ESO Archives

October 10, 2012December 23, 2015 by John Williams

Dying Star Blows Surprising Spiral Bubble

Using the Atacama Large Millimeter/submillimeter Array, or ALMA, astronomers found an unexpected spiral structure surrounding the red giant star R Sculptoris shown here in this visualization. Credit: ALMA (ESO/NAOJ/NRAO)

Sometimes what we can’t see is just as surprising as what lies directly in front of us. This especially holds true in a new finding from the astronomers using the Atacama Large Millimeter/sumbillimeter Array, or ALMA, in Chile. A surprising and strange spiral structure surrounding the old star R Sculptoris is likely being created by an unseen companion, say astronomers.

The team using ALMA, the most powerful millimeter/submillimeter telescope in the world, mapped the spiral structure in three-dimensions. The astronomers say this is the first time a spiral of material, with a surrounding shell, has been observed. They report their findings in the journal Nature this week.

“We’ve seen shells around this kind of star before,” says lead author Matthias Maercker of the European Southern Observatory and Argelander Institute for Astronomy, University of Bonn, Germany in a press release. “But this is the first time we’ve ever seen a spiral of material coming out from a star, together with a surrounding shell.”

Scientists, using the NASA/ESA Hubble Space Telescope found a similar spiral, but without a surrounding shell, while observing the star LL Pegasi. Unlike the new ALMA observations, however, the astronomers could not create a three-dimensional map of the structure. Hubble observations saw the dust while ALMA detected the molecular emission.

ALMA detects the warm glow of carbon monoxide molecules in the far infrared through the multimeter wavelengths allowing astronomers to map the gas emissions surrounding the star in high-resolution. The team believes the strangely shaped bubble of material was probably created by an invisible companion star orbiting the red giant.

As stars like our Sun reach the ends of their lives, they become red giants. Swollen and cool, the stars begin a short-lived helium burning phase. During this time, the stars slough off large amounts of their mass in a dense stellar wind forming an expanding glowing shell around the stellar core. The pulses occur about every 10,000 to 50,000 years and last just a few hundred years. New observations of R Sculptoris show a pulse event rocked the star about 1,800 years ago and lasted for about 200 years. Computer simulations following the evolution of a binary system fit the new ALMA observations, according to the astronomers.

“It’s a real challenge to describe theoretically all the observed details coming from ALMA,” says co-author Shazrene Mohamed, of Argelander Institute for Astronomy in Bonn, Germany and South African Astronomical Observatory. “But our computer models show that we really are on the right track. ALMA is giving us new insight into what’s happening in these stars and what might happen to the Sun in a few billion years from now.”

A wide field view of the red giant variable star R Sculptoris. Credit: ESO/Digitized Sky Survey 2. Acknowledgement: Davide De Martin

R Sculptoris is considered by astronomers to be an asymptotic giant branch, or AGB, star. With masses between 0.8 and 8 solar masses, they are cool red giants with a tiny central core of carbon and oxygen surrounded by a burning shell of helium and hydrogen burning. Eventually, our Sun will evolve into an AGB star. The glowing shell is made up of gas and dust, material that will be used for making future stars with their retinue of planets and moons and even the building blocks of life.

“In the near future, observations of stars like R Sculptoris with ALMA will help us to understand how the elements we are made up of reached places like the Earth. They also give us a hint of what our own star’s far future might be like,” says Maercker.

This new video shows a series of slices through the data, each taken at a slightly different frequency. These reveal the shell around the star, appearing as a circular ring, that seems to gets bigger and then smaller, as well as a clear spiral structure in the inner material that it best seen about half-way through the video sequence.

Source: European Southern Observatory

Small image caption: What appears to be a thin spiral pattern winding away from a star is shown in this remarkable picture from the Advanced Camera for Surveys on the NASA/ESA Hubble Space Telescope shows one of the most perfect geometrical forms created in space. It captures the formation of an unusual pre-planetary nebula, known as IRAS 23166+1655, around the star LL Pegasi (also known as AFGL 3068) in the constellation of Pegasus (the Winged Horse). Credit: NASA/ESA Hubble

October 1, 2012December 23, 2015 by Nancy Atkinson

Watch Live: A Day in the Life of the Very Large Telescope

Ever wonder what takes place on a daily basis at one of the premier ground-based observatories? The European Southern Observatory (ESO) is celebrating its 50th anniversary, and on October 5, 2012, they will host a free, live event on the web, “A Day in the Life of ESO.” There will be live observations from ESO’s flagship observatory, the Very Large Telescope (VLT), on Cerro Paranal in Chile’s Atacama Desert, as well as talks from astronomers at ESO’s Headquarters in Germany. Members of the public are invited to ask questions in advance of the event, or during the stream, by Facebook, Twitter, and email.

The webcast will be streamed through Livestream.

For the first time in ESO’s history, the VLT will be pointed towards an object in the sky selected by members of the public — the Thor’s Helmet Nebula (NGC 2359). This striking nebula was selected as part of the Choose What the VLT Observes competition. Brigitte Bailleul, from France, won the Tweet Your Way to the VLT! competition, and will travel to the Paranal Observatory in Chile to help make the observations. The live link to Paranal will show the observations and the telescopes on the mountaintop, in the stunning landscape of the Atacama Desert, letting viewers join Brigitte on her trip of a lifetime.

The webcast will run from 9:00 to 15:00 UTC on October 5. It will be hosted by astronomer — and host of the ESOcasts — “Dr J” — Dr. Joe Liske, from ESO. There will also be talks from astronomers at ESO’s Headquarters in Germany, on topics ranging from ESO’s state-of-the-art telescopes, via the latest news from the frontiers of astronomy, to what the life of an astronomer is like. Throughout the day there will be question and answer sessions, and the chance to test your ESO knowledge in a quiz to win some astronomical prizes.

Members of the public are invited to ask questions about the activities at the Paranal Observatory, the talks of the day, or general questions about ESO. You can send us your questions before the event, or during the webcast, in English in the following ways:

Send a tweet @ESO, also using the hashtag #ESO50years.

Write a question on your Facebook wall in which you tag ESO’s Facebook page.

Send an email to [email protected] with the subject ESO50years. Optionally, please include your name and country.

See this ESO webpage for more info and schedule of the webcast.

September 26, 2012December 23, 2015 by Jason Major

Take a Gander at a Cosmic Gull

The head and “eye” of the Seagull Nebula (ESO)

This colorful new image from ESO’s La Silla Observatory highlights the heart of a shining stellar nursery located between the constellations Monoceros and Canis Major. Officially named Sharpless 2-292, the cloud of gas and dust forms the “head” of the Seagull Nebula (IC 2177) and gets its glow from the energy emitted by the young, bright star within its “eye”.

A wide-angle image of the Seagull Nebula shows the soaring birdlike shape that gives it its nickname. The cloud seen above forms the gull’s head.

A wide-field view of the Seagull Nebula from the ESO’s Digitized Sky Survey 2 (ESO/Digitized Sky Survey 2. Acknowledgement: Davide De Martin)

The wings of this gull span an impressive 100 light-years from tip to tip. A birthplace for new stars, the nebula is located within our galaxy about 3,700 light-years away.

For an idea of how far that is, if the distance between the Sun and Earth were scaled down to 1 inch (2.5 cm) and you were standing in New York City, the stars in the Seagull Nebula would be in Paris, France (considering the most direct flight route.)

Powerful radiation from young stars causes the surrounding hydrogen gas to glow with a red color. Light from the hot blue-white stars also gets scattered off tiny dust particles in the nebula to create a blue haze.

Blowing a Super-duper Celestial Bubble

Image credit: X-ray: NASA/CXC/U.Mich./S.Oey, IR: NASA/JPL, Optical: ESO/WFI/2.2-m. Zoom by John Williams/TerraZoom using Zoomify

When NASA combines images from different telescopes, they create dazzling scenes of celestial wonder and in the process we learn a few more things. Behold this wonder of combined light, known as LHA 120-N 44, or N 44 for short. Zoom into the scene using the toolbar at the bottom of the image. Click the farthest button on the right of the toolbar to see this wonder in full-screen. (Hint: press the “Esc” key to get back to work)

Continue reading “Blowing a Super-duper Celestial Bubble”

August 16, 2012January 4, 2016 by John Williams

Celestial Dreaming in a Bit of Pipe Smoke

Zoom into the Pipe Nebula by using the zoom slider, or pan around the image by using the arrow icons on the toolbar or by click-dragging the image. You can also zoom into a particular area by double-clicking on your area of interest. Image credit: ESO. Zoomify by John Williams.

Images like this of the Pipe Nebula from the European Southern Observatory’s La Silla Observatory help me dream about the grandeur of the night sky and the richness of the star lanes that make up the Milky Way.

Continue reading “Celestial Dreaming in a Bit of Pipe Smoke”

August 1, 2012December 23, 2015 by Nancy Atkinson

Tranquil Galaxy is Home to Violent Events

This beautiful spiral galaxy looks peaceful, with its swirling white and blue arms appearing like they could be home to countless solar systems similar to ours. But NGC 1187 has hosted two supernova explosions during the last thirty years, and these violent stellar explosions are the result of the powerful death of either a massive star or a white dwarf in a binary system. Astronomers are keeping an eye on this galaxy for more outbursts.

This lovely new image of NGC 1187 was taken with ESO’s Very Large Telescope, and is the most detailed image of this galaxy. This impressive spiral lies about 60 million light-years away in the constellation of Eridanus (The River).

The galaxy is seen almost face-on, which provides a good view of its spiral structure. About half a dozen prominent spiral arms can be seen, each containing large amounts of gas and dust. The bluish feature in the spiral arms indicate the presence of young stars born out of clouds of interstellar gas.

Looking towards the central regions, we see the bulge of the galaxy glowing yellow. This part of the galaxy is mostly made up of old stars, gas and dust. In the case of NGC 1187, rather than a round bulge, there is a subtle central bar structure. Such bar features are thought to act as mechanisms that channel gas from the spiral arms to the center, enhancing star formation there.

Around the outside of the galaxy many much fainter and more distant galaxies can also be seen. Some even shine right through the disc of NGC 1187 itself. Their mostly reddish hues contrast with the pale blue star clusters of the much closer object.

In October 1982, the first supernova detected in NGC 1187 took place, SN 1982R, and more recently, in 2007, SN 2007Y made an appearance, and was initially discovered by an amateur astronomer Berto Monard in South Africa, and was monitored by other astronomers for almost a year. This new image of NGC 1187 was created from observations taken as part of this study and the supernova can be seen, long after the time of maximum brightness, near the bottom of the image.

These data were acquired using the FORS1 instrument attached to the ESO’s Very Large Telescope at the Paranal Observatory in Chile.

Lead image caption: Spiral galaxy NGC 1187 Credit: ESO

Source: ESO

July 18, 2012December 23, 2015 by Nancy Atkinson

Looking Into the Heart of a Quasar

Caption: Artist’s impression of the quasar 3C 279. Credit: ESO/M. Kornmesser

From an ESO press release:

An international team of astronomers has observed the heart of a distant quasar with unprecedented sharpness, two million times finer than human vision. The observations, made by connecting the Atacama Pathfinder Experiment (APEX) telescope to two others on different continents for the first time, is a crucial step towards the dramatic scientific goal of the “Event Horizon Telescope” project: imaging the supermassive black holes at the centre of our own galaxy and others.

Astronomers connected APEX, in Chile, to the Submillimeter Array (SMA) in Hawaii, USA, and the Submillimeter Telescope (SMT) in Arizona, USA. They were able to make the sharpest direct observation ever of the center of a distant galaxy, the bright quasar 3C 279, which contains a supermassive black hole with a mass about one billion times that of the Sun, and is so far from Earth that its light has taken more than 5 billion years to reach us. APEX is a collaboration between the Max Planck Institute for Radio Astronomy (MPIfR), the Onsala Space Observatory (OSO) and ESO. APEX is operated by ESO.

The telescopes were linked using a technique known as Very Long Baseline Interferometry (VLBI). Larger telescopes can make sharper observations, and interferometry allows multiple telescopes to act like a single telescope as large as the separation — or “baseline” — between them. Using VLBI, the sharpest observations can be achieved by making the separation between telescopes as large as possible. For their quasar observations, the team used the three telescopes to create an interferometer with transcontinental baseline lengths of 9447 km from Chile to Hawaii, 7174 km from Chile to Arizona and 4627 km from Arizona to Hawaii. Connecting APEX in Chile to the network was crucial, as it contributed the longest baselines.

The observations were made in radio waves with a wavelength of 1.3 millimetres. This is the first time observations at a wavelength as short as this have been made using such long baselines. The observations achieved a sharpness, or angular resolution, of just 28 microarcseconds — about 8 billionths of a degree. This represents the ability to distinguish details an amazing two million times sharper than human vision. Observations this sharp can probe scales of less than a light-year across the quasar — a remarkable achievement for a target that is billions of light-years away.

The observations represent a new milestone towards imaging supermassive black holes and the regions around them. In future it is planned to connect even more telescopes in this way to create the so-called Event Horizon Telescope. The Event Horizon Telescope will be able to image the shadow of the supermassive black hole in the centre of our Milky Way galaxy, as well as others in nearby galaxies. The shadow — a dark region seen against a brighter background — is caused by the bending of light by the black hole, and would be the first direct observational evidence for the existence of a black hole’s event horizon, the boundary from within which not even light can escape.

The experiment marks the first time that APEX has taken part in VLBI observations, and is the culmination of three years hard work at APEX’s high altitude site on the 5000-metre plateau of Chajnantor in the Chilean Andes, where the atmospheric pressure is only about half that at sea level. To make APEX ready for VLBI, scientists from Germany and Sweden installed new digital data acquisition systems, a very precise atomic clock, and pressurized data recorders capable of recording 4 gigabits per second for many hours under challenging environmental conditions. The data — 4 terabytes from each telescope — were shipped to Germany on hard drives and processed at the Max Planck Institute for Radio Astronomy in Bonn.

The successful addition of APEX is also important for another reason. It shares its location and many aspects of its technology with the new Atacama Large Millimeter/submillimeter Array (ALMA) telescope. ALMA is currently under construction and will finally consist of 54 dishes with the same 12-metre diameter as APEX, plus 12 smaller dishes with a diameter of 7 metres. The possibility of connecting ALMA to the network is currently being studied. With the vastly increased collecting area of ALMA’s dishes, the observations could achieve 10 times better sensitivity than these initial tests. This would put the shadow of the Milky Way’s supermassive black hole within reach for future observations.

July 9, 2012December 23, 2015 by John Williams

Remastering a Cosmic Cat Print

Cat's Paw Nebula. Credit: ESO/R. Gendler & R.M. Hannahoe

Glowing red against a backdrop of stars, amateur astronomers have remastered one of the sky’s most distinctive nebulae, the Cat’s Paw Nebula.

In a stunning combination of data from amateur and professional telescopes, Robert Gendler and Ryan M. Hannahoe mixed their 60 hours of exposures of the nebula on a 0.4-meter telescope with existing images from the 2.2-meter MPG/ESO telescope at the La Silla Observatory in Chile. (See the original image.)

The result is nothing short of beautiful (zoom into all its nebular grandeur at StarryCritters.com). The Cat’s Paw Nebula, also known as NGC 6334, Gum 64 and the Bear Claw Nebula, is found about 5,500 light-years from Earth toward the constellation Scorpius, the Scorpion. The nebula is one of the most active star-forming regions in the Milky Way Galaxy, spanning about 50 light-years, and contains thousands of new stars although most are hidden in the dense clouds of gas and dust. Blistering ultraviolet radiation from these stars excites hydrogen atoms within the star cloud causing it to glow with a characteristic red hue. English astronomer John Herschel first described the nebula in 1837 while observing from the Cape of Good Hope in South Africa.

Anyone using Adobe Photoshop might be familiar with the process used. By combining the luminance, or brightness, of the ESO image with color information from the pair’s long exposures, Gendler and Hannahoe were able to bring out more vibrant color, such as the faint blue nebulosity near the center of the nebula and surrounding some of the brighter stars. The image from the ESO telescope adds finer details.

Does anyone else see the similarity between the arched shape in the middle of the nebula with the Federation insignia from the popular television series Star Trek?

Image Credit: ESO/R. Gendler & R.M. Hannahoe

June 27, 2012December 23, 2015 by Jason Major

How to Measure a Hot Jupiter

An international team of astronomers has figured out a way to determine details of an exoplanet’s atmosphere from 50 light-years away… even though the planet doesn’t transit the face of its star as seen from Earth.

Tau Boötis b is a “hot Jupiter” type of exoplanet, 6 times more massive than Jupiter. It was the first planet to be identified orbiting its parent star, Tau Boötis, located 50 light-years away. It’s also one of the first exoplanets we’ve known about, discovered in 1996 via the radial velocity method — that is, Tau Boötis b exerts a slight tug on its star, shifting its position enough to be detectable from Earth. But the exoplanet doesn’t pass in front of its star like some others do, which until now made measurements of its atmosphere impossible.

Today, an international team of scientists working with the Very Large Telescope (VLT) at ESO’s Paranal Observatory in Chile have announced the success of a “clever new trick” of examining such non-transiting exoplanet atmospheres. By gathering high-quality infrared observations of the Tau Boötis system with the VLT’s CRIRES instrument the researchers were able to differentiate the radiation coming from the planet versus that emitted by its star, allowing the velocity and mass of Tau Boötis b to be determined.

“Thanks to the high quality observations provided by the VLT and CRIRES we were able to study the spectrum of the system in much more detail than has been possible before,” said Ignas Snellen with Leiden Observatory in the Netherlands, co-author of the research paper. “Only about 0.01% of the light we see comes from the planet, and the rest from the star, so this was not easy.”

Using this technique, the researchers determined that Tau Boötis b’s thick atmosphere contains carbon monoxide and, curiously, exhibits cooler temperatures at higher altitudes — the opposite of what’s been found on other hot Jupiter exoplanets.

“Maybe one day we may even find evidence for biological activity on Earth-like planets in this way.”

– Ignas Snellen, Leiden Observatory, the Netherlands

In addition to atmospheric details, the team was also able to use the new method to determine Tau Boötis b’s mass and orbital angle — 44 degrees, another detail not previously identifiable.

“The new technique also means that we can now study the atmospheres of exoplanets that don’t transit their stars, as well as measuring their masses accurately, which was impossible before,” said Snellen. “This is a big step forward.

“Maybe one day we may even find evidence for biological activity on Earth-like planets in this way.”

This research was presented in a paper “The signature of orbital motion from the dayside of the planet Tau Boötis b”, to appear in the journal Nature on June 28, 2012.

Gas Cloud Will Collide with our Galaxy’s Black Hole in 2013

Scientists have determined a giant gas cloud is on a collision course with the black hole in the center of our galaxy, and the two will be close enough by mid-2013 to provide a unique opportunity to observe how a super massive black hole sucks in material, in real time. This will give astronomers more information on how matter behaves near a black hole.

“The next few years will be really fantastic and exciting because we are probing new territory,” said Reinhard Genzel, leading a team from the ESO in observations with the Very Large Telescope. “Here this cloud comes in gets disrupted and now it will begin to interact with the hot gas right around the black hole. We have never seen this before.”

By June of 2013, the gas cloud is expected to be just 36 light-hours (equivalent to 40,000,000,000 km) away from our galaxy’s black hole, which is extremely close in astronomical terms.

Astronomers have determined the speed of the gas cloud has increased, doubling over the past seven years, and is now reaching more than 8 million km per hour. The cloud is estimated to be three times the mass of Earth and the density of the cloud is much higher than that of the hot gas surrounding black hole. But the black hole has a tremendous gravitational force, and so the gas cloud will fall into the direction of the black hole, be elongated and stretched and look like spaghetti, said Stefan Gillessen, astrophysicist at the Max Planck Institute for Extraterrestrial Physics in Munich, Germany, who has been observing our galaxy’s black hole, known as Sagittarius A* (or Sgr A*), for 20 years.

“So far there were only two stars that came that close to Sagittarius A*,” Gillessen said. “They passed unharmed, but this time will be different: the gas cloud will be completely ripped apart by the tidal forces of the black hole.”

Watch a video of observations of the cloud for the past 10 years:

No one really knows how the collision will unfold, but the cloud’s edges have already started to shred and it is expected to break up completely over the coming months. As the time of actual collision approaches, the cloud is expected to get much hotter and will probably start to emit X-rays as a result of the interaction with the black hole.

Although direct observations of black holes are impossible, as they do not emit light or matter, astronomers can identify a black hole indirectly due to the gravitational forces observed in their vicinity.

A black hole is what remains after a super massive star dies. When the “fuel” of a star runs low, it will first swell and then collapse to a dense core. If this remnant core has more than three times the mass of our Sun, it will transform to a black hole. So-called super massive black holes are the largest type of black holes, as their mass equals hundreds of thousands to a billion times the mass of our Sun.

Black holes are thought to be at the center of all galaxies, but their origin is not fully understood and astrophysicists can only speculate as to what happens inside them. And so this upcoming collision just 27,000 light years away will likely provide new insights on the behavior of black holes.

Lead image caption: Images taken over the last decade using the NACO instrument on ESO’s Very Large Telescope show the motion of a cloud of gas that is falling towards the supermassive black hole at the centre of the Milky Way. This is the first time ever that the approach of such a doomed cloud to a supermassive black hole has been observed and it is expected to break up completely during 2013. Credit: ESO/MPE

Read our previous article about this topic, from Dec. 2011.

Source: European Research Media Center