Tracks from the Curiosity rover are visible from orbit to the HiRISE camera on the Mars Reconnaissance Orbiter. Credit: NASA/JPL/University of Arizona.
Amazing, the things a birds-eye view allows you to see. Here’s a color image from the HiRISE camera on board the Mars Reconnaissance Orbiter showing the tracks of the Curiosity rover. In this most recent HiRISE image of the MSL rover, the tracks are visible from Yellowknife Bay to its location on 11 December 2013, several kilometers to the southwest. Even though some of these tracks are more than a year old, they are still visible.
As HiRISE team member Christian Schaller said via Twitter, “Take only pictures; leave only footprints.” In this case, HiRISE took the pictures while MSL left the footprints!
HiRISE principal investigator Alfred McEwen explained the image: “Curiosity is progressing from the bright dust-covered area to a region with a darker surface, where saltating sand keeps the surface relatively free of dust. The scenery seen by the rover will be getting more interesting as it progresses toward Mount Sharp.”
See a black and white image below, where you can actually see Curiosity, too:
Can you spot the Curiosity rover from orbit? Credit: NASA/JPL/University of Arizona.
See more details on these images, as well as get access to higher resolution versions at the HiRISE website. You can see a collection of images of Curiosity taken by HiRISE here.
An artist's conception of ESA's Rosetta and Philae spacecraft approaching comet 67P/Churyumov-Gerasimenko. (Credit: ESA-J. Huart, 2013)
On January 20, 2014 it will be time for the snoozing Rosetta spacecraft to awaken from 31 months of hibernation. Through an online contest, ESA has been looking for a little help in sending a wake-up call to the spacecraft, which will be 673 million kilometers from Earth. The “Wake Up Rosetta!” video contest has yielded some heartwarming, funny, and creative videos from families, school children and more. Here are a few of our favorites, and you can go to the contest’s Facebook page to find out how to submit your own video, as well as see more videos and vote for your favorite.
The top ten vote-getting videos will be transmitted out to Rosetta via one of ESA’s deep-space tracking stations, and there are additional prizes as well, including the top two video creators will be invited to the control center in Darmstadt, Germany for when the Philae lander attempts landing on comet 67P/Churyumov–Gerasimenko in November 2014 after latching on with a harpoon.
ESA themselves have come up with a video story of the Rosetta mission and how it will be awakened:
Find out more about Rosetta’s mission here, and the contest here.
An illustration of the triple millisecond pulsar with its two white dwarf companions. According to the new model, this remarkable system has survived three phases of mass transfer and a supernova explosion, and yet it remained dynamically stable. Credit: Thomas Tauris
If you’re looking for something truly unique, then check out the cosmic menage aux trois ferreted out by a team of international astronomers using the Green Bank Telescope (GBT). This unusual group located in the constellation of Taurus includes a pulsar which is orbited by a pair of white dwarf stars. It’s the first time researchers have identified a triple star system containing a pulsar and the team has already employed the clock-like precision of the pulsar’s beat to observe the effects of gravitational interactions.
“This is a truly remarkable system with three degenerate objects. It has survived three phases of mass transfer and a supernova explosion, and yet it remained dynamically stable”, says Thomas Tauris, first author of the present study. “Pulsars have previously been found with planets and in recent years a number of peculiar binary pulsars were discovered which seem to require a triple system origin. But this new millisecond pulsar is the first to be detected with two white dwarfs.”
This wasn’t just a chance discovery. The observations of 4,200 light year distant J0337+1715 came from an intensive study program involving several of the world’s largest radio telescopes including the GBT, the Arecibo radio telescope in Puerto Rico, and ASTRON’s Westerbork Synthesis Radio Telescope in the Netherlands. West Virginia University graduate student Jason Boyles was the first to detect the millisecond pulsar, spinning nearly 366 times per second, and captured in a system which isn’t any larger than Earth’s orbit around the Sun. This close knit association, coupled with the fact the trio of stars is far denser than the Sun create the perfect conditions to examine the true nature of gravity. Generations of scientists have waited for such an opportunity to study the ‘Strong Equivalence Principle’ postulated in Einstein’s theory of General Relativity. “This triple star system gives us the best-ever cosmic laboratory for learning how such three-body systems work, and potentially for detecting problems with General Relativity, which some physicists expect to see under such extreme conditions,” says first author Scott Ransom of the National Radio Astronomy Observatory (NRAO).
“It was a monumental observing campaign,” comments Jason Hessels, of ASTRON (the Netherlands Institute for Radio Astronomy) and the University of Amsterdam. “For a time we were observing this pulsar every single day, just so we could make sense of the complicated way in which it was moving around its two companion stars.” Hessels led the frequent monitoring of the system with the Westerbork Synthesis Radio Telescope.
Not only did the research team tackle a formidable amount of data, but they also took on the challenge of modeling the system. “Our observations of this system have made some of the most accurate measurements of masses in astrophysics,” says Anne Archibald, also from ASTRON. “Some of our measurements of the relative positions of the stars in the system are accurate to hundreds of meters, even though these stars are about 10,000 trillion kilometers from Earth” she adds.
Leading the study, Archibald created the system simulation which predicts its motions. Using the solid science methods once employed by Isaac Newton to study the Earth-Moon-Sun system, she then combined the data with the ‘new’ gravity of Albert Einstein, which was necessary to make sense of the information. “Moving forward, the system gives the scientists the best opportunity yet to discover a violation of a concept called the Strong Equivalence Principle. This principle is an important aspect of the theory of General Relativity, and states that the effect of gravity on a body does not depend on the nature or internal structure of that body.”
Need a refresher on the equivalence principle? Then if you don’t remember Galileo’s dropping two different weighted balls from the Leaning Tower of Pisa, then perhaps you’ll recall Apollo 15 Commander Dave Scott’s dropping of a hammer and a falcon feather while standing on the airless surface of the Moon in 1971. Thanks to mirrors left on the lunar surface, laser ranging measurements have been studied for years and provide the strongest constraints on the validity of the equivalence principle. Here the experimental masses are the stars themselves, and their different masses and gravitational binding energies will serve to check whether they all fall towards each other according to the Strong Equivalence Principle, or not. “Using the pulsar’s clock-like signal we’ve started testing this,” Archibald explains. “We believe that our tests will be much more sensitive than any previous attempts to find a deviation from the Strong Equivalence Principle.” “We’re extremely happy to have such a powerful laboratory for studying gravity,” Hessels adds. “Similar star systems must be extremely rare in our galaxy, and we’ve luckily found one of the few!”
At the break of dawn the southern Milky Way is photographed over Mount Kilimanjaro, as seen from Amboseli National Park, Kenya. The Great Carina Nebula is the red cloud at top. Constellation Crux or the Southern Cross appear on the left. On the Earth is the second peak of Mount Kilimanjaro reaching 5149 m high, known as Mawenzi (meaning the moon in Swahili). Credit and copyright: Babak A. Tafreshi.
You might find yourself humming Paul Simon’s “Under African Skies” after seeing these stunning images! The World At Night photographer Babak Tafreshi has just returned from a trip to Kenya and has amassed a gorgeous collection of astrophotography showing Mt. Kilimanjaro by night (and some in the day, as well). Below you can see a panoramic view of Kilimanjaro in the moonlight, flanked by giraffes (can you spot the zebra, too?) and starry skies.
“His path was marked by the stars in the southern hemisphere
and he walked his days under African skies…”
Giraffes and acacia trees against the spectacular moonlit backdrop of Mount Kilimanjaro, as seen from Amboseli National Park, Kenya. The head of a zebra is also visible on the left. The main peak of Kilimanjaro is Kibo that reaches 5,895 m (19,341 ft). The smaller peak is Mawenzi at 5,149 m (16,893 ft) and meaning the moon in Swahili. Credit and copyright: Babak A. Tafreshi.
Want to get your astrophoto featured on Universe Today? Join our Flickr group or send us your images by email (this means you’re giving us permission to post them). Please explain what’s in the picture, when you took it, the equipment you used, etc.
A composite x-ray and optical image of a dwarf galaxy showing the x-ray transcient in the inset. Credit-CFHT (Optical), NASA/CXC/University of Alabama/GSCF/UMD/W.P. Maksym, D.Donato et al.
This week, astronomers announced the detection of a rare event, a star being torn to shreds by a massive black hole in the heart of a distant dwarf galaxy. The evidence was presented Wednesday January 8th at the ongoing 223rd meeting of the American Astronomical Society being held this week in Washington D.C.
Although other instances of the death of stars at the hands of black holes have been witnessed before, Chandra may have been the first to document an intermediate black hole at the heart of a dwarf galaxy “in the act”.
The results span observations carried out by the space-based Chandra X-ray observatory over a period spanning 1999 to 2005. The search is part of an archival study of observations, and revealed no further outbursts after 2005.
“We can’t see the star being torn apart by the black hole, but we can track what happens to the star’s remains,” said University of Alabama’s Peter Maksym in a recent press release. A comparison of with similar events seen in larger galaxies backs up the ruling of “death by black hole.” A competing team led by Davide Donato also looked at archival data from Chandra and the Extreme Ultraviolet Explorer (EUVE), along with supplementary observations from the Canada-France-Hawaii Telescope to determine the brightness of the host galaxy, and gained similar results.
The dwarf galaxy in the Abell 1795 cluster that was observed has the name WINGS J134849.88+263557.5, or WINGS J1348 for short. The Abell 1795 cluster is about 800 million light years distant.
WINGS denotes the galaxy’s membership in the WIde-field Nearby Galaxy-cluster Survey, and the phone number-like designation is the galaxy’s position in the sky in right ascension and declination.
Like most galaxies associated with galaxy clusters, WINGS J1348 a dwarf galaxy probably smaller than our own satellite galaxy known as the Large Magellanic Cloud. The Abell 1795 cluster is located in the constellation Boötes, and WINGS J1348 has an extremely faint visual magnitude of +22.46.
An optical view of the Abell 1795 galaxy cluster. Credit- NASA/CFHT/D. Donato et al.
“Scientists have been searching for these intermediate mass black holes for decades,” NASA’s Davide Donato said in a recent press release “We have lots of evidence for small black holes and very big ones, but these medium-sized ones have been tough to pin down.”
Maksym notes in an interview with Universe Today that this isn’t the first detection of an intermediate-mass black hole, which are a class of black holes often dubbed the “mostly” missing link between stellar mass and super massive black holes.
The mass range for intermediate black holes is generally pegged at 100 to one million solar masses.
What makes the event witnessed by Chandra in WINGS J1348 special is that astronomers managed to capture a rare tidal flare, as opposed to a supermassive black hole in the core of an active galaxy.
A closeup view of the bright, long duration flare witnessed by Chandra pre-2005. Credit- NASA/CXC/University of Alabama/W.P. Maksym et al.
“Most of the time, black holes eat very little, so they can hide very well,” Maksym said in the AAS meeting on Wednesday.
This discovery pushes the limits on what we know of intermediate black holes. By documenting an observed number of tidal flare events, it can be inferred that a number of inactive black holes must be lurking in galaxies as well. The predicted number of tidal events that occur also have implications for the eventual detection of gravity waves from said mergers.
And more examples of these types of X-ray flare events could be waiting to be uncovered in the Chandra data as well.
“Chandra has taken quite a few pictures over the past 13+ years, and collaborators and I have an ongoing program to look for more tidal flares,” Maksym told Universe Today. “We’ve found one other this way, from a larger galaxy, and hope to find more. Abell 1795 was a particularly good place to look because as a calibration source, there were tons of pictures.”
Use of Chandra data was also ideal for the study because its spatial resolution allowed researchers to pinpoint an individual galaxy in the cluster. Maksym also notes that while it’s hard to get follow-up observations of events based on archival data, future missions dedicated to X-ray astronomy with wider fields of view may be able to scour the skies looking for such tidal flaring events.
The NuSTAR satellite was the latest X-Ray observatory to launch in 2012. NASA’s Extreme Ultraviolet Explorer picked up a strong ultraviolet source in 1998 right around the time of the tidal flare event, and ESA’s XMM-Newton satellite may have detected the event in 2000 as well.
This was also one of the smallest galaxies ever observed to contain a black hole. Maksym noted in Wednesday’s press conference that an alternative explanation could be a super-massive black hole in a tiny galaxy that just “nibbled” on a passing star, but said that new data from the Gemini observatory does not support this.
“It would be like looking into a dog house and finding a large ogre crammed in there,” Maksym said at Wednesday’s press conference.
This discovery provides valuable insight into the nature of intermediate mass black holes and their formation and behavior. What other elusive cosmological beasties are lying in wait to be discovered in the archives?
Congrats to Maksym and teams on this exciting new discovery, and the witnessing of a rare celestial event!
Zodiacal light over Charleston, RI (Scott MacNeill, Frosty Drew Observatory)
The result of sunlight reflected off fine particles of dust aligned along the plane of the Solar System, zodiacal light appears as a diffuse, hazy band of light stretching upwards from the horizon after sunset or before sunrise. Most people have never seen zodiacal light because it’s very dim, and thus an extremely dark sky is required. But thanks to recent dark sky regulations that were passed in the coastal Rhode Island town of Charlestown, this elusive astronomical phenomenon has become visible — to the particular delight of one local observatory.
Frosty Drew Observatory is a small, privately-run observatory featuring a Meade Schmidt Cassegrain LX200 16″ telescope mounted on an alt-azimuth pier inside a dome that stands among the sports fields, parking areas, and nature trails of Ninigret Park and Wildlife Refuge in southern Rhode Island. Being a good distance from urban centers and developed areas, the skies there are some of the darkest in the state. But situated along the eastern seaboard of the United States, even Charlestown’s coast lies beneath a perpetual haze of light pollution.
A new town ordinance, passed in 2012, helped to darken the skies a notch. And while watching comet ISON one evening, astronomer Scott MacNeill became aware of the results.
The following is an excerpt from a Jan. 7 article by Cynthia Drummond of The Westerly Sun, reprinted with permission:
Scott MacNeill was in Ninigret Park, his telescope trained on the comet “Ison,” when he saw something he had never seen before: a celestial phenomenon called “zodiacal light.” After several decades of being obscured by light pollution, the feature was visible again, thanks to the town’s “dark sky” ordinance.
At first, MacNeill, an astronomer and the assistant director of the Frosty Drew observatory, didn’t believe what he was seeing. The cone of light, which he initially thought was light pollution, turned out to be a faint, white glow that astronomers at the observatory hadn’t glimpsed in recent memory.
A line of visitors is cast in silhouette against the evening sky as they wait to go into the Frosty Drew Observatory. (Susannah Snowden / The Westerly Sun)
“To see it in New England, period, is amazing, Zodiacal light is a common marker for the quality of a dark sky location.”
– Scott MacNeill, Astronomer, Frosty Drew Observatory
“I was sitting back for a minute, just looking at the sky, and I said ‘wait a minute. This is the southeast, and to the southeast is the ocean. What is coming up in the southeast?’ And then I noticed the cone. And I’m like ‘no way. That can’t be zodiacal light.’ I’ve heard so many stories about the days of old at Frosty Drew when you used to see zodiacal light here,” he said.
MacNeill credits Charlestown’s dark sky ordinance with reducing light pollution to the point where zodiacal light can be seen again. The ordinance, adopted in October 2012, regulates commercial outdoor lighting in order to improve the town’s dark sky for star-gazers, and to protect residents, wildlife and light-sensitive plants from the effects of light pollution.
One of the provisions of the ordinance requires that new lighting fixtures be designed to focus downward so light does not radiate up into the sky. Lighting installed before the ordinance was passed is exempt from the new regulations.
Building and Zoning Official Joe Warner explained that after the ordinance passed, two major sources of light pollution near the observatory were modified so they would be less polluting.
“At Ninigret Wildlife Refuge, some of the pole lights were changed to dark sky compliant lighting. The Charlestown Ambulance barn also replaced their lights with dark sky compliant lights,” he said.
Charlestown has been recognized as one of the only dark spots on the New England coast — a rare treat for people who enjoy looking at the night sky.
It’s fantastic to see results like this both occurring and being publicized, as dark skies have become quite rare in many populated areas of the world. People who live in or near major metropolitan areas — even in the surrounding sprawling suburbs — often never truly get a dark sky, not such that the dimmer stars, the Milky Way, meteor showers — and yes, the zodiacal light — can be readily seen on an otherwise clear night. The view of a star-filled night sky that has been a part of the human existence for millennia has steadily been doused by the murky glow of artificial lighting. Luckily groups like the International Dark Sky Association are actively trying to change that, but change isn’t always welcome — or quick.
At least, in one Rhode Island town anyway, a small victory has been won for the night.
(HT to Brown University’s Ladd Observatory in Providence for the heads-up on this story.)
Astronaut Rick Mastraccio works outside the International Space Station during a spacewalk on Dec. 24, 2013. Credit: NASA
NASA announced today that the Obama administration has approved NASA’s request for an extension of operations for the International Space Station for an additional four years to 2024. This means work on board the orbiting laboratory will continue at least for another decade.
“I think this is a tremendous announcement for us here in the space station world,” said Bill Gerstenmaier, associate administrator for NASA’s Human Exploration and Operations Mission Directorate, speaking during a press briefing today, “ and also for all of human spaceflight and for our international partnership.”
“This is a tremendous gift the administration has given us,” he added later.
Gerstenmaier said the extension allows NASA to expand their planning horizons, and it will change the way scientists and commercial companies look at their “investment” in the future of the ISS.
“We’re starting to see a lot of science benefits on ISS that have a lot of applications here on Earth, such as pharmaceuticals, materials processing, and climate change equipment, and operating until least 2024 opens up a large avenue of research on the ISS,” he said. “This also changes the perspective for commercial providers … as the commercial sector now has a larger market to carry cargo to space for NASA, as well as crew.”
Commercial Spaceflight Federation president and former astronaut Michael Lopez-Alegria agreed. “The International Space Station is the crown jewel of NASA’s human spaceflight program,” he said in a statement. “This extension comes at a critical time and paves the way for the ISS to fulfill its extensive and multifaceted potential – as a research lab that will provide countless benefits here on Earth, as an anchor destination for America’s commercial space race and as a jumping off point for deep space technology development and exploration.”
Gerstenmaier also sees the ISS as a proving ground for future human spaceflight plans to head out to deep space. “NASA doesn’t think of ISS and deep space human plans as separate, but as a combined strategy,” he said.
A recent review of ISS modules and equipment ensured that the station could likely last until 2028, and Gerstenmaier said this new extension allows operations to be at least considered until nearly 2030.
“Ten years from today is a far-reaching vision,” he said. “Our international partners are well aware of this extension and they were involved in hardware studies to see if station operations could extend. They will continue to evaluate their hardware and they all see this as a positive step in moving forward. … This is truly an international endeavor and we all work together.”
The International Space Station as seen from the crew of STS-119. (Credit: NASA).
Gerstenmeier added that it’s not immediately clear whether all of the 15 nations involved in the ISS along with the US will continue to participate for the duration of the life of the ISS, but that NASA is prepared to work with whatever plans the international partnership evolves into over time.
He said that no additional funding for the ISS was currently required for the extension, as the basic budget now covers the ISS to at least 2020, and the funds set aside for eventually deorbiting the ISS will be shifted towards operations.
Additional funding will likely be required at some point, however, but well past when the current Administration and Congress will be obligated to decide.
An exciting new discovery was unveiled early this week at the 223rd meeting of the American Astronomical Society being held in Washington D.C., when astronomers announced that a gravitational lens was detected for the first time at gamma-ray wavelengths.
The study was conducted using NASA’s Fermi Gamma Ray Space Telescope, and promises to open a new window on the universe, giving astrophysicists another tool to study the emission regions that exist near supermassive black holes.
But the hunt wasn’t easy. A gravitational lens occurs when a massive foreground object, such as a galaxy, bends the light from a distant background object. In the case of this study, researchers targeted a blazar known as B0218+357, a energetic source located 4.35 billion light years away in the direction of the constellation Triangulum.
Blazar and quasar sources are named using their respective coordinates in the sky. Think of “0218+357” as translating into “Right Ascension 2 Hours 18 Minutes, Declination +35.7 degrees north” in backyard astronomer-speak. A blazar is a compact form of quasar that results from a supermassive black hole at the heart of an active galaxy. The term blazar was first coined by Edward Spiegel in 1978. The first quasar discovered was 3C 273 in 1970, which was also later found to be a blazar. 3C 273 is visible in Virgo using a large backyard telescope.
A foreground spiral galaxy seen face on lies along our line of sight between our vantage point and B0218+357. At 4 billion light years distant, the two have the smallest angular separation of any gravitationally lensed system so far identified at less than a third of an arc second across.
“We began thinking about the possibility of making this observation a couple of years after Fermi launch, and all of the pieces finally came together in late 2012,” said Naval Research Laboratory astrophysicist and lead scientist on the study Teddy Cheung in a recent NASA Goddard Spaceflight Center press release.
Observations of the blazar suggested that it would be flaring in September 2012, making it a prime target for the study. In fact, B0218+357 was the brightest extra-galactic gamma-ray source at the time. Cheung was granted time spanning late September into October 2012 to use Fermi’s Large Area Telescope (LAT) instrument to study the blazar in outburst.
Fermi‘s LAT instrument doesn’t have the resolution possessed by radio and optical instruments to catch the blazar in single images. Instead, the team exploited a phenomenon known as the “delayed playback effect” to catch the blazar in action.
“One light path is slightly longer than the other, so when we detect flares in one image we try and catch them days later when they replay in the other image,” Said team member Jeff Scargle, astrophysicist based at NASA’s Ames Research Center.
Cheung presented the findings of the study Monday at the American Astronomical Society meeting, which included three distinct flaring episodes from the background blazar that demonstrated the tell-tale delayed playback events with a period spanning 11.46 days.
A Hubble Space Telescope image of the gravitational lensing of B0218+357. Credit: NASA/ESA and the Hubble Legacy Archive.
Follow-up observations in radio and optical wavelengths supported the key observations, and demonstrate that Fermi’s LAT imager did indeed witness the event. Interestingly, the delay for the gamma-rays from the lensed blazar takes about a day longer than radio waves to reach the Earth. B0218+357 is also about four times brighter in gamma-rays than in radio wavelengths.
This occurs because the gamma-rays are emanating from a slightly different region than radio waves generated by the blazar, and are taking a different path though the gravitational field of the foreground galaxy. This demonstrates that assets like Fermi can be used to probe the heart of the distant energetic galactic nuclei which harbor supermassive black holes. This opens the hot topic of gravitationally lensed blazars and their role in extra-galactic astronomy up to the gamma-ray spectrum, and gives cosmologists another gadget for their tool box.
“Over the course of a day, one of these flares can brighten the blazar by 10 times in gamma-rays but only 10 percent in visible light and radio, which tells us that the region emitting gamma-rays is very small compared to those emitting at lower energies,” Said Stockholm University team member Stefan Larsson in the recent press release.
Using the analysis of lensing systems at gamma-ray wavelengths will not only help to probe these enigmatic cosmological beasts, but it may also assist with refining the all-important Hubble Constant, which measures the rate at which the universe is expanding.
But Fermi may just beginning to show its stuff when it comes to hunting for extra-galactic sources. The really exciting breakthrough, researchers say, would be the discovery of an energetic extra-galactic source being lensed by a foreground galaxy in gamma-rays that hasn’t been seen been seen at other wavelengths. This recent finding has certainly demonstrated how Fermi can “see” these tell-tale flashes via a clever method. Expect more news in the coming years!
If you’re a frequent reader of Universe Today you know that, despite the end of the Shuttle program and the constant battle for a piece of the federal budget, NASA has a lot on their plate for future space exploration missions. But there are still a lot of people among the general public who think that the U.S. space administration is “dead,” or, at the very least, in the process of dying. Which is unfortunate because there’s actually a lot going on, both in space and in development on the ground.
The video above, released Monday by Johnson Space Center, shows highlights from 2013 as well as some of the many things NASA has in progress. As anyone can see, rumors of its death have been greatly exaggerated! (By whom I’m still not quite sure.)
Visit the Johnson Space Center site for more information and updates on current and future missions.
NASA's Hubble Space Telescope and Spitzer Space Telescope joined forces to discover and characterize four unusually bright galaxies as they appeared more than 13 billion years ago, just 500 million years after the big bang. Credit: NASA, ESA, G. Illingworth (University of California, Santa Cruz), P. Oesch (University of California, Santa Cruz; Yale University), R. Bouwens and I. Labbé (Leiden University), and the Science Team.
What was the Universe like more than 13 billion years ago, just 500 million years after the big bang? New data from the Hubble and Spitzer space telescopes reveal some surprisingly bright galaxies that are about 10 to 20 times more luminous than anything seen previously in that epoch.
Garth Illingworth from the University of California, Santa Cruz said the discovery of these four bright galaxies came from combining the power of both telescopes, but these galaxies lie right at the limit of the telescopes’ capabilities.
“We’re actually reaching back 13.2 billion years through the life of the Universe — that’s 96% of the life of the Universe that we are looking back at these galaxies,” said Illingworth, speaking at the American Astronomical Society meeting in Washington D.C. this week. “That’s an astonishing undertaking and an astonishing accomplishment that Hubble and Spitzer have achieved.”
Detail of the Hubble and Spitzer observations of a galaxy from the early Universe. Credit: NASA, ESA, G. Illingworth (University of California, Santa Cruz), P. Oesch (University of California, Santa Cruz; Yale University), R. Bouwens and I. Labbé (Leiden University), and the Science Team.
Illingworth said the typical galaxy candidate from that far back in time is very faint and hard to see. But these new galaxies are about 15-20 % brighter than what astronomers have seen before at redshift 10.
The tiny are bright because they are bursting with star formation activity. The brightest one is forming stars approximately 50 times faster than the Milky Way does today. Although these fledgling galaxies are only one-twentieth the size of the Milky Way, they probably contain around a billion stars crammed together.
Astronomers think these bright, young galaxies grew exceptionally fast because of interactions and mergers of smaller infant galaxies that started forming stars even earlier in the Universe. Since the ancient time billions of years ago when the light that we now see started its long journey to us, they have probably kept growing to become similar to the largest modern galaxies. Many of the stars of these infant galaxies likely live on today in the centers of giant elliptical galaxies, much larger even than our own Milky Way.
Slide from Garth Illingworth’s presentation at the 223rd American Astronomical Society meeting, describing the discovery of bright galaxies from early in the Universe. Credit: Garth Illingworth.
Illingworth said this era appears to be a timeframe where things were changing quite rapidly. “We’ve gone back to a very interesting time when the Universe is changing,” he said.
The galaxies were first detected with Hubble, and astronomers were able to measure their star-formation rates and sizes. But using Spitzer, the scientists were also able to measure the galaxies’ masses.
“This is the first-ever measurement of the mass density of the galaxies when the Universe was at 500 million years of age,” Illingworth said. “These galaxies are about a billion times the mass of our Sun, which is massive for those times, but still only 1% the mass of the Milky Way.”
Illingworth added that the mass measurements are rough estimates because of how challenging the task was.
Illingworth and team member Ivo Labbé from Leiden University said they are looking forward to finding out more about these galaxies, particularly from future observations with the upcoming James Webb Space Telescope.
“At the same time, the extreme masses and star formation rates are really mysterious,” Labbé said, “and we are eager to confirm them with future observations on our powerful telescopes.”
You can find out more about these early galaxies — and more — at the First Galaxies website.
