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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/

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Man in the Moon Looking Younger

August 17, 2011 Leave a comment

Earth’s Moon could be younger than previously thought, according to
new research from a team that includes Carnegie’s Richard Carlson and
former-Carnegie fellow Maud Boyet. Their work will be published online
in Nature on August 17.

The prevailing theory of our Moon’s origin is that it was created by a
giant impact between a large planet-like object and the proto-Earth.
The energy of this impact was sufficiently high that the Moon formed
from melted material that was ejected into space. As the Moon cooled,
this magma solidified into different mineral components.

Analysis of lunar rock samples thought to have been derived from the
original magma has given scientists a new estimate of the Moon’s age.

According to this theory for lunar formation, a rock type called
ferroan anorthosite, or FAN, is the oldest of the Moon’s crustal
rocks, but scientists have had difficulty dating FAN samples. The
research team, led by Lars E. Borg of the Lawrence Livermore National
Laboratory, included Carlson of Carnegie’s Department of Terrestrial
Magnetism, Boyet — now at Université Blaise Pascal — and James N.
Connelly of the University of Copenhagen. They used newly refined
techniques to determine the age of a sample of FAN from the lunar rock
collection at the NASA Johnson Space Center.

The team analyzed the isotopes of the elements lead and neodymium to
place the FAN sample’s age at 4.36 billion years. This figure is
significantly younger than earlier estimates of the Moon’s age that
range as old as the age of the solar system at 4.568 billion years.
The new, younger age obtained for the oldest lunar crust is similar to
ages obtained for the oldest terrestrial minerals — zircons from
western Australia — suggesting that the oldest crusts on both Earth
and Moon formed at approximately the same time, and that this time
dates from shortly after the giant impact.

This study is the first in which a single sample of FAN yielded
consistent ages from multiple isotope dating techniques. This result
strongly suggests that these ages pinpoint the time at which the
sample crystallized.

“The extraordinarily young age of this lunar sample either means that
the Moon solidified significantly later than previous estimates, or
that we need to change our entire understanding of the Moon’s
geochemical history,” Carlson said.

# # #

Funding for this work was provided by the Department of Energy, and
portions of the work were supported by the NASA Cosmochemistry
Program.

The Carnegie Institution for Science (http://carnegiescience.edu) is a
private, nonprofit organization headquartered in Washington, D.C.,
with six research departments throughout the U.S. Since its founding
in 1902, the Carnegie Institution has been a pioneering force in basic
scientific research. Carnegie scientists are leaders in plant biology,
developmental biology, astronomy, materials science, global ecology,
and Earth and planetary science.

Space Shuttle Crew to Discuss Final Mission at NASA Ames

August 17, 2011 Leave a comment

MOFFETT FIELD, Calif. – NASA’s space shuttle Atlantis astronauts will be available for interviews and to discuss their mission to the International Space Station — the flight that brought the illustrious Space Shuttle Program to a close — Monday, Aug. 22, 2011, in the Syvertson Auditorium, N-201, at NASA’s Ames Research Center, Moffett Field, Calif.
The STS-135 mission crew members will be available for media interviews from 12:15 to 1 p.m. PDT. Reporters are then invited to view a crew presentation to NASA employees about their 13-day mission.

Reporters must contact Michael Mewhinney at michael.s.mewhinney@nasa.gov by 9 a.m., Monday, Aug. 22, to schedule an interview and attend the presentation. To reach Ames, take U.S. Highway 101 to the Moffett Field, NASA Parkway exit and drive east on Moffett Boulevard towards the main gate. Reporters must obtain a visitor pass from the Visitor Registration and Badge Office at the main gate.

Chris Ferguson commanded the STS-135 mission and was joined by fellow veteran astronauts Pilot Doug Hurley and Mission Specialists Sandra Magnus and Rex Walheim.

The STS-135 mission launched July 8, 2011, and landed July 21, 2011. It was the 33rd and final flight for Atlantis, which spent 307 days in space, orbited Earth 4,848 times and traveled 125,935,769 miles. In addition to carrying supplies to the space station, space shuttle Atlantis flew a system to study robotic spacecraft refueling and returned a failed ammonia pump module to help NASA improve pump designs for future systems.

This was Ferguson, Magnus and Walheim’s third spaceflight and Hurley’s second. Ferguson has logged more than 28 days in space; Magnus has logged more than four months in space and Walheim has logged more than 24 days in space including five spacewalks; Hurley has logged more than 4,000 hours in 25 different aircraft.

For more information about the STS-135 crew members and their mission, visit:

http://go.usa.gov/KMk

Source: http://www.nasa.gov/centers/ames/news/releases/2011/M11-63.html