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Herschel telescope reveals invisible cosmos

HERSHEL, A CUTTING-EDGE SPACE OBSERVATORY, carries the largest, most powerful infrared telescope ever launched.

A pioneering mission of the European Space Agency, it is studying the origin and evolution of stars and galaxies to help understand how the Universe came to be the way it is today.

For this purpose Herschel is looking, at far-infrared and submillimetre wavelengths, at objects that are among the coldest in space.

Launched in May 2009 it has already given great results to the scientific community by revealing invisible parts of the universe.

More information:

ESA Herschel mission

Adapted from information issued by ESA.

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Airborne observatory reaches milestone

SOFIA observatory

The Stratospheric Observatory for Infrared Astronomy (SOFIA) is a modified Boeing 747SP, equipped with a 2.5-metre-diameter telescope.

NASA’s STRATOSPHERIC OBSERVATORY for Infrared Astronomy, or SOFIA, has completed the first of three science flights to demonstrate the aircraft’s potential to make discoveries about the universe.

SOFIA is a heavily modified Boeing 747SP that cruises at altitudes between 39,000 and 45,000 feet. At that altitude, it is above most of the atmosphere that interferes with astronomical observations.

In particular, it is above most of the water vapour that inhibits observations at infrared wavelengths.

It will enable researchers to better understand a wide range of astronomical phenomena including how stars and planets are born, how organic substances form in interstellar space, and how supermassive black holes feed and grow.

“These initial science flights mark a significant milestone in SOFIA’s development and ability to conduct peer-reviewed science observations,” said NASA Astrophysics Division Director Jon Morse.

“We anticipate a number of important discoveries from this unique observatory, as well as extended investigations of discoveries by other space telescopes.”

SOFIA is fitted with a 2.5-metre-diameter telescope that views the sky through a hatch toward the back of the aircraft.

The telescope’s instruments can analyse light from a wide range of celestial objects, including warm interstellar gas and dust of bright star forming regions, by observing wavelengths between 0.3 and 1,600 microns. (A micron equals one millionth of a metre.) For comparison, the human eye sees light with wavelengths between 0.4 and 0.7 microns.

The airborne observatory is an international collaboration between NASA and the German Aerospace Centre, Deutsches Zentrum fur Luft und Raumfahrt (DLR).

Adapted from information issued by NASA.

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Unicorn cloud reveals its inner self

Monoceros R2

Infrared image of the nearby star formation region Monoceros R2, located 2,700 light-years away in the constellation Monoceros (the Unicorn).

  • Infrared images can look through dust clouds
  • VISTA telescope designed for infrared sky surveys
  • Image penetrates into the heart of region called Monoceros R2

A new infrared image from the European Southern Observatory’s (ESO) VISTA survey telescope reveals a scene of glowing tendrils of gas, dark dust clouds and young stars within the constellation Monoceros (the Unicorn).

Known as Monoceros R2, this star-forming region is embedded within a huge dark cloud rich in molecules and dust and hiding an active stellar “nursery”.

VISTA telescope

The enclosure of the VISTA survey telescope at the ESO Paranal Observatory in northern Chile.

At “normal”, visible light wavelengths (see comparison images below), a grouping of massive hot stars can be seen amidst a beautiful collection of “reflection nebulae”, where bluish starlight is scattered from parts of the foggy outer layers of a cloud of molecular gas.

Most of the newborn massive stars in the nursery remain hidden at visible light wavelengths, as the thick dust clouds strongly absorb and block the stars’ ultraviolet and visible light from reaching us.

But spectacular detail pops out at VISTA’s infrared wavelengths. See the full-size, high-resolution version here (0.7MB, new window)

Taken from ESO’s Paranal Observatory in northern Chile, the VISTA image shows how the dark curtain of cosmic dust is penetrated to reveal in detail the folds, loops and filaments sculpted from the dusty interstellar matter by the intense particle winds and radiation emitted by hot young stars.

“When I first saw this image I just said, ‘Wow!’” says Jim Emerson, of Queen Mary, University of London and leader of the VISTA consortium. “I was amazed to see all the dust streamers so clearly around the Monoceros R2 cluster, as well as the jets from highly embedded young stellar objects.”

Stars form in a process that typically lasts few million years and which takes place inside large clouds of interstellar gas and dust, hundreds of light-years across.

Interstellar dust blocks visible light wavelengths but lets infrared and radio wavelengths through… so observations at the latter wavelengths are crucial in the understanding of the earliest stages of the stellar evolution.

Visible light wavelength image of Monoceros R2

A visible light wavelength image of Monoceros R2. Compare this to the infrared image at the top of the page. At infrared wavelengths, the thick, rich dust clouds that cover much of the image become nearly transparent and a whole host of young stars and associated outflows become apparent.

Home to newborn stars

Since dust is largely transparent at infrared wavelengths, many young stars that cannot be seen in visible-light images become apparent in Monoceros R2. The most massive of these stars are less than 10 million years old.

At the centre of the image lies Monoceros R2 dense core, no more than two light-years in extent, which is packed with very massive young stars, as well as a cluster of bright infrared sources, which are typically newborn massive stars still surrounded by dusty clouds.

The rightmost of the bright clouds in the centre is called NGC 2170, the brightest reflection nebula in this region. In visible light, the nebulae appear as bright, light blue islands in a dark ocean, while infrared reveals their interiors where hundreds of massive stars are coming into existence.

NGC 2170—faintly visible through a small telescope—was discovered from England in 1784 by astronomer William Herschel.

Although Monoceros R2 appears close in the sky to the more familiar Orion Nebula it is actually almost twice as far from Earth, at a distance of about 2,700 light-years. The width of VISTA’s field of view is equivalent to about 80 light-years at this distance.

With its 4.1-metre primary mirror, VISTA is the largest survey telescope in the world and is equipped with the largest infrared camera on any telescope, with 67 million pixels. It is dedicated to sky surveys.

By mapping the southern sky systematically, VISTA will gather some 300 gigabytes per night, providing a huge amount of information on those regions that will be studied in greater detail by the Very Large Telescope (VLT), the Atacama Large Millimetre/submillimetre Array (ALMA) and, in the future, by the European Extremely Large Telescope (E-ELT).

Adapted from information issued by ESO / J. Emerson / VISTA / Cambridge Astronomical Survey Unit.

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WISE eyes on the sky

WISE image of the Pleiades star cluster

This image shows the famous Pleiades cluster of stars as seen through the eyes of WISE, or NASA's Wide-field Infrared Survey Explorer. The mosaic contains a few hundred image frames—just a fraction of the more than one million WISE has captured so far as it completes its first survey of the entire sky in infrared light.

  • Infrared mapping telescope completes all-sky survey
  • Over 1 million images in total, with more to come
  • Spotted 100,000+ asteroids, and discovers a dozen comets

NASA’s Wide-field Infrared Survey Explorer, or WISE, completed its first survey of the entire sky on July 17. The mission has generated more than 1 million images so far, of everything from asteroids to distant galaxies.

“Like a globe-trotting shutterbug, WISE has completed a world tour with 1.3 million slides covering the whole sky,” said Edward Wright, the principal investigator of the mission at the University of California, Los Angeles.

Some of the images have been processed and stitched together into a new picture just released. It shows the Pleiades cluster of stars, also known as the Seven Sisters, resting in a tangled bed of wispy dust.

The pictured region covers seven square degrees, or an area equivalent to 35 full Moons, highlighting the telescope’s ability to take wide shots of vast regions of space.

WISE all-sky infrared map

WISE all-sky map. If you eyes could see infrared instead of normal visible light, this is what the sky would look like.

The new picture was taken in February. It combines infrared light from WISE’s four detectors in a range of wavelengths, and highlights the region’s expansive dust cloud, through which the Seven Sisters and other stars in the cluster are passing. Infrared light also reveals the smaller and cooler stars of the family.

Mapping job almost finished

The mission scanned strips of the sky as it orbited around the Earth’s poles since its launch last December. WISE always stays over the Earth’s day-night line. As the Earth moves around the Sun, new slices of sky come into the telescope’s field of view.

It has taken six months, or the amount of time for Earth to travel halfway around the sun, for the mission to complete one full scan of the entire sky.

For the next three months, the mission will map half of the sky again. This will enhance the telescope’s data, revealing more hidden asteroids, stars and galaxies. The mapping will give astronomers a look at what’s changed in the sky.

The mission will end when the instrument’s block of solid hydrogen coolant, needed to chill its infrared detectors, runs out.

Artist's impression of WISE

Artist's impression of WISE, NASA's Wide-field Infrared Survey Explorer.

“The eyes of WISE have not blinked since launch,” said William Irace, the mission’s project manager at NASA’s Jet Propulsion Laboratory. “Both our telescope and spacecraft have performed flawlessly and have imaged every corner of our universe, just as we planned.”

Over 100,000 asteroids spotted

So far, WISE has spotted more than 100,000 asteroids, both known and previously unseen. Most of these space rocks are in the main belt between Mars and Jupiter.

However, some are “near-Earth objects”, asteroids and comets with orbits that pass relatively close to Earth. WISE has discovered more than 90 of these new near-Earth objects.

The infrared telescope is also good at spotting comets that orbit far from Earth and has discovered more than a dozen of these so far.

WISE’s infrared vision also gives it a unique ability to pick up the glow of cool stars, called brown dwarfs, in addition to distant galaxies bursting with light and energy. These galaxies are called ultra-luminous infrared galaxies. WISE can see the brightest of them.

Adapted from information issued by NASA / JPL-Caltech / UCLA .

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Cosmic grandeur: the Sculptor Galaxy

Infrared view of galaxy NGC 253

NGC 253 is one of the closest galaxies to our own. At infrared wavelengths shown here, dust clouds in the galaxy’s spiral arms become nearly transparent and a host of cool, red stars can be seen.

  • Sculptor Galaxy, also known as NGC 253
  • 13 million light-years from Earth
  • “Starburst” galaxy, in the throes of massive star formation

A new image of the Sculptor Galaxy (NGC 253) has been taken with the European Southern Observatory (ESO) VISTA telescope at the Paranal Observatory in Chile as part of one of its first major observational campaigns.

By observing in infrared light, VISTA’s view is less affected by dust in the galaxy, and reveals a myriad of cooler, red stars, as well as a prominent elongated belt of stars across the central region.

NGC 253 is one of the brightest galaxies in the sky. It is prominent enough to be seen with good binoculars and was discovered by Caroline Herschel from England in 1783.

A spiral galaxy that lies about 13 million light-years away, it is the brightest member of a small collection of galaxies called the Sculptor Group, one of the closest such groupings to our own Local Group of galaxies.

Part of its visual prominence comes from its status as a “starburst galaxy”, one in the throes of rapid star formation.

Infrared and visible light views of galaxy NGC 253

Comparison of the infrared (top) and visible light (bottom) views.

NGC 253 is also very dusty, which obscures the view of many parts of the galaxy. Seen from Earth, the galaxy is almost edge on, with the spiral arms clearly visible in the outer parts, along with a bright core at its centre.

See the full-size image here.

As VISTA works at infrared wavelengths it can see right through most of the dust that is such a prominent feature of the Sculptor Galaxy when viewed in visible light. Huge numbers of cooler stars that are barely detectable with visible-light telescopes suddenly can be seen.

The VISTA view reveals most of what was hidden by the thick dust clouds in the central part of the galaxy and allows a clear view of a prominent elongated section, or “bar”, of stars across the nuclear region — a feature that is not seen in visible light pictures. The majestic spiral arms now spread over the whole disc of the galaxy.

Astronomers are peeling away some of the mysteries of the Sculptor Galaxy. They are studying the myriad cool, red giant stars in the halo that surrounds the galaxy, measuring the composition of some of NGC 253’s small dwarf satellite galaxies, and searching for as yet undiscovered new objects such as globular clusters and ultra-compact dwarf galaxies that would otherwise be invisible without the deep VISTA infrared images.

Adapted from information issued by ESO / J. Emerson / VISTA / Cambridge Astronomical Survey Unit.

Airborne telescope sees “first light”

Image of SOFIA in flight with the telescope door open

Image of SOFIA in flight with its telescope door open. The converted Boeing 747SP flies above 99% of atmospheric water vapour, affording an excellent view of the infrared sky.

  • Telescope fitted inside a Boeing 747
  • Flies above 99% of atmospheric water vapour
  • Detects infrared wavelengths from space

The Stratospheric Observatory for Infrared Astronomy (SOFIA), a joint program by NASA and the German Aerospace Centre, achieved a major milestone May 26, with its first in-flight night observations.

“With this flight, SOFIA begins a 20-year journey that will enable a wide variety of astronomical science observations not possible from other Earth and space-borne observatories,” said Jon Morse, Astrophysics Division director in the Science Mission Directorate at NASA Headquarters in Washington.

“It clearly sets expectations that SOFIA will provide us with “Great Observatory”-class astronomical science.”

The highly modified SOFIA Boeing 747SP jetliner fitted with a 2.5-metre-diameter reflecting telescope took off from its home base at the Aircraft Operations Facility in Palmdale, California, of NASA’s Dryden Flight Research Centre.

The in-flight personnel consisted of an international crew from NASA, the Universities Space Research Association, Cornell University and the German SOFIA Institute (DSI) in Stuttgart.

During the six-hour flight, at altitudes up to 35,000 feet, the crew of 10 scientists, astronomers, engineers and technicians gathered telescope performance data at consoles in the aircraft’s main cabin.

“Wind tunnel tests and supercomputer calculations made at the start of the SOFIA program predicted we would have sharp enough images for front-line astronomical research,” said SOFIA project scientist Pam Marcum of NASA’s Ames Research Centre in Moffett Field, California.

View of the telescope through SOFIA's door

View of the 2.5-metre telescope through SOFIA's side door.

“A preliminary look at the first light data indicates we indeed accomplished that.”

Stable and sensitive

The stability and precise pointing of the German-built telescope met or exceeded the expectations of the engineers and astronomers who put it through its paces during the flight.

“The crowning accomplishment of the night came when scientists on board SOFIA recorded images of Jupiter,” said USRA SOFIA senior science advisor Eric Becklin. “The composite image from SOFIA shows heat, trapped since the formation of the planet, pouring out of Jupiter’s interior through holes in its clouds.”

The highly sensitive Faint Object infraRed CAmera for the SOFIA Telescope (FORCAST) used for these initial observations was operated in flight by its builders, a team led by Cornell’s Terry Herter. FORCAST captures in minutes images that would require many hour-long exposures by ground-based observatories blocked from a clear infrared view by water vapour in the Earth’s atmosphere.

SOFIA’s operational altitude, which is above more than 99 percent of that water vapour, enables it to receive 80 percent or more of the infrared light accessible to space observatories.

Adapted from information issued by NASA.