ESO Archives - Page 10 of 11

October 1, 2012December 23, 2015

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

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.

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

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

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.

June 27, 2012December 23, 2015

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

May 21, 2012December 23, 2015

Dark Matter Makes a Comeback

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Recent reports of dark matter’s demise may be greatly exaggerated, according to a new paper from researchers at the Institute for Advanced Study.

Astronomers with the European Southern Observatory announced in April a surprising lack of dark matter in the galaxy within the vicinity of our solar system.

The ESO team, led by Christian Moni Bidin of the Universidad de Concepción in Chile, mapped over 400 stars near our Sun, spanning a region approximately 13,000 light-years in radius. Their report identified a quantity of material that matched what could be directly observed: stars, gas, and dust… but no dark matter.

“Our calculations show that it should have shown up very clearly in our measurements,” Bidin had stated, “but it was just not there!”

But other scientists were not so sure about some assumptions the ESO team had based their calculations upon.

Researchers Jo Bovy and Scott Tremaine from the Institute for Advanced Study in Princeton, NJ, have submitted a paper claiming that the results reported by Moni Biden et al are “incorrect”, and based on an “invalid assumption” of the motions of stars within — and above — the plane of the galaxy.

(Read: Astronomers Witness a Web of Dark Matter)

“The main error is that they assume that the mean azimuthal (or rotational) velocity of their tracer population is independent of Galactocentric cylindrical radius at all heights,” Bovy and Tremaine state in their paper. “This assumption is not supported by the data, which instead imply only that the circular speed is independent of radius in the mid-plane.”

The researchers point out the stars within the local neighborhood move slower than the average velocity assumed by the ESO team, in a behavior called asymmetric drift. This lag varies with a cluster’s position within the galaxy, but, according to Bovy and Tremaine, “this variation cannot be measured for the sample [used by Moni Biden’s team] as the data do not span a large enough range.”

When the IAS researchers took Moni Biden’s observations but replaced the ESO team’s “invalid” assumptions on star movement within and above the galactic plane with their own “data-driven” ones, the dark matter reappeared.

eso1217b — Artist's impression of dark matter surrounding the Milky Way. (ESO/L. Calçada)

“Our analysis shows that the locally measured density of dark matter is consistent with that extrapolated from halo models constrained at Galactocentric distances,” Bovy and Tremaine report.

As such, the dark matter that was thought to be there, is there. (According to the math, that is.)

And, the two researchers add, it’s not only there but it’s there in denser amounts than average — at least in the area around our Sun.

“The halo density at the Sun, which is the relevant quantity for direct dark matter detection experiments, is likely to be larger because of gravitational focusing by the disk,” Bovy and Tremaine note.

When they factored in their data-driven calculations on stellar velocities and the movement of the halo of non-baryonic material that is thought to envelop the Milky Way, they found that “the dark matter density in the mid-plane is enhanced… by about 20%.”

So rather than a “serious blow” to the existence of dark matter, the findings by Bovy and Tremaine — as well as Moni Biden and his team — may have not only found dark matter, but given us 20% more!

Now that’s a good value.

Read the IAS team’s full paper here.

(Tip of the non-baryonic hat to Christopher Savage, post-doctorate researcher at the Oskar Klein Centre for Cosmoparticle Physics at Stockholm University for the heads up on the paper.)

May 17, 2012December 23, 2015

How Do The Biggest Telescopes Work?

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Located high in the mountains of Chile’s Atacama Desert, the enormous telescopes of the European Southern Observatory have been providing astronomers with unprecedented views of the night sky for 50 years. ESO’s suite of telescopes take advantage of the cold, clear air over the Atacama, which is one of the driest places on Earth. But as clear as it is, there is still some turbulence and variations to contend with — especially when peering billions of light-years out into the Universe.

So how do they do it?

Thanks to adaptive optics and advanced laser calibration, ESO can negate the effects of atmospheric turbulence, bringing the distant Universe into focus. It’s an impressive orchestration of innovation and engineering and the ESO team has put together a video to show us how it’s done.

We all love the images (and the science) so here’s a look behind the scenes!

Video: ESO

May 2, 2012December 23, 2015

Beautiful, Glowing Dust in Orion

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On Earth, dust can be pretty mundane. But in space, dust can be beautiful, especially when the dust reflects starlight – and even more so when we have the chance to see the reflections in different wavelengths. Here in NGC 2068, also called Messier 78, this dazzling submillimetre-wavelength view from the Atacama Pathfinder Experiment (APEX) telescope Dust shows the glow of interstellar dust grains, pointing the way to where new stars are being formed.
This reflection nebula lies just to the north of Orion’s Belt. When seen in visible light glimmers in a pale blue glow of starlight, but much of the light is blocked by the dust. In this image, the APEX observations are overlaid on the visible-light image in orange. APEX’s view reveals the gentle glow of dense cold clumps of dust, some of which are even colder than -250 C.

A visible light image from ESO of the reflection nebula Messier 78. Credit: ESO and Igor Chekalin

Compare the new image with this earlier, visible light image of M78.

One filament seen by APEX appears in visible light as a dark lane of dust cutting across Messier 78. This tells us that the dense dust lies in front of the reflection nebula, blocking its bluish light. Another prominent region of glowing dust seen by APEX overlaps with the visible light from Messier 78 at its lower edge. The lack of a corresponding dark dust lane in the visible light image tells us that this dense region of dust must lie behind the reflection nebula.

Observations of the gas in these clouds reveal gas flowing at high velocity out of some of the dense clumps. These outflows are ejected from young stars while the star is still forming from the surrounding cloud. Their presence is therefore evidence that these clumps are actively forming stars.

At the top of the image is another reflection nebula, NGC 2071. While the lower regions in this image contain only low-mass young stars, NGC 2071 contains a more massive young star with an estimated mass five times that of the Sun, located in the brightest peak seen in the APEX observations.

eso1105b — This chart shows the location of Messier 78 in the famous constellation of Orion (The Hunter). This map shows most of the stars visible to the unaided eye under good conditions, and Messier 78 itself is highlighted with a red circle on the image. This reflection nebula is quite bright and can be seen well in moderate-sized amateur telescopes. Credit: ESO, IAU and Sky & Telescope

Source: ESO