First all-sky map of the edge of the solar system

This IBEX data image shows a dark sky map with the first orbit’s coincidence counts from hydrogen atoms at speeds from about 100,000 (161,000 km) to 36 million miles (58 million km) per hour. The IBEX team is collecting additional orbit data to expose adjacent swaths of the sky to reveal the edge of our solar system. SWRI, San Antonio, Texas

January 13, 2009
Provided by SWRI, San Antonio, Texas

Following two months of commissioning, during which the spacecraft and sensors were tuned for optimum mission performance, the Interstellar Boundary Explorer (IBEX) spacecraft began gathering data to build the first maps of the edge of the heliosphere, the region of space influenced by the Sun.

IBEX is using energetic neutral atom (ENA) imaging to create the first global maps of interactions between the million miles per hour (1,609,000 km/h) solar wind blown out in all directions by the Sun and the low-density material between the stars, known as the interstellar medium.

The maps are built by two ENA cameras, which collectively measure energetic neutral atoms coming in from the edge of the solar system with speeds from about 100,000 miles per hour (161,000 km/h) to some 36 million miles per hour (58 million km/h). Each sensor uses a charge-exchange process that converts incoming neutral atoms into charged ions so they can be analyzed and detected.

The sensors look out from opposite sides of the spacecraft in directions perpendicular to the Sun-pointed spin axis. As the spacecraft spins at four revolutions per minute, the measured ENAs fill in the pixels to build a circular swath that appears as a crescent on the map. As the spacecraft's spin axis tracks the Sun, the swaths move across the sky to complete the image.

"We are seeing fabulous initial results from IBEX, but, just as artisans use looms to build up colorful textiles by weaving one thread at a time, the IBEX sensors also need time - six months - to build up a complete map of the sky," said Dr. David McComas, IBEX principal investigator and senior executive director of the Space Science and Engineering Division at Southwest Research Institute in San Antonio, Texas. "So far, the intricate pattern of this fascinating interaction is only just beginning to disclose itself to us."

IBEX will enable researchers to examine the structures and dynamics of the outer heliosphere and to investigate the acceleration and propagation of charged particles in this complex and important region. IBEX also will address a serious challenge facing manned exploration by studying the region that shields Earth from the majority of galactic cosmic ray radiation.

"The space physics community is holding its collective breath waiting for these maps, which will provide a much deeper understanding of the Sun's interaction with the galaxy," said McComas. "We expect the first complete image, due this summer, to tell us a great deal about the heliosphere's fundamental nature."

NASA balloon mission tunes in to a cosmic radio mystery

A mysterious screen of extra-loud radio noise permeates the cosmos, preventing astronomers from observing heat from the first stars. The balloon-borne ARCADE instrument discovered this cosmic static (white band, top) on its July 2006 flight. The noise is six times louder than expected. Astronomers have no idea why. NASA/ARCADE/Roen Kelly

January 7, 2009

Listening to the early universe just got harder. A team led by Alan Kogut of NASA's Goddard Space Flight Center in Greenbelt, Maryland, announced January 7, 2009, the discovery of cosmic radio noise that booms six times louder than expected.

The finding comes from a balloon-borne instrument named Absolute Radiometer for Cosmology, Astrophysics, and Diffuse Emission (ARCADE). In July 2006, the instrument launched from NASA's Columbia Scientific Balloon Facility in Palestine, Texas, and flew to an altitude of 22 miles (35 km), where the atmosphere thins into the vacuum of space.

ARCADE's mission was to search the sky for heat from the first generation of stars. Instead, it found a cosmic puzzle.

"The universe really threw us a curve," Kogut said. "Instead of the faint signal we hoped to find, here was this booming noise six times louder than anyone had predicted." Detailed analysis ruled out an origin from primordial stars or from known radio sources, including gas in the outermost halo of our own galaxy. The source of this cosmic radio background remains a mystery.

Many objects in the universe emit radio waves. In 1931, American physicist Karl Jansky first detected radio static from our own Milky Way galaxy. Similar emission from other galaxies creates a background hiss of radio noise.

The problem, said team member Dale Fixsen of the University of Maryland at College Park, is that there doesn't appear to be enough radio galaxies to account for the signal ARCADE detected. "You'd have to pack them into the universe like sardines," he said. "There wouldn't be any space left between one galaxy and the next."

The sought-for signal from the earliest stars remains hidden behind the newly detected cosmic radio background. This noise complicates efforts to detect the very first stars, which are thought to have formed about 13 billion years ago - not long, in cosmic terms, after the Big Bang. Nevertheless, this cosmic static may provide important clues to the development of galaxies when the universe was less than half its present age. Unlocking its origins should provide new insight into the development of radio sources in the early universe.

"This is what makes science so exciting," said Michael Seiffert, a team member at NASA's Jet Propulsion Laboratory in Pasadena, California. "You start out on a path to measure something - in this case, the heat from the very first stars - but run into something else entirely, something unexplained."

ARCADE is the first instrument to measure the radio sky with enough precision to detect this mysterious signal. To enhance the sensitivity of ARCADE's radio receivers, they were immersed in more than 500 gallons of ultra-cold liquid helium. The instrument's operating temperature was just 2.7° Celsius above absolute zero.

This is the same temperature as the cosmic microwave background (CMB) radiation, the remnant heat of the Big Bang that was discovered as cosmic radio noise in 1965. "If ARCADE is the same temperature as the microwave background, then the instrument's heat cannot contaminate the cosmic signal," Kogut said.

Astronomers crack lunar mystery

Scientist-astronaut Harrison H. Schmitt is photographed standing next to a huge, split boulder during the third Apollo 17 extravehicular activity (EVA-3) at the Taurus-Littrow landing site on the Moon. NASA

January 14, 2009

Provided by MIT, Cambridge, Maryland

The collection of rocks that the Apollo astronauts brought back from the Moon carried with it a riddle that has puzzled scientists since the early 1970s: What produced the magnetization found in many of those rocks?

Researchers at Massachusetts Institute of Technology (MIT) carried out the most detailed analysis of the oldest pristine rock from the Apollo collection and have solved the longstanding puzzle. Magnetic traces recorded in the rock provide strong evidence that 4.2 billion years ago the Moon had a liquid core with a dynamo, like Earth's core today, that produced a strong magnetic field.

The Moon rock that produced the new evidence was long known to be a very special one. It is the oldest of all the Moon rocks that have not been subjected to major shocks from later impacts - something that tends to erase all evidence of earlier magnetic fields. In fact, it's older than any known rocks from Mars or even from Earth.

"Many people think that it's the most interesting lunar rock," said Ben Weiss, the Victor P. Starr assistant professor of planetary sciences in MIT's Department of Earth, Atmospheric and Planetary Sciences. The rock was collected during the last lunar landing mission, Apollo 17, by Harrison "Jack" Schmidt, the only geologist to walk on the Moon.

"It is one of the oldest and most pristine samples known," said graduate student Ian Garrick-Bethell. "If that wasn't enough, it is also perhaps the most beautiful lunar rock, displaying a mixture of bright green and milky white crystals."

The team studied faint magnetic traces in a small sample of the rock in great detail. Using a commercial rock magnetometer that was specially fitted with an automated robotic system to take many readings "allowed us to make an order of magnitude more measurements than previous studies of lunar samples," Garrick-Bethell said. "This permitted us to study the magnetization of the rock in much greater detail than previously possible."

And the data enabled them to rule out the other possible sources of the magnetic traces, such as magnetic fields briefly generated by huge impacts on the Moon. Those magnetic fields are short lived, ranging from just seconds for small impacts up to one day for the most massive strikes. But the evidence written in the lunar rock showed it must have remained in a magnetic environment for a long period of time - millions of years - and thus the field had to have come from a long-lasting magnetic dynamo.

That's not a new idea, but it has been "one of the most controversial issues in lunar science," Weiss said. Until the Apollo missions, many prominent scientists were convinced that the Moon was born cold and stayed cold, never melting enough to form a liquid core. Apollo proved that there had been massive flows of lava on the Moon's surface, but the idea that it has, or ever had, a molten core remained controversial. "People have been vociferously debating this for 30 years," Weiss said.

The magnetic field necessary to have magnetized this rock would have been about one-fiftieth as strong as Earth's is today. Weiss said, "This is consistent with dynamo theory," and also fits in with the prevailing theory that the Moon was born when a Mars-sized body crashed into Earth and blasted much of its crust into space, where it clumped together to form the Moon.

The new finding underscores how much we still don't know about our nearest neighbor in space, which will soon be visited by humans once again under current NASA plans. "While humans have visited the Moon six times, we have really only scratched the surface when it comes to our understanding of this world," said Garick-Bethell.

Chandrayaan-1 peeks inside Moon craters

This image is a Mini-RF synthetic aperture radar (SAR) strip overlain on an Earth-based, Arecibo Observatory radar telescope image. Taken November 17, 2008, the south-polar SAR strip shows a part of the moon never seen before: a portion of Haworth crater that is permanently shadowed from Earth and the Sun. The only way to explore these regions is by using an orbital radar such as Mini-RF. ISRO/NASA/JHUAPL/LPI/Cornell University/Smithsonian

January 16, 2009

Using a NASA radar flying aboard India's Chandrayaan-1 spacecraft, scientists are getting their first look inside the Moon's coldest, darkest craters.

The Mini-SAR instrument, a lightweight, synthetic aperture radar, has passed its initial in-flight tests and sent back its first data. The images show the floors of permanently shadowed polar craters on the Moon that aren't visible from Earth. Scientists are using the instrument to map and search the insides of the craters for water ice.

"The only way to explore such areas is to use an orbital imaging radar such as Mini-SAR," said Benjamin Bussey, deputy principal investigator for Mini-SAR, from the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland. "This is an exciting first step for the team which has worked diligently for more than three years to get to this point."

The images, taken November 17, 2008, cover part of the Haworth crater at the Moon's south pole and the western rim of Seares crater, an impact feature near the north pole. Bright areas in each image represent either surface roughness or slopes pointing toward the spacecraft. Further data collection by Mini-SAR and analysis will help scientists to determine if buried ice deposits exist in the permanently shadowed craters near the Moon's poles.

"The only way to explore such areas is to use an orbital imaging radar such as Mini-SAR," said Benjamin Bussey, deputy principal investigator for Mini-SAR, from the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland. "This is an exciting first step for the team which has worked diligently for more than three years to get to this point."

The images, taken November 17, 2008, cover part of the Haworth crater at the Moon's south pole and the western rim of Seares crater, an impact feature near the north pole. Bright areas in each image represent either surface roughness or slopes pointing toward the spacecraft. Further data collection by Mini-SAR and analysis will help scientists to determine if buried ice deposits exist in the permanently shadowed craters near the Moon's poles.

Brown dwarfs aplenty in star-forming region

Tricolor composite image of W3 Main where massive stars are being born. Red colored objects to the left of center are extremely young massive stars, surrounded by less massive stars of one million years old. Nebulas with a variety of colors and appearances are ionized gas reflecting light from these stars. Filamentary dark clouds are also conspicuous. The line at bottom left shows a scale of 0.2 parsecs, which is approximately 40 thousand astronomical units. National Astronomical Observatory of Japan


January 29, 2009
Subaru Telescope facility, Hilo, Hawai

To explore dim, distant, low mass stars, a team of Japanese and Indian astronomers used the high sensitivity and spatial resolution of the Cooled Infrared Spectrograph and Camera for OHS (CISCO) at the Subaru Telescope in Hilo, Hawaii, to obtain unprecedented detailed data toward the W3 Main star forming region. W3 Main, located approximately 6,000 light-years away in the constellation Cassiopeia, is a very active and massive star-forming region. To date, this near-infrared image (at right) is the deepest and finest image from a ground-based telescope among the images of massive star forming regions. The deep and high-resolution image shows distinctive reddish and bluish nebulosity features, dark filaments between the diffuse nebulosities, and a significant population of faint stars in W3 Main.

The study has shown for the first time that there is a significant number of brown dwarfs in the W3 Main star forming region. This result is significantly different from that obtained in the cases of Trapezium and IC 348, where a decrease of relative population of brown dwarfs was found. The research findings indicate that a relative number of brown dwarfs may differ among regions in the galaxy. For the future, the team will proceed with the observations toward much more massive star forming regions in remote areas to study whether the results are widespread.

Superoutburst of the Dwarf Nova QZ Virginis

Dwarf Nova QZ Virginis
Annotated - Image Credit: Dr. Joe Brimacombe


AAVSO Locator Chart for QZ Vir

For all of you variable star fans, there's a new kid on the block - Dwarf Nova QZ Virginis. It was originally discovered by T. Meshkova on Moscow photographic plates in 1944 and had a magnitude range of 12.9 to as little as 14.5 But what is it? Try a cataclysmic variable star - one that our good friends down under caught just for Universe Today readers!

According to recently released AAVSO Special Notice #144, dwarf nova QZ Vir (once known as T Leo) is currently in outburst, and it appears that this outburst is a supermaximum. Says M. Templeton, "The most recent visual estimate of QZ Vir puts the star at visual magnitude 10.2 (JD 2454857.6201; W. Kriebel, Walkenstetten, Germany). Time series photometry by W. Stein (New Mexico, United States) on 2009 Jan 25 indicates the presence of superhumps in the light curve. Observations by P. Schmeer (Saarburecken-Bischmisheim, Germany), E. Morelle (Lauwin-Planque, France), ASAS-3 (Pojmanski 2002, AcA52, 397) and R. Stubbings (Tetoora Road, Vic., Australia) published on VSNET. (T. Kato; vsnet-alert 10980) suggest QZ Vir may have had a short precursor outburst lasting 2-3 days and fading immediately before the rise to supermaximum. All observations, including both visual estimates and CCD time-series photometry, are strongly encouraged at this time."

Of course, it didn't take a lot of encouragement - only some clear skies to get astrophotographer and serious researcher Joe Brimacombe of Southern Galactic to set his telescope towards QZ Virginis and image for us. All we needed to do was provide the following coordinates:
RA: 11 38 26.80 , Dec: +03 22 07.0

As you can see, learning proper stellar coordinates is essential to practicing astronomy. Without them, a stellar field is simply a stellar field as it would be next to impossible to distinguish one background star from the next. While some of us understand what these strange sets of numbers mean - maybe some of our readers don't. Let's take just a moment out from our busy days and learn, shall we?

RA stands for Right Ascension. It is the celestial equivalent of terrestrial longitude. RA's zero point is the Prime Meridian, located in the constellation of Aries where the Sun crosses the celestial equator at the March equinox. Each set of numbers is then measured eastward in three sets - hours, minutes, and seconds, with 24 hours being equivalent to a full circle. Declination, or "Dec" is comparable to latitude, projected onto the celestial sphere, and is measured in degrees north and south of the celestial equator. Points north of the celestial equator have positive declinations, while those to the south have negative declinations. These are also measured in three sets of numbers - degrees, minutes, and seconds of arc.

Now that you know, how do you use them? Chances are, if you have a telescope that has an equatorial mount, you already have the tools in your hands - called "setting circles". These same sets of numbers are waiting right on your telescope for you to set them! Once your telescope is accurately polar aligned, you just use the setting circles to dial in these numbers and you'll be right in the approximate area. For those with electronic setting circles, it's just a matter of inputting the correct coordinates and comparing star fields. Once the general area is found, you simply need to understand how big the field your eyepiece gives and compare it to a star chart - like this one supplied by the AAVSO for QZ Vir.

Make note of your observations and compare the suspect nova to other stars of known magnitude nearby. When you're done - don't keep your observations to yourself! Please report all observations to the AAVSO using the name "QZ Vir" and contribute!

NGC 604 - Wall Divides East and West Sides of Cosmic Metropolis

Credit X-ray: NASA/CXC/CfA/R. Tuellmann et al.;
Optical: NASA/AURA/STScI

A new study unveils NGC 604, the largest region of star formation in the nearby galaxy M33, in its first deep, high-resolution view in X-rays. This composite image from Chandra X-ray Observatory data (colored blue), combined with optical light data from the Hubble Space Telescope (red and green), shows a divided neighborhood where some 200 hot, young, massive stars reside.

Throughout the cosmic metropolis, giant bubbles in the cool dust and warm gas are filled with diffuse, multi-million degree gas that emits X-rays. Scientists think these bubbles are generated and heated to X-ray temperatures when powerful stellar winds from the young massive stars collide and push aside the surrounding gas and dust. So, the vacated areas are immediately repopulated with the hotter material seen by Chandra.

However, there is a difference between the two sides of this bifurcated stellar city. (Rollover the image above or view this separate annotated image for the location of the "wall".) On the western (right) side, the amount of hot gas found in the bubbles corresponds to about 4300 times the mass of the sun. This value and the brightness of the gas in X-rays imply that the western part of NGC 604 is entirely powered by winds from the 200 hot massive stars.

This result is interesting because previous modeling of other bubbles usually predicted them to be fainter than observed, so that additional heating from supernova remnants is required. The implication is that in this area of NGC 604, none or very few of the massive stars must have exploded as supernovas.

The situation is different on the eastern (left) side of NGC 604. On this side, the X-ray gas contains 1750 times the mass of the sun and winds from young stars cannot explain the brightness of the X-ray emission. The bubbles on this side appear to be much older and were likely created and powered by young stars and supernovas in the past.

A similar separation between east and west is seen in the optical results. This implies that a massive wall of gas shields the relatively quiet region in the east from the active star formation in the west.

This study was led by Ralph Tuellmann of the Harvard Smithsonian Center for Astrophysics and was part of a very deep, 16-day long observation of M33 called the Chandra ACIS Survey of M33, or ChASeM33.

Astronomers Observe Planet with Wild Temperature Swings

Tour of Planet with Extreme Temperature Swings
Credit: NASA/JPL-Caltech/D. Kasen (UC Santa Cruz)

This image shows a computer simulation of the planet HD 80606b from an observer located at a point in space lying between the Earth and the HD 80606 system. The animation starts 2.2 days before the moment of close approach and ends 8.9 days later. The blue areas are reflected starlight (the blue color arises mainly from absorption by sodium and potassium in the planetary atmosphere). Red regions are areas of the planet that are glowing with their own intrinsic heat.The point of closest approach -- and maximum heating -- occurs about 4.5 seconds into the animation. As the planet whips around the star, we see the evolving thermal storm patterns across its unilluminated side. The planetÍs transit behind its star (as would be seen from Earth four seconds into the animation) is not shown in this simulation.These theoretical models allow astronomers to better understand weather patterns on distant planets. While direct telescopic observations of the atmospheres of such worlds may be many decades away, such simulations give us a clue to what we may see when it becomes possible.


Light From Red-Hot Planet
Credit: NASA/JPL-Caltech/G. Laughlin (UC Santa Cruz)

This figure charts 30 hours of observations taken by NASA's Spitzer Space Telescope of a strongly irradiated exoplanet (an planet orbiting a star beyond our own). Spitzer measured changes in the planet's heat, or infrared light.The lower graph shows precise measurements of infrared light with a wavelength of 8 microns coming from the HD 80606 stellar system. The system consists of a sun-like star and a planetary companion on an extremely eccentric, comet-like orbit. The geometry of the planet-star encounter is shown in the upper part of the figure.As the planet swung through its closest approach to the star, the Spitzer observations indicated that it experienced very rapid heating (as shown by the red curve). Just
before close approach, the planet was eclipsed by the star as seen from Earth, allowing astronomers to determine the amount of energy coming from the planet in comparison to the amount coming from the star.The observations were made in Nov. of 2007, using Spitzer's infrared array camera. They represent a significant first for astronomers, opening the door to studying changes in atmospheric conditions of planets far beyond our own solar system.


Severe Exoplanetary Storm
Credit: NASA/JPL-Caltech/J. Langton (UC Santa Cruz)

These computer-generated images chart the development of severe weather patterns on the highly eccentric exoplanet HD 80606b during the days after its closest approach to its parent star. An exoplanet is a planet that orbits a star other than our sun.
The images were produced by computer simulations that modeled NASA's Spitzer
Space Telescope's measurements of heat radiating from the planet. The six frames are evenly spaced in time, starting from 4.4 days after the planet's close approach to the star, a moment known as "periastron," and running through 8.9 days after periastron. The blue glow of the crescent is starlight that has been scattered and reflected by the planet. The starlight appears blue because the planet is a very efficient absorber of red light. The night side appears reddish orange as it glows with its own internal heat.These theoretical models allow astronomers to better understand weather patterns on distant planets. While direct telescopic observations of the atmospheres of such worlds may be many decades away, such simulations give us a clue to what we may see when it becomes possible.The Spitzer observations themselves spanned the relatively brief period when the heating of the planet was most intense, running from 20 hours prior to 10 hours after periastron. The data were taken in Nov. of 2007.HD 80606b is located 190 light-years away in the constellation Ursa Major. Its star can be seen with binoculars.

Wednesday, January 28, 2009

NASA's Spitzer Space Telescope has observed a planet that heats up to red-hot temperatures in a matter of hours before quickly cooling back down.

The "hot-headed" planet is HD 80606b, a gas giant that orbits a star 190 light-years from Earth. It was already known to be quite unusual, with an orbit shuttling it nearly as far out as Earth is from our sun, and much closer in than our planet Mercury. Astronomers used Spitzer, an infrared observatory, to measure heat emanating from the planet as it whipped behind and close to its star. In just six hours, the planet's temperature rose from 800 to 1,500 Kelvin (980 to 2,240 degrees Fahrenheit).

"We watched the development of one of the fiercest storms in the galaxy," said astronomer Greg Laughlin of the Lick Observatory, University of California at Santa Cruz. "This is the first time that we've detected weather changes in real time on a planet outside our solar system." Laughlin is lead author of a new report about the discovery appearing in the Jan. 29 issue of Nature.

HD 80606b was originally discovered in 2001 by a Swiss planet-hunting team led by Dominique Naef of the Geneva Observatory in Switzerland. Using a method known as the Doppler-velocity technique, the astronomers learned that the planet is wildly eccentric, with an orbit more like a comet's than a planet's. HD 80606b's orbit takes it as far out as 0.85 astronomical units from its star, and as close in as 0.03 astronomical units (one astronomical unit is the distance between Earth and the sun).

The planet takes about 111 days to circle its star, but it spends most of its time at farther distances while zipping through the closest part of its orbit in less than a day. (This is a consequence of Kepler's Second Law of Planetary Motion, which states that orbiting bodies -- planets and comets -- sweep out an equal area in equal time.)

"If you could float above the clouds of this planet, you'd see its sun growing larger and larger at faster and faster rates, increasing in brightness by almost a factor of 1,000," said Laughlin.

Spitzer observed HD 80606b before, during and just after its closest passage to the star in November of 2007, as the planet sizzled under the star's heat. When Laughlin and his colleagues planned the observation, they did not know whether the planet would disappear completely behind the star, an event called a secondary eclipse, or whether it would remain in view. Luckily for the team, the planet did indeed temporarily disappear from view, providing the planet's initial and final temperatures (had the planet had not been eclipsed, the team would have known only the temperature change without knowing the starting point).

The extreme temperature swing observed by Spitzer indicates that the air near the planet's gaseous surface must quickly absorb and lose heat. This type of atmospheric information revealing how a planet responds to sudden changes in heating -- an extreme version of seasonal change -- had never been obtained before for any exoplanet (a planet orbiting another star).

"By studying this planet under such extreme circumstances, we figure out how it handles heat -- does it retain it or dissipate it? In this case, the answer is that the planet releases the heat right away," said Laughlin. "We were essentially able to perform the 'thought experiment' -- what would happen to a planet like Jupiter if we could drag it very close to the sun?"

Laughlin and his colleagues say that a key factor in being able to make the observations is the planet's eccentric orbit. Unlike so-called hot Jupiter planets that remain in tight orbits around their stars, HD 80606b rotates around its axis roughly every 34 hours. Hot Jupiters, on the other hand, are thought to be tidally locked like our moon, so one side always faces their stars. Because HD 80606b spins on its axis many times per orbit, the astronomers were able to measure how its atmosphere responds to being baked by the star.

"The planet is spinning at a fast enough rate for the planet's hot spot to come into view," said co-author Drake Deming of NASA's Goddard Space Flight Center, Greenbelt, Md. "The hot spot can't hide."

Amateur and professional astronomers alike are gearing up to observe HD 80606b this coming Valentine's Day, when it will swing around the front of its star. There's a 15 percent chance that the planet will eclipse its star, an event known as the primary transit. If so, the event would not only be remarkable to see, but would also provide more details about the nature of this temperamental world.

Other authors include Jonathan Langton, Daniel Kasen, Steve Vogt, Eugenio Rivera and Stefano Meschiari from the University of California, Santa Cruz, and Paul Butler of the Carnegie Institution's Department of Terrestrial Magnetism, Washington. NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology, also in Pasadena. Caltech manages JPL for NASA.

Black hole outflows from Centaurus A detected with APEX

About this image:

Colour composite image of Centaurus A, revealing the lobes and jets emanating from the active galaxy’s central black hole. This is a composite of images obtained with three instruments, operating at very different wavelengths. The 870-micron submillimetre data, from LABOCA on APEX, are shown in orange. X-ray data from the Chandra X-ray Observatory are shown in blue. Visible light data from the Wide Field Imager (WFI) on the MPG/ESO 2.2 m telescope located at La Silla, Chile, show the background stars and the galaxy’s characteristic dust lane in close to "true colour".
Credit: ESO/WFI (Optical); MPIfR/ESO/APEX/A.Weiss et al. (Submillimetre); NASA/CXC/CfA/R.Kraft et al. (X-ray)

Astronomers have a new insight into the active galaxy Centaurus A (NGC 5128), as the jets and lobes emanating from the central black hole have been imaged at submillimetre wavelengths for the first time. The new data, from the Atacama Pathfinder Experiment (APEX) telescope in Chile, which is operated by ESO, have been combined with visible and X-ray wavelengths to produce this striking new image.

Centaurus A is our nearest giant galaxy, at a distance of about 13 million light-years in the southern constellation of Centaurus. It is an elliptical galaxy, currently merging with a companion spiral galaxy, resulting in areas of intense star formation and making it one of the most spectacular objects in the sky. Centaurus A hosts a very active and highly luminous central region, caused by the presence of a supermassive black hole (see ESO 04/01), and is the source of strong radio and X-ray emission.

In the image, we see the dust ring encircling the giant galaxy, and the fast-moving radio jets ejected from the galaxy centre, signatures of the supermassive black hole at the heart of Centaurus A. In submillimetre light, we see not only the heat glow from the central dust disc, but also the emission from the central radio source and – for the first time in the submillimetre – the inner radio lobes north and south of the disc. Measurements of this emission, which occurs when fast-moving electrons spiral around the lines of a magnetic field, reveal that the material in the jet is travelling at approximately half the speed of light. In the X-ray emission, we see the jets emerging from the centre of Centaurus A and, to the lower right of the galaxy, the glow where the expanding lobe collides with the surrounding gas, creating a shockwave.

The Large APEX Bolometer Camera (LABOCA), built by the Max-Planck-Institute for Radio Astronomy (MPIfR), is mounted on APEX, a 12-metre diameter submillimetre-wavelength telescope located on the 5000 m high plateau of Chajnantor in the Chilean Atacama region. APEX is a collaboration between the MPIfR, the Onsala Space Observatory and ESO. The telescope is based on a prototype antenna constructed for the next generation Atacama Large Millimeter/submillimeter Array (ALMA) project. Operation of APEX at Chajnantor is entrusted to ESO.

A Twist on the "Trunk"

IC1396 and Van den Berg 142 by Takayuki Yoshida

Out in the reaches of the constellation of Cepheus some 2400 light years from Earth, a cloud of hydrogen gas and dust harbors young star cluster IC 1396. These newborn stars emit their light upon the scene… shedding infrared radiation through a 20 light year wide corridor known as the "Elephant's Trunk"…

Cataloged by Dreyer as far back as 1888, galactic cluster IC 1396 has long been known to have an air of nebulosity around it and perhaps a shroud of mystery as well. As telescopes improved, so did the view and observers began to notice dark patches and a bright, sinuous rim. The dark interstellar clouds took a very special observer in the late 1800s to discover them - E.E. Barnard - and he labeled his discovery B163. Nothing more than a cold area in space - obscuring dust waiting to gel into stars. Just another dark hole obscuring a mystery inside IC 1396… and tiny patch of nebula that would one day be known as Van den Berg 142.

In 1975 Robert B. Loren (et al) was the first to report on the molecular cloud structure in IC 1396. His observations were made using the Kitt Peak scope, doing their best to confirm the hypothesis that cometary like structure was the result of an ionization front as it progressed into neutral hydrogen territory. High density gases, a dark rimmed nebula… But, they still didn't quite grasp what lay inside - a concentration of interstellar gas and dust that is being illuminated and ionized by a very bright, massive star.

And the tiny dense globules hiding from the intense ultraviolet rays…

In 1996, G. H. Moriarty Schieven was the first to announce H I "Tails" from cometary globules in IC 1396. In his reports he writes: "IC 1396 is a relatively nearby, large, H ii region ionized by a single O6.5 V star and containing bright rimmed cometary globules. We have made the first arcminute resolution images of atomic hydrogen toward IC 1396, and have found remarkable "tail" like structures associated with some of the globules and extending up to 6.5 pc radially away from the central ionizing star. These H i "tails" may be material which has been ablated from the globule through ionization and/or photodissociation and then accelerated away from the globule by the stellar wind, but which has since drifted into the "shadow" of the globules." This report was the first results of the Galactic Plane Survey Project began by the Dominion Radio Astrophysical Observatory and opened the gateway into the twisted tale of the "Trunk".

The Elephant's Trunk nebula is an intense concentration of interstellar gas which contains embedded globule IC 1396A and is now believed to be the site of star formation. Located inside the opening where the stellar winds have cleared a cavity are two very young stars - their pressure driving the material outwards and revealing the presence of protostars.

In 2003, Alaina Henry picked up the ball once again. "Since emission line stars are relatively rare, the discovery of a cluster of emission line stars is adequate proof that star formation is taking place in a cluster. In addition, young stars often display variable luminosity. It is thought that non-constant mass accretion rates cause variations in the luminosity of young stellar objects. BRC 37 is a small globule in the extended, HII region, IC 1396. It is about I' wide and 5' long in the optical, and has a bright rim of Ho emission in the north, due to recombination of ionized hydrogen. The source of the ionization is thought to be the 06 star, HO 206267, which lies several degrees away on the sky. The infrared source, IRAS 21388+5622 is located at the head of the globule and showed another signature of star formation in BRC 37 by discovering a bipolar molecular outflow associated with the IRAS source. We identify eight likely young stellar objects in BRC 37, based on the presence of an infrared excess. We also identify four of our observed sources with Ho emission line stars. Of these 11 sources, five are sub-stellar objects, below the hydrogen burning limit. While the eleven objects in table 1 are apparently young stellar objects, it is likely that there are many more young stellar objects in BRC 37… "

As recently as mid-2005 even more discovery was made by Astrofisico di Arcetri at the end of a 16 year study. "In spite of the relatively high far-infrared luminosities of the embedded sources H2O maser emission was detected towards three globules only. Since the occurrence of water masers is higher towards bright IRAS sources, the lack of frequent H2O maser emission is somewhat surprising if the suggestion of induced intermediate- and high-mass star formation within these globules is correct. The maser properties of two BRCs are characteristic of exciting sources of low-mass, while the last one (BRC 38) is consistent with an intermediate-mass object."
Around 18 months later at the beginning of 2007, Konstantin V. Getman (et al) used the Chandra X-Ray Observatory to draw conclusions on this same strange area as well: "The IC 1396N cometary globule (CG) within the large nearby H II region IC 1396 has been observed with the ACIS detector on board the Chandra X-Ray Observatory. We detect 117 X-ray sources, of which ~50-60 are likely members of the young open cluster Trumpler 37 dispersed throughout the H II region, and 25 are associated with young stars formed within the globule…. We find that the Chandra source associated with the luminous Class 0/I protostar IRAS 21391+5802 is one of the youngest stars ever detected in the X-ray band."

Is there even more things yet to be discovered inside the twisted "Trunk"? Astronomers haven't stopped looking. Just as recently as November 2008 yet another study was released Zoltan Bolag (et al) searching for protoplanetary discs. "Overall, our observations support theoretical predictions in which photoevaporation removes the gas relatively quickly (<=105 yr) from the outer region of a protoplanetary disk, but leaves an inner, more robust, and possibly gas-rich disk component of radius 5-10 AU. With the gas gone, larger solid bodies in the outer disk can experience a high rate of collisions and produce elevated amounts of dust. This dust is being stripped from the system by the photon pressure of the O star to form a gas-free dusty tail." What will the future hold? My many thanks to Takayuki Yoshida of Northern Galactic for turning me on to this incredible image which sparked my desire to learn and share what I'd learned about this region. Arigato!