The space between the galaxies is expanding. How big is it? Credit: NASA/HST
Did some of the oldest galaxies grow up quickly? That’s an intriguing possibility raised by a research team that found “mature” galaxies some 12 billion light years away, when the universe was less than 2 billion years old.
“Today the universe is old and filled with galaxies that have largely stopped forming stars, a sign of galactic maturity,” stated Caroline Straatman from the Netherlands’ Leiden University, a graduate student who led the research. “However, in the distant past, galaxies were still actively growing by consuming gas and turning it into stars. This means that mature galaxies are expected to be almost non-existent when the universe was still young.”
Using data from the Magellan Baade Telescope’s FourStar Galaxy Evolution Survey and combining with other observatories, researchers looked at the young universe using near infrared wavelengths and found 15 galaxies at an average of 12 billion light-years away. While the galaxies are faint using visual wavelengths, they were easy to spot in infrared — and hosted as many as 100 billion stars per galaxy, on average.
The Milky Way over the ESO 3.6-metre Telescope, a photo submitted via Your ESO Pictures Flickr Group. Credit: ESO/A. Santerne
These galaxies each have a similar mass to the Milky Way, but stopped making stars when the universe was “only 12 percent of its current age”, researchers said. This implies that star-forming happened much more quickly in the past than right now, since the rate is estimated at several hundred times higher than what is observed in the Milky Way now.
It’s not clear what caused the rapid aging, but you can be sure researchers will look into this further. You can read the research in Astrophysical Journal Letters or in preprint version on Arxiv. Other databases used include Hubble’s Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey and the Great Observatories Origins Deep Survey.
Like many kids his age, 4-year-old Lucas Whiteley is fascinated about space and astronauts and has a lot of questions to ask. Unlike most kids, though, Lucas got his answers directly from a NASA engineer, with a custom-made video no less!
Multi-wavelength view of the elliptical galaxy NGC 5044. Credit: Digitised Sky Survey/NASA Chandra/Southern Observatory for Astrophysical Research/Very Large Array (Robert Dunn et al. 2010)
Contradicting past theories, cold gas has been found in abundance in some elliptical galaxies — showing that there must be some other explanation why these types of galaxies don’t form new stars. Astronomers believe that the jets from supermassive black holes in these galaxies’ center must push around the gas and prevent stars from forming.
Researchers spotted the gas for the first time using old data from the recently retired Herschel space observatory, which was able to peer well into the infrared — where it spotted carbon ions and oxygen atoms. This find stands against the previous belief that these galaxies were “red and dead”, referring to their physical appearance and the fact that they form no new stars.
“We looked at eight giant elliptical galaxies that nobody had looked at with Herschel before and we were delighted to find that, contrary to previous belief, six out of eight abound with cold gas”, stated Norbert Werner, a researcher at Stanford University in California who led the study.
“These galaxies are red, but with the giant black holes pumping in their hearts, they are definitely not dead,” added Werner.
NGC 1399, an elliptical galaxy about 65 million light years from Earth. Credit: NASA, Chandra
Previously, scientists thought that the galaxies got rid of their cold gas or had used it all up during a burst of earlier star formation. With cold gas found in the majority of the sample, researchers then used other observatories to try to find warmer gas up to tens of millions of Kelvin (or Fahrenheit or Celsius).
X-ray information from NASA’s Chandra X-ray Observatory revealed that there is hot gas cooling in six of the eight galaxies, but not in the remaining two of the sample.
“This is consistent with theoretical expectations: once cooled, the hot gas would become the warm and cold gas that are observed at longer wavelengths. However, in these galaxies the cooling process somehow stopped, and the cold gas failed to condense and form stars,” the European Space Agency stated.
“While the six galaxies with plenty of cold gas harbour moderately active black holes at their centres,” ESA added, “the other two show a marked difference. In the two galaxies without cold gas, the central black holes are accreting matter at frenzied pace, as confirmed by radio observations showing powerful jets of highly energetic particles that stem from their cores.”
The speeding rogue star Kappa Cassiopeiae sets up a glowing bow shock in this Spitzer image (NASA/JPL-Caltech)
That might seem like a sensational headline worthy of a supermarket tabloid but, taken in context, it’s exactly what’s happening here!
The bright blue star at the center of this image is a B-type supergiant named Kappa Cassiopeiae, 4,000 light-years away. As stars in our galaxy go it’s pretty big — over 57 million kilometers wide, about 41 times the radius of the Sun. But its size isn’t what makes K Cas stand out — it’s the infrared-bright bow shock it’s creating as it speeds past its stellar neighbors at a breakneck 1,100 kilometers per second.
K Cas is what’s called a runway star. It’s traveling very fast in relation to the stars around it, possibly due to the supernova explosion of a previous nearby stellar neighbor or companion, or perhaps kicked into high gear during a close encounter with a massive object like a black hole.
As it speeds through the galaxy it creates a curved bow shock in front of it, like water rising up in front of the bow of a ship. This is the ionized glow of interstellar material compressed and heated by K Cas’ stellar wind. Although it looks like it surrounds the star pretty closely in the image above, the glowing shockwave is actually about 4 light-years out from K Cas… slightly less than the distance from the Sun to Proxima Centauri.
The bow shock of Zeta Ophiuchi, another runaway star observed by Spitzer (NASA/JPL-Caltech)
Although K Cas is visible to the naked eye, its bow shock isn’t. It’s only made apparent in infrared wavelengths, which NASA’s Spitzer Space Telescope is specifically designed to detect. Some other runaway stars have brighter bow shocks — like Zeta Ophiuchi at right — which can be seen in optical wavelengths (as long as they’re not obscured by dust, which Zeta Oph is.)
The bright wisps seen crossing K Cas’ bow shock may be magnetic filaments that run throughout the galaxy, made visible through interaction with the ionized gas. In fact bow shocks are of particular interest to astronomers precisely because they help reveal otherwise invisible features and allow deeper investigation into the chemical composition of stars and the regions of the galaxy they are traveling through. Like a speeding car on a dark country road, runaway stars’ bow shocks are — to scientists — like high-beam headlamps lighting up the space ahead.
Runaway stars are not to be confused with rogue stars, which, although also feel the need for speed, have been flung completely out of their home galaxies.
Artist's impression of an asteroid breaking up. Credit: NASA/JPL-Caltech
When you throw a bunch of rock and debris at a rapidly spinning star, what happens? A new study suggests that so-called pulsar stars change their dizzying spin rate as asteroids fall into the gaseous mass. This conclusion comes from observations of one pulsar (PSR J0738-4042) that is being “pounded” with debris from rocks, researchers said.
Lying 37,000 light-years from our planet in the southern constellation Puppis, this supernova remnant’s environment is swarming with rocks, radiation and “winds of particles”. One of those rocks likely was more than a billion metric tonnes in mass, which is nowhere near the mass of Earth (5.9 sextillion tonnes), but is still substantial.
“If a large rocky object can form here, planets could form around any star. That’s exciting,” stated Ryan Shannon, a researcher with the Commonwealth Scientific and Industrial Research Organisation who participated in the study.
Pulsars are sometimes called the clocks of the universe because their spins, fast as they are, precisely emit radio beams with each revolution — a beam that can be seen from Earth if our planet and the star are aligned in the right way. A 2008 study by Shannon and others predicted the spin could be altered by debris falling into the pulsar, which this new research appears to confirm.
Artist’s conception of stellar rubble around pulsar 4U 0142+61. Credit: NASA/JPL-Caltech
“We think the pulsar’s radio beam zaps the asteroid, vaporizing it. But the vaporized particles are electrically charged and they slightly alter the process that creates the pulsar’s beam,” Shannon said.
As stars explode, the researchers further suggest that not only do they leave behind a pulsar star remnant, but they also throw out debris that could then fall back towards the pulsar and create a debris disc. Another pulsar, J0146+61, appears to display this kind of disc. As with other protoplanetary systems, it’s possible the small bits of matter could gradually clump together to form bigger rocks.
You can read the study in Astrophysical Journal Letters or in preprint version on Arxiv. The study was led by Paul Brook, a Ph.D. student co-supervised by the University of Oxford and CSIRO. Observations were performed with the Hartebeesthoek Radio Astronomy Observatory in South Africa, and CSIRO’s Parkes radio telescope.
Wow. It’s always amazing to get new views of familiar sky targets. And you always know that a “feast for the eyes” is in store when astronomers turn a world-class instrument towards a familiar celestial object.
Such an image was released this morning from the European Southern Observatory (ESO). Astronomers turned ESO’s 2.2-metre telescope towards Messier 7 in the constellation Scorpius recently, and gave us the star-studded view above.
Also known as NGC 6475, Messier 7 (M7) is an open cluster comprised of over 100 stars located about 800 light years distant. Located in the curved “stinger” of the Scorpion, M7 is a fine binocular object shining at a combined magnitude of about +3.3. M7 is physically about 25 light years across and appears about 80 arc minutes – almost the span of three Full Moons – in diameter from our Earthly vantage point.
One of the most prominent open clusters in the sky, M7 lies roughly in the direction of the galactic center in the nearby astronomical constellation of Sagittarius. When you’re looking towards M7 and the tail of Scorpius you’re looking just south of the galactic plane in the direction of the dusty core of our galaxy. The ESO image reveals the shining jewels of the cluster embedded against the more distant starry background.
Messier 7 is middle-aged as open clusters go, at 200 million years old. Of course, that’s still young for the individual stars themselves, which are just venturing out into the galaxy. The cluster will lose about 10% of its stellar population early on, as more massive stars live their lives fast and die young as supernovae. Our own solar system may have been witness to such nearby cataclysms as it left its unknown “birth cluster” early in its life.
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Other stars in Messier 7 will eventually mature, “join the galactic car pool” in the main sequence as they disperse about the plane of the galaxy.
But beyond just providing a pretty picture, studying a cluster such as Messier 7 is crucial to our understanding stellar evolution. All of the stars in Messier 7 were “born” roughly around the same time, giving researchers a snapshot and a chance to contrast and compare how stars mature over there lives. Each open cluster also has a unique spectral “fingerprint,” a chemical marker that can even be used to identify the pedigree of a star.
For example, there’s controversy that the open cluster Messier 67 may actually be the birth place of our Sun. It is interesting to note that the spectra of stars in this cluster do bear a striking resemblance in terms of metallicity percentage to Sol. Remember, metals in astronomer-speak is any element beyond hydrogen and helium. A chief objection to the Messier 67 “birth-place hypothesis” is the high orbital inclination of the open cluster about the core of our galaxy: our Sun would have had to have undergone a series of improbable stellar encounters to have ended up its current sedate quarter of a billion year orbit about the Milky Way galaxy.
Still, this highlights the value of studying clusters such as Messier 6. It’s also interesting to note that there’s also data in what you can’t see in the above image – dark gaps are thought to be dust lanes and globules in the foreground. Though there is some thought that this dust is debris that may also be related to the cluster and may give us clues as to its overall rotation, its far more likely that these sorts of “dark spirals” related to the cluster have long since dispersed. M7 has completed about one full orbit about the Milky Way since its formation.
Another famous binocular object, the open cluster Messier 6 (M6) also known as the Butterfly Cluster lies nearby. Messier 7 also holds the distinction as being the southernmost object in Messier’s catalog. Compiled from Parisian latitudes, Charles Messier entirely missed southern wonders such as Omega Centauri in his collection of deep sky objects that were not to be mistaken for comets. We also always thought it curious that he included such obvious “non-comets” such as the Pleiades, but missed fine northern sky objects as the Double Cluster in the northern constellation Perseus.
Finding Messier 6: the view from latitude 30 degrees north before dawn in mid-February. Credit: Stellarium.
Messier 7 is also sometimes called Ptolemy’s Cluster after astronomer Claudius Ptolemy, who first described it in 130 A.D. as the “nebula following the sting of Scorpius.” The season for hunting all of Messier’s objects in an all night marathon is coming right up in March, and Messier 7 is one of the last targets on the list, hanging high due south in the early morning sky.
Interested in catching how Messier 7 will evolve, or might look like up close? Check out Messier 45 (the Pleiades) and the V-shaped Hyades high in the skies in the constellation Taurus at dusk to see what’s in store as Messier 7 disperses, as well as the Ursa Major Moving Group.
And be sure to enjoy the fine view today of Messier 7 from the ESO!
Got pics of Messier 7 or any other deep sky objects? Send ’em, in to Universe Today!
Artist's impression of brown dwarf ULAS J222711-004547, which has a very thick cloud layer of mineral dust. The dust is making the brown dwarf appear redder than its counterparts. Credit: Neil J. Cook, Centre for Astrophysics Research, University of Hertfordshire
Dust clouds on a brown dwarf or “failed star” are making it appear redder than its counterparts, new research reveals. Better studying this phenomenon could improve the weather forecast on these objects, which are larger than gas giant planets but not quite big enough to ignite nuclear fusion processes to become stars.
“These are not the type of clouds that we are used to seeing on Earth. The thick clouds on this particular brown dwarf are mostly made of mineral dust, like enstatite and corundum,” stated Federico Marocco, who led the research team and is an astrophysicist at the United Kingdom’s University of Hertfordshire.
Using the Very Large Telescope in Chile as well as data analysis, “not only have we been able to infer their presence, but we have also been able to estimate the size of the dust grains in the clouds,” he added.
The brown dwarf (known as ULAS J222711-004547) has an unusual concoction in its atmosphere of water vapor, methane, (likely) ammonia and these mineral particles. While scientists are only beginning to wrap their head around what’s going on in the atmosphere, they noted that the size of the dust grains can influence the color of the sky and make it turn redder.
Size comparison of stellar vs substellar objects. (Credit: NASA/JPL-Caltech/UCB).
“Being one of the reddest brown dwarfs ever observed, ULAS J222711-004547 makes an ideal target for multiple observations to understand how the weather is in such an extreme atmosphere,” stated Avril Day-Jones, an astrophysicist at the University of Hertfordshire who co-authored the paper.
“By studying the composition and variability in luminosity and colours of objects like this, we can understand how the weather works on brown dwarfs and how it links to other giant planets.”
Starbursts in M82 as seen as radio frequencies from the by the Karl G. Jansky Very Large Array. Credit: Josh Marvil (NM Tech/NRAO), Bill Saxton (NRAO/AUI/NSF), NASA
Radio light, radio bright: when you look at M82 in this frequency range, a whole lot of activity pops out. The “Cigar Galaxy” is just 12 million light-years away from Earth and these days, is best known for hosting a supernova or star explosion so bright that amateurs can spot it in a small telescope.
Take a big radio telescope and peer at the galaxy’s center, and a violent picture emerges. Bright star nurseries and supernova leftovers are visible in this image from the Karl G. Jansky Very Large Array (the scientists can tell those apart using other data from the telescope.)
“The radio emission seen here is produced by ionized gas and by fast-moving electrons interacting with the interstellar magnetic field,” the National Radio Astronomy Observatory stated.
Most intriguing to scientists in this picture are the streamers of material in this area of M82, which is about 5,200 light-years across in the pictured central region. These previously undetected “wispy features” could be related to “superwind” coming from all this stellar activity, but scientists are still examining the link.
By the way, Supernova SN 2014J is not visible in this image because it is not active in radio waves. You can check out optical pictures of it, however, at this past Universe Today story.
Think the weather is nasty this winter here on Earth? Try vacationing on the brown dwarf Luhman 16B sometime.
Two studies out this week from the Max Planck Institute for Astronomy based at Heidelberg, Germany offer the first look at the atmospheric features of a brown dwarf.
A brown dwarf is a substellar object which bridges the gap between at high mass planet at over 13 Jupiter masses, and a low mass red dwarf star at above 75 Jupiter masses. To date, few brown dwarfs have been directly imaged. For the study, researchers used the recently discovered brown dwarf pair Luhman 16A & B. At about 45(A) and 40(B) Jupiter masses, the pair is 6.5 light years distant and located in the constellation Vela. Only Alpha Centauri and Barnard’s Star are closer to Earth. Luhman A is an L-type brown dwarf, while the B component is a T-type substellar object.
“Previous observations have inferred that brown dwarfs have mottled surfaces, but now we can start to directly map them.” Ian Crossfield of the Max Planck Institute for Astronomy said in this week’s press release. “What we see is presumably patchy cloud cover, somewhat like we see on Jupiter.”
To construct these images, astronomers used an indirect technique known as Doppler imaging. This method takes advantage of the minute shifts observed as the rotating features on brown dwarf approach and recede from the observer. Doppler speeds of features can also hint at the latitudes being observed as well as the body’s inclination or tilt to our line of sight.
But you won’t need a jacket, as researchers gauge the weather on Luhman 16B be in the 1100 degrees Celsius range, with a rain of molten iron in a predominately hydrogen atmosphere.
The study was carried out using the CRyogenic InfraRed Echelle Spectrograph (CRIRES) mounted on the 8-metre Very Large Telescope based at the European Southern Observatory’s (ESO) Paranal observatory complex in Chile. CRIRES obtained the spectra necessary to re-construct the brown dwarf map, while backup brightness measurements were accomplished using the GROND (Gamma-Ray Burst Optical/Near-Infrared Detector) astronomical camera affixed to the 2.2 metre telescope at the ESO La Silla Observatory.
A closeup of the GROND instrument (the blue cylinder to the lower left) on the La Silla 2.2-metre telescope. Credit-ESO/European Organization for Astronomical Research in the Southern Hemisphere.
The next phase of observations will involve imaging brown dwarfs using the Spectro-Polarimetric High-contrast Exoplanet Research (SPHERE) instrument, set to go online at the Very Large Telescope facility later this year.
And that may just usher in a new era of directly imaging features on objects beyond our solar system, including exoplanets.
“The exciting bit is that this is just the start. With the next generations of telescopes, and in particular the 39-metre European Large Telescope, we will likely see surface maps of more distant brown dwarfs — and eventually, a surface map for a young giant planet,” said Beth Biller, a researcher previously based at the Max Planck Institute and now based at the University of Edinburgh. Biller’s study of the pair went even more in-depth, analyzing changes in brightness at different wavelengths to peer into the atmospheric structure of the brown dwarfs at varying depths.
“We’ve learned that the weather pattern on these brown dwarfs are quite complex,” Biller said. “The cloud structure of the brown dwarf varies quite strongly as a function of atmospheric depth and cannot be explained with single layer clouds.”
A rotational surface map of Luhman 16B Credit-ESO/I. Crossfield.
The paper on brown dwarf weather pattern map comes out today in the January 30th, 2014 edition of Nature under the title Mapping Patchy Clouds on a Nearby Brown Dwarf.
The brown dwarf pair targeted in the study was designated Luhman 16A & B after Pennsylvania State University researcher Kevin Luhman, who discovered the pair in mid-March, 2013. Luhman has discovered 16 binary systems to date. The WISE catalog designation for the system has the much more cumbersome and phone number-esque designation of WISE J104915.57-531906.1.
We caught up with the researchers to ask them some specifics on the orientation and rotation of the pair.
“The rotation period of Luhman 16B was previously measured watching the brown dwarf’s globally-averaged brightness changes over many days. Luhman 16A seems to have a uniformly thick layer of clouds, so it exhibits no such variation and we don’t yet know its period,” Crossfield told Universe Today. “We can estimate the inclination of the rotation axis because we know the rotation period, we know how big brown dwarfs are, and in our study, we measured the “projected” rotational velocity. From this, we know we must be seeing the brown dwarf near equator-on.”
The maps constructed correspond with an amazingly fast rotation period of just under 6 hours for Luhman 16B. For context, the planet Jupiter – one of the fastest rotators in our solar system – spins once every 9.9 hours.
“The rotational period of Luhman 16B is known from 12 nights of variability monitoring,” Biller told Universe Today. “The variability in the B component is consistent with the results from 2013, but the A component has a lower amplitude of variability and a somewhat different rotational period of maybe 3-4 hours, but that is still a very tentative result.”
This first mapping of the cloud patterns on a brown dwarf is a landmark, and promises to provide a much better understanding of this transitional class of objects.
Couple this announcement with the recent nearby brown dwarf captured in a direct image, and its apparent that a new era of exoplanet science is upon us, one where we’ll not only be able to confirm the existence of distant worlds and substellar objects, but characterize what they’re actually like.
Arp 147 contains a spiral galaxy (right) that collided with an elliptical galaxy (left), triggering a wave of star formation. Credit: X-ray: NASA/CXC/MIT/S.Rappaport et al, Optical: NASA/STScI
Like millionaires that burn through their cash too quickly, astronomers have found one factor behind why compact elliptical galaxies stopped growing stars about 11 billion years ago: they ate through their gas reserves.
The revelation comes as researchers released a new evolutionary track for compact elliptical galaxies that stopped their star formation when the universe was just three billion years old. When these galaxies ran out of gas, some of them cannibalized smaller galaxies to create giant elliptical galaxies. The “burned-out”galaxies have stars crowding 10 to 100 times more densely than elliptical galaxies formed more recently through a different evolutionary track.
“We at last show how these compact galaxies can form, how it happened, and when it happened. This basically is the missing piece in the understanding of how the most massive galaxies formed, and how they evolved into the giant ellipticals of today,” stated Sune Toft, who led the study and is a researcher at the Dark Cosmology Center at the Niels Bohr Institute in Copenhagen.
“This had been a great mystery for many years, because just three billion years after the Big Bang we see that half of the most massive galaxies have already completed their star formation.”
How massive elliptical galaxies evolved in about 13 billion years. Credit: NASA, ESA, S. Toft (Niels Bohr Institute), and A. Feild (STScI)
The team got a snapshot of these galaxies’ evolution by looking at a representative sample with the Hubble Space Telescope, specifically through the Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey (CANDELS) and a spectroscopic survey called 3D-HST. To find out how old the stars were, they combined the Hubble work with data gathered from the Spitzer Space Telescope and the Subaru Telescope in Hawaii.
Next, they examined ancient, fast-star-forming submillimeter galaxies with data gathered from a range of space and ground-based telescopes.
The Hubble Space Telescope. image credit: NASA, tweaked by D. Majaess.
“This multi-spectral information, stretching from optical light through submillimeter wavelengths, yielded a full suite of information about the sizes, stellar masses, star-formation rates, dust content, and precise distances of the dust-enshrouded galaxies that were present early in the universe,” Hubble’s news center stated.
The group found that that the submillimeter galaxies were likely “progenitors” of compact elliptical galaxies, as they share predicted characteristics of the ancestors. Further, researchers calculated that starbursts in submillimeter galaxies only went on for about 40 million years before the galaxies ran out of gas.
