possible sites of star formation. This particular set is nicknamed the Thackeray Globules.

Larger Bok globules in quieter locations often collapse to form new stars but the ones in this picture are under fierce bombardment from the ultraviolet radiation from nearby hot young stars. They are both being eroded away and also fragmenting, like lumps of butter dropped into a hot frying pan. It is likely that Thackeray’s Globules will be destroyed before they can collapse and form stars.

This new picture celebrates an important anniversary for the the VLT – it will be fifteen years since first light on the first of its four Unit Telescopes on May 25, 1998. Since then the four original giant telescopes have been joined by the four small Auxiliary Telescopes that form part of the VLT Interferometer (VLTI) – one of the most powerful and productive ground-based astronomical facilities in existence.

The selection of images below — one per year — gives a taste of the VLT’s scientific productivity since first light in 1998:

A selection of images from 15 years of the VLT
A selection of images from 15 years of the VLT (Credits: ESO/P.D. Barthel/M. McCaughrean/M. Andersen/S. Gillessen et al./Y. Beletsky/R. Chini/T. Preibisch)

Read more on the ESO site here, and watch an ESOCast video below honoring the VLT’s fifteen-year milestone:

Happy Anniversary VLT!

Source: ESO

One Astronaut’s Kids Get a Valentine’s Day View of Dad’s Office in Orbit

It’s a wonderful thing for children to look up to their fathers, but some kids have to look a little further than others — especially when dad is in command of the International Space Station!

Around 6 p.m. EST on February 14, the ISS passed over southern New England, and for a few brief moments the Station was directly above Rhode Island, at 37 miles wide the smallest state in the US. 240 miles up and heading northeast at 17,500 mph, the ISS quickly passed out of sight for anyone watching from the ground, but it was enough time for Heidi and Anthony Ford to get a view of the place where their father Kevin Ford has been living and working since the end of October… and thanks to Brown University’s historic Ladd Observatory and astronomer Robert Horton they got to see the Station up close while talking to their dad on the phone.

“One of the things [Anthony and I] like to do is to pop outside to watch dad fly over, which you can do on occasion when the timing is just right,” Heidi said. “We were looking at the schedule to see when the flyover would be so we could go see him. I remembered that the Ladd was open to the public, so I thought I’d call over there and see if this is something we could visit the Ladd to do.”

Robert Horton, an astronomer with Brown University, was happy to meet Heidi and Anthony at the Ladd for the flyover.

Heidi and Anthony Ford's view of the ISS (Robert Horton/Brown University)
Heidi and Anthony Ford’s view of the ISS (Robert Horton/Brown University)

While the Ladd’s main 12″ telescope doesn’t have the ability to track fast-moving objects like the ISS, Horton had some at home that could. So he set one of them up at the observatory and prepared to track the station during its six-minute pass.

Just before the flyby, Heidi’s phone rang — it was her dad calling from the ISS.

“He told her, ‘I’m over Texas. I’ll be there in a few minutes,’” Horton said later in an interview with Brown reporters. “Sure enough the point of light appeared in the sky and we started to track it. They could look through the eyepiece and actually make out the solar panels while they were talking with him.”

The Brown University-run Ladd Observatory holds free public viewing nights every Tuesday, weather permitting. People line up inside the 122-year-old dome to peer through its recently restored 12″ refracting telescope at objects like the Moon, Jupiter, and Saturn, and local amateur astronomers set up their own ‘scopes on the observatory’s rooftop deck for additional viewing opportunities.

Heidi had told their dad that they’d be watching from Providence as he passed over, and luckily his schedule allowed him to make a phone call during that particular evening’s pass.

NASA astronauts Kevin Ford (foreground) and Tom Marshburn working with the Combustion Integrated Rack (CIR) Multi-user Droplet Combustion Apparatus (MDCA) in the ISS' Destiny laboratory on Jan. 9 (NASA)
NASA astronauts Kevin Ford (foreground) and Tom Marshburn working with the Combustion Integrated Rack (CIR) Multi-user Droplet Combustion Apparatus (MDCA) in the ISS’ Destiny laboratory on Jan. 9 (NASA)

While they had both watched flyovers before, it was the first time either of them had ever seen the ISS through a telescope.

It made for a “very special Valentine’s Day,” Heidi said.

And as for Horton, who had donated the use of his telescope? He got a chance to talk with Commander Ford as well — an experience he’ll likely never forget.

“I can think of a thousand questions to ask him now that I’m not on the phone with him,” Horton said. “But, frankly, I was awestruck at the time.”

Read more on the Brown University news article by Kevin Stacey here. (Excerpts used with permission.)

Ladd Observatory today and after its opening in 1891. (Brown University)
Ladd Observatory today and after its opening in 1891. (Brown University)

Thanks to Jim Hendrickson of Skyscrapers, Inc. for the story alert.

A Parting Look at 2012 DA14: Was This a Warning Shot from Space?

Just as anticipated, on Friday, Feb. 15, asteroid 2012 DA14 passed us by, zipping 27,000 kilometers (17,000 miles) above Earth’s surface — well within the ring of geostationary weather and communications satellites that ring our world. Traveling a breakneck 28,100 km/hr (that’s nearly five miles a second!) the 50-meter space rock was a fast-moving target for professional and amateur observers alike. And even as it was heading away from Earth DA14 was captured on camera by a team led by MIT researcher Dr. Nicholas Moskovitz using the 2.1-meter telescope at the Kitt Peak National Observatory in Tucson, AZ. The team’s images are shown above as an animated gif (you may need to click the image to play it.)

This object’s close pass, coupled with the completely unexpected appearance of a remarkably large meteor in the skies over Chelyabinsk, Russia on the morning of the same day, highlight the need for continued research of near-Earth objects (NEOs) — since there are plenty more out there where these came from.

“Flybys like this, particularly for objects smaller than 2012 DA14, are not uncommon. This one was special because we knew about it well in advance so that observations could be planned to look at how asteroids are effected by the Earth’s gravity when they come so close.”

– Dr. Nicholas Moskovitz, MIT

The animation shows 2012 DA14 passing inside the Little Dipper, crossing an area about a third the size of the full Moon in 45 minutes. North is to the left.

(For a high-resolution version of the animation, click here.)

Exterior of the 2.1-meter telescope of the Kitt Peak National Observatory (NOAO)
Exterior of the 2.1-meter telescope of the Kitt Peak National Observatory (NOAO/AURA/NSF)

According to the National Optical Astronomy Observatory, which operates the Kitt Peak Observatory, Dr. Moskovitz’ NSF-supported team “are analyzing their data to measure any changes in the rotation rate of the asteroid after its close encounter with the Earth. Although asteroids are generally too small to resolve with optical telescopes, their irregular shape causes their brightness to change as they rotate. Measuring the rotation rate of the asteroid in this way allows the team to test models that predict how the earth’s gravity can affect close-passing asteroids. This will lead to a better understanding of whether objects like 2012 DA14 are rubble piles or single solid rocks.

“This is critical to understanding the potential hazards that other asteroids could pose if they collide with the Earth.”

So just how close was DA14’s “close pass?” Well, if Earth were just a few minutes farther along in its orbit, we would likely be looking at images of its impact rather than its departure.*

Although this particular asteroid isn’t expected to approach Earth so closely at any time in the foreseeable future — at least within the next 130 years — there are lots of such Earth-crossing objects within the inner Solar System… some we’re aware of, but many that we’re not. Identifying them and knowing as many details as possible about their orbits, shapes, and compositions is key.

Even this soon after the Feb. 15 flyby observations of 2012 DA14 have provided more information on its orbit and characteristics., allowing for fine-tuning of the data on it.

According to the Goldstone Radar Observatory web page, the details on 2012 DA14 are as follows:
Semimajor axis                   1.002 AU
Eccentricity                          0.108
Inclination                           10.4 deg
Perihelion distance           0.893 AU
Aphelion distance              1.110 AU
Absolute magnitude (H)   24.4
Diameter                               ~50 meters (+- a factor of two)
Rotation period                   ~6 h  (N. Moskovitz, pers. comm.)
Pole direction                      unknown
Lightcurve amplitude        ~1 mag  (N. Moskovitz, pers. comm.)
Spectral class                       Ld  (N. Moskovitz, pers. comm.)

Goldstone is currently conducting radar observations on the asteroid. A radar map of its surface and motion is anticipated in the near future.

Read more about Dr. Moskovitz’ observations on the NOAO website here, and see more images of 2012 DA14 captured by astronomers around the world in our previous article.

A bright meteor witnessed over Russia on Feb. 15, 2013 (RussiaToday)
A bright daytime meteor witnessed over Russia on Feb. 15, 2013 (RussiaToday)

Also, in an encouraging move by international leaders in the field, during the fiftieth session of the Scientific and Technical Subcommittee of the Committee on the Peaceful Uses of Outer Space, currently being held from at the United Nation Office in Vienna, near-Earth objects are on the agenda with a final report to be issued by an Action Team. Read the report PDF here.

*According to astronomer Phil Plait, while the orbits of Earth and DA14 might intersect at some point, on the 15th of February 2013 the asteroid slipped just outside of Earth’s orbit — a little over 17,000 miles shy. “It was traveling one way and the Earth another, so they could not have hit each other on this pass no matter where Earth was in its orbit,” he wrote in an email. Still, 17,000 miles is a very close call astronomically, and according to Neil deGrasse Tyson on Twitter, it “will one day hit us, like the one in Russian [sic] last night.” When? We don’t know yet. That’s why we must keep watching.

Here There Be Planets: Stellar Disk Gap May Reveal Newborn Worlds

HiCIAO near-infrared image of the protoplanetary disk around PDS 70. The circular mask hides the star itself, as well as a smaller internal disk structure. (Credit: NAOJ)

Over the past couple of decades astronomers have figured out several methods for finding planets around other stars in our galaxy. Some have revealed their presence by the slight “wobble” they impart to their host stars as they orbit, while others have been discovered as they pass in front of their stars from our perspective, briefly dimming the light we see.

Now, some astronomers think they may have identified the presence of multiple planets, based on a large gap found in the disk of  gas and dust surrounding a Sun-like star 460 light-years from Earth.

Using the High Contrast Instrument for the Subaru Next Generation Adaptive Optics (HiCIAO) mounted on Japan’s 8.2-meter optical-infrared Subaru telescope atop Mauna Kea in Hawaii, an international team of astronomers targeted PDS 70, a young star (10 million years old) about the same mass as the Sun located 460 light-years away in the constellation Centaurus.

The near-infrared observations made by HiCIAO reveal a protoplanetary disk surrounding PDS 70. This disk is composed of gas and dust and extends billions of miles out from the star. Quite literally the stuff that planets are made of, it’s a disk much like this that our solar system likely started out as over 4.6 billion years ago.

“Thanks to the powerful combination of the Subaru Telescope and HiCIAO, we are able to probe the disks around Sun-like stars. PDS 70 shows how our solar system may have looked in its infancy. I want to continue this kind of research to understand the history of planetary formation.”

– Team Leader Jun Hashimoto (NAOJ)

Within PDS 70’s disk are several large gaps positioned at varying distances from the star itself, appearing as dark regions in the near-infrared data. These gaps — especially the largest, located about 70 AU from the star — are thought to be the result of newly-formed planets having cleared the surrounding space of dust and smaller material. It’s also believed that multiple planets may be present since, according to the team, “no single planet, regardless of how heavy or efficient it is in its formation, is sufficient to create such a giant gap.”

In addition to the large disk structure and outer gap, PDS 70 also has a smaller disk located only 1 AU away. (This disk is obscured by the HiCIAO mask in the image above.)

Further observations will be needed to locate any actual exoplanets directly, since the light from the star and scattered light within the disk makes it difficult — if not impossible with current technology — to detect the incredibly faint light reflected by planets.

Still, it’s fascinating to come across what may very well be a solar system in its infancy, giving us a glimpse back in time to our own formation.

“Direct imaging of planets in the process of forming in protoplanetary disks would be ideal so that we can learn when, where, and how planets form,” said team leader Ruobing Dong of Princeton University.

Read more on the NAOJ website for the Subaru Observatory here.

The goal of the Strategic Exploration of Exoplanets and Disks with Subaru (SEEDS) Project is to study the disks around less massive stars like the Sun.

Inset image: Artist’s rendition of PDS 70 and its two protoplanetary disks (NAOJ)

First Images in a New Hunt for Dark Energy

Zoomed-in image from the Dark Energy Camera of the barred spiral galaxy NGC 1365, about 60 million light-years from Earth. (Dark Energy Survey Collaboration)

The ongoing search for dark energy now has a new set of eyes: the Dark Energy Camera, mounted on the 4-meter Victor M. Blanco telescope at the National Science Foundation’s Cerro Tololo Inter-American Observatory in Chile. The culmination of eight years of planning and engineering, the phone-booth-sized 570-megapixel Dark Energy Camera has now gathered its very first images, capturing light from cosmic structures tens of millions of light-years away.

Eventually the program’s survey will help astronomers uncover the secrets of dark energy — the enigmatic force suspected to be behind the ongoing and curiously accelerating expansion of the Universe.

Zoomed-in image from the Dark Energy Camera of the Fornax cluster

“The Dark Energy Survey will help us understand why the expansion of the universe is accelerating, rather than slowing due to gravity,” said Brenna Flaugher, project manager and scientist at Fermilab.

Read more: Polar Telescope Casts New Light on Dark Energy

The most powerful instrument of its kind, the Dark Energy Camera will be used to create highly-detailed color images of  a full 1/8th of the night sky — about 5,000 square degrees — surveying thousands of supernovae, galactic clusters and literally hundreds of millions of galaxies, peering as far away as 8 billion light-years.

The survey will attempt to measure the effects of dark energy on large-scale cosmic structures, as well as identify its gravitational lensing effects on light from distant galaxies. The images seen here, acquired on September 12, 2012, are just the beginning… the Dark Energy Survey is expected to begin actual scientific investigations this December.

Full Dark Energy Camera composite image of the Small Magellanic Cloud

“The achievement of first light through the Dark Energy Camera begins a significant new era in our exploration of the cosmic frontier,” said James Siegrist, associate director of science for high energy physics with the U.S. Department of Energy. “The results of this survey will bring us closer to understanding the mystery of dark energy, and what it means for the universe.”

Read more on the Symmetry Magazine article here, and you can also follow the Dark Energy Survey on Facebook here. (The Fermilab press release can be found here.)

Images: Dark Energy Survey Collaboration. Inset image: the 4-meter Blanco Telescope dome at CTIO (NOAO)

The Dark Energy Survey is supported by funding from the U.S. Department of Energy; the National Science Foundation; funding agencies in the United Kingdom, Spain, Brazil, Germany and Switzerland; and the participating DES institutions.


A New Species of Type Ia Supernova?

Artist’s conception of a binary star system that produces recurrent novae, and ultimately, the supernova PTF 11kx. (Credit: Romano Corradi and the Instituto de Astrofísica de Canarias)

Although they have been used as the “standard candles” of cosmic distance measurement for decades, Type Ia supernovae can result from different kinds of star systems, according to recent observations conducted by the Palomar Transient Factory team at California’s Berkeley Lab.

Judging distances across intergalactic space from here on Earth isn’t easy. Within the Milky Way — and even nearby galaxies — the light emitted by regularly pulsating stars (called Cepheid variables) can be used to determine how far away a region in space is. Outside of our own local group of galaxies, however, individual stars can’t be resolved, and so in order to figure out how far away distant galaxies are astronomers have learned to use the light from much brighter objects: Type Ia supernovae, which can flare up with a brilliance equivalent to 5 billion Suns.

Type Ia supernovae are created from a special pairing of two stars orbiting each other: one super-dense white dwarf drawing material in from a companion until a critical mass — about 40% more massive than the Sun — is reached. The overpacked white dwarf suddenly undergoes a rapid series of thermonuclear reactions, exploding in an incredibly bright outburst of material and energy… a beacon visible across the Universe.

Because the energy and luminance of Type Ia supernovae have been found to be so consistently alike, distance can be gauged by their apparent brightness as seen from Earth. The dimmer one is when observed, the farther away its galaxy is. Based on this seemingly universal similarity it’s been thought that these supernovae must be created under very similar situations… especially since none have been directly observed — until now.

An international team of astronomers working on the Palomar Transient Factory collaborative survey have observed for the first time a Type Ia supernova-creating star pair — called a progenitor system — located in the constellation Lynx. Named PTF 11kx, the system, estimated to be some 600 million light-years away, contains a white dwarf and a red giant star, a coupling that has not been seen in previous (although indirect) observations.

“It’s a total surprise to find that thermonuclear supernovae, which all seem so similar, come from different kinds of stars,” says Andy Howell, a staff scientist at the Las Cumbres Observatory Global Telescope Network (LCOGT) and a co-author on the paper, published in the August 24 issue of Science. “How could these events look so similar, if they had different origins?”

The initial observations of PTF 11kx were made possible by a robotic telescope mounted on the 48-inch Samuel Oschin Telescope at California’s Palomar Observatory as well as a high-speed data pipeline provided by the NSF, NASA and Department of Energy. The supernova was identified on January 16, 2011 and supported by subsequent spectrography data from Lick Observatory, followed up by immediate “emergency” observations with the Keck Telescope in Hawaii.

“We basically called up a fellow UC observer and interrupted their observations in order to get time critical spectra,” said Peter Nugent, a senior scientist at the Lawrence Berkeley National Laboratory and a co-author on the paper.

The Keck observations showed the PTF 11kx post-supernova system to contain slow-moving clouds of gas and dust that couldn’t have come from the recent supernova event. Instead, the clouds — which registered high in calcium in the Lick spectrographic data — must have come from a previous nova event in which the white dwarf briefly ignited and blew off an outer layer of its atmosphere. This expanding cloud was then seen to be slowing down, likely due to the stellar wind from a companion red giant.

(What’s the difference between a nova and a supernova? Read NASA’s STEREO Spots a New Nova)

Eventually the decelerating nova cloud was impacted by the rapidly-moving outburst from the supernova, evidenced by a sudden burst in the calcium signal which had gradually diminished in the two months since the January event. This calcium burst was, in effect, the supernova hitting the nova and causing it to “light up”.

The observations of PTF 11kx show that Type Ia supernova can occur in progenitor systems where the white dwarf has undergone nova eruptions, possibly repeatedly — a scenario that many astronomers had previously thought couldn’t happen. This could even mean that PTF 11kx is an entirely new species of Type Ia supernova, and while previously unseen and rare, not unique.

Which means our cosmic “standard candles” may need to get their wicks trimmed.

“We know that Type 1a supernovae vary slightly from galaxy to galaxy, and we’ve been calibrating for that, but this PTF 11kx observation is providing the first explanation of why this happens,” Nugent said. “This discovery gives us an opportunity to refine and improve the accuracy of our cosmic measurements.”

Source: Berkeley Lab news center

Inset images: PTF 11kx observation (BJ Fulton, Las Cumbres Observatory Global Telescope Network) / The 48-inch Samuel Oschin Telescope dome at Palomar Observatory. Video: Romano Corradi and the Instituto de Astrofísica de Canarias