Posts Tagged ‘Herschel’

Bullying Black Holes Force Galaxies To Stay Red And Dead

February 26, 2014 Leave a comment

Copyright: Digitised Sky Survey/NASA Chandra/Southern Observatory for Astrophysical Research/Very Large Array (Robert Dunn et al. 2010)

Copyright: Digitised Sky Survey/NASA Chandra/Southern Observatory for Astrophysical Research/Very Large Array (Robert Dunn et al. 2010)

Giant elliptical galaxies are the most puzzling type of galaxy in the Universe. Since they mysteriously shut down their star-forming activity and remain home only to the longest-lived of their stars – which are low-mass ones and appear red – astronomers often call these galaxies ‘red and dead’.

Up until now, it was thought that red-and-dead galaxies were poor in cold gas – the vital raw material from which stars are born. While cold gas is abundant in spiral galaxies with lively star formation, the lack of it in giant ellipticals seemed to explain the absence of new stars.

Astronomers have long been debating the physical processes leading to the end of their star formation. They speculated that these galaxies somehow expelled the cold gas, or that they had simply used it all to form stars in the past. Although the reason was uncertain, one thing seemed to have been established: these galaxies are red and dead because they no longer possess the means to sustain the production of stars.

This view is being challenged by a new study based on data from ESA’s Herschel Space Observatory. The results are published in Monthly Notices of the Royal Astronomical Society.

“We looked at eight giant elliptical galaxies that nobody had looked at with Herschel before and we were delighted to find that, contrary to previous belief, six out of eight abound with cold gas”, explains Norbert Werner from Stanford University in California, USA, who led the study.
This is the first time that astronomers have seen large amounts of cold gas in red-and-dead galaxies that are not located at the centre of a massive galaxy cluster.

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Herschel Telescope Detects Water On Dwarf Planet

January 23, 2014 Leave a comment

Scientists using the Herschel space observatory have made the first definitive detection of water vapor on the largest and roundest object in the asteroid belt, Ceres.

Plumes of water vapor are thought to shoot up periodically from Ceres when portions of its icy surface warm slightly. Ceres is classified as a dwarf planet, a solar system body bigger than an asteroid and smaller than a planet.

Herschel is a European Space Agency (ESA) mission with important NASA contributions.

“This is the first time water vapor has been unequivocally detected on Ceres or any other object in the asteroid belt and provides proof that Ceres has an icy surface and an atmosphere,” said Michael Küppers of ESA in Spain, lead author of a paper in the journal Nature.

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A Rare Snapshot Of A Planetary Construction Site

October 25, 2013 Leave a comment

Credit: Á. Kóspál (ESA) and A. Moór (Konkoly Observatory)

Credit: Á. Kóspál (ESA) and A. Moór (Konkoly Observatory)

When a star similar to our Sun is born, it is surrounded by a disk of dust and gas. Within that disk, the star’s planetary system begins to form: The dust grains stick together to build larger, solid, kilometer-sized bodies known as planetesimals. Those either survive in the form of asteroids and comets, or clump together further to form solid planets like our Earth, or the cores of giant gas planets.

Current models of planet formation predict that, as a star reaches the planetesimal stage, the original gas should quickly be depleted. Some of the gas falls into the star, some is caught up by what will later become giant gas planets like Jupiter, and the rest is dispersed into space, driven by the young star’s intense radiation. After 10 million years or so, all the original gas should be gone.

But now a team of astronomers from the Netherlands, Hungary, Germany, and the US has found what appears to be a rare hybrid disk, which contains plenty of original gas, but also dust produced much later in the collision of planetesimals. As such, it qualifies as a link between an early and a late phase of disk evolution: the primordial disk and a later debris phase.

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Shining A Light On Cool Pools Of Gas In The Galaxy

Newly formed stars shine brightly, practically crying out, “Hey, look at me!” But not everything in our Milky Way galaxy is easy to see. The bulk of material between the stars in the galaxy — the cool hydrogen gas from which stars spring — is nearly impossible to find.

A new study from the Hershel Space Observatory, a European Space Agency mission with important NASA participation, is shining a light on these hidden pools of gas, revealing their whereabouts and quantities. In the same way that dyes are used to visualize swirling motions of transparent fluids, the Herschel team has used a new tracer to map the invisible hydrogen gas.

The discovery reveals that the reservoir of raw material for making stars had been underestimated before — almost by one third — and extends farther out from our galaxy’s center than known before.

“There is an enormous additional reservoir of material available to form new stars that we couldn’t identify before,” said Jorge Pineda of NASA’s Jet Propulsion Laboratory, Pasadena, Calif., lead author of a new paper on the findings published in the journal Astronomy and Astrophysics.

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Herschel Space Observatory Finds Galaxy Mega Merger

Image credit: ESA/NASA/JPL-Caltech/UC Irvine/STScI/Keck/NRAO/SAO

Image credit: ESA/NASA/JPL-Caltech/UC Irvine/STScI/Keck/NRAO/SAO

A massive and rare merging of two galaxies has been spotted in images taken by the Herschel space observatory, a European Space Agency mission with important NASA participation.

Follow-up studies by several telescopes on the ground and in space, including NASA’s Hubble Space Telescope and Spitzer Space Telescope, tell a tale of two faraway galaxies intertwined and furiously making stars. Eventually, the duo will settle down to form one super-giant elliptical galaxy.

The findings help explain a mystery in astronomy. Back when our universe was 3 billion to 4 billion years old, it was populated with large reddish elliptical-shaped galaxies made up of old stars. Scientists have wondered whether those galaxies built up slowly over time through the acquisitions of smaller galaxies, or formed more rapidly through powerful collisions between two large galaxies.

The new findings suggest massive mergers are responsible for the giant elliptical galaxies.

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Herschel Finds Hot Gas On The Menu For Milky Way’s Black Hole

ESA’s Herschel space observatory has made detailed observations of surprisingly hot molecular gas that may be orbiting or falling towards the supermassive black hole lurking at the centre of our Milky Way galaxy.

Our local black hole is located in a region known as Sagittarius A* – Sgr A* – after a nearby radio source. It has a mass about four million times that of our Sun and lies around 26 000 light-years away from the Solar System.

Herschel has detected a great variety of simple molecules at the Milky Way’s heart, including carbon monoxide, water vapour and hydrogen cyanide. By analysing the signature from these molecules, astronomers have been able to probe some of the fundamental properties of the interstellar gas surrounding the black hole.

“Herschel has resolved the far-infrared emission within just 1 light-year of the black hole, making it possible for the first time at these wavelengths to separate emission due to the central cavity from that of the surrounding dense molecular disc,” says Javier Goicoechea of the Centro de Astrobiología, Spain, and lead author of the paper reporting the results.

The biggest surprise was quite how hot the molecular gas in the innermost central region of the Galaxy gets. At least some of it is around 1000ºC, much hotter than typical interstellar clouds, which are usually only a few tens of degrees above the –273ºC of absolute zero.

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Herschel Links Water In Jupiter’s Stratosphere To 1994 Comet Impact

Distribution of water in Jupiter's stratosphere. Credit: Water map: ESA/Herschel/T. Cavalié et al.; Jupiter image: NASA/ESA/Reta Beebe (New Mexico State University)

Distribution of water in Jupiter’s stratosphere. Credit: Water map: ESA/Herschel/T. Cavalié et al.; Jupiter image: NASA/ESA/Reta Beebe (New Mexico State University)

Astronomers have finally found direct proof that almost all water present in Jupiter’s stratosphere was delivered by comet Shoemaker-Levy 9, which struck the planet in 1994. The result is based on new data from Herschel that revealed more water in Jupiter’s southern hemisphere, where the impacts occurred, than in the north as well as probing the vertical distribution of water in the planet’s stratosphere.

The origin of water in the upper atmospheres of the Solar System’s giant planets has been debated for almost two decades. Astronomers were quite surprised at the discovery of water in the stratosphere – an intermediate atmospheric layer – of Jupiter, Saturn, Uranus and Neptune, which dates to observations performed with ESA’s Infrared Space Observatory (ISO) in 1997. While the source of water in the lower layers of their atmospheres can be explained as internal, the presence of this molecule in their upper atmospheric layers is puzzling due to the scarcity of oxygen there – its supply must have an external origin. Since then, astronomers have investigated several possible candidates that may have delivered water to these planets, from icy rings and satellites to interplanetary dust particles and cometary impacts.

Answers are now starting to flow in from studies using ESA’s Herschel space observatory. Herschel boasts unprecedented sensitivity as well as high spatial and spectral resolution at the far-infrared wavelengths, where many water emission lines can be observed.

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Star Factory In The Early Universe Challenges Galaxy Evolution Theory

A team including Mat Page (UCL Space and Climate Physics) has discovered an extremely distant galaxy making stars more than 2000 times faster than our own Milky Way. Seen at a time when the Universe was less than a billion years old, its mere existence challenges our theories of galaxy evolution. The observations were carried out using the European Space Agency’s Herschel Space Observatory.

The galaxy, known as HFLS3, appears as little more than a faint, red smudge in images from the Herschel Multi-tiered Extragalactic Survey (HerMES). Yet appearances can be deceiving: this small smudge is actually a star-building factory, furiously transforming gas and dust into new stars.

Our own Milky Way makes stars at a rate equivalent to one solar mass per year, but HFLS3 is seen to be churning out new stars at more than two thousand times more rapidly. This is one of the highest star formation rates ever seen in any galaxy.

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Herschel And Hubble See The Horsehead In New Light

April 19, 2013 1 comment

Hubble’s view of the Horsehead Nebula. Credit: NASA, ESA & Hubble Heritage Team (AURA/STScI)

Hubble’s view of the Horsehead Nebula. Credit: NASA, ESA & Hubble Heritage Team (AURA/STScI)

New views of the Horsehead Nebula and its turbulent environment have been unveiled by ESA’s Herschel space observatory and the NASA/ESA Hubble space telescope.

The Horsehead Nebula lies in the constellation Orion, about 1300 light-years away, and is a popular target for amateur and professional astronomers alike. It sits just to the south of star Alnitak, the easternmost of Orion’s famous three-star belt, and is part of the vast Orion Molecular Cloud complex.

The new far-infrared Herschel view shows in spectacular detail the scene playing out around the Horsehead Nebula at the right-hand side of the image, where it seems to surf like a ‘white horse’ in the waves of turbulent star-forming clouds.

The new Hubble view, taken at near-infrared wavelengths with its Wide Field Camera 3 to celebrate the 23rd anniversary of the launch of the observatory, zooms in on the Horsehead to reveal fine details of its structure.

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Retired Star Found With Planets And Debris Disc

April 9, 2013 1 comment

Copyright ESA/Bonsor et al (2013)

Copyright ESA/Bonsor et al (2013)

ESA’s Herschel space observatory has provided the first images of a dust belt – produced by colliding comets or asteroids – orbiting a subgiant star known to host a planetary system.

After billions of years steadily burning hydrogen in their cores, stars like our Sun exhaust this central fuel reserve and start burning it in shells around the core. They swell to become subgiant stars, before later becoming red giants.

At least during the subgiant phase, planets, asteroids and comet belts around these ‘retired’ stars are expected to survive, but observations are needed to measure their properties. One approach is to search for discs of dust around the stars, generated by collisions between populations of asteroids or comets.

Thanks to the sensitive far-infrared detection capabilities of the Herschel space observatory, astronomers have been able to resolve bright emission around Kappa Coronae Borealis (κ CrB, or Kappa Cor Bor), indicating the presence of a dusty debris disc.

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