Institute of Astronomy

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Rosetta's 10-billion-tonne comet

Astronomy News - 21 August 2014 - 3:06pm
Scientists determine the comet being followed by Europe's Rosetta spacecraft to have a mass of 10 billion tonnes.

Nearby galaxy may be victim of dark matter hit-and-run

Astronomy News - 20 August 2014 - 3:17pm
A massive hole in a small spiral galaxy may have been punched by a huge "subhalo" of dark matter – and the same thing may have happened to the Milky Way






A Spectacular Landscape of Star Formation

Astronomy News - 20 August 2014 - 11:00am
This image, captured by the Wide Field Imager at ESO’s La Silla Observatory in Chile, shows two dramatic star formation regions in the southern Milky Way. The first is of these, on the left, is dominated by the star cluster NGC 3603, located 20 000 light-years away, in the Carina–Sagittarius spiral arm of the Milky Way galaxy. The second object, on the right, is a collection of glowing gas clouds known as NGC 3576 that lies only about half as far from Earth.

Astronomy: Dusty visitors from interstellar space

Astronomy News - 20 August 2014 - 1:00am

Astronomy: Dusty visitors from interstellar space

Nature 512, 7514 (2014). doi:10.1038/512235b

Seven particles captured by NASA's Stardust spacecraft may be the first sample of dust from beyond the Solar System that has been brought back to Earth.Andrew Westphal at the University of California, Berkeley, and his colleagues — with the help of 30,714 citizen scientists

Astronomy: Comets forge organic molecules

Astronomy News - 20 August 2014 - 1:00am

Astronomy: Comets forge organic molecules

Nature 512, 7514 (2014). doi:10.1038/512234d

Astronomers have captured three-dimensional images of organic compounds streaming from two comets.Comets contain some of the oldest materials in the Solar System. Using the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, Martin Cordiner of the NASA Goddard Space Flight Center in Greenbelt, Maryland, and

Planetary science: Second rock from the Sun

Astronomy News - 20 August 2014 - 1:00am

Planetary science: Second rock from the Sun

Nature 512, 7514 (2014). doi:10.1038/512252a

Author: Andrew P. Ingersoll

Andrew P. Ingersoll relishes a study of scientific discoveries on hot, toxic Venus.

Just how rare is intelligent life in the universe?

Astronomy News - 19 August 2014 - 7:00pm
Although intelligent life may exist on other planets, The Copernicus Complex by Caleb Scharf argues that Earth will still be special after all






NASA's RXTE Satellite Decodes the Rhythm of an Unusual Black Hole

Astronomy News - 18 August 2014 - 5:00pm
Astronomers have uncovered rhythmic pulsations from a rare type of black hole 12 million light-years away by sifting through archival data from NASA's Rossi X-ray Timing Explorer (RXTE) satellite.

Exoplanet Measured with Remarkable Precision

Astronomy News - 18 August 2014 - 4:51pm
Astronomers are not only discovering planets around distant suns, they are also starting to measure those worlds with astonishing precision. The diameter of a super-Earth named "Kepler 93 b" is now known to within an accuracy of 1%.

A 400-solar-mass black hole in the galaxy M82

Astronomy News - 17 August 2014 - 1:00am

A 400-solar-mass black hole in the galaxy M82

Nature 513, 7516 (2014). doi:10.1038/nature13710

Authors: Dheeraj R. Pasham, Tod E. Strohmayer & Richard F. Mushotzky

M82 X-1, the brightest X-ray source in the galaxy M82, has been thought to be an intermediate-mass black hole (100 to 10,000 solar masses) because of its extremely high luminosity and variability characteristics, although some models suggest that its mass may be only about 20 solar masses. The previous mass estimates were based on scaling relations that use low-frequency characteristic timescales which have large intrinsic uncertainties. For stellar-mass black holes, we know that the high-frequency quasi-periodic oscillations (100–450 hertz) in the X-ray emission that occur in a 3:2 frequency ratio are stable and scale in frequency inversely with black hole mass with a reasonably small dispersion. The discovery of such stable oscillations thus potentially offers an alternative and less ambiguous means of mass determination for intermediate-mass black holes, but has hitherto not been realized. Here we report stable, twin-peak (3:2 frequency ratio) X-ray quasi-periodic oscillations from M82 X-1 at frequencies of 3.32 ± 0.06 hertz and 5.07 ± 0.06 hertz. Assuming that we can extrapolate the inverse-mass scaling that holds for stellar-mass black holes, we estimate the black hole mass of M82 X-1 to be 428 ± 105 solar masses. In addition, we can estimate the mass using the relativistic precession model, from which we get a value of 415 ± 63 solar masses.

Earth's early life endured long asteroid bombardment

Astronomy News - 15 August 2014 - 1:00pm
Massive asteroids may have pounded Earth for a billion years longer than we thought – with early life forms suffering periodic melting of the surface






Space is the place to solve the riddle of life, maybe

Astronomy News - 15 August 2014 - 8:00am
Understanding how life got started here on planet Earth may mean searching for its counterparts "out there"






Cosmic grains pre-date Solar System

Astronomy News - 14 August 2014 - 7:41pm
Scientists may have identified the first known dust particles from outside our Solar System, in samples returned to Earth by a Nasa space mission.

Stardust team reveals first specks of interstellar dust

Astronomy News - 14 August 2014 - 7:00pm
The NASA spacecraft caught seven grains of dust that probably originated beyond our solar system – and now scientists have analysed them on Earth






Stardust Team Reports Discovery of First Potential Interstellar Space Particles

Astronomy News - 14 August 2014 - 5:00pm
Seven rare, microscopic interstellar dust particles that date to the beginnings of the solar system are among the samples collected by scientists who have been studying the payload from NASA's Stardust spacecraft since its return to Earth in 2006. If confirmed, these particles would be the first samples of contemporary interstellar dust.

Rosetta: Comet probe starts work

Astronomy News - 14 August 2014 - 4:43pm
A week after arriving at Comet 67P/Churyumov-Gerasimenko, Europe's Rosetta probe is busy acquiring the information needed to select a landing site.

Rosetta probe poised to touch and taste a comet

Astronomy News - 14 August 2014 - 4:00pm
Now that it has finally reached comet 67P/Churyumov-Gerasimenko, the Rosetta spacecraft is ready to help tackle the question of how Earth got its oceans






NASA’s Chandra Observatory Searches for Trigger of Nearby Supernova

Astronomy News - 14 August 2014 - 3:45pm
New data from NASA’s Chandra X-ray Observatory offer a glimpse into the environment of a star before it exploded earlier this year, and insight into what triggered one of the closest supernovas witnessed in decades.

Big, spinning black hole blurs light

Astronomy News - 14 August 2014 - 10:51am

A compact source of x-rays that sits near the black hole, called the corona, has moved closer to the black hole over a period of just days.

“The corona recently collapsed in toward the black hole, with the result that the black hole's intense gravity pulled all the light down onto its surrounding disk, where material is spiralling inward,” said Michael Parker of Cambridge’s Institute of Astronomy, lead author of a paper on the findings which appears in the journal Monthly Notices of the Royal Astronomical Society.

As the corona shifted closer to the black hole, the gravity of the black hole exerted a stronger tug on the x-rays emitted by it. The result was an extreme blurring and stretching of the x-ray light. Such events had been observed previously, but never to this degree and in such detail.

Supermassive black holes are thought to reside in the centres of all galaxies. Some are more massive and rotate faster than others. The black hole in this new study, referred to as Markarian 335, or Mrk 335, is about 324 million light-years from Earth in the direction of the Pegasus constellation. It is one of the most extreme of the systems for which the mass and spin rate have ever been measured. The black hole squeezes about 10 million times the mass of our sun into a region only 30 times the diameter of the sun, and it spins so rapidly that space and time are dragged around with it.

Even though some light falls into a supermassive black hole never to be seen again, other high-energy light emanates from both the corona and the surrounding accretion disk of superheated material. Though astronomers are uncertain of the shape and temperature of coronas, they know that they contain particles that move close to the speed of light.

NASA's Swift satellite has monitored Mrk 335 for years, and recently noted a dramatic change in its x-ray brightness. In what is called a target-of-opportunity observation, NuSTAR was redirected to take a look at high-energy x-rays from this source in the range of 3 to 79 kiloelectron volts. This particular energy range offers astronomers a detailed look at what is happening near the event horizon, the region around a black hole from which light can no longer escape gravity's grasp.

Follow-up observations indicate that the corona still is in this close configuration, months after it moved. Researchers don't know whether and when the corona will shift back. What is more, the NuSTAR observations reveal that the grip of the black hole's gravity pulled the corona's light onto the inner portion of its superheated disk, better illuminating it. Almost as if somebody had shone a flashlight for the astronomers, the shifting corona lit up the precise region they wanted to study.

The new data could ultimately help determine more about the mysterious nature of black hole coronas. In addition, the observations have provided better measurements of Mrk 335's furious relativistic spin rate. Relativistic speeds are those approaching the speed of light, as described by Albert Einstein's theory of relativity.

“We still don't understand exactly how the corona is produced or why it changes its shape, but we see it lighting up material around the black hole, enabling us to study the regions so close in that effects described by Einstein's theory of general relativity become prominent,” said NuSTAR Principal Investigator Fiona Harrison of the California Institute of Technology (Caltech) in Pasadena. “NuSTAR's unprecedented capability for observing this and similar events allows us to study the most extreme light-bending effects of general relativity.”

NuSTAR is a Small Explorer mission led by Caltech and managed by NASA's Jet Propulsion Laboratory (JPL) in Pasadena for NASA's Science Mission Directorate in Washington. The spacecraft was built by Orbital Sciences Corporation in Dulles, Virginia. Its instrument was built by a consortium including Caltech, JPL, the University of California, Berkeley, Columbia University, New York, NASA's Goddard Space Flight Center, Greenbelt, Maryland, the Danish Technical University in Denmark, Lawrence Livermore National Laboratory in Livermore, California, ATK Aerospace Systems in Goleta, California, and with support from the Italian Space Agency (ASI) Science Data Center.

NuSTAR's mission operations centre is at UC Berkeley, with the ASI providing its equatorial ground station located in Malindi, Kenya. The mission's outreach program is based at Sonoma State University, Rohnert Park, California. NASA's Explorer Program is managed by Goddard. JPL is managed by Caltech for NASA.

NASA's Nuclear Spectroscopic Telescope Array (NuSTAR) has captured an extreme and rare event in the regions immediately surrounding a supermassive black hole.

NASABlack Holes: Monsters in Space (Artist's Concept)

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Small, sticky asteroids could be extra dangerous

Astronomy News - 13 August 2014 - 6:00pm
Fast-spinning small asteroids hold together using the same, weak forces that make flour clumpy. This could make it difficult to protect Earth from them