Celestial Tapestry is Born of Uncertain Parentage

Gemini Legacy image of the complex planetary nebula Sh2-71 as imaged by the Gemini Multi-Object Spectrograph on Gemini North on Mauna Kea in Hawai‘i. The long-assumed central star is the brightest star near the center, but some astronomers wonder if the much dimmer and bluer star (just to the right and down a bit) might be the parent of this beautiful object. The image is composed of three narrow-band images, and each is assigned a color as follows: H-alpha (orange), HeII (blue) and [OIII] (cyan). Each image is 15 minutes in duration, the field-of-view is 5.3 x 3.6 arcminutes, and the image is rotated 110 degrees clockwise from north up, east left. Image credit: Gemini Observatory/AURA. Full Resolution TIFF (23.5MB) | JPEG (4.1MB)

A new Legacy Image from the Gemini Observatory reveals the remarkable complexity of the planetary nebula Sharpless 2-71 (Sh 2-71). Embroiled in a bit of controversy over its “birth parents” the nebula likely resulted from interactions between a pair of two old and dying stars. Legacy images like this one share the stunning beauty of the universe as revealed by the twin 8-meter Gemini telescopes in Hawai‘i and Chile.

Often what seems obvious isn’t.

Take this new Gemini Legacy Image of the elaborate planetary nebula Sharpless 2-71. For most of its recorded history, astronomers assumed that it formed from the death throes of an obvious bright star (a known binary system) near its center. Arguments against that claim, however, have turned this case into a classic mystery of uncertain parentage.

The Gemini Legacy Image shows the long-assumed central star shining as the brightest object very close to the center of the nebula’s beautiful gas shell. But new observations have shown that the nature of a dimmer, bluer star – just to the right, and a bit lower than the obvious central star – might provide a better fit for the nebula’s “birth parent.”

The uncertainty arises from the fact that the brighter central star doesn’t appear to radiate enough high-energy (ultraviolet) light to cause the surrounding gas to glow as intensely as it does, whereas the dimmer, bluer star likely does. On the other hand, the brighter star’s binary nature would help explain the nebula’s asymmetrical structure. Astronomers do not yet known if the dimmer, bluer star also has a companion.

Another unresolved issue is whether the brighter star’s unseen companion might be hot enough to excite the gas to glow. If so, this pair might be able to hold on to its parental connection to the nebula.

A research team, led by Australian astronomers David Frew and Quentin Parker (Macquarie University, Sydney) are studying the dimmer, bluer star to understand its nature. “At the assumed distance to the nebula (roughly 1 kiloparsec or about 3,260 light-years), the faint star has about the right brightness to be the fading remnant of the nebula’s progenitor star,” says Frew.

Then again, the brighter binary star is an uncommon one that shows strong and broad hydrogen-alpha emission, which are seen in some planetary nebulae. According to Frew, this star is also unlikely to be a chance projection or alignment with the nebula, “So there could be at least three stars in this system,” he says.

Putting aside the complex issue of which star or stars formed this object, the nebula’s striking morphology also poses difficult questions. “The nebula presents a multi-polar structure and several pairs of bipolar lobes at different orientations,” says Luis Miranda of Spain’s Instituto de Astrofísica de Andalucía (CSIC) who has also studied this object extensively. “These lobes most certainly formed at different times and likely involved a binary progenitor – in particular with mass-transfer and multiple episodes of mass ejection along an axis where the orientation changes with time.”

Adding to the puzzle, Parker and Romano Corradi (Instituto de Astrofisica de Canarias, Spain) have recently discovered faint outer wisps and lobes surrounding the planetary on deep hydrogen-alpha images, taken as part of the Isaac Newton Telescope Photometric HydrogenAlpha Survey of the Northern Galactic Plane Survey. These features extend over many arcminutes (not shown in the new Gemini image), suggesting the mass loss history of this object has even more levels of complexity.

Miranda agrees, noting that the nebula’s structure is difficult to explain without a binary pair for parents. “The chaotic morphology of Sh2-71 implies that very complex processes have been involved in its formation,” says Miranda. Unfortunately, not much is known about either possible central star’s known or speculated companions. So the mystery of the nebula’s uncertain parentage remains unsolved ... for now.

Image Background Information: Gemini’s Multi-Object Spectrograph (GMOS) captured the light of Sh2-71 in its imaging mode using filters that selectively allow specific colors of visible light to reach the detector. Each color is produced by energized gas in the nebula glowing in a manner similar to a neon sign. Travis Rector of the University of Alaska Anchorage assembled the data from three filters (hydrogen alpha, helium II, and oxygen III) to form the composite color image.

Planetary nebulae are the end-state of stars like our Sun. They form when old, medium-sized stars run low on nuclear fuel, become unstable, and begin expelling their outer layers of gas into space. Often these objects appear quite symmetrical, but when multiple stars are involved, their structure looks much more complex. In such cases, astronomers believe that the transfer of gas from one star to another results in explosions and eruptions that disrupt the symmetry of the nebula - as is clearly seen in this new Gemini image.

Discovered in 1946 by Rudolph Minkowski, the nebula is located in the direction of the constellation Aquila and visible in amateur telescopes. Sh2-71 is the 71st object in a catalogue of nebulae originally assembled by the U.S. astronomer Stewart Sharpless of the US Naval Observatory in Flagstaff, Arizona. It is from his second catalogue, of 313 nebulae, published in 1959.

ABOUT THE GEMINI OBSERVATORY

The Gemini Observatory is an international collaboration with two identical 8-meter telescopes. The Frederick C. Gillett Gemini Telescope is located on Mauna Kea, Hawai'i (Gemini North) and the other telescope on Cerro Pachón in central Chile (Gemini South); together the twin telescopes provide full coverage over both hemispheres of the sky. The telescopes incorporate technologies that allow large, relatively thin mirrors, under active control, to collect and focus both visible and infrared radiation from space.

The Gemini Observatory provides the astronomical communities in seven partner countries with state-of-the-art astronomical facilities that allocate observing time in proportion to each country's contribution. In addition to financial support, each country also contributes significant scientific and technical resources. The national research agencies that form the Gemini partnership include: the US National Science Foundation (NSF), the UK Science and Technology Facilities Council (STFC), the Canadian National Research Council (NRC), the Chilean Comisión Nacional de Investigación Cientifica y Tecnológica (CONICYT), the Australian Research Council (ARC), the Argentinean Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) and the Brazilian Conselho Nacional de Desenvolvimento Científico e Tecnológico CNPq). The observatory is managed by the Association of Universities for Research in Astronomy, Inc. (AURA) under a cooperative agreement with the NSF. The NSF also serves as the executive agency for the international partnership.

Press Contact:

Peter Michaud
Gemini Observatory
Hilo, HI 96720
Office: +1 (808) 974-2510
Cell: +1 (808) 936-6643
pmichaud@gemini.edu

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Gemini South Reveals First Nitrogen-Sequence Wolf-Rayet Nucleus of a Planetary Nebula

Figure 1: Gemini South GMOS spectrum of the WN central star of IC4663 (black) with model atmosphere (red). The model has a very hot stellar temperature of 140,000 degrees. According to the standard classification scheme for massive WN stars, the subtype is WN3 due to the absence of carbon and neutral helium emission lines.

Figure 2: The planetary nebula IC4663 viewed by the HST (inset; red, green and blue channels made from ionized hydrogen and nitrogen, doubly ionized oxygen and visual light, respectively) and GMOS at Gemini South (background; doubly ionized oxygen). The central star is at the center of the image which measures one arcminute on each side. The full size inner portion may be found separatelyhere.

Astronomers using the Gemini South telescope have discovered the first clear-cut example of a windy helium and nitrogen rich central star of a planetary nebula. This work provides the best evidence yet that there is another way to make hydrogen poor stars in the late-life stages of low mass stars - like the Sun.

The international team, led by Brent Miszalski of the South African Astronomical Observatory and the Southern African Large Telescope, were searching for binary companions to central stars of planetary nebulae, when they stumbled across the rarest of stellar gems. Gemini observations of the nucleus of IC4663 (Figure 1) revealed a peculiar mix of helium and nitrogen emission lines, unique and entirely out of place for a planetary nebula, but nonetheless an apparent clone of high mass Wolf-Rayet stars.

Planetary nebulae nuclei are the extremely hot, inert cores of low mass stars like the Sun, which are not far away from retiring as Earth-sized white dwarfs. The atmospheres of most nuclei show absorption lines of hydrogen and helium similar to white dwarfs. Many other strange flavors also exist. Around 100 planetary nebulae with Wolf-Rayet type nuclei are known, uniquely displaying emission lines of carbon, oxygen and helium, as a result of their powerful winds. These are the low-mass cousins of massive carbon-rich (WC-type) Wolf-Rayet stars, the final pre-supernova phase of very massive stars. A second flavor of massive Wolf-Rayet star, rich in helium and nitrogen (WN-type), are also common, but no clear-cut counterparts amongst planetary nebulae nuclei have been identified to date. While a handful of candidates have been identified, most cannot be unequivocally distinguished apart from ejecta known to surround some massive WN stars. A well known example is the WN star WR124, and its nebula M1-67, which is a proven massive star.

Is IC4663 just another case of a massive star with a confused identity? Team member Professor Paul Crowther, from the University of Sheffield, explains, "IC4663 may walk and talk like a duck, but our analysis reveals a completely different beast." It would have likely taken billions of years for IC4663 to reach old age, whereas it’s heftier cousins could get there in just a few million years. According to Dr Miszalski, the properties of the central star were "just right" for the team to prove that it is the first low-mass counterpart to nitrogen-rich WN stars. Relative to its massive cousins, it is exceptionally faint, and possesses an elliptical inner nebula, exquisitely captured by the Hubble Space Telescope (Figure 2), that is characteristic of other planetary nebulae. In addition, Gemini images reveal the presence of a faint halo (also seen in Figure 2). Haloes are widely accepted as a telltale signature of a previous cool giant phase, one that massive Wolf-Rayet stars do not experience.

Dr Miszalski’s team discovered that IC4663 hosted a helium and nitrogren rich central star that unambiguously had a WN-type spectrum, a composition that had never previously been predicted by theoretical models that aim to trace the evolutionary steps of low mass stars like the Sun. Models are able to reproduce the composition of carbon-rich planetary nebulae nuclei, but not IC4663. According to Dr Miszalski, "if our understanding of Solar-type stars were complete, then the central star of IC4663 simply should not exist!".

It is hard enough to explain why Wolf-Rayet central stars lack hydrogen, but it is even harder to come to terms with the extremely helium-rich nature of IC4663. Its existence is the first solid evidence that there's a second way to make hydrogen poor central stars, producing a helium-rich atmosphere instead of the more common carbon-rich atmosphere. Further work is needed to identify the evolutionary origins of the helium-rich composition. Although IC4663 does not appear to be a binary at the present time, binary stellar evolution may be the answer, since it may be the product of a stellar merger. Binary central stars are the leading explanation for the perplexing variety of exquisite shapes of planetary nebulae and several new discoveries have been made by Dr Miszalski and colleagues in recent years such that we now know of around 50 such systems. This paper has been accepted for publication in Monthly Notices of Royal Astronomical Society. The pre-print is available at http://arxiv.org/abs/1203.3303.

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NASA's SOFIA Captures Images of the Planetary Nebula M2-9

NASA's SOFIA telescope and the FORCAST instrument captured this color-composite image of the planetary nebula Minkowski 2-9 (M2-9) showing a dying sun-like star. (NASA/DLR/USRA/DSI/FORCAST team). Full size image

MOFFETT FIELD, Calif. -- Researchers using NASA's Stratospheric Observatory for Infrared Astronomy (SOFIA) have captured infrared images of the last exhalations of a dying sun-like star.

The object observed by SOFIA, planetary nebula Minkowski 2-9, or M2-9 for short, is seen in this three-color composite image. The SOFIA observations were made at the mid-infrared wavelengths of 20, 24, and 37 microns. The 37-micron wavelength band detects the strongest emissions from the nebula and is impossible to observe from ground-based telescopes.

Objects such as M2-9 are called planetary nebulae due to a mistake made by early astronomers who discovered these objects while sweeping the sky with small telescopes. Many of these nebulae have the color, shape and size of Uranus and Neptune, so they were dubbed planetary nebulae. The name persists despite the fact that these nebulae are now known to be distant clouds of material, far beyond our solar system, that are shed by stars about the size of our sun undergoing upheavals during their final life stages.

Although the M2-9 nebular material is flowing out from a spherical star, it is extended in one dimension, appearing as a cylinder or hourglass. Astronomers hypothesize that planetary nebulae with such shapes are produced by opposing flows of high-speed material caused by a disk of material around the dying star at the center of the nebula. SOFIA's observations of M2-9 were designed to study the outflow in detail with the goal of better understanding this stellar life cycle stage that is important in our galaxy's evolution.

"The SOFIA images provide our most complete picture of the outflowing material on its way to being recycled into the next generation of stars and planets," said Michael Werner of NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif., principal investigator of these observations. "We were gratified to see the lobes so clearly using SOFIA. These early results demonstrate the scientific potential of this important new observatory."

The observations were made using the Faint Object Infrared Camera for the SOFIA Telescope (FORCAST) instrument in June 2011 by a team consisting of astronomers from JPL, the California Institute of Technology, the University of California at Los Angeles, Cornell University and Ithaca College, Ithaca, N.Y. Preliminary analyses of these data were first presented in January 2012 at the American Astronomical Society meeting in Austin, Texas.

The SOFIA observatory combines an extensively modified Boeing 747SP aircraft and a 17-metric-ton reflecting telescope with an effective diameter of 2.5 meters (100 inches) that is capable of reaching altitudes as high as 45,000 feet (14 km), above more than 99 percent of the water vapor in Earth's atmosphere that blocks most infrared radiation from celestial sources.

SOFIA is a joint project of NASA and the German Aerospace Center (DLR), and is based and managed at NASA's Dryden Aircraft Operations Facility in Palmdale, Calif. NASA's Ames Research Center in Moffett Field, Calif., manages the SOFIA science and mission operations in cooperation with the Universities Space Research Association (USRA), headquartered in Columbia, Md., and the German SOFIA Institute (DSI) at the University of Stuttgart.

To view the latest image, visit: http://www.nasa.gov/mission_pages/SOFIA/multimedia/imagegallery/index.html

For more information about SOFIA, visit: http://www.nasa.gov/sofia or http://www.dlr.de/en/sofia

For information about SOFIA's science mission, visit: http://www.sofia.usra.edu or http://www.dsi.uni-stuttgart.de/index.en.html

Nicholas A. Veronico
SOFIA Science Center
NASA Ames Research Center, Moffett Field, Calif.
650-604-4589
nveronico@sofia.usra.edu

Beth Hagenauer
Dryden Flight Research Center, Edwards, Calif.
661-276-7960
beth.hagenauer-1@nasa.gov

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Stellar Voyage of a Butterfly-like Planetary Nebula

NGC 6881
Credit: ESA/Hubble & NASA

The breathtaking butterfly-like planetary nebula NGC 6881 is visible here in an image taken by the NASA/ESA Hubble Space Telescope. Located in the constellation of Cygnus, it is formed of an inner nebula, estimated to be about one fifth of a light-year across, and symmetrical “wings” that spread out about one light-year from one tip to the other. The symmetry could be due to a binary star at the nebula’s centre.

NGC 6881 has a dying star at its core which is about 60% of the mass of the Sun. It is an example of a quadrupolar planetary nebula, made from two pairs of bipolar lobes pointing in different directions, and consisting of four pairs of flat rings. There are also three rings in the centre.

A planetary nebula is a cloud of ionised gas, emitting light of various colours. It typically forms when a dying star — a red giant — throws off its outer layers, because of pulsations and strong stellar winds.

The star’s exposed hot, luminous core starts emitting ultraviolet radiation, exciting the outer layers of the star, which then become a newly born planetary nebula. At some point, the nebula is bound to dissolve in space, leaving the central star as a white dwarf — the final evolutionary state of stars.

The name “planetary” dates back to the 18th century, when such nebulae were first discovered — and when viewed through small optical telescopes, they looked a lot like giant planets.

Planetary nebulae usually live for a few tens of thousands of years, a short phase in the lifetime of a star.

The image was taken through three filters which isolate the specific wavelength of light emitted by nitrogen (shown in red), hydrogen (shown in green) and oxygen (shown in blue).

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The Helix in New Colours

PR Image eso1205a
VISTA’s look at the Helix Nebula

PR Image eso1205b
The Helix Nebula in the constellation of Aquarius

PR Image eso1205c
Digitized Sky Survey Image of the Helix Nebula

PR Image eso1205d
Infrared/visible light comparison view of the Helix Nebula

PR Video eso1205a
Zooming into the Helix Nebula

PR Video eso1205b
An infrared/visible light comparison of views of the Helix Nebula

ESO’s VISTA telescope, at the Paranal Observatory in Chile, has captured a striking new image of the Helix Nebula. This picture, taken in infrared light, reveals strands of cold nebular gas that are invisible in images taken in visible light, as well as bringing to light a rich background of stars and galaxies.

The Helix Nebula is one of the closest and most remarkable examples of a planetary nebula [1]. It lies in the constellation of Aquarius (The Water Bearer), about 700 light-years away from Earth. This strange object formed when a star like the Sun was in the final stages of its life. Unable to hold onto its outer layers, the star slowly shed shells of gas that became the nebula. It is evolving to become a white dwarf star and appears as the tiny blue dot seen at the centre of the image.

The nebula itself is a complex object composed of dust, ionised material as well as molecular gas, arrayed in a beautiful and intricate flower-like pattern and glowing in the fierce glare of ultraviolet light from the central hot star.

The main ring of the Helix is about two light-years across, roughly half the distance between the Sun and the nearest star. However, material from the nebula spreads out from the star to at least four light-years. This is particularly clear in this infrared view since red molecular gas can be seen across much of the image.

While hard to see visually, the glow from the thinly spread gas is easily captured by VISTA’s special detectors, which are very sensitive to infrared light. The 4.1-metre telescope is also able to detect an impressive array of background stars and galaxies.

The powerful vision of ESO’s VISTA telescope also reveals fine structure in the nebula’s rings. The infrared light picks out how the cooler, molecular gas is organised. The material clumps into filaments that radiate out from the centre and the whole view resembles a celestial firework display.

Even though they look tiny, these strands of molecular hydrogen, known as cometary knots, are about the size of our Solar System. The molecules in them are able to survive the high-energy radiation that emanates from the dying star precisely because they clump into these knots, which in turn are shielded by dust and molecular gas. It is currently unclear how the cometary knots may have originated.

Notes

Please note that this text was modified on 18 January 2012 to correct some minor errors.

[1] Planetary nebulae have nothing to do with planets. This confusing name arose because many of them show small bright discs when observed visually and resemble the outer planets in the Solar System, such as Uranus and Neptune. The Helix Nebula, which also bears the catalogue number NGC 7293, is unusual as it appears very large, but also very faint, when viewed through a small telescope.
More information

The year 2012 marks the 50th anniversary of the founding of the European Southern Observatory (ESO). ESO is the foremost intergovernmental astronomy organisation in Europe and the world's most productive astronomical observatory. It is supported by 15 countries: Austria, Belgium, Brazil, 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 powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world's most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world's largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning a 40-metre-class European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become "the world's biggest eye on the sky".

Links
Photos of VISTA

Contacts

Richard Hook

ESO, La Silla, Paranal, E-ELT and Survey Telescopes Public Information Officer

Garching bei München, Germany
Tel: +49 89 3200 6655
Cell: +49 151 1537 3591
Email: rhook@eso.org

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NASA's Hubble Finds Stellar Life and Death in a Globular Cluster

Credit: NASA and The Hubble Heritage Team (STScI/AURA)

Acknowledgment: P. Goudfrooij (STScI)

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A new NASA Hubble Space Telescope image shows globular cluster NGC 1846, a spherical collection of hundreds of thousands of stars in the outer halo of the Large Magellanic Cloud, a neighboring dwarf galaxy of the Milky Way that can be seen from the southern hemisphere.

Aging bright stars in the cluster glow in intense shades of red and blue. The majority of middle-aged stars, several billions of years old, are whitish in color. A myriad of far distant background galaxies of varying shapes and structure are scattered around the image.

The most intriguing object, however, doesn't seem to belong in the cluster. It is a faint green bubble in the white box near the bottom center of the image. This so-called "planetary nebula" is the aftermath of the death of a star. The burned-out central star can be seen inside the bubble. It is uncertain whether the planetary nebula is a member of NGC 1846, or simply lies along the line of sight to the cluster. Measurements of the motion of the cluster stars and the planetary nebula's central star suggest it might be a cluster member.

This Hubble image was taken with the Advanced Camera for Surveys in January of 2006. The cluster was observed in filters that isolate blue, green, and infrared starlight. As a member of the Large Magellanic Cloud, NGC 1846 is located roughly 160,000 light-years away in the direction of the constellation Doradus.

For more information, contact:

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

Brad Whitmore
Space Telescope Science Institute, Baltimore, Md.
410-338-4474
whitmore@stsci.edu

Paul Goudfrooij
Space Telescope Science Institute, Baltimore, Md.
410-338-4981
goudfroo@stsci.edu

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Hubble Offers a Dazzling 'Necklace'

The Necklace Planetary Nebula

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

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The Necklace Nebula is located 15,000 light-years away in the constellation Sagitta (the Arrow). In this composite image, taken on July 2, 2011, Hubble's Wide Field Camera 3 captured the glow of hydrogen (blue), oxygen (green), and nitrogen (red). Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA). Print quality download (2 Mb)



A giant cosmic necklace glows brightly in this NASA Hubble Space Telescope image.



The object, aptly named the Necklace Nebula, is a recently discovered planetary nebula, the glowing remains of an ordinary, Sun-like star. The nebula consists of a bright ring, measuring 12 trillion miles wide, dotted with dense, bright knots of gas that resemble diamonds in a necklace.



A pair of stars orbiting close together produced the nebula, also called PN G054.2-03.4. About 10,000 years ago one of the aging stars ballooned to the point where it engulfed its companion star. The smaller star continued orbiting inside its larger companion, increasing the giant’s rotation rate.



The bloated companion star spun so fast that a large part of its gaseous envelope expanded into space. Due to centrifugal force, most of the gas escaped along the star’s equator, producing a ring. The embedded bright knots are dense gas clumps in the ring.



The pair is so close, only a few million miles apart, they appear as one bright dot in the center. The stars are furiously whirling around each other, completing an orbit in a little more than a day.



The Necklace Nebula is located 15,000 light-years away in the constellation Sagitta. In this composite image, taken on July 2, Hubble’s Wide Field Camera 3 captured the glow of hydrogen (blue), oxygen (green), and nitrogen (red).



Hubble is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center in Greenbelt, Md., manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy Inc. in Washington.

For images and more information about Hubble, visit:

http://www.nasa.gov/hubble

http://hubblesite.org/news/2011/24





Donna Weaver / Ray Villard

Space Telescope Science Institute, Baltimore, Md.

dweaver@stsci.edu / villard@stsci.edu

410-338-4493 / 410-338-4514

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Smoke Signals in Space

Fine Ring Nebula
Credit: ESO

The hazy and aptly named Fine Ring Nebula, shown here, is an unusual planetary nebula. Planetary nebulae form when some dying stars, having expanded into a red giant phase, expel a shell of gas as they evolve into white dwarfs. Most planetary nebulae are either spherical or elliptical in shape, or bipolar (featuring two symmetric lobes of material).

But the Fine Ring Nebula — captured here by the ESO Faint Object Spectrograph and Camera mounted on the New Technology Telescope at the La Silla Observatory in Chile — looks like an almost perfect circular ring. Astronomers believe that some of these more unusually shaped planetary nebulae are formed when the progenitor star is actually a binary system. The interaction between the primary star and its orbiting companion shapes the ejected material.

The stellar object at the centre of the Fine Ring Nebula is indeed thought to be a binary system, orbiting with a period of 2.9 days. Observations suggest that the binary pair is almost perfectly face-on from our vantage point, implying that the planetary nebula’s structure is aligned in the same way. We are looking down on a torus (doughnut shape) of ejected material, leading to the strikingly circular ring shape in the image.

Planetary nebulae are shaped by the complex interplay of many physical processes. Not only can these celestial objects be admired for their beauty, but the study of precisely how they form their striking shapes is a fascinating topic in astronomical research.

This image was made using multiple filters: light observed through B and O-III filters is shown in blue, V is shown in green, R is shown in orange, and H-alpha in red. The image is approximately 200 arcseconds across.

Source: ESO

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