NASA's Kepler Captures First Views of Planet-Hunting Territory

This image from NASA's Kepler mission shows the telescope's full field of view -- an expansive star-rich patch of sky in the constellations Cygnus and Lyra stretching across 100 square degrees, or the equivalent of two side-by-side dips of the Big Dipper.

Image credit: NASA/Ames/JPL-Caltech

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Kepler Eyes Cluster and Known Planet Image
Credit: NASA/Ames/JPL-Caltech
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Cluster of Stars in Kepler's Sight

This image zooms into a small portion of Kepler's full field of view -- an expansive, 100-square-degree patch of sky in our Milky Way galaxy. An eight-billion-year-old cluster of stars 13,000 light-years from Earth, called NGC 6791, can be seen in the image. Clusters are families of stars that form together out of the same gas cloud. This particular cluster is called an open cluster, because the stars are loosely bound and have started to spread out from each other.

Image credit: NASA/JPL-Caltech

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Host to 'Hot Jupiter' (labeled)

This image zooms into a small portion of Kepler's full field of view -- an expansive, 100-square-degree patch of sky in our Milky Way galaxy. At the center of the field is a star with a known "hot Jupiter" planet, named "TrES-2," zipping closely around it every 2.5 days. Kepler will observe TrES-2 and other known planets as a test to demonstrate that it is working properly, and to obtain new information about those planets. Image credit: NASA/JPL-Caltech

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NASA's Kepler mission has taken its first images of the star-rich sky where it will soon begin hunting for planets like Earth.

The new "first light" images show the mission's target patch of sky, a vast starry field in the Cygnus-Lyra region of our Milky Way galaxy. One image shows millions of stars in Kepler's full field of view, while two others zoom in on portions of the larger region. The images can be seen online at: http://www.nasa.gov/mission_pages/kepler/multimedia/20090416.html

"Kepler's first glimpse of the sky is awe-inspiring," said Lia LaPiana, Kepler's program executive at NASA Headquarters in Washington. "To be able to see millions of stars in a single snapshot is simply breathtaking."

One new image from Kepler shows its entire field of view -- a 100-square-degree portion of the sky, equivalent to two side-by-side dips of the Big Dipper. The regions contain an estimated 14 millions stars, more than 100,000 of which were selected as ideal candidates for planet hunting.
Two other views focus on just one-thousandth of the full field of view. In one image, a cluster of stars located about 13,000 light-years from Earth, called NGC 6791, can be seen in the lower left corner. The other image zooms in on a region containing a star, called Tres-2, with a known Jupiter-like planet orbiting every 2.5 days.

"It's thrilling to see this treasure trove of stars," said William Borucki, science principal investigator for Kepler at NASA's Ames Research Center at Moffett Field, Calif. "We expect to find hundreds of planets circling those stars, and for the first time, we can look for Earth-size planets in the habitable zones around other stars like the sun."

Kepler will spend the next three-and-a-half years searching more than 100,000 pre-selected stars for signs of planets. It is expected to find a variety of worlds, from large, gaseous ones, to rocky ones as small as Earth. The mission is the first with the ability to find planets like ours -- small, rocky planets orbiting sun-like stars in the habitable zone, where temperatures are right for possible lakes and oceans of water.

To find the planets, Kepler will stare at one large expanse of sky for the duration of its lifetime, looking for periodic dips in starlight that occur as planets circle in front of their stars and partially block the light. Its 95-megapixel camera, the largest ever launched into space, can detect tiny changes in a star's brightness of only 20 parts per million. Images from the camera are intentionally blurred to minimize the number of bright stars that saturate the detectors. While some of the slightly saturated stars are candidates for planet searches, heavily saturated stars are not.

"Everything about Kepler has been optimized to find Earth-size planets," said James Fanson, Kepler's project manager at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "Our images are road maps that will allow us, in a few years, to point to a star and say a world like ours is there."
Scientists and engineers will spend the next few weeks calibrating Kepler's science instrument, the photometer, and adjusting the telescope's alignment to achieve the best focus. Once these steps are complete, the planet hunt will begin.

"We've spent years designing this mission, so actually being able to see through its eyes is tremendously exciting," said Eric Bachtell, the lead Kepler systems engineer at Ball Aerospace & Technology Corp. in Boulder, Colo. Bachtell has been working on the design, development and testing of Kepler for nine years.

Kepler is a NASA Discovery mission. Ames is responsible for the ground system development, mission operations and science data analysis. JPL manages the Kepler mission development. Ball Aerospace & Technologies Corp. is responsible for developing the Kepler flight system and supporting mission operations.

For images, animations and more information about the Kepler mission, visit:

http://www.nasa.gov/kepler

Whitney Clavin 818-354-4673
Jet Propulsion Laboratory, Pasadena, Calif.
whitney.clavin@jpl.nasa.gov

J.D. Harrington 202-358-5241
Headquarters, Washington
j.d.harrington@nasa.gov

Michael Mewhinney 650-604-3937
Ames Research Center, Moffett Field, Calif.

michael.s.mewhinney@nasa.gov

MACSJ0717.5+3745: Cosmic Heavyweights in Free-For-All

Credit: X-ray (NASA/CXC/IfA/C. Ma et al.);
Optical (NASA/STScI/IfA/C. Ma et al.)

Press Image and Caption

This composite image shows the massive galaxy cluster MACSJ0717.5+3745 (MACSJ0717, for short), where four separate galaxy clusters have been involved in a collision, the first time such a phenomenon has been documented.

Labeled X-ray & Optical Image of MACSJ0717.5+3745
Credit: X-ray (NASA/CXC/IfA/C. Ma et al.);
Optical (NASA/STScI/IfA/C. Ma et al.)
View Animation

A labeled version of the MACSJ0717 image shows the galaxies in the four different clusters involved in the collision, plus the direction of motion for the three fastest moving clusters. The length of the arrow shows the approximate speed in a direction perpendicular to the line of sight. Note that the direction of motion of the clusters is roughly parallel to the direction of the filament. Data from Keck Observatory was used to derive the speed of the clusters along the line of sight, allowing the three-dimensional geometry and dynamics of MACSJ0717 to be derived.

A Larger Scale Chandra View of MACSJ0717
Credit: X-ray (NASA/CXC/IfA/C. Ma et al.)

This Chandra image shows a larger scale view of the galaxy cluster MACSJ0717, where the white box shows the field-of-view of the Chandra/HST composite image. The green line shows the approximate position of the large-scale filament leading into MACSJ0717, based on analysis of the positions of galaxies using optical data (not shown here). Material flows along the filament into MACSJ0717. Faint X-ray emission is seen along the filament, showing that it contains hot gas as well as galaxies.

The most crowded collision of galaxy clusters has been identified by combining information from three different telescopes. This result gives scientists a chance to learn what happens when some of the largest objects in the Universe go at each other in a cosmic free-for-all.

Using data from NASA's Chandra X-ray Observatory, Hubble Space Telescope and the Keck Observatory on Mauna Kea, Hawaii, astronomers were able to determine the three-dimensional geometry and motion in the system MACSJ0717.5+3745 (or MACSJ0717 for short) located about 5.4 billion light years from Earth.

The researchers found that four separate galaxy clusters are involved in a triple merger, the first time such a phenomenon has been documented. Galaxy clusters are the largest objects bound by gravity in the Universe.

In MACSJ0717, a 13-million-light-year-long stream of galaxies, gas and dark matter - known as a filament - is pouring into a region already full of matter. Like a freeway of cars emptying into a full parking lot, this flow of galaxies has caused one collision after another.

"In addition to this enormous pileup, MACSJ0717 is also remarkable because of its temperature," said Cheng-Jiun Ma of the University of Hawaii and lead author of the study. "Since each of these collisions releases energy in the form of heat, MACS0717 has one of the highest temperatures ever seen in such a system."

While the filament leading into MACJ0717 had been previously discovered, these results show for the first time that it was the source of this galactic pummeling. The evidence is two-fold. First, by comparing the position of the gas and clusters of galaxies, the researchers tracked the direction of clusters' motions, which matched the orientation of the filament in most cases. Secondly, the largest hot region in MACSJ0717 is where the filament intersects the cluster, suggesting ongoing impacts.

MACSJ0717 shows how giant galaxy clusters interact with their environment on scales of many millions of light years," said team member Harald Ebeling, also from University of Hawaii. "This is a wonderful system for studying how clusters grow as material falls into them along filaments."

Computer simulations show that the most massive galaxy clusters should grow in regions where large-scale filaments of intergalactic gas, galaxies, and dark matter intersect, and material falls inward along the filaments.

"It's exciting that the data we get from MACSJ0717 appear to beautifully match the scenario depicted in the simulations," said Ma.

Multiwavelength data were crucial for this work. The optical data from Hubble and Keck give information about the motion and density of galaxies along the line of sight, but not about their course perpendicular to that direction. By combining the X-ray and optical data, scientists were able to determine the three-dimensional geometry and motion in the system.

In the future, Ma and his team hope to use even deeper X-ray data to measure the temperature of gas over the full 13-million-light-year extent of the filament. Much remains to be learned about the properties of hot gas in filaments and whether its infall along these structures can significantly heat the gas in clusters over large scales.

"This is the most spectacular and most disturbed cluster I have ever seen," says Ma, "and we think that we can learn a whole lot more from it about how structure in our Universe grows and evolves."

The paper describing these results appeared in the March 10th issue of the Astrophysical Journal Letters. NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra's science and flight operations from Cambridge, Mass.

Media contacts:

Kimberly Newton
Marshall Space Flight Center, Huntsville, Ala.
256-544-0371
kimberly.d.newton@nasa.gov

Megan Watzke
Chandra X-ray Center, Cambridge, Mass.
617-496-7998
cxcpress@cfa.harvard.edu

Additional information and images are available at:
http://chandra.harvard.edu/ and http://chandra.nasa.gov

 

Fast Facts for MACSJ0717.5+3745:

 

Scale: Image is 4.5 arcmin across
Category: Groups & Clusters of Galaxies
Coordinates: (J2000) RA 07h 17m 31.00s | Dec +37° 45' 39.60
Constellation: Aurigae
Observation Date: January 10, 2003
Observation Time: 16 hours 40 minutes
Obs. ID: 4200
Color Code: X-ray (Blue, Violet); Optical (Cyan, Yellow)
Instrument: ACIS
References: Ma C. et al 2009
Distance Estimate: About 5.4 billion light years  

Source:   NASA’s Chandra X-ray Observatory

Capturing a Solar Storm in 3-D

Image from telescopes onboard STEREO spacecraft showing a coronal mass ejection event on December 12-13, 2008. Data from both spacecraft are shown simultaneously. Credit: Nasa

Video 1: Quicktime Movie (4.81 mb)
Video 2: Quicktime Movie (17 mb)

Image depicting STEREO-A viewing a coronal mass ejection leaving the sun between December 12-13, 2008. Credit : Nasa

APL Spacecraft Experts Enhance Systems to Reconstruct 3-D STEREO Imagery

The APL–built and –operated twin STEREO observatories have made the first 3-D measurements of solar explosions, known as coronal mass ejections, enabling scientists to see their size and shape, and image them as they travel approximately 93 million miles from the sun to Earth. Scientists will be able to use this information to help determine how these strong solar storms will impact Earth’s atmosphere.

The Solar TErrestrial RElations Observatory’s science data is enhanced, in part, due to the STEREO guidance and control team at the Johns Hopkins University Applied Physics Laboratory (APL), in Laurel, Md. They’re helping mission scientists more easily reconstruct 3-D imagery by very accurately pointing the spacecraft and reducing its jitter or movement. “By tuning each spacecraft’s control software, much like a race car’s control system is tuned for optimal performance on the track, spacecraft system performance is now approximately five times better than at launch and seven times better than specifications require,” says Andy Driesman, STEREO’s system engineer at APL.

Since launch in 2006, the APL team has been proactively tuning spacecraft and ground systems, maximizing data return and optimizing contact with satellites used to downlink data. The APL-based STEREO mission operations center downloads 6-9 gigabytes of data each day — approximately 20-80 percent more data than the science team expected.

Coronal mass ejections are powerful solar explosions that can have damaging effects when hitting Earth’s upper atmosphere at speeds of nearly one million miles-per-hour. These giant clouds of electrically charged gas called plasma can disrupt satellite communications, GPS and/or cell phone signals, or induce large currents in power grids, which can cause power disruptions or black outs.

“Using STEREO observations, we can extract a CME’s properties and are able to determine when it will reach Earth, at what speed, and with how much energy it will impact Earth’s magnetosphere,” says Angelos Vourlidas, of the Naval Research Laboratory, and project scientist for STEREO’s SECCHI (Sun Earth Connection Coronal and Heliospheric Investigation) imaging suite. Disruptions to the magnetic envelope surrounding Earth can often trigger auroras. These bright bands of light, often visible at night in northern and southern regions, can interfere with communications between air-traffic controllers and pilots flying near Earth’s polar regions.

STEREO is sponsored by NASA Headquarters' Science Mission Directorate, Washington, D.C. NASA Goddard Space Flight Center's (GSFC) Solar Terrestrial Probes Program Office, in Greenbelt, Md., manages the mission, instruments and science center. APL designed and built the spacecraft and is operating the twin observatories for NASA during the mission.

For more information, visit http://stereo.jhuapl.edu/ and http://stereo.gsfc.nasa.gov/.

Media Contacts:
Kristi Marren, Johns Hopkins University Applied Physics Laboratory
(240) 228-6268 or (443) 778-6268

Rani Gran, NASA Goddard Space Flight Center
(301) 286-2483

The Applied Physics Laboratory, a division of The Johns Hopkins University, meets critical national challenges through the innovative application of science and technology.For more information, visit www.jhuapl.edu.

Hubble Witnesses Spectacular Flaring in Gas Jet from M87's Black Hole

Credit: NASA, ESA, and J. Madrid (McMaster University)

About this image: These images taken in ultraviolet light by NASA's Hubble Space Telescope reveal the brightening of a jet of gas blasting from the core of the gigantic elliptical galaxy M87. M87 is located 54 million light-years away in the Virgo Cluster.

The flare-up is coming from a knot of hot gas, called HST-1, embedded in the jet. The jet is powered by accretion onto a supermassive black hole, one of the most massive black holes yet discovered.

Hubble's Space Telescope Imaging Spectrograph (STIS) snapped the top row of images and Hubble's Advanced Camera for Surveys (ACS) the bottom row. The core of M87 is located at lower left in the images. HST-1 is the bright blob at center. The glowing material at far right is part of a stream of particles in the jet that speed up and glow in the ultraviolet.

The Hubble images, obtained from the Hubble archive, show the jet growing brighter over a seven-year period, eventually outshining even the luminous core of M87. The ACS image taken on May 9, 2005, reveals that HST-1 has become brighter than M87's core. HST-1 is 214 light-years from the core.

Hubble's crisp vision gives astronomers a clear view of the brightening knot. The telescope resolves HST-1 and separates it from the galaxy's core.

Compass and Scale Image of M87 Jet

Illustration Credit: NASA, ESA, and Z. Levay (STScI)

Credit: NASA, ESA, and J. Madrid (McMaster University)

A flare-up in a jet of matter blasting from a monster black hole is giving astronomers an incredible light show.

The outburst is coming from a blob of matter, called HST-1, embedded in the jet, a powerful narrow beam of hot gas produced by a supermassive black hole residing in the core of the giant elliptical galaxy M87. HST-1 is so bright that it is outshining even M87's brilliant core, whose monster black hole is one of the most massive yet discovered.

The glowing gas clump has taken astronomers on a rollercoaster ride of suspense. Astronomers watched HST-1 brighten steadily for several years, then fade, and then brighten again. They say it's hard to predict what will happen next.

NASA's Hubble Space Telescope has been following the surprising activity for seven years, providing the most detailed ultraviolet-light view of the event. Other telescopes have been monitoring HST-1 in other wavelengths, including radio and X-rays. The Chandra X-ray Observatory was the first to report the brightening in 2000. HST-1 was first discovered and named by Hubble astronomers in 1999. The gas knot is 214 light-years from the galaxy's core.

The flare-up may provide insights into the variability of black hole jets in distant galaxies, which are difficult to study because they are too far away. M87 is located 54 million light-years away in the Virgo Cluster, a region of the nearby universe with the highest density of galaxies.

"I did not expect the jet in M87 or any other jet powered by accretion onto a black hole to increase in brightness in the way that this jet does," says astronomer Juan Madrid of McMaster University in Hamilton, Ontario, who conducted the Hubble study. "It grew 90 times brighter than normal. But the question is, does this happen to every single jet or active nucleus, or are we seeing some odd behavior from M87?"

Hubble gives astronomers a unique near-ultraviolet view of the flare that cannot be accomplished with ground-based telescopes. "Hubble's sharp vision allows it to resolve HST-1 and separate it from the black hole," Madrid explains.

Despite the many observations by Hubble and other telescopes, astronomers are not sure what is causing the brightening. One of the simplest explanations is that the jet is hitting a dust lane or gas cloud and then glows due to the collision. Another possibility is that the jet's magnetic field lines are squeezed together, unleashing a large amount of energy. This phenomenon is similar to how solar flares develop on the Sun and is even a mechanism for creating Earth's auroras.

The disk around a rapidly spinning black hole has magnetic field lines that entrap ionized gas falling toward the black hole. These particles, along with radiation, flow rapidly away from the black hole along the magnetic field lines. The rotational energy of the spinning accretion disk adds momentum to the outflowing jet.

Madrid assembled seven years' worth of Hubble archival images of the jet to capture changes in the HST-1's behavior over time. Hubble's view of the event. Some of the images came from observing programs that studied the galaxy, but not the jet.

He found data from the Space Telescope Imaging Spectrograph (STIS) that showed a noticeable brightening between 1999 and 2001. In images from 2002 to 2005, HST-1 continued to rise steadily in brightness. In 2003 the jet knot was more brilliant than M87's luminous core. In May 2005 HST-1 became 90 times brighter than it was in 1999. After May 2005 the flare began to fade, but it intensified again in November 2006. This second outburst was fainter than the first one.

"By watching the outburst over several years, I was able to follow the brightness and see the evolution of the flare over time," Madrid says. "We are lucky to have telescopes like Hubble and Chandra, because without them we would see the increase in brightness in the core of M87, but we would not know where it was coming from."

Madrid hopes that future observations of HST-1 will reveal the cause of the mysterious activity. "We hope the observations will yield some theories that will give us some good explanations as to the mechanism that is causing the flaring," Madrid says. "Astronomers would like to know if this is an intrinsic instability of the jet when it plows its way out of the galaxy, or if it is something else."

The study's results are published in the April 2009 issue of the Astronomical Journal.

CONTACT
Donna Weaver/Ray Villard
Space Telescope Science Institute, Baltimore, Md.
410-338-4514
villard@stsci.edu

Juan Madrid
McMaster University, Ontario, Canada
905-525-9140, ext. 26057
madridjp@mcmaster.ca

The Extended Region Around the Planetary Nebula NGC 3242

Image credit: NASA/JPL-Caltech
High-resolution TIFF (14Mb)

This ultraviolet image from NASA's Galaxy Evolution Explorer shows NGC 3242, a planetary nebula frequently referred to as "Jupiter's Ghost."

The unfortunate name of "planetary nebula" for this class of celestial object is a historical legacy credited to William Herschel during the 18th century -- a time when telescopes where small and objects like these, at least the central region, looked very similar to gas-giant planets such as Saturn and Jupiter. In fact, NGC 3242 has no relation to Jupiter or any other planet.

Telescopes and their detectors have dramatically improved over the past few centuries. Our understanding of what planetary nebulae truly are has improved accordingly.

When stars with a mass similar to our sun approach the end of their lives by exhausting supplies of hydrogen and helium fuel in their cores, they swell up into cool red-giant stars. In a last gasp before death, they expel the layers of gas in their outer atmosphere. This exposes the core of the dying star, a dense hot ball of carbon and oxygen called a white dwarf. The white dwarf is so hot that it shines very brightly in the ultraviolet. The ultraviolet light from the white dwarf, in turn, ionizes the gaseous material expelled by the star causing it to glow. A planetary nebula is really the death of a low-mass star.

Although low-mass stars like our sun live for billions of years, planetary nebulae only last for about ten thousand years. As the central white dwarf quickly cools and the ultraviolet light dwindles, the surrounding gas also cools and fades.

In this image of NGC 3242 from the Galaxy Evolution Explorer, the extended region around the planetary nebula is shown in dramatic detail. The small circular white and blue area at the center of the image is the well-known portion of the famous planetary nebula. The precise origin and composition of the extended wispy white features is not known for certain. It is most likely material ejected during the star's red-giant phase before the white dwarf was exposed. However, it may be possible that the extended material is simply interstellar gas that, by coincidence, is located close enough to the white dwarf to be energized by it, and induced to glow with ultraviolet light.

NGC 3242 is located 1,400 to 2,500 light-years away in the constellation Hydra. It was discovered by William Herschel in 1785.

Source: GALEX - Galaxy Evolution Explorer

Join STEREO and Explore Gravitational "Parking Lots" That May Hold Secret of Moon's Origin

Click to view animation (19Mb)

Click to visit the SVS site for high resolution stills and alternate animation formats

The STEREO spacecraft are entering the L4 and L5 Lagrangian point regions. L4 and L5 are where the combined gravity of the sun and Earth balance the forces from the object's orbital motion. Scientists believe these places may hold small asteroids which could be leftovers from the formation of the solar system. STEREO will be imaging these regions in an attempt to detect these asteroids. Credit: NASA

Two places on opposite sides of Earth may hold the secret to how the moon was born. NASA's twin Solar Terrestrial Relations Observatory (STEREO) spacecraft are about to enter these zones, known as the L4 and L5 Lagrangian points, each centered about 93 million miles away along Earth's orbit.

"These places may hold small asteroids, which could be leftovers from a Mars-sized planet that formed billions of years ago," said Michael Kaiser, Project Scientist for STEREO at NASA's Goddard Space Flight Center in Greenbelt, Md. "According to Edward Belbruno and Richard Gott at Princeton University, about 4.5 billion years ago when the planets were still growing, this hypothetical world, called Theia, may have been nudged out of L4 or L5 by the increasing gravity of the other developing planets like Venus and sent on a collision course with Earth. The resulting impact blasted the outer layers of Theia and Earth into orbit, which eventually coalesced under their own gravity to form the moon."

This theory is a modification of the "giant impact" theory of the moon's origin, which has become the dominant theory because it explains some puzzling properties of the moon, such as its relatively small iron core. According to giant impact, at the time of the collision, the two planets were large enough to be molten, so heavier elements, like iron, sank to their centers to form their cores.

The impact stripped away the outer layers of the two worlds, which contained mostly lighter elements, like silicon. Since the moon formed from this material, it is iron-poor.

STEREO will look for asteroids with a wide-field-of-view telescope that's part of the Sun Earth Connection Coronal and Heliospheric Investigation instrument. Any asteroid will probably appear as just a point of light. Like a picky person circling the mall for the perfect parking space, the asteroids orbit the L4 or L5 points. The team will be able to tell if a dot is an asteroid because it will shift its position against stars in the background as it moves in its orbit. The team is inviting the public to participate in the search by viewing the davta and filing a report at: http://sungrazer.nrl.navy.mil

Kaiser said, "If we discover the asteroids have the same composition as the Earth and moon, it will support Belbruno and Gott's version of the giant impact theory. The asteroids themselves could well be left-over from the formation of the solar system. Also, the L4/L5 regions might be the home of future Earth-impacting asteroids."

Analyses of lunar rocks brought to Earth by the Apollo missions reveal that they have the same isotopes (heavier versions of an element) as terrestrial rocks. Scientists believe that the sun and the worlds of our solar system formed out of a cloud of gas and dust that collapsed under its gravity. The composition of this primordial cloud changed with temperature. Since the temperature decreased with distance from the sun, whatever created the moon must have formed in the same orbital location as Earth in order for them to have the same isotope composition.

In a planetary version of "the rich get richer", Earth's gravity should have swept up most of the material in its orbit, leaving too little to create our large moon or another planet like Theia. "However, computer models by Belbruno and Gott indicate that Theia could have grown large enough to produce the moon if it formed in the L4 or L5 regions, where the balance of forces allowed enough material to accumulate," said Kaiser.

The STEREO spacecraft are designed to give 3D views of space weather by observing the sun from two points of view and combining the images in the same way your eyes work together to give a 3D view of the world. STEREO "A" is moving slightly ahead of Earth and will pass through L4, and STEREO "B" is moving slightly behind Earth and will pass through L5. "Taking the time to observe L4 and L5 is kind of cool because it's free. We're going through there anyway -- we're moving too fast to get stuck," said Kaiser. "In fact, after we pass through these regions, we will see them all the time because our instruments will be looking back through them to observe the sun – they will just happen to be in our field of view."

Although L4 and L5 are just points mathematically, their region of influence is huge – about 50 million miles along the direction of Earth's orbit, and 10 million miles along the direction of the sun. It will take several months for STEREO to pass through them, with STEREO A making its closest pass to L4 in September, and STEREO B making its closest pass to L5 in October.

"L4 or L5 are excellent places to observe space weather. With both the sun and Earth in view, we could track solar storms and watch them evolve as they move toward Earth. Also, since we could see sides of the sun not visible from Earth, we would have a few days warning before stormy regions on the solar surface rotate to become directed at Earth," said Kaiser.

Bill Steigerwald Goddard

Space Flight Center

XMM-Newton exclusive photo: Messier 82

Messier 82

Credits: ESA

ESA’s space-borne X-ray observatory, XMM-Newton, has carried out an exclusive observation of the galaxy Messier 82, for the ‘100 Hours of Astronomy’ cornerstone project for the International Year of Astronomy 2009.

The observatory was featured in the ‘Around the World in 80 Telescopes’ live webcast last week. This European space telescope has been studying the sky in X-ray, optical and ultraviolet wavelengths simultaneously, since its launch in December 1999.

The image is composed of several different XMM-Newton observations of Messier 82, adding up to 52.5 hours of observing time in total. The observations were carried out in X-ray, ultraviolet and visible wavelengths and include the special observation for the International Year of Astronomy 2009.

Optical and ultraviolet image of Messier 82
Credits: ESA

Messier 82 has several names including: M82, the Cigar Galaxy and NGC 3034. Located in the constellation Ursa Major at a distance of about 12 million light-years, it is the nearest and one of the most active starburst galaxies, i.e. it shows an exceptionally high rate of star formation. M82 is interacting gravitationally with its neighbour, the spiral galaxy Messier 81, which is most probably the cause for the violent starburst activity in the region around its centre, or the circumnuclear region.

X-ray Image of Messier 82

Credits: ESA

The active star formation taking place in its interior and its effect on the gas and dust in its interstellar medium can be observed very well from Earth. This makes M82 is one of the best-studied galaxies in the sky.

The optical, ultraviolet and X-ray images from which this image has been derived are visible on the panels to the left and right of the image. The emission at different wavelengths is colour-coded as seen in each figure.

The optical and ultraviolet images show the very bright starry disc of the galaxy with striking dust lanes. The central image shows plumes of hot gas glowing in X-rays bursting out of the galactic disk (in blue). This results from very intense bursts of star formation in the circumnuclear region.

Messier 82 Poster

Credits: ESA

The last X-ray and ultraviolet observation of this galaxy was carried out on 3 April for the 100 Hours of Astronomy project. This last observation will also be made available for a scientific project led by Dr Feng from the University of Iowa, US.

Cool Stars Have Different Mix of Life-Forming Chemicals

This artist's conception shows a young, hypothetical planet around a cool star. A soupy mix of potentially life-forming chemicals can be seen pooling around the base of the jagged rocks. Observations from NASA's Spitzer Space Telescope hint that planets around cool stars -- the so-called M-dwarfs and brown dwarfs that are widespread throughout our galaxy -- might possess a different mix of life-forming, or prebiotic, chemicals than our young Earth.

Credit:NASA/JPL-Caltech

NASA's Spitzer Space Telescope detected a prebiotic, or potentially life-forming, molecule called hydrogen cyanide (HCN) in the planet-forming disks around yellow stars like our sun, but not in the disks around cooler, reddish stars. Credit: NASA/JPL-Caltech/JHU

Life on Earth is thought to have arisen from a hot soup of chemicals. Does this same soup exist on planets around other stars? A new study from NASA's Spitzer Space Telescope hints that planets around stars cooler than our sun might possess a different mix of potentially life-forming, or "prebiotic," chemicals.

Astronomers used Spitzer to look for a prebiotic chemical, called hydrogen cyanide, in the planet-forming material swirling around different types of stars. Hydrogen cyanide is a component of adenine, which is a basic element of DNA. DNA can be found in every living organism on Earth.

The researchers detected hydrogen cyanide molecules in disks circling yellow stars like our sun -- but found none around cooler and smaller stars, such as the reddish-colored "M-dwarfs" and "brown dwarfs" common throughout the universe.

"Prebiotic chemistry may unfold differently on planets around cool stars," said Ilaria Pascucci, lead author of the new study from Johns Hopkins University, Baltimore, Md. The study will appear in the April 10 issue of the Astrophysical Journal.

Young stars are born inside cocoons of dust and gas, which eventually flatten to disks. Dust and gas in the disks provide the raw material from which planets form. Scientists think the molecules making up the primordial ooze of life on Earth might have formed in such a disk. Prebiotic molecules, such as adenine, are thought to have rained down to our young planet via meteorites that crashed on the surface.

"It is plausible that life on Earth was kick-started by a rich supply of molecules delivered from space," said Pascucci.

Could the same life-generating steps take place around other stars? Pascucci and her colleagues addressed this question by examining the planet-forming disks around 17 cool and 44 sun-like stars using Spitzer's infrared spectrograph, an instrument that breaks light apart, revealing signatures of chemicals. The stars are all about one to three million years old, an age when planets are thought to be growing. The astronomers specifically looked for ratios of hydrogen cyanide to a baseline molecule, acetylene.

They found that the cool stars, both the M-dwarf stars and brown dwarfs, showed no hydrogen cyanide at all, while 30 percent of the sun-like stars did. "Perhaps ultraviolet light, which is much stronger around the sun-like stars, may drive a higher production of the hydrogen cyanide," said Pascucci.

The team did detect their baseline molecule, acetylene, around the cool stars, demonstrating that the experiment worked. This is the first time that any kind of molecule has been spotted in the disks around cool stars.

The findings have implications for planets that have recently been discovered around M-dwarf stars. Some of these planets are thought to be large versions of Earth, the so-called super Earths, but so far none of them are believed to orbit in the habitable zone, where water would be liquid. If such a planet is discovered, could it sustain life?

Astronomers aren't sure. M-dwarfs have extreme magnetic outbursts that could be disruptive to developing life. But, with the new Spitzer results, they have another piece of data to consider: these planets might be deficient in hydrogen cyanide, a molecule thought to have eventually become a part of us.

Said Douglas Hudgins, the Spitzer program scientist at NASA Headquarters, Washington, "Although scientists have long been aware that the tumultuous nature of many cool stars might present a significant challenge for the development of life, this result begs an even more fundamental question: Do cool star systems even contain the necessary ingredients for the formation of life? If the answer is no then questions about life around cool stars become moot."

Other authors include Daniel Apai of the Space Telescope Science Institute, Baltimore, Md.; Kevin Luhman of Pennsylvania State University, University Park; Thomas Henning and Jeroen Bouwman of the Max Planck Institute for Astronomy, Germany; Michael Meyer of the University of Arizona, Tucson; Fred Lahuis of the SRON Netherlands Institute for Space Research, the Netherlands; and Antonella Natta of the Arcetri Astrophysical Observatory, Italy.

Whitney Clavin 818-354-4673
Jet Propulsion Laboratory, Pasadena, Calif.
whitney.clavin@jpl.nasa.gov

Dramatically backlit dust in giant galaxy

Image credit: NASA, ESA and W. Harris
(McMaster University, Ontario, Canada)
More Images: Image 1, Image 2, Image 3 and Print Layout
Videos: Video 1 and Video 2

A new Hubble image highlights striking swirling dust lanes and glittering globular clusters in oddball galaxy NGC 7049.

The NASA/ESA's Hubble Space Telescope has captured this image of NGC 7049, a mysterious looking galaxy on the border between spiral and elliptical galaxies. NGC 7049 is found in the constellation of Indus, and is the brightest of a cluster of galaxies, a so-called Brightest Cluster Galaxy (BCG). Typical BCGs are some of the oldest and most massive galaxies. They provide excellent opportunities for astronomers to study the elusive globular clusters lurking within.

The globular clusters in NGC 7049 are seen as the sprinkling of small faint points of light in the galaxy’s halo. The halo – the ghostly region of diffuse light surrounding the galaxy – is composed of myriads of individual stars and provides a luminous background to the remarkable swirling ring of dust lanes surrounding NGC 7049's core. Globular clusters are very dense and compact groupings of a few hundreds of thousands of stars bound together by gravity. They contain some of the first stars to be produced in a galaxy. NGC 7049 has far fewer such clusters than other similar giant galaxies in very big, rich groups. This indicates to astronomers how the surrounding environment influenced the formation of galaxy halos in the early Universe.

The image was taken by the Advanced Camera for Surveys on Hubble, which is optimised to hunt for galaxies and galaxy clusters in the remote and ancient Universe, at a time when our cosmos was very young.

The constellation of Indus, or the Indian, is one of the least conspicuous in the southern sky. It was named in the 16th century by Dutch astronomer Petrus Plancius from observations made by Dutch navigator Pieter Dirkszoon Keyser and Dutch explorer Frederick de Houtman.

Notes for editors:

The Hubble Space Telescope is a project of international cooperation between ESA and NASA.

Contacts:

Colleen Sharkey
Hubble/ESA, Garching, Germany
Tel: +49-89-3200-6306
Cell: +49-151-153-73591
E-mail: csharkey@eso.org

Source: http://www.spacetelescope.org/index.html

Two Galaxies for a Unique Event

ESO PR Photo 14a/09

Image of the irregular galaxy NGC 55 obtained with the Wide Field Imager on the 2.2-metre MPG/ESO telescope at ESO La Silla Observatory. The galaxy is about 7.5 million light-years away and 70 000 light-years across. The image is based on data obtained through B, V, and H-alpha filters. North is up, East to the left. The field of view is 30 arcminutes wide.

ESO PR Photo 14b/09

Image of the chaotic spiral galaxy NGC 7793, observed with the FORS instrument attached to ESO’s Very Large Telescope at Paranal. The image is based on data obtained through B, V, I and H-alpha filters.

To celebrate the 100 Hours of Astronomy, ESO is sharing two stunning images of unusual galaxies, both belonging to the Sculptor group of galaxies. The images, obtained at two of ESO’s observatories at La Silla and Paranal in Chile, illustrate the beauty of astronomy.

As part of the International Year of Astronomy 2009 Cornerstone project, 100 Hours of Astronomy, the ambitious “Around the World in 80 Telescopes” event is a unique live webcast over 24 hours, following night and day around the globe to some of the most advanced observatories on and off the planet. To provide a long-lasting memory of this amazing world tour, observatories worldwide are revealing wonderful, and previously unseen, astronomical images. For its part, ESO is releasing outstanding pictures of two galaxies, observed with telescopes at the La Silla and Paranal observatories.

The first of these depicts the irregular galaxy NGC 55, a member of the prominent Sculptor group of galaxies in the southern constellation of Sculptor. The galaxy is about 70 000 light-years across, that is, a little bit smaller than our own Milky Way. NGC 55 actually resembles more our galactic neighbour, the Large Magellanic Cloud (LMC), although the LMC is seen face-on, whilst NGC 55 is edge-on.

By studying about 20 planetary nebulae in this image, a team of astronomers found that NGC 55 is located about 7.5 million light-years away. They also found that the galaxy might be forming a bound pair with the gorgeous spiral galaxy NGC 300 . Planetary nebulae are the final blooming of Sun-like stars before their retirement as white dwarfs.

This striking image of NGC 55, obtained with the Wide Field Imager on the 2.2-metre MPG/ESO telescope at La Silla, is dusted with a flurry of reddish nebulae, created by young, hot massive stars. Some of the more extended ones are not unlike those seen in the LMC, such as the Tarantula Nebula. The quality of the image is clearly demonstrated by the remarkable number of background galaxies seen, as well as the huge numbers of individual stars that can be counted within NGC 55.

The second image shows another galaxy belonging to the Sculptor group. This is NGC 7793, which has a chaotic spiral structure, unlike the class of grand-design spiral galaxies to which our Milky Way belongs. The image shows how difficult it is to identify any particular spiral arm in these chaotic structures, although it is possible to guess at a general rotating pattern. NGC 7793 is located slightly further away than NGC 55, about 12.5 million light-years from us, and is about half the size of NGC 55.

NGC 7793 was observed with one of the workhorses of the ESO Paranal Observatory, the FORS instrument, attached to the Very Large Telescope.

Notes:

ESO, the European Southern Observatory, is the foremost intergovernmental astronomy organisation in Europe. It is supported by 14 countries: Austria, Belgium, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerfvvul ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO plays also a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in the Atacama Desert region of Chile: La Silla, Paranal and Chajnantor.

ESO La Silla - Paranal - ELT Press Officer: Dr. Henri Boffin - +49 89 3200 6222 - hboffin@eso.org
ESO Press Officer in Chile: Valentina Rodriguez - +56 2 463 3123 - vrodrigu@eso.org

M33: A Close Neighbor Reveals its True Size and Splendor

Credit: NASA/JPL-Caltech/Univ. of Ariz.

One of our closest galactic neighbors shows its awesome beauty in this new image from NASA's Spitzer Space Telescope. M33, also known as the Triangulum Galaxy, is a member of what's known as our Local Group of galaxies. Along with our own Milky Way, this group travels together in the universe, as they are gravitationally bound. In fact, M33 is one of the few galaxies that is moving toward the Milky Way despite the fact that space itself is expanding, causing most galaxies in the universe to grow farther and farther apart.

When viewed with Spitzer's infrared eyes, this elegant spiral galaxy sparkles with color and detail. Stars appear as glistening blue gems (several of which are actually foreground stars in our own galaxy), while dust rich in organic molecules glows green. The diffuse orange-red glowing areas indicate star-forming regions, while small red flecks outside the spiral disk of M33 are most likely distant background galaxies. But not only is this new image beautiful, it also shows M33 to be surprising large - bigger than its visible-light appearance would suggest. With its ability to detect cold, dark dust, Spitzer can see emission from cooler material well beyond the visible range of M33's disk. Exactly how this cold material moved outward from the galaxy is still a mystery, but winds from giant stars or supernovas may be responsible.

M33 is located about 2.9 million light-years away in the constellation Triangulum. This is a three-color composite image showing infrared observations from two of Spitzer instruments. Blue represents combined 3.6- and 4.5-micron light and green shows light of 8 microns, both captured by Spitzer's infrared array camera. Red is 24-micron light detected by Spitzer's multiband imaging photometer.

Attendees of the Peyton Rhodes Lecture Series were treated to a preview unveiling of this image at Rhodes College in Memphis, Tennessee, and will be on display as an addition to the "From the Earth to the Universe" image exhibition at the Memphis Public Library.

About the Object:
Object name: M33
Object type: Nebula
Position (J2000): RA: 01h 33m 51.02s Dec: 30° 39' 36.70"
Distance: 2800 Light Years
Constellation: Triangulum

About the Data
Spitzer Data
Image Credit: NASA/JPL-Caltech/Univ. of Ariz.
Instrument: IRAC + MIPS

Wavelength: Blue represents combined 3.6 and 4.5 microns, green is 8 microns, Red is 24-micron

PSR B1509-58 - A Young Pulsar Shows its Hand

PSR B1509-58
Credit NASA/CXC/SAO/P.Slane, et al.

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Sequence of PSR B1509-58 Images
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A small, dense object only twelve miles in diameter is responsible for this beautiful X-ray nebula that spans 150 light years. At the center of this image made by NASA's Chandra X-ray Observatory is a very young and powerful pulsar, known as PSR B1509-58, or B1509 for short. The pulsar is a rapidly spinning neutron star which is spewing energy out into the space around it to create complex and intriguing structures, including one that resembles a large cosmic hand. In this image, the lowest energy X-rays that Chandra detects are red, the medium range is green, and the most energetic ones are colored blue. Astronomers think that B1509 is about 1700 years old and is located about 17,000 light years away.

Neutron stars are created when massive stars run out of fuel and collapse. B1509 is spinning completely around almost 7 times every second and is releasing energy into its environment at a prodigious rate - presumably because it has an intense magnetic field at its surface, estimated to be 15 trillion times stronger than the Earth's magnetic field.

The combination of rapid rotation and ultra-strong magnetic field makes B1509 one of the most powerful electromagnetic generators in the Galaxy. This generator drives an energetic wind of electrons and ions away from the neutron star. As the electrons move through the magnetized nebula, they radiate away their energy and create the elaborate nebula seen by Chandra.

In the innermost regions, a faint circle surrounds the pulsar, and marks the spot where the wind is rapidly decelerated by the slowly expanding nebula. In this way, B1509 shares some striking similarities to the famous Crab Nebula. However B1509's nebula is 15 times wider than the Crab's diameter of 10 light years.

Finger-like structures extend to the north, apparently energizing knots of material in a neighboring gas cloud known as RCW 89. The transfer of energy from the wind to these knots makes them glow brightly in X-rays (orange and red features to the upper right). The temperature in this region appears to vary in a circular pattern around this ring of emission, suggesting that the pulsar may be precessing like a spinning top and sweeping an energizing beam around the gas in RCW 89.

Fast Facts for PSR B1509-58:

Scale: Image is 19.6 arcmin across
Category: Supernovas & Supernova Remnants, Neutron Stars/X-ray Binaries
Coordinates: (J2000) RA 15h 13m 55.52s | Dec -59° 08' 08.8"
Constellation: Circinus
Observation Date: 12/28/2004-10/18/2005
Observation Time: 52 hours
Obs. ID: 5534, 5535, 6116, 6117
Color Code: Red (0.5-1.7 keV); Green (1.7-3.0 keV) ; Blue (3.0-8.0 keV)
Instrument: ACIS
Distance Estimate: About 17,000 light years

Hubble Celebrates the International Year of Astronomy with the Galaxy Triplet Arp 274

Credit: NASA, ESA, M. Livio and the Hubble Heritage Team (STScI/AURA)

Illustration Credit: NASA, ESA, and Z. Levay (STScI)
Photo Credit: NASA, ESA, M. Livio and the Hubble Heritage Team (STScI/AURA)

Illustration Credit: NASA, ESA, and Z. Levay (STScI) Photo Credit: A. Fujii for STScI

On April 1-2, the Hubble Space Telescope photographed the winning target in the Space Telescope Science Institute's "You Decide" competition in celebration of the International Year of Astronomy (IYA).

The winner is a group of galaxies called Arp 274. The striking object received 67,021 votes out of the nearly 140,000 votes cast for the six candidate targets.

Arp 274, also known as NGC 5679, is a system of three galaxies that appear to be partially overlapping in the image, although they may be at somewhat different distances. The spiral shapes of two of these galaxies appear mostly intact. The third galaxy (to the far left) is more compact, but shows evidence of star formation.

Two of the three galaxies are forming new stars at a high rate. This is evident in the bright blue knots of star formation that are strung along the arms of the galaxy on the right and along the small galaxy on the left.

The largest component is located in the middle of the three. It appears as a spiral galaxy, which may be barred. The entire system resides at about 400 million light-years away from Earth in the constellation Virgo.

Hubble's Wide Field Planetary Camera 2 was used to image Arp 274. Blue, visible, and infrared filters were combined with a filter that isolates hydrogen emission. The colors in this image reflect the intrinsic color of the different stellar populations that make up the galaxies. Yellowish older stars can be seen in the central bulge of each galaxy. A bright central cluster of stars pinpoint each nucleus. Younger blue stars trace the spiral arms, along with pinkish nebulae that are illuminated by new star formation. Interstellar dust is silhouetted against the starry population. A pair of foreground stars inside our own Milky Way are at far right.

The International Year of Astronomy is the celebration of the 400th anniversary of Galileo's first observations with a telescope. People around the world are coming together to participate in the IYA's 100 Hours of Astronomy, April 2 to 5. This global astronomy event is geared toward encouraging as many people as possible to experience the night sky.

For additional information, contact:

Ray Villard
Space Telescope Science Institute, Baltimore, Md.
410-338-4514
villard@stsci.edu

Mario Livio
Space Telescope Science Institute, Baltimore, Md.
410-338-4439
mlivio@stsci.edu

Keith Noll
Space Telescope Science Institute, Baltimore, Md.
410-338-1828
noll@stsci.edu

Dissecting a stellar explosion

About this image: This artist's impression illustrates how a gamma-ray burst can flare dramatically over a short time period (gamma ray bursts usually last between a hundredth of a second to a hundred seconds). The bursts can occur as often as several times a day. There is no way to predict when or where they will next occur.

ESA missions such as XMM-Newton, Integral and Ulysses study these mysterious, powerful bursts. Credits: ESA (Illustration by AOES Medialab)

About this image: This artist's impression shows the centre of a dying star collapsing minutes before the star implodes. The blast from a Gamma Ray Burst is thought to be produced by a jet of fast-moving gas that bursts from near the central engine; probably a black hole created by such a collapse of the massive star. Credits: NASA/Dana Berry

Integral has captured one of the brightest gamma-ray bursts ever seen. A meticulous analysis of the data has allowed astronomers to investigate the initial phases of this giant stellar explosion, which led to the ejection of matter at velocities close to the speed of light. In particular, the astronomers believe that the explosion lifted a piece of the central engine’s magnetic field into space.

On 19 December 2004, the blast from an exploding star arrived at Earth. ESA’s Integral satellite, an orbiting gamma-ray observatory, recorded the entire event, providing information for what may prove to be one of the most important gamma-ray bursts (GRBs) seen in recent years. As the data was collected, astronomers saw the 500-second-long burst rise to extraordinary brilliance.

“It is in the top 1% of the brightest GRBs we have seen,” says Diego Götz, CEA Saclay, France, who headed the investigation.

The brightness of the event, known as GRB 041219A, has allowed the team to perform a painstaking investigation to extract a property known as the polarisation of the gamma rays. The team have shown that the gamma rays were highly polarised and varied tremendously in level and orientation. 

Polarisation refers to the preferred direction in which the radiation wave oscillates. Polaroid sunglasses work with visible light by letting through only a single direction of polarisation, blocking most of the light from entering our eyes.

The blast from a GRB is thought to be produced by a jet of fast-moving gas bursting from near the central engine; probably a black hole created by the collapse of the massive star. The polarisation is directly related to the structure of the magnetic field in the jet. So it is one of the best ways for astronomers to investigate how the central engine produces the jet. There are a number of ways this might happen.

In the first scenario, the jet carries a portion of the central engine’s magnetic field into space. A second involves the jet generating the magnetic field far from the central engine. A third concerns the extreme case in which the jet contains no gas just magnetic energy, and a fourth scenario entails the jet moving through an existing field of radiation.

In each of the first three scenarios, the polarisation is generated by what is called synchrotron radiation. The magnetic field traps particles, known as electrons, and forces them to spiral, releasing polarised radiation. In the fourth scenario, the polarisation is imparted through interactions between the electrons in the jet and photons in the existing radiation field.

Götz believes that the Integral results favour a synchrotron model and, of those three, the most likely scenario is the first, in which the jet lifts the central engine’s magnetic field into space. “It is the only simple way to do it,” he says.

What Götz would most like to do is measure the polarisation for every GRB, to see whether the same mechanism applies to all. Unfortunately, many GRBs are too faint for the current instrumentation to succeed. Even the state-of-the-art IBIS instrument on Integral can only record the polarisation state of gamma rays if a celestial source is as bright as GRB 041219A.

“So, for now we just have to wait for the next big one,” he says.

Notes for editors:

The team members are from: Commissariat à l'énergie atomique (Astrophysique Interactions Multi-´echelles, Astroparticules et Cosmologie), and the Institut d’Astrophysique de Paris (CNRS), all based in France.

Variable Polarisation in the prompt emission of GRB 041219A using IBIS on board Integral by Diego Götz et al. will be published in the Astrophysical Journal Letters.

Hubble Finds Hidden Exoplanet in Archival Data

Credit: NASA, ESA, and G. Bacon (STScI)

Exoplanet HR 8799B Recovered in NICMOS Data Archive (Annotated)
Credit: NASA, ESA, and D. Lafrenière (University of Toronto, Canada)

Compass and Scale Image of Extrasolar Planet HR 8799b

Illustration Credit: NASA, ESA, and Z. Levay (STScI)
Photo Credit: NASA, ESA, and D. Lafrenière (University of Toronto, Canada)

A powerful, newly refined image-processing technique may allow astronomers to discover extrasolar planets that are possibly lurking in over a decade's worth of Hubble Space Telescope archival data.

David Lafreniere of the University of Toronto, Ontario, Canada, has successfully demonstrated this new strategy for planet hunting by identifying an exoplanet that went undetected in Hubble images taken in 1998 with its Near Infrared Camera and Multi-Object Spectrometer (NICMOS). In addition to illustrating the power of new data-processing techniques, this finding underscores the value of the Hubble data archive, on which those new techniques can be used.

The planet, estimated to be at least seven times Jupiter's mass, was originally discovered in images taken with the Keck and Gemini North telescopes in 2007 and 2008. It is the outermost of three massive planets known to orbit the dusty young star HR 8799, which is 130 light-years away. NICMOS could not see the other two planets because its coronagraphic spot — a device which blots out the glare of the star — also interferes with observing the two inner planets.

"We've shown that NICMOS is more powerful than previously thought for imaging planets," says Lafreniere. "Our new image-processing technique efficiently subtracts the glare from a star that spills over the coronagraph's edge, allowing us to see planets that are one-tenth the brightness of what could be detected before with Hubble." Lafreniere adapted an image reconstruction technique that was first developed for ground-based observatories.

Using the new technique, he recovered the planet in NICMOS observations taken 10 years before the Keck/Gemini discovery. The Hubble picture not only provides important confirmation of the planet's existence, it provides a longer baseline for demonstrating that the object is in an orbit about the star. "To get a good determination of the orbit we have to wait a very long time because the planet is moving so slowly (it has a 400-year period)," says Lafreniere. "The 10-year-old Hubble data take us that much closer to having a precise measure of the orbit."

NICMOS's view provided new insights into the physical characteristics of the planet, too. This was possible because NICMOS works at near-infrared wavelengths that are severely blocked by Earth's atmosphere due to absorption by water vapor.

"The planet seems to be only partially cloud covered and we could be detecting the absorption of water vapor in the atmosphere," says Travis Barman of Lowell Observatory, Flagstaff, Ariz. "The infrared light measured from the Hubble data is consistent with a spectrum showing a broad water absorption feature (at 1.4-1.49 microns), but the level of absorption seen is lower than it would be if the photosphere were completely devoid of dust. Dust clouds can smooth out many of the spectral features that would otherwise be there—including water absorption bands," Barman says. "Measuring the water absorption properties will tell us a great deal about the temperatures and pressures in the atmospheres, in addition to the cloud coverage. If we can accurately measure the water absorption features for the outermost planet around HR 8799, we will learn a great deal about their atmospheric properties. Hubble, situated well above the Earth's atmosphere, is excellently located for such a study."

"During the past 10 years Hubble has been used to look at over 200 stars with coronagraphy, looking for planets and disks. We plan to go back and look at all of those archived images and see if anything can be detected that has gone undetected until now," says Christian Marois of the Herzberg Institute of Astrophysics, Victoria, Canada. "We'll need a baseline of a few years for most objects to detect Keplerian motion and hence confirm their status as planets. The hardest part is to find them in the first place."

If his team sees a companion object to a star in more than one NICMOS picture, and it appears to have moved along an orbit, follow-up observations will be made with ground-based telescopes. If they see something once but its brightness and separation from the star would be reasonable for a planet, they will also do follow-up observations with ground-based telescopes.

Taking the image of an exoplanet is not an easy task. Planets can be billions of times fainter than the star around which they orbit and are typically located at separations smaller than 1/2000th the angular size of the full moon from their star. The planet recovered in the NICMOS data is about 100,000 times fainter than the star when viewed in the near-infrared.

"Even when using the best telescopes available, with the best resolution, the light from the bright star spills out in the area where the much fainter planets are located, making them impossible to see. It is essential to subtract out this bright glare of stellar light from the image to see faint dots, i.e., planets, that could be hidden underneath," says Rene Doyon of the University of Montreal.

The stability of how light is scattered in the NICMOS camera, called the point spread function (PSF), is key for using Hubble images to recover planets. This technique works by taking images of different stars and combining them to create a PSF of a star that closely resembles the star that is being studied for planets. This requires a reasonably steady PSF because images of different stars are taken on different days. Atmospheric conditions would vary from day-to-day for ground-based telescopes, but not for a space telescope that enjoys unprecedented image stability over repeated visits to a target.

CONTACT
Ray Villard
Space Telescope Science Institute, Baltimore, Md.
410-338-4514
villard@stsci.edu

David Lafreniere
University of Toronto, Ontario, Canada
416-978-4971
lafreniere@astro.utoronto.ca