This image of Cep OB 3b was created by combining the light from four separate observations taken through different filters on the 0.9 meter telescope at Kitt Peak. The brightest yellow star near the center of the image is a foreground star, lying between us and the young cluster. The other bright stars are the massive young stars of the cluster that are heating the gas and dust in the cloud and blowing out cavities. Image processing was done by Dr. Travis Rector. Credit: NOAO.
It takes time to understand the life of stars. A star like our Sun takes tens of millions of years to form, and so much like archeologists who reconstruct ancient cities from shards of debris strewn over time, astronomers must reconstruct the birth process of stars indirectly, by observing stars in different stages of the process and inferring the changes that take place.
One of the best places to study the lives of stars is in star clusters. These regions that are rich with young stars provide astronomers much information that is relevant to the study of stars in general, but within a cluster, stars can form during a wide range of time, as a new study of the star cluster named Cep OB3b has shown.
“By studying nearby massive young clusters like Cep OB3b, we can gain a greater understanding of the environments out of which planets form,” said Thomas Allen from the University of Toledo, who is one of the authors of the new paper.
Located in the northern constellation of Cepheus, CepOB3b is similar in some ways to the famous cluster found in the Orion Nebula. But unlike the Orion Nebula, there is relatively little dust and gas obscuring our view of Cep OB3b. Its massive, hot stars have blown out cavities in the gaseous cloud with their intense ultraviolet radiation which mercilessly destroys everything in its path. Cep OB3b may show us what the Orion Nebular Cluster will look like in the future.
Allen and an international team of astronomers have found that the total number of young stars in the cluster is as high as 3,000. Infrared observations of the stars from the NASA Spitzer satellite show about 1,000 stars that are surrounded by disks of gas and dust from which solar systems may form. As the stars age, the disks disappear as the dust and gas get converted into planets or are dispersed into space.
But these observations pointed to a new mystery. Although the stars in Cep OB3b are thought to be about three million years old, in some parts of the cluster most of the stars had lost their disks, suggesting that the stars in those parts were older. This suggests that the cluster is surrounded by older stars, potential relics of previous clusters that have since expanded and dispersed.
To search for evidence for these relic clusters, Allen used the Mosaic camera on the 0.9 meter telescope at Kitt Peak National Observatory to observe wide field images of CepOB3b. These images show hot gas and its interaction with the stars and permit the team to study a curious cavity in the gas for evidence of older, yet still juvenile, stars that have lost their disks of gas and dust.
With these data, the team is searching for the previous generations of star formation in the region surrounding Cep OB3b, and piecing together the history of star formation in this magnificent region. When finished, this may provide clues how previous generations may have influenced the current generation of stars and planets forming in Cep OB3b.
Vistas of Many Worlds: A Journey Through Space and Time by Erik Anderson (Ashland Astronomy Studio)
While many astronomy books are based around images that show us how the Universe appears to us right now, as seen through the sensitive electronic eyes of powerful space telescopes and observatories around the world, Erik Anderson’s Vistas of Many Worlds: a Journey Through Space and Time takes a different, but no less fascinating, approach and shows us what the night sky used to look like, will one day look like, and how it may look from other much more distant worlds.
The nearby orange dwarf star Epsilon Eridani reveals its circumstellar debris disks in this close-up perspective. (Pages 14-15)
Written and illustrated by Erik Anderson of the Ashland Astronomy Studio in Ashland, Oregon, Vistas of Many Worlds first takes us on a tour of our local region of the galaxy, introducing us to some of our Sun’s closest neighbors in space. From Alpha Centauri to Altair, we get scientifically-based renderings of several nearby stars as they’d appear close up, along with a detailed description of each — as well as an accurate depiction of the background stars (including the Sun) as they’d appear from such slightly different vantage points. We soon find out there’s an amazing amount of variety in our own stellar neighborhood alone!
Next we get a tour through time itself with images and detailed descriptions of the night sky as it appeared at various points in Earth’s history. Based on the actual movements of the stars across the galaxy, Anderson is able to accurately show the star-filled sky as it looked when the ocean cascaded over the Strait of Gibraltar to fill in the Mediterranean 5.3 million years ago, when the ancestors of modern humans were first learning to use fire 1.5 million years ago… and also what it will look like when the Solar System eventually dips back down into the galactic plane 25 million years from now — a time when nearly all the stars in the sky will be strangers, unfamiliar to us today.
After that Anderson takes us on a hunt for exoplanets, both known and imagined. We first visit the star systems that have been recently discovered to host planets — some a little like Earth, some a little like Jupiter, and some like nothing we’ve ever seen before. Then it’s off to look for truly Earthlike worlds by looking back at how our own planet became so favorable for life in the first place. From a stable parent star like the Sun to the chance birth of a large, stabilizing moon, from the delivery of life-sustaining liquid water (that stays liquid!) to having a protective “big brother” gas giant ready to take the heavy hits, and eventually what first drew organisms up from the sea onto dry land, Anderson speculates about Earth’s distant exoplanetary twins by reflecting on our planet itself.
The Earth’s ancient past is depicted as it looked 4.4 million years ago when an ancient ape, “Ardi” the Ardipithecus, roamed Africa. (Pages 36-37)
And all the while showing what stars are where in the sky.
Vistas of Many Worlds is a true gem… it inspires imagination with the turn of each page. Anderson’s photorealistic computer-generated illustrations are lush and intriguing, and he does an excellent job combining speculation with scientific knowledge. It’s science as envisioned by an artist as well as art created by a scientist — truly the best of both many worlds.
A primordial ocean-world orbited by two moons is depicted in Ptolemy’s Cluster (star cluster M7). The scene parallels Earth’s own natural history, commemorating the origins of watery oceans out of volcanic steam and infalling comets. (Pages 96-97)
Your Ticket to the Universe: A Guide to Exploring the Cosmos (Available April 2)
Your Ticket to the Universe is full of images and graphics of astronomical wonders.
Every once in a while an astronomy book comes out that combines stunning high-definition images from the world’s most advanced telescopes, comprehensive descriptions of cosmic objects that are both approachable and easy to understand (but not overly simplistic) and a gorgeous layout that makes every page spread visually exciting and enjoyable.
This is one of those books.
Your Ticket to the Universe: A Guide to Exploring the Cosmosis a wonderful astronomy book by Kimberly K. Arcand and Megan Watzke, media coordinator and press officer for NASA’s Chandra X-ray Observatory, respectively. Published by Smithsonian Books, it features 240 pages of gorgeous glossy images from space exploration missions, from the “backyard” of our own Solar System to the more exotic environments found throughout the Galaxy… and even beyond to the very edges of the visible Universe itself.
Find out how you can win a copy of this book here!
As members of the Chandra team, headquartered at the Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, Kim and Megan have long had firsthand experience with incredible astronomical images — they previously designed and coordinated the internationally-acclaimed From Earth to the Universe and From Earth to the Solar System photo installation projects, which helped set up presentations of space exploration images in public locations around the world.
Your Ticket to the Universe even features images from some of the most recent missions – like MSL!
Your Ticket to the Universe takes such impressive images — from telescopes and observatories like Hubble, Spitzer, SDO, Chandra, Cassini, GOES, VLT, and many others, as well as from talented photographers on Earth and in orbit aboard the ISS — and puts them right into your hands, along with in-depth descriptions that are comprehensive yet accessible to even the most casual fans of space exploration.
This is my favorite kind of astronomy book. Although I look at images like the ones in Your Ticket to the Universe online every day, there’s something special about having them physically in front of you in print — and well-written text that can be understood by everyone is crucial, in my opinion, as it means a book may very well become an inspiration to a whole new generation of scientists and explorers.
“The sky belongs to everyone. That’s the premise of this guidebook to the Universe. You don’t need a medical degree to know when you’re sick or a doctorate in literature to appreciate a novel. In the same spirit, even those of us who don’t have advanced degrees in astronomy can gain access to all the wonder and experience that the Universe has to offer.”
I’ve had the pleasure of meeting co-author Kimberly Arcand on several occasions — I attended high school with her husband — and her knowledge about astronomy imaging as well as her ability to present it in an understandable way is truly impressive, to say the least. She’s quite an enthusiastic ambassador for space exploration, and Your Ticket to the Universe only serves to further demonstrate that.
I highly recommend it for anyone who finds our Universe fascinating.
Your Ticket to the Universe will be available online starting April 2 at Smithsonian Books, or you can pre-order a copy at Barnes & Noble or on Amazon.com. Don’t explore the cosmos without it!
Find Arcturus easily by using the handle of the Big Dipper. This map shows the sky facing northeast around 9:30-10 p.m. local time in late March. Stellarium
Every star has a story but some are more curious than others. The star Arcturus has an electrifying story with a mysterious twist involving the 1933 World’s Fair.
If you step out on a clear night in mid-March and follow the curve of the Big Dipper’s handle toward the eastern horizon, you’ll come face to face with Arcturus, the 4th brightest star in the sky. Pale orange and fluttering in the low air like a candle in the breeze, Arcturus is a bellwether of spring. By late May it shines high in the south at the onset of night. For the moment, the star hunkers down in the east, sparking through tree branches and over neighborhood rooftops.
The name Arcturus comes from the ancient Greek word “arktos” for bear and means “Bear Watcher”. That’s easy to remember because he follows Ursa Major the Great Bear, the brightest part of which is the Big Dipper, across the spring sky.
Arcturus is 37 light years from Earth and classified as an orange giant star. It spans 25 times the sun’s diameter and shines 113 times more brightly.
It was another spring 80 years ago on May 27,1933, that the city of Chicago opened its Century of Progress Exposition as part of the World’s Fair highlighting progress in science and industry. 40 years prior in 1893 the city had hosted its first big fair, the World’s Columbian Exposition.
In the early 1930s astronomers estimated Arcturus’ distance at 40 light years. Edwin Frost, retired director of the Yerkes Observatory in Williams Bay, Wis., home to the world’s largest refracting telescope, hit upon the idea of using Arcturus to symbolically link both great fairs which were separated by a span of 40 years.
Poster from the Century of Progress Exposition also called the Chicago World’s Fair. Its theme was the significance of science and how it had bettered mankind. The event was celebrated on Chicago’s 100th anniversary. Credit: Wikipedia
At the time, the photocell, a device that produces an electric current when exposed to light, was all the rage. Clever entrepreneurs had figured out how to take advantage of light’s ability to knock electrons loose from atoms to open doors and count shoppers automatically. They’re still in wide use today from burglar alarms to toilets that magically flush when you step away.
Edwin Frost around the time he was director of Yerkes Observatory in Williams Bay, Wis. Credit: National Academy of Sciences
Technological innovation through scientific progress was the theme of the 1933 fair. What better way, thought Frost, to highlight the benefits of science and link both great events than by focusing the light of Arcturus onto a photocell and using the electric current generated to flip a switch that would turn on the lights at the fair’s opening.
Though we now know Arcturus is 37 light years away, at the time it was thought to be about 40. The light that left the star during the first world’s fair in 1893 would arrive just in time 40 years later to open the next. Arcturus was not only at the right distance but bright and easy to see during May at the fair’s opening. Could a more perfect marriage of poetry and science ever be arranged?
From left: Edwin B. Frost, Christian T. Elvey, staff, and Otto Struve, Yerkes director, examine a General Electric photoelectric relay and the photocell tube that will help activate the lights of the “Century of Progress,” thus opening the Chicago world fair of 1933. Courtesy Yerkes Observatory
On May 27, 1933 shortly before the appointed time, Century of Progress Fair president Rufus C. Dawes spoke to a crowd of some 30,000 people assembled in the courtyard at the Hall of Science:
“We recall the great Columbian Exposition of 1893. Never will its beauty be surpassed.
Never will there be held an exposition of more lasting value to this city. It was for Chicago a great triumph.”
Visitors throng the Hall of Science at the Chicago World’s Fair in 1933, site of the Arcturus lighting ceremony. Click to enlarge Credit: Century of Progress Records, 1927-1952, University of Illinois at Chicago Library (COP_17_0002_00023_027)
“We remind ourselves of that triumph tonight by taking rays of light that left the star Arcturus during the period of that exposition and which have traveled at the rate of 186,000 miles a second until at last they have reached us. We shall use these rays to put into operation the mysterious forces of electricity which will make light our grounds, decorate our buildings with brilliant colors, and move the machinery of the exposition.”
Above the speaker’s platform hung a large illuminated panel, the bottom half of which displayed a map of the eastern U.S. with the locations of the four observatories. The top half contained the instruments that completed the circuit from Arcturus to a searchlight in the Hall of Science.
When light beams from the star Arcturus were picked up by photoelectric tubes at four observatories, signals flashed on this display board on the rostrum of the Hall of Science to the show the audience. Click to enlarge. Credit: Century of Progress Records, 1927-1952, University of Illinois at Chicago Library (COP_17_0002_00023_016)
At 9:15 p.m. each of the four observatories borrowed bits of Arcturus’ light, focused them onto their respective photocells and sent the electric current by Western Union telegraph lines to the Chicago fairgrounds.
In the book Fair Management – The Story of a Century of Progress, author Lenox Lohr described what happened next. One of the speakers, probably Philip Fox, director of Chicago’s Adler Planetarium, stepped to the podium to issue the final instructions :
“Harvard, are you ready?”
“Yes.”
A red glow ran across the map from Cambridge to Chicago.
“Is Allegheny ready?”
“Ready.”
“Illinois ready?”
“Yes.”
“Yerkes?”
“Let’s go.”
The switch was thrown, and a searchlight at the top of the Hall of Science shot a great white beam across the sky.”
The crowd went bananas. It was such a huge hit, nearby Elgin Observatory was pressed into operation to light the fair in similar fashion every night for the remainder of the season.
The Hall of Science area at the fair along with the Arcturus sign (far left) and a group of people creating a large star shape on a stage. Click for large version. Credit: Century of Progress Records, 1927-1952, University of Illinois at Chicago Library (COP_17_0002_00023_017)
Harnessing a distant star for mankind’s benefit. We marvel at the 1933 fair promoters and astronomers for conceiving of this most ingenious way of linking past and present.
That would be the end of a wonderful story if it wasn’t for one Ralph Mansfield. Mansfield, a student at the time at the University of Chicago, worked as a guide at Chicago’s Alder Planetarium, which was also involved in the lighting ceremony. Before passing away in 2007, Mansfield shared the story of how he was the one to point the telescope at Arcturus and fire up the fairground lights.
The Adler Planetarium on Chicago’s Lake Michigan lakefront. Credit:Fritz Geller-Grimm
I learned this while reading an article by Nathan B. Myron, PhD on the topic in which Mansfield sought to set the record straight. In his version, then-director of the Adler Planetarium, Philip Fox. was apprehensive about cloudy skies, so he arranged for Mansfield to set up a telescope in the balcony of the Hall of Science. As Fox delivered opening remarks, Mansfield used the Dipper’s Handle to find Arcturus in a lucky break in the clouds, and at the key moment, fed its light to the photocell. The spotlight fired up and the day was saved.
So which is the true story?
“It’s a bit of a mystery,” said Richard Dreiser, public information officer for Yerkes Observatory. “No one really knows absolutely.”
His sentiments were echoed by Bruce Stephenson, current curator at the Adler Planetarium: “The truth as far as we can ascertain it today is not really known. These things happened long ago.”
Most historical accounts indicate that four observatories participated, but Mansfield’s story remains. Will the real version please stand up?
The Wreath Nebula (Barnard 3) glows green in space in this Wide-field Infrared Survey Explorer (WISE) image. Credit: NASA/JPL-Caltech/UCLA
While a quest for green beer in space would be difficult, we’re happy to report there are other ways you can celebrate Saint Patrick’s Day while looking at the night sky. Just check out the nebulae and aurorae in these pictures!
A word of caution, these pictures are taken by cameras that expose light for a very long time, sometimes using different filters, to bring out the colors. A nebula, for example, seen with our own eyes does not look quite as stunning.
The picture above shows the Wreath Nebula, which apparently is filled with warm dust bits that are about the same composition as smog.
RCW 120. Credit: NASA/JPL-Caltech
Here’s a picture of a “Green Ring” Nebula; the NASA press release is worth a read for the hilarious Green Lantern references. But besides the science fiction, there is some neat science in action here: “The green color represents infrared light coming from tiny dust grains called polycyclic aromatic hydrocarbons,” NASA writes. “These small grains have been destroyed inside the bubble. The red color inside the ring shows slightly larger, hotter dust grains, heated by the massive stars.”
A portion of the Lagoon nebula imaged by the Gemini South telescope with the Gemini Multi-Object Spectrograph. Credit: Julia I. Arias and Rodolfo H. Barbá Departamento de Física, Universidad de La Serena (Chile), and ICATE-CONICET (Argentina).
You can even see hints of green in the Lagoon Nebula picture above. Using a filter that picks up green (sulfur) emission, the astronomers ferreted out a bit of emerald.
An October 2012 picture from Jason Arhns in Alaska, which he calls a “ghost flame.” Credit: Jason Arhns
If you live far enough north or south, you occasionally get to see aurorae dancing across the sky. These events, sometimes known as the Northern Lights or Southern Lights, occur due to interactions between the sun’s particles and the Earth’s upper atmosphere. We had some green stunners in October 2012 after a solar flare pushed a bunch of these particles in Earth’s direction. Most of the light you see in auroras comes from oxygen atoms being “excited” from the interaction with the sun’s particles; green occurs at higher altitudes, and red at lower ones.
Light curve of different stars.
One object that can’t glow green in space, however, is a star. Stellar colors depend on the surface of the star. Blue stars, the hottest ones, are at about 12,000 Kelvin and red stars, the coolest ones, are less than 3,500 Kelvin. (The sun is about in the middle, at 6,800 Kelvin, as it emits white light.)
As Universe Today publisher Fraser Cain pointed out in a past post, the only way a green star could be possible is if the light curve peaks at green. That doesn’t work, however: “If you make the star hotter, it just gets bluer,” he wrote. “And if you make a star cooler, it just becomes orange and then redder. There’s no way to have a light curve that makes a star look green.” Check out more details here.
A young star is spotted firing jets of material out into space (ESA/Hubble & NASA. Acknowledgement: Gilles Chapdelaine)
Like very young humans, very young stars also tend to make a big mess out of the stuff around them — except in the case of stars it’s not crayon on the walls and Legos on the floor (ouch!) but rather huge blasts of superheated material that are launched from their poles far out into space.
The image above, acquired by the Hubble Space Telescope, shows one of these young stars caught in the act.
HL Tau is a relatively newborn star, formed “only” within the past several hundred thousand years. During that time it has scooped up vast amounts of gas and dust from the area around itself, forming a disc of hot, accelerated material that surrounds it. While most of this material eventually falls into the star, increasing its mass, some of it gets caught up in the star’s complex, rotating magnetic fields and is thrown out into space as high-speed jets.
As these jets plow thorough surrounding interstellar space they ram into nearby clouds of molecular gas, ionizing the material within them and causing them to glow brightly. These “shocks” are known as Herbig-Haro objects, after researchers George Herbig and Guillermo Haro who each discovered them independently in the early 1950s.
Detail of HH 151’s jet
In this Hubble image HH 151 is visible as a multiple-lobed cone of material fired away from HL Tau, with the leftover glows from previous outbursts dimly illuminating the rest of the scene.
The material within these jets can reach speeds of several hundred to a thousand kilometers a second. They can last anywhere from a few years to a few thousand years.
HH 151 is embedded within the larger star-forming region LDN 1551, located about 450 light-years away in the constellation Taurus. LDN 1551 is a stellar nursery full of dust, dark nebulae, newborn stars… and Herbig-Haro objects like HH 151.
(Hey, if baby stars are going to make a mess at least they can do it in the nursery.)
Using data gathered by NASA’s exoplanet-hunting Kepler spacecraft, the CfA researchers discovered that many red dwarf stars harbor planets, and some of those planets are rocky, Earth-sized worlds. Considering that red dwarfs, albeit optically dim, are the most abundant type of stars in our galaxy, this means that even a small percentage of them being host to Earthlike exoplanets puts the total number of potentially habitable worlds very high — and some of them could be right next door.
“We thought we would have to search vast distances to find an Earth-like planet,” said CfA astronomer and the paper’s lead author Courtney Dressing. “Now we realize another Earth is probably in our own backyard, waiting to be spotted.”
And our own backyard, in cosmic terms, could mean a mere 13 light-years away.
Our solar system is surrounded by red dwarfs. You can’t see them in the night sky because they are much too dim — less than a thousandth the brightness of the Sun. But they make up 75% of the stars in the local neighborhood, and based on the Kepler data the CfA team estimates that 6% of those red dwarfs likely have an Earth-sized planet in orbit around them.
And with at least 75 billion red dwarfs scattered across the galaxy… well, you do the math.*
“We now know the rate of occurrence of habitable planets around the most common stars in our galaxy,” said co-author David Charbonneau (CfA). “That rate implies that it will be significantly easier to search for life beyond the solar system than we previously thought.”
A visualization of the “unseen” red dwarfs in the night sky. Credit: D. Aguilar & C. Pulliam (CfA) See original here.
The conditions on a planet orbiting a red dwarf wouldn’t be exactly like Earth, of course. The planet would have to orbit rather closely to its star to be within its habitable zone, and would have to have a reasonably thick atmosphere to regulate heat and protect it from stellar outbursts. But one benefit to orbiting a red dwarf is that they have very long life spans — potentially longer than the current age of the Universe! So a habitable world around a red dwarf would literally have billions of years for life to evolve, thrive and develop on it.
“We might find an Earth that’s 10 billion years old,” Charbonneau said.
The team’s findings were presented today, Feb. 6, by Dressing during a press conference at the Harvard-Smithsonian Center for Astrophysics in Cambridge, MA. The results will be published in The Astrophysical Journal. (Added 2/7/13: here’s the video of the press conference.)
CfA astronomers identified 95 planetary candidates circling red dwarf stars. Of those, three orbit within the habitable zone (marked in green) – the distance at which they should be warm enough to host liquid water on the surface. Those three planetary candidates (marked with blue dots) are 0.9, 1.4, and 1.7 times the size of Earth. Credit: C. Dressing (CfA)
Cold rings of dust are illuminated in this image taken by Herschel’s Spectral and Photometric Imaging Receiver (SPIRE) instrument. Credit: ESA/NASA/JPL-Caltech/B. Schulz (NHSC)
Looking wispy and delicate from 2.5 million light-years away, cold rings of dust are seen swirling around the Andromeda galaxy in this new image from the Herschel Space Observatory, giving us yet another fascinating view of our galaxy’s largest neighbor.
The colors in the image correspond to increasingly warmer temperatures and concentrations of dust — blue rings are warmer, while pinks and reds are colder lanes of dust only slightly above absolute zero. Dark at shorter wavelengths, these dust rings are revealed by Herschel’s amazing sensitivity to the coldest regions of the Universe.
The image above shows data only from Herschel’s SPIRE (Spectral and Photometric Imaging Receiver) instrument; below is a mosaic made from SPIRE as well as the Photodetecting Array Camera and Spectrometer (PACS) instrument:
“Cool Andromeda” Credit: ESA/Herschel/PACS & SPIRE Consortium, O. Krause, HSC, H. Linz
Estimated to be 200,000 light-years across — almost double the width of the Milky Way — Andromeda (M31) is home to nearly a trillion stars, compared to the 200–400 billion that are in our galaxy. And within these cold, dark rings of dust even more stars are being born… Andromeda’s star-making days are far from over.
Herschel’s mission will soon be coming to an end as the telescope runs out of the liquid helium coolant required to keep its temperatures low enough to detect such distant heat signatures. This is expected to occur sometime in February or March.
Herschel is a European Space Agency cornerstone mission with science instruments provided by consortia of European institutes, and with important participation by NASA. Launched May 14, 2009, the telescope orbits the second Lagrange point of the Earth-Sun system (L2), located 1.5 million km (932,000 miles) from Earth. Read more from the Herschel mission here.
Infrared image of globular cluster 47 Tucanae (NGC 104) captured by ESO’s VISTA telescope.
“My god, it’s full of stars!” said Dave Bowman in the movie 2010 as he entered the monolith, and one could imagine that the breathtaking view before him looked something like this.
Except this isn’t science fiction, it’s reality — this is an image of globular cluster 47 Tucanae taken by the European Southern Observatory’s VISTA telescope at the Paranal Observatory in Chile. It reveals in stunning detail a brilliant collection of literally millions of stars, orbiting our Milky Way galaxy at a distance of 15,000 light-years.
The full image can be seen below.
47 Tucanae (also known as NGC 104) is located in the southern constellation Tucana. It’s bright enough to be seen without a telescope and, even though it’s very far away for a naked-eye object, covers an area about the size of the full Moon.
In reality the cluster is 124 light-years across.
Although globular clusters like 47 Tucanae are chock-full of stars — many of them very old, even as stars go — they are noticeably lacking in clouds of gas and dust. It’s thought that all the gaseous material has long since condensed to form stars, or else has been blown away by radiation and outbursts from the cluster’s exotic inhabitants.
At the heart of 47 Tucanae lie many curious objects like powerful x-ray sources, rapidly-spinning pulsars, “vampire” stars that feed on their neighbors, and strange blue stragglers — old stars that somehow manage to stay looking young. (You could say that a globular cluster is the cosmic version of a trashy reality show set in Beverly Hills.)
Red giants can be seen surrounding the central part of the cluster, old bloated stars that are running out of fuel, their outer layers expanding.
The background stars in the image are part of the Small Magellanic Cloud, which was in the distance behind 47 Tucanae when this image was taken.
VISTA is the world’s largest telescope dedicated to mapping the sky in near-infrared wavelengths. Located at ESO’s Paranal Observatory in Chile, VISTA is revealing new views of the southern sky. Read more about the VISTA survey here.
This artist's conception illustrates what a "hot jupiter" might look like.
Artist’s concept of brown dwarf 2MASSJ22282889-431026 (NASA/JPL-Caltech)
The complex weather patterns within the atmosphere of a rapidly-rotating brown dwarf have been mapped in the highest detail ever by researchers using the infrared abilities of NASA’s Spitzer and Hubble space telescopes… talk about solar wind!
Sometimes referred to as failed stars, brown dwarfs form from condensing gas and dust like regular stars but never manage to gather enough mass to ignite full-on hydrogen fusion in their cores. As a result they more resemble enormous Jupiter-like planets, radiating low levels of heat while possessing bands of wind-driven eddies in their upper atmospheric layers.
Although brown dwarfs are by their nature very dim, and thus difficult to observe in visible wavelengths of light, their heat can be detected by Hubble and the Spitzer Space Telescope — both of which can “see” just fine in near- and far-infrared, respectively.
Led by researchers from the University of Arizona, a team of astronomers used these orbiting observatories on July 7, 2011 to measure the light curves from a brown dwarf named 2MASSJ22282889-431026 (2M2228 for short.) What they found was that while 2M2228 exhibited periodic brightening in both near- and far-infrared over the course of its speedy 1.43-hour rotation, the amount and rate of brightening varied between the different wavelengths detected by the two telescopes.
“With Hubble and Spitzer, we were able to look at different atmospheric layers of a brown dwarf, similar to the way doctors use medical imaging techniques to study the different tissues in your body.”
– Daniel Apai, principal investigator, University of Arizona
This unexpected variance — or phase shift — most likely indicates different layers of cloud material and wind velocities surrounding 2M2228, swirling around the dwarf star in very much the same way as the stormy cloud bands seen on Jupiter or Saturn.
But while the clouds on Jupiter are made of gases like ammonia and methane, the clouds of 2M2228 are made of much more unusual stuff.
“Unlike the water clouds of Earth or the ammonia clouds of Jupiter, clouds on brown dwarfs are composed of hot grains of sand, liquid drops of iron, and other exotic compounds,” said Mark Marley, a research scientist at NASA’s Ames Research Center and co-author of the paper. “So this large atmospheric disturbance found by Spitzer and Hubble gives a new meaning to the concept of extreme weather.”
While it might seem strange to think about weather on a star, remember that brown dwarfs are much more gas planet-like than “real” stars. Although the temperatures of 1,100–1,600 ºF (600–700 ºC) found on 2M2228 might sound searingly hot, it’s downright chilly compared to even regular stars like our Sun, which has an average temperature of nearly 10,000 ºF (5,600 ºC). Different materials gather at varying layers of its atmosphere, depending on temperature and pressure, and can be penetrated by different wavelengths of infrared light — just like gas giant planets.
“What we see here is evidence for massive, organized cloud systems, perhaps akin to giant versions of the Great Red Spot on Jupiter,” said Adam Showman, a theorist at the University of Arizona involved in the research. “These out-of-sync light variations provide a fingerprint of how the brown dwarf’s weather systems stack up vertically. The data suggest regions on the brown dwarf where the weather is cloudy and rich in silicate vapor deep in the atmosphere coincide with balmier, drier conditions at higher altitudes — and vice versa.”
The team’s results were presented today, January 8, during the 221st meeting of the American Astronomical Society in Long Beach, CA.
Read more on the Spitzer site, and find the team’s paper in PDF form here.
Inset image: the anatomy of a brown dwarf’s atmosphere (NASA/JPL).
The background stars in the image are part of the Small Magellanic Cloud, which was in the distance behind 47 Tucanae when this image was taken.
