A new view of the Horsehead Nebula in infrared. Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA).
Here’s the iconic Horsehead Nebula as we’ve not seen it before. As the Hubble team so poetically puts it, the nebula looks “like an apparition rising from whitecaps of interstellar foam.” The new image of the Horsehead was photographed in celebration of the 23rd anniversary of the launch of Hubble aboard the space shuttle Discovery, on April 24, 1990.
Can you believe the Hubble Space Telescope has been in space for 23 years? … and it’s been churning out great images for almost 20 years since it was fixed in space during the first Hubble servicing mission in 1993.
This view shows the nebula in infrared wavelengths. When seen in optical light (see below), it appears dark and shadowy, but is “transparent and ethereal when seen in the infrared, represented here with visible shades. The rich tapestry of the Horsehead Nebula pops out against the backdrop of Milky Way stars and distant galaxies that are easily seen in infrared light,” the Hubble team said.
Gas clouds surrounding the Horsehead have already dissipated, but the tip of the jutting pillar contains a slightly higher density of hydrogen and helium, laced with dust. This casts a shadow that protects material behind it from being photo-evaporated, and a pillar structure forms. Astronomers estimate that the Horsehead formation has about five million years left before it too disintegrates.
The Horsehead Nebula is part of a much larger complex in the constellation Orion. Known collectively as the Orion Molecular Cloud, it also houses other famous objects such as the Great Orion Nebula (M42), the Flame Nebula, and Barnard’s Loop. At about 1,500 light-years away, this complex is one of the nearest and most easily photographed regions in which massive stars are being formed.
Hubble’s pairing of infrared sensitivity and unparalleled resolution offers a tantalizing hint of what the upcoming James Webb Space Telescope, set for launch in 2018, will be able to do.
Here’s a view in optical from Hubble:
The Horsehead Nebula is a cold, dark cloud of gas and dust, silhouetted against the bright nebula IC 434. The bright area at the top left edge is a young star still embedded in its nursery of gas and dust. Image Credit: NASA, NOAO, ESA and The Hubble Heritage Team (STScI/AURA)
Our very own International Space Station is in the cosmic crosshairs.
As cosmonauts are to begin Extra Vehicular Activity (EVA) this morning to perform routine maintenance, an article reminding us of the hazards of such activity came to us via NASA’s Orbital Debris Quarterly Newsletter.
The problem is Micrometeoroid and Orbital Debris (MMOD) impacts. These are nothing new. Pits and tiny cratering has been observed during post-flight inspections of space shuttle orbiters. But this is the first time we’d seen talk of damage caused by tiny impacts on the exterior of the International Space Station.
The handrails are a particularly sensitive area of concern.
The study examined damage incurred on handrails exposed to the environment of space for years on end. These present a hazard to spacewalking astronauts who rely on the handles to move about. These craters often become spalled, presenting a sharp metal rim raised from the surface of the handle.
Close-up of a micro-meteoroid impact on a handrail. (Credit: NASA/JSC Image & Science Analysis Group).
Of course, these razor sharp rims present a problem, especially to space suit gloves. One 34.8 centimeter long handrail returned on the final Space Shuttle mission STS-135 had six impact craters along its length. The handrail had been in service and exposed to the vacuum of space for 8.7 years.
Craters as large as 1.85 millimetres (mm) in diameter with raised lips of 0.33mm have been observed on post-inspection. In studies conducted by NASA engineers, craters with lip heights as little as 0.25mm have been sufficient to snag and tear spacesuit gloves.
There have also been reported incidents of glove tears during EVAs conducted from the ISS over the years. For example, the report cites a tear noticed by astronaut Rick Mastracchio during STS-118 that cut the EVA short.
Analysis of an impact seen on STS-122. (Credit: NASA/JSC Image & Science Analysis Group).
To protect astronauts and cosmonauts during EVAs, the following measures have been instituted:
– Toughening space suit gloves by adding reinforcement to areas exposed to potential MMOD damage.
– Monitoring and analyzing MMOD impacts along handrails and maintaining a database of problem areas.
– Equipping spacewalkers with the ability to cover and/or repair hazardous MMOD areas during spacewalks.
The studies were carried out by the Johnson Space Center Hypervelocity Impact Technology Group in conjunction with a test facility at White Sands, New Mexico. Astronaut Rick Mastracchio can also be seen talking about the hazards of spacewalking on this video.
Today’s 6 hour EVA by cosmonauts Vinogradov & Romanenko begins at 14:06 UT 10:06AM EDT.
This will be the 32nd Russian EVA from the International Space Station and will use the Pirs hatch on Zvezda.
Tasks include retrieving and installing experiment packages and replacing a defective retro-reflector device on the station’s exterior. The device is a navigational aid necessary for the Albert Einstein ATV-4 mission headed to the ISS on June 5th.
Progress 51P is also scheduled to launch towards the ISS next week on April 24 for docking on April 26th.
Debris in Low Earth Orbit is becoming an increasing concern. The Chinese anti-satellite test in 2007 and the collision of Kosmos 2251 and Iridium 33 in 2009 have increased hazards to the ISS. Many fear that a tipping point, known as an ablation cascade, could eventually occur with one collision showering LEO with debris that in turn trigger many more. The ISS was only finished in 2011, and it would be a tragic loss to see it abandoned due to a catastrophic collision only years after completion.
More than once, ISS crew members have sat out a debris conjunction that was too close to call in their Soyuz life boats, ready to evacuate the station if necessary. DAMs (Debris Avoidance Maneuvers) are now common for the ISS throughout the year.
Several ideas have been proposed to deal with space debris. In the past year, NanoSail-2D demonstrated the ability to deploy a solar sail from a satellite for reentry at the end of a spacecraft’s life span. Such technology may be standard equipment on future satellites.
Expect reentries to increase as we near the solar maximum for cycle #24 in late 2013 & early 2014. This occurs because the exosphere of Earth “puffs out” due to increased solar activity and increases drag on satellites in low Earth orbit.
All food for thought as we watch today’s EVA… space travel is never routine!
The April 2013 edition of the Orbital Debris Quarterly News is available for free online.
Relative sizes of Kepler habitable zone planets discovered as of 2013 April 18.
Left to right: Kepler-22b, Kepler-69c, Kepler-62e, Kepler-62f, and Earth (except for Earth, these are artists' renditions). Credit: NASA/Ames/JPL-Caltech.
The Kepler mission has discovered two new planetary systems that include three super-Earth-size planets in the “habitable zone,” the range of distance from a star where the surface temperature of an orbiting planet might be suitable for liquid water.
The Kepler-62 system has five planets; 62b, 62c, 62d, 62e and 62f. The Kepler-69 system has two planets; 69b and 69c. Kepler-62e, 62f and 69c are the super-Earth-sized planets. (Read all the details in our full article here.)
The new planets brings the number of confirmed exoplanets to 861. According to the Planetary Habitability Laboratory, there are now nine potential habitable worlds outside of our solar system, with 18 more potentally habitable planetary candidates found by Kepler waiting to be confirmed. Additionally, astronomers predict there are 25 potentially habitable exomoons.
Here is some of the imagery (sorry, but they are artists concepts!), graphs and video used in today’s briefing about the new discoveries, as well as some some from the Planetary Habitability Laboratory:
Here’s a flythrough of the Kepler 62 system:
The diagram compares the planets of the inner solar system to Kepler-69, a two-planet system about 2,700 light-years from Earth. Image credit: NASA Ames/JPL-Caltech Much like our solar system, Kepler-62 is home to two habitable zone worlds. The small shining object seen to the right of Kepler-62f is Kepler-62e. Orbiting on the inner edge of the habitable zone, Kepler-62e is roughly 60 percent larger than Earth. Image credit: NASA Ames/JPL-Caltech.The diagram compares the planets of the inner solar system to Kepler-62, a five-planet system about 1,200 light-years from Earth. Image credit: NASA Ames/JPL-CaltechCurrent known potentially habitable exoplanets. Credit: Planetary Habitability Laboratory/University of Puerto Rico, Arecibo.Current potentially habitable exoplanets showing the new additions, Kepler-62e and Kepler-62f. Credit: Planetary Habitability Laboratory/University of Puerto Rico, Arecibo.Comparison of the orbit and size of the exoplanets of Kepler-62 with the terrestrial planets of our Solar Systems. The darker green shaded area corresponds to the ‘conservative habitable zone’ while its lighter borders to its ‘optimistic habitable zone’ extension. Planet sizes and orbits are not to scale between them. Credit: Planetary Habitability Laboratory/University of Puerto Rico, Arecibo.
Artist's concept of the Hubble Space Telescope viewing ultraviolet light from the jet of the active galactic nucleus of PKS 1424+240. Clouds of hydrogen gas along the line of sight absorb the light at known frequencies, allowing the redshift and distance of each cloud to be determined. The most distant gas cloud determines the minimum distance to PKS 1424+240. Data from the Fermi Gamma-ray Space Telescope, shown on the horizon at the left, were also used for this study. (Image composition by Nina McCurdy, component images courtesy of NASA)
When it comes to sheer wattage, blazars definitely rule. As the brightest of active galactic nuclei, these sources of extreme high-energy gamma rays are usually associated with relativistic jets of material spewing into space and enabled by matter falling into a host galaxy’s black hole. The further away they are, the dimmer they should be, right? Not necessarily. According to new observations of blazar PKS 1424+240, the emission spectrum might hold a new twist… one that can’t be readily explained.
David Williams, adjunct professor of physics at UC Santa Cruz, said the findings may indicate something new about the emission mechanisms of blazars, the extragalactic background light, or the propagation of gamma-ray photons over long distances. “There may be something going on in the emission mechanisms of the blazar that we don’t understand,” Williams said. “There are more exotic explanations as well, but it may be premature to speculate at this point.”
The Fermi Gamma-ray Space Telescope was the first instrument to detect gamma rays from PKS 1424+240, and the observation was then seconded by VERITAS (Very Energetic Radiation Imaging Telescope Array System) – a terrestrially based tool designed to be sensitive to gamma-rays in the very high-energy (VHE) band. However, these weren’t the only science gadgets in action. To help determine the redshift of the blazar, researchers also employed the Hubble Space Telescope’s Cosmic Origins Spectrograph.
To help understand what they were seeing, the team then set a lower limit for the blazar’s redshift, taking it to a distance of at least 7.4 billion light-years. If their guess is correct, such a huge distance would mean that the majority of the gamma rays should have been absorbed by the extragalactic background light, but again the answers didn’t add up. For that amount of absorption, the blazar itself would be creating a very unexpected emission spectrum.
“We’re seeing an extraordinarily bright source which does not display the characteristic emission expected from a very high-energy blazar,” said Amy Furniss, a graduate student at the Santa Cruz Institute for Particle Physics (SCIPP) at UCSC and first author of a paper describing the new findings.
Bright? You bet. In this circumstance it has to over-ride the ever-present extragalactic background light (EBL). The whole Universe is filled with this “stellar light pollution”. We know it’s there – produced by countless stars and galaxies – but it’s just hard to measure. What we do know is that when a high-energy gamma ray photo meets with a low-energy EBL photon, they essentially cancel each other out. It stands to reason that the further a gamma ray has to travel, the more likely it is to encounter the EBL, putting a limit on the distance to which we can detect high-energy gamma ray sources. By lowering the limit, the new model was then used to ” calculate the expected absorption of very high-energy gamma rays from PKS 1424+240″. This should have allowed Furniss’ team to gather an intrinsic gamma-ray emission spectrum for the most distant blazar yet captured – but all it did was confuse the issue. It just doesn’t coincide with expected emissions using current models.
“We’re finding very high-energy gamma-ray sources at greater distances than we thought we might, and in doing so we’re finding some things we don’t entirely understand,” Williams said. “Having a source at this distance will allow us to better understand how much background absorption there is and test the cosmological models that predict the extragalactic background light.”
The newly discovered planets named Kepler-62e and -f are super-Earths in the habitable zone of a distant sun-like star. The largest planet in the image, Kepler-62f, is farthest from its star and covered by ice. Kepler-62e, in the foreground, is nearer to its star and covered by dense clouds. Closer in orbits a Neptune-size ice giant with another small planet transiting its star. Both habitable-zone planets may be capable of supporting life.
Credit: David A. Aguilar (CfA)
This might be the most exciting exoplanet news yet. An international team of scientists analyzing data from NASA’s Kepler mission has found a planetary system with two small, potentially rocky planets that lie within the habitable zone of their star. The star, Kepler-62, is a bit smaller and cooler than our Sun, and is home to a five-planet system. Two of the worlds, Kepler-62e and Kepler-62f are the smallest exoplanets yet found in a habitable zone, and they might both be covered in water or ice, depending on what kind of atmosphere they might have.
“Imagine looking through a telescope to see another world with life just a few million miles from your own. Or, having the capability to travel between them on a regular basis. I can’t think of a more powerful motivation to become a space-faring society,” said Harvard astronomer Dimitar Sasselov, who is co-author of a new paper describing the discovery.
Masses and sizes for selected planets. The curves show the mass-radius-relation (average density) for different types of planets: The blue line indicates the loci of planets made mostly (75%) of water, the black line that of planets like our Earth that consist almost exclusively of rock (represented here by the mineral Enstatite, MgSiO3, a member of the pyroxite silicate mineral series that makes up most of the Earth’s mantle), and so on. The measured radii of Kepler-62e and Kepler-62f plus an estimate of their mass places them in a region (blue areas) where it is highly probable for them to be earth-like planets, that is: planets with a solid (if possibly covered in water) surface. Kepler-11f, on the other hand, is a Mini-Neptune, showing clearly that a comparatively low mass does not necessarily make for a solid planet. Image: L. Kaltenegger (MPIA)
Kepler-62 in the constellation Lyra, and is about 1,200 light-years from Earth.
62e is 1.61 times Earth’s size, circles the star in 122.4 (Earth) days. 62f is 1.4 times the size of Earth, and orbits its star in 267.3 days. Previously, the smallest planet with known radius inside a habitable zone was Kepler-22b, with a radius of 2.4 times that of the Earth.
A third planet in another star system was also announced at a press briefing today. Kepler-69c is 70 percent larger than the size of Earth, and orbits in the habitable zone of a star similar to our Sun. Researchers are uncertain about the composition of Kepler-69c, but astronomer Thomas Barclay from the BAER Institute said its closer orbit of 242 days around a Sun-like star means it is likely more like a super-Venus rather than a super-Earth.
The habitable zone (in which liquid water on a planet’s surface can exist) for different types of stars. The inner planets of our Solar System are shown on top, with Earth and Mars in the habitable zone. Kepler-62 is a notably cooler star, and Kepler-62e and -62f are in its habitable zone. For Kepler-69c, another planet announced today by NASA, the error bars for the star’s radiation are such that it could possibly in the habitable zone as well. Kepler-22b, the smallest planet found in a habitable zone before the recent discoveries, is very likely a Mini-Neptune, and not a solid planet. In what is denoted the empirical habitable zone, liquid water can exist on the surface of a planet if that planet has sufficient cloud cover. In the narrow habitable zone, liquid water can exist on the surface even without the presence of a cloud cover. Image: L. Kaltenegger (MPIA)
The team says that while the sizes of Kepler 62e and 62f are known, their mass and densities are not. However, every planet found in their size range so far has been rocky, like Earth.
Kepler-62 system. Five planets, two of which are in the Habitable Zone. Credit: NASA
“These planets are unlike anything in our solar system. They have endless oceans,” said lead author Lisa Kaltenegger of the Max Planck Institute for Astronomy and the Harvard Smithsonian Center for Astrophysics. “There may be life there, but could it be technology-based like ours? Life on these worlds would be under water with no easy access to metals, to electricity, or fire for metallurgy. Nonetheless, these worlds will still be beautiful blue planets circling an orange star — and maybe life’s inventiveness to get to a technology stage will surprise us.”
As the warmer of the two worlds, Kepler-62e would have a bit more clouds than Earth according to computer models. More distant Kepler-62f would need the greenhouse effect from plenty of carbon dioxide to warm it enough to host an ocean. Otherwise, it might become an ice-covered snowball.
“Kepler-62e probably has a very cloudy sky and is warm and humid all the way to the polar regions. Kepler-62f would be cooler, but still potentially life-friendly,” said Harvard astronomer and co-author Dimitar Sasselov. “The good news is — the two would exhibit distinctly different colors and make our search for signatures of life easier on such planets in the near future. “
The Kepler spacecraft is able to detect planets that transit or cross the face of their host star. Measuring a transit tells astronomers the size of the planet relative to its star.
“All of the other interesting planets in the habitable zone were until now discovered by what is known as the radial velocity method,” said Kaltenegger. “This method gives you a lower limit for the planet’s mass, but no information about its radius. This makes it difficult to assess whether or not a planet is rocky, like the Earth. A small radius (less than 2 Earth radii), on the other hand, is a strong indicator that a planet around is indeed rocky – unless we are talking about a planet around a very young star.”
“What makes Kepler-62e and Kepler-62f so exciting is a combination of two factors,” Kaltenegger added. “We know their radius, which indicates that these are indeed rocky planets, and they orbit their star in the habitable zone. That makes them our best candidates for habitable planets out there yet.
Kaltenegger provides more details on these exoplanets in this video:
An artist's illustration of a planetary nebula engulfing its orbiting planets (image credit: Regulus36/deviantart, adjusted by DM to mitigate compression effects).
Textbooks often cite that planetary nebulae (PNe, plural) represent an endstate for lower-mass single stars. But conversely, recent research suggests that most PNe stem from binary systems. The lowest mass star theorized to form the typical PN is near 1 solar mass, and thus without a companion the Sun may not surpass the mass limit required to generate the hot glowing (ionized) nebula typically tied to PNe. New research continues to question our original understanding of how the Sun’s life may end.
A new study spearheaded by G. Jacoby aimed in part to test that binary hypothesis by searching for PNe in star clusters occupying M31. The team remarked that, “while the binary interaction model explains some of the anomalies associated with the observed planetary nebula population, this theory awaits final confirmation.”
“The traditional theory states that the progenitors of PNe are low- to intermediate-mass single stars … However, this theory does not provide a natural explanation for the non-spherical morphologies observed for the great majority of PNe, nor their low rate of formation. For these and other inconsistencies, a new paradigm has been developed, wherein most PNe are shaped via the interaction … with a binary companion,” said Jacoby et al. 2013. Continue reading “Astronomers Hint that our Sun won’t Terminate as the Typical Planetary Nebula”
Screenshot of Chris Hadfield showing the NASA washcloths.
The first thing I want to know is where we can get the cool, compacted NASA washcloths. But this new video from Chris Hadfield, commander of the International Space Station is pretty amazing. Hadfield has been working with schools and doing experiments suggested by students. This one was designed by students Kendra Lemke and Meredith Faulkner (10th grade) from Lockview High School in Fall River, Nova Scotia . They won a national science contest held by the Canadian Space Agency with their experiment on surface tension in space using a wet washcloth, and you can see the really nifty results here.
Below is another water-themed demonstration from Hadfield, how to wash your hands in space:
Known as Cubesats, several of these tiny but cost-effective payloads use off-the-shelf technology that you may currently carry in your pocket. In fact, engineers have put out a call for app designers to write programs for these tiny micro-satellites. Four of this new breed of satellites are part of the Antares A-One mission and another four are slated to launch tomorrow atop a Soyuz rocket from Plesetsk along with the Bion M-1 payload.
Yesterday’s launch of Orbital Sciences’ Antares rocket was scrubbed with minutes to go due to the premature retraction of an umbilical. Current plans call for a 48 hour turnaround with a new launch window opening Friday night on April 19th at 5:00 PM EDT/ 21:00 UT.
Cubesats are nothing new. As technology becomes miniaturized, so have the satellites that they’re contained in. Cubesats have even been deployed from the International Space Station.
The primary goal of the Antares A-One mission is to deploy a test mass into low Earth Orbit that simulates the Cygnus spacecraft. If all goes well, Cygnus is set to make its first flight to the ISS this summer.
But also onboard are the three unique payloads; the PhoneSat-1a, 1b & 1c cubesats and the Dove 1 cubesat.
As the name implies, the PhoneSat series of satellites are each constructed around a Nexus Smartphone and operate using Google’s very own Android operating system. The mission serves as NASA’s test bed for the concept. The phone system will monitor the orientation of the satellites. The PhoneSats will also use their off-the-shelf built-in cameras to take pictures of the Earth from orbit.
A separate watchdog circuit will reboot the phones if necessary. The PhoneSats are expected to last about a week in orbit until their batteries die. One of the PhoneSats is equipped with solar panels to test rechargeable technology for the platform.
Two of the nano satellites are built around a Samsung Nexus S and the other around a HTC Nexus Smartphone. The satellites will also use the SD card for info storage plus the 3-axis magnetometer and accelerometer incorporated into the phones for measurements and orientation.
A PhoneSat 1.0 during a balloon test flight. (Credit: NASA).
Dove-1 will test a similar technology. It is built around a low-cost bus using off-the-shelf components. Each of the three PhoneSats cost less than $3,500 dollars U.S. to build.
Amateur radio operators will also be able to monitor the satellites as well. The PhoneSats will transmit at 437.425 MHz. Information will also available to track them in real time on the web once they’re deployed.
The two PhoneSat 1.0 satellites are dubbed Graham and Bell and will transmit every 28 and 30 seconds, and the one PhoneSat 2.0 satellite is named Alexandre and will transmit every 25 seconds.
The PhoneSat 2.0 series will also employ magnets that interact with the Earth’s magnetic field. A future application of this could include use of a PhoneSat for a possible heliophysics mission.
Although the Antares A-One mission is aiming to place the Cygnus test mass and the Cubesats in an inclination of 51.6° degrees similar to the ISS, it will not be following the ISS in its orbit and won’t present a hazard to the station.
The goal of NASA’s PhoneSat team based out of the Ames Research Center at Moffett Field California is to “release early and often.” Missions like Antares A-One present a unique opportunity for the teams to get “piggyback payloads” into orbit. To this end, NASA’s Cubesat Launch Initiative (CSLI) issues periodic calls for teams across the nation to make proposals and build tiny satellites.
Basic dimensions of a cubesat are 10x10x14 centimetres (for comparison, a CD jewel case is about 14×12 cm) and must weigh less than 1.33 kilograms for 1U, 2U & 3U variants. Up to 14kg is allowed for 6U models. Cubesats are deployed from a Poly-Picosatellite Deployer, or P-Pod.
Another set of cubesats is also slated to launch tomorrow from Plesetsk. The primary payload of the mission is deployment of the Bion M-1 biological research satellite. Bion M-1 will carry an assortment of organisms including lizards, mice and snails for a one month mission to study the effects of a long duration spaceflight on micro-organisms.
The Bion M-1 mission will also deploy the AIST microsatellite built by students of Samara Aerospace University, & BeeSats 2 & 3 provided by the Technical University of Berlin. A twin of the Dove-1 satellite launching on Antares named Dove-2 is also onboard.
One of the micro-satellites named OSSI-1 is of particular interest to backyard satellite trackers. Part of the Open Source Satellite Initiative, OSSI-1 was developed by radio amateur and artist Hojun Song. In addition to a Morse Code beacon, OSSI-1 will also contain a 44 watt optical LED beacon that will periodically be visible to observers on Earth.
Another similar project, FITSAT-1, has been tracked and imaged by observers in recent months. Follow the AmSat-UK website for predictions and visibility prospects of OSSI-1 after launch and deployment. FITSAT-1 has been visible with binoculars only, but OSSI-1 may just be visible to the unaided eye during shadow passes while it’s operational.
It will be interesting to watch these “home-brewed” projects take to orbit. The price tag and the technology is definitely within reach of a sufficiently motivated basement tinker or student team with an idea. Hey, how about the world’s first free-flying “Amateur Space Telescope?” Just throwing that out there!
A team of astronomers has used ALMA (the Atacama Large Millimeter/submillimeter Array) to pinpoint the locations of over 100 of the most fertile star-forming galaxies in the early Universe. Credit:: ALMA (ESO/NAOJ/NRAO), J. Hodge et al., A. Weiss et al., NASA Spitzer Science Center
In a scenario where millions of years are considered a short period of time, hours are barely a blink of an eye. While it might take ten years or more to observe a group of galaxies with a modicum of detail for telescopes around the world, the Atcama Large Millimeter/submillimeter Array (ALMA) telescope was able to do the job at amazing speed. In just a matter of hours, a team of astronomers using this super-powerful telescope homed in on the location of over a hundred star-forming galaxies in the early Universe.
Once upon a time, huge amounts of star birth occurred in early galaxies which were rich in cosmic dust. Studying these galaxies is imperative to our understanding of galactic formation and evolution – but it has proved difficult in visible light because the very dust which supports star formation also cloaks the galaxies in which they are formed. However, thanks to telescopes like ALMA, we’re able to identify and observe these galaxies by focusing on longer wavelengths. Light that comes in around one millimetre is the perfect playground for such study.
“Astronomers have waited for data like this for over a decade. ALMA is so powerful that it has revolutionised the way that we can observe these galaxies, even though the telescope was not fully completed at the time of the observations,” said Jacqueline Hodge (Max-Planck-Institut für Astronomie, Germany), lead author of the paper presenting the ALMA observations.
Just how do we know where these galaxies are located? Through the use of the ESO-operated Atacama Pathfinder Experiment telescope (APEX), astronomers were able to map these dust obscured targets to a certain degree. APEX focused its capabilities on an area of sky about the size of the full Moon in the constellation of Fornax. The study – Chandra Deep Field South – has been taken on by a variety of telescopes located both here on Earth and in space. Here is where APEX has been credited with locating 126 dusty galaxies. However, these images aren’t all they could be. Star forming areas appeared as blobs and sometimes could over-ride better images made at other wavelengths. Through the use of ALMA, these observations have been augmented, furthering the resolution in the millimetre/submillimetre portion of the spectrum and assisting astronomers in knowing precisely which galaxies are forming stars.
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This video sequence starts with a broad view of the sky, including the famous constellation of Orion (The Hunter). We gradually close in on an unremarkable patch of sky called the Chandra Deep Field South that has been studied by many telescopes on the ground and in space. Credit: ALMA (ESO/NAOJ/NRAO), APEX (MPIfR/ESO/OSO), J. Hodge et al., A. Weiss et al., NASA Spitzer Science Center, Digitized Sky Survey 2, and A. Fujii. Music: Movetwo
As all backyard astronomers know, the larger the aperture – the better the resolution. To improve their observations of the early Universe, astronomers needed a bigger telescope. APEX consists of a twelve meter diameter dish-shaped antenna, but ALMA consists of many dishes spread over long distances. The signals from all of its parts are then combined and the result is the same as if it were a giant telescope which measured the same size as the entire array. A super dish!
With the assistance of ALMA, the astronomers then took on the galaxies from the APEX map. Even though the ALMA array is still under construction and using less than a quarter of its capabilities, the team was able to complete this beginning phase of scientific observations. Speedy ALMA was up to the task. At only two minutes per galaxy, this “Super Scope” was able to resolve each one within a minuscule area two hundred times smaller than the original APEX blobs… and with 300% more sensitivity! With a track record like that, ALMA was able to double the number of observations in a matter of hours. Now the researchers were able to clearly see which galaxies contained active star forming regions and distinguish cases where multiple star-forming galaxies had melded to appear as one in earlier studies.
“We previously thought the brightest of these galaxies were forming stars a thousand times more vigorously than our own galaxy, the Milky Way, putting them at risk of blowing themselves apart. The ALMA images revealed multiple, smaller galaxies forming stars at somewhat more reasonable rates,” said Alexander Karim (Durham University, United Kingdom), a member of the team and lead author of a companion paper on this work.
Apparently ALMA is going to be a huge success. These new observations have helped to confidently document dusty star-forming galaxies from the early Universe and help to create a more detailed catalog than ever before. These new findings will assist future astronomical observations by giving researchers a reliable base on these galaxies’ properties at different wavelengths. No longer will astronomers have to “guess” at which galaxies may have melded together in images… ALMA has made it clear. However, don’t rule out the use of other venues such as APEX. The combination of both play a powerful part in observing the early Universe.
“APEX can cover a wide area of the sky faster than ALMA, and so it’s ideal for discovering these galaxies. Once we know where to look, we can use ALMA to locate them exactly,” concluded Ian Smail (Durham University, United Kingdom), co-author of the new paper.
The galaxy HFLS3 appears as a small red dot in these Herschel submillimeter images (main image, and panels on right). Subsequent observations with ground-based telescopes, ranging from optical to millimeter wavelengths (insets), revealed two galaxies appearing very close together. The two are actually at very different distances, however, and HFLS3 (blue, in millimeter wavelengths) is so far away that we are seeing it as it was when the universe was just 880 million years old. Credit: ESA/Herschel/HerMES/IRAM/GTC/W.M. Keck Observatory.
Most of the early galaxies that astronomers have been able to observe are small with a low-to-moderate amount of star production. But now the Herschel Space Observatory has found a massive dust-filled galaxy churning out stars at an incredible rate, with all of this taking place back when the cosmos was a just 880 million years old. The galaxy is about as massive as our Milky Way, but produces stars at a rate 2,000 times greater, prompting the researchers to call it a “maximum-starburst” galaxy.
The astronomers involved in its discovery say its mere existence challenges our theories of galaxy evolution.
“Massive, intense starburst galaxies are expected to only appear at later cosmic times,” says Dominik Riechers, currently an assistant professor at Cornell. “Yet, we have discovered this colossal starburst just 880 million years after the Big Bang, when the universe was at little more than 6 percent of its current age. Riechers is the first author of the paper describing the findings in the April 18 issue of the journal Nature.
The prevailing thought on early galaxy and star formation has been that the first galaxies to form were relatively small and lightweight, containing only a few billion times the mass of our Sun. They form their first stars at rates of a few times that experienced by the Milky Way today, and the galaxies would grow by merging with other small galaxies. In theory, galaxies as massive as the newly found galaxy – named HFLS3 — should not be present so soon after the Big Bang.
HFLS3 appears as little more than a faint, red smudge in images from the Herschel Multi-tiered Extragalactic Survey (HerMES).
The extreme distance to HFLS3 means that its light has travelled for almost 13 billion years across space before reaching us. We therefore see it as it existed in the infant Universe, just 880 million years after the Big Bang or at 6.5% of the Universe’s current age.
This artist’s impression shows the “starburst” galaxy HFLS3. The galaxy appears as little more than a faint, red smudge in images from the Herschel space observatory. Image credit: ESA-C. Carreau.
Even at that young age, HFLS3 was already close to the mass of the Milky Way, with roughly 140 billion times the mass of the Sun in the form of stars and star-forming material. After another 13 billion years, it should have grown to be as big as the most massive galaxies known in the local Universe.
“Looking for the first examples of these massive star factories is like searching for a needle in a haystack; the Herschel dataset is extremely rich,” said Riechers.
Tens of thousands of massive, star-forming galaxies have been detected by Herschel as part of HerMES and sifting through them to find the most interesting ones is a challenge.
“This particular galaxy got our attention because it was bright, and yet very red compared to others like it,” said co-investigator Dave Clements of Imperial College London.
While the discovery of this single galaxy isn’t enough to overturn current theories of galaxy formation, finding more galaxies like this one could challenge those theories, the astronomers say. At the very least, theories will have to be modified to explain how this galaxy formed, Riechers says.
“This galaxy is just one spectacular example, but it’s telling us that extremely vigorous star formation was possible early in the universe,” says Jamie Bock, professor of physics at Caltech and a coauthor of the paper.
