Archive

Posts Tagged ‘ESO (European Southern Observatory)’

Star Blasts Planet With X-rays

September 13, 2011 Leave a comment

Illustration: NASA/CXC/M.Weiss

Illustration: NASA/CXC/M.Weiss

New data from NASA’s Chandra X-ray Observatory and the European Southern Observatory’s Very Large Telescope suggest that high-energy radiation is evaporating about 5 million tons of matter from the planet every second. This result gives insight into the difficult survival path for some planets.

The planet, known as CoRoT-2b, has a mass about 3 times that of Jupiter (1000 times that of Earth) and orbits its parent star, CoRoT-2a at a distance roughly ten times the distance between Earth and the Moon.

The CoRoT-2 star and planet — so named because the French Space Agency’s Convection, Rotation and planetary Transits (CoRoT) satellite discovered them in 2008 — is a relatively nearby neighbor of the Solar System at a distance of 880 light years.

“This planet is being absolutely fried by its star,” said Sebastian Schroeter of the University of Hamburg in Germany. “What may be even stranger is that this planet may be affecting the behavior of the star that is blasting it.”

Full Story: http://chandra.si.edu/press/11_releases/press_091311.html

50 New Exoplanets Discovered, Including 16 New Super-Earths

September 13, 2011 Leave a comment

Credit: ESO/M. Kornmesser

Credit: ESO/M. Kornmesser

Astronomers using ESO’s world-leading exoplanet hunter HARPS have today announced a rich haul of more than 50 new exoplanets, including 16 super-Earths, one of which orbits at the edge of the habitable zone of its star. By studying the properties of all the HARPS planets found so far, the team has found that about 40% of stars similar to the Sun have at least one planet lighter than Saturn.

The HARPS spectrograph on the 3.6-metre telescope at ESO’s La Silla Observatory in Chile is the world’s most successful planet finder [1]. The HARPS team, led by Michel Mayor (University of Geneva, Switzerland), today announced the discovery of more than 50 new exoplanets orbiting nearby stars, including sixteen super-Earths [2]. This is the largest number of such planets ever announced at one time[3]. The new findings are being presented at a conference on Extreme Solar Systems where 350 exoplanet experts are meeting in Wyoming, USA.

Full Story: http://www.eso.org/public/news/eso1134/

Young Stars in the Spotlight

September 7, 2011 Leave a comment

Credit: ESO

Credit: ESO

ESO’s New Technology Telescope (NTT) has captured a striking image of the open cluster NGC 2100. This brilliant star cluster is around 15 million years old, and located in the Large Magellanic Cloud, a nearby satellite galaxy of the Milky Way. The cluster is surrounded by glowing gas from the nearby Tarantula Nebula.

Observers often overlook NGC 2100 because of its close proximity to the impressive Tarantula Nebula (eso0650) and the super star cluster RMC 136 (eso1030). The glowing gas of the Tarantula Nebula even tries to steal the limelight in this image — the bright colours here are the nebula’s outskirts. This new picture was created from exposures through several different colour filters using the EMMI instrument [1]on the New Technology Telescope at ESO’s La Silla Observatory in Chile. The stars are shown in their natural colours, while light from glowing ionised hydrogen (shown here in red) and oxygen (shown in blue) is overlaid.

Full Story: http://www.eso.org/public/news/eso1133/

The Star That Should Not Exist

September 1, 2011 Leave a comment

A star that should not exist

Image Credit: ESO/Digitized Sky Survey 2

A team of European astronomers has used ESO’s Very Large Telescope (VLT) to track down a star in the Milky Way that many thought was impossible. They discovered that this star is composed almost entirely of hydrogen and helium, with only remarkably small amounts of other chemical elements in it. This intriguing composition places it in the “forbidden zone” of a widely accepted theory of star formation, meaning that it should never have come into existence in the first place. The results will appear in the 1 September 2011 issue of the journal Nature.

A faint star in the constellation of Leo (The Lion), called SDSS J102915+172927, has been found to have the lowest amount of elements heavier than helium (what astronomers call “metals”) of all stars yet studied. It has a mass smaller than that of the Sun and is probably more than 13 billion years old.

Full Story: http://www.eso.org/public/news/eso1132/

VLT Looks into the Eyes of the Virgin

August 24, 2011 Leave a comment

VLT looks into The Eyes of the Virgin

Credit: ESO/Gems project

ESO’s Very Large Telescope has taken a striking image of a beautiful yet peculiar pair of galaxies nicknamed The Eyes. The larger of these, NGC 4438, was once a spiral galaxy but has become badly deformed by collisions with other galaxies in the last few hundred million years. This picture is the first to come out of ESO’s Cosmic Gems programme, an initiative in which ESO has granted dedicated observing time for outreach purposes.

 

Full Story: http://www.eso.org/public/news/eso1131/

Giant Space Blob Glows from Within

August 17, 2011 Leave a comment

This image shows one of the largest known single objects in the Universe, the Lyman-alpha blob LAB-1. This picture is a composite of two different images taken with the FORS instrument on the Very Large Telescope (VLT) — a wider image showing the surrounding galaxies and a much deeper observation of the blob itself at the centre made to detect its polarisation. The intense Lyman-alpha ultraviolet radiation from the blob appears green after it has been stretched by the expansion of the Universe during its long journey to Earth. These new observations show for the first time that the light from this object is polarised. This means that the giant "blob" must be powered by galaxies embedded within the cloud. Credit: ESO/M. Hayes

** Synopsis: Observations from ESO’s Very Large Telescope have shed  light on the power source of a rare vast cloud of glowing gas in the early Universe. The observations show for the first time that this
giant “Lyman-alpha blob” — one of the largest single objects known — must be powered by galaxies embedded within it. The results appear in the 18 August issue of the journal Nature. **

A team of astronomers has used ESO’s Very Large Telescope (VLT) to study an unusual object called a Lyman-alpha blob [1]. These huge and very luminous rare structures are normally seen in regions of the early Universe where matter is concentrated. The team found that the light coming from one of these blobs is polarized [2]. In everyday life, for example, polarized light is used to create 3D effects in cinemas [3]. This is the first time that polarization has ever been found in a Lyman-alpha blob, and this observation helps to unlock the mystery of how the blobs shine.

“We have shown for the first time that the glow of this enigmatic object is scattered light from brilliant galaxies hidden within, rather than the gas throughout the cloud itself shining.” Explains Matthew Hayes (University of Toulouse, France), lead author of the paper.

Lyman-alpha blobs are some of the biggest objects in the Universe: gigantic clouds of hydrogen gas that can reach diameters of a few hundred thousand light-years (a few times larger than the size of the Milky Way), and which are as powerful as the brightest galaxies. They are typically found at large distances, so we see them as they were when the Universe was only a few billion years old. They are therefore important in our understanding of how galaxies formed and evolved when the Universe was younger. But the power source for their extreme luminosity, and the precise nature of the blobs, has remained unclear.

The team studied one of the first and brightest of these blobs to be found. Known as LAB-1, it was discovered in 2000, and it is so far away that its light has taken about 11.5 billion years to reach us (redshift 3.1). With a diameter of about 300,000 light-years it is also one of the largest known, and has several primordial galaxies inside it, including an active galaxy [4].

There are several competing theories to explain Lyman-alpha blobs. One idea is that they shine when cool gas is pulled in by the blob’s powerful gravity, and heats up. Another is that they are shining because of brilliant objects inside them: galaxies undergoing vigorous star formation, or containing voracious black holes engulfing matter. The new observations show that it is embedded galaxies, and not gas being pulled in, that power LAB-1.

The team tested the two theories by measuring whether the light from the blob was polarized. By studying how light is polarized astronomers can find out about the physical processes that produced the light, or what has happened to it between its origin and its arrival at Earth. If it is reflected or scattered it becomes polarized and this subtle effect can be detected by a very sensitive instrument. To measure polarization of the light from a Lyman-alpha blob is, however, a very challenging observation, because of their great distance.

“These observations couldn’t have been done without the VLT and its FORS instrument. We clearly needed two things: a telescope with at least an eight-meter mirror to collect enough light, and a camera
capable of measuring the polarization of light. Not many observatories in the world offer this combination.” adds Claudia Scarlata (University of Minnesota, USA), co-author of the paper.

By observing their target for about 15 hours with the Very Large Telescope, the team found that the light from the Lyman-alpha blob LAB-1 was polarized in a ring around the central region, and that there was no polarization in the center. This effect is almost impossible to produce if light simply comes from the gas falling into the blob under gravity, but it is just what is expected if the light originally comes from galaxies embedded in the central region, before being scattered by the gas.

The astronomers now plan to look at more of these objects to see if the results obtained for LAB-1 are true of other blobs.

Notes

[1] The name comes from the fact that these blobs emit a characteristic wavelength of light, known as “Lyman-alpha” radiation, that is produced when electrons in hydrogen atoms drop from the second-lowest to the lowest energy level.

[2] When light waves are polarized, their component electric and magnetic fields have a specific orientation. In unpolarized light the orientation of the fields is random and has no preferred direction.

[3] The 3D effect is created by making sure the left and right eyes are seeing slightly different images. The trick used in some 3D cinemas involves polarized light: separate images made with differently polarized light are sent to our left and right eyes by polarizing filters in the glasses.

[4] Active galaxies are galaxies whose bright cores are believed to be powered by a vast black hole. Their luminosity comes from material being heated as it is pulled in by the black hole.

# # #

This research was presented in the paper “Central Powering of the Largest Lyman-alpha Nebula is Revealed by Polarized Radiation” by Hayes et al. to appear in the journal Nature on 18 August 2011:
http://www.eso.org/public/archives/releases/sciencepapers/eso1130/eso1130.pdf

The team is composed of Matthew Hayes (University of Toulouse, France and Observatory of Geneva, Switzerland), Claudia Scarlata (University of Minnesota, USA) and Brian Siana (University of California, Riverside, USA).

Photos of the VLT:
http://www.eso.org/public/images/archive/category/paranal/

ESO, the European Southern Observatory, is the foremost intergovernmental astronomy organization 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 program 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 organizing 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-meter-class European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

Original Story: http://www.eso.org/public/news/eso1130/