Institute of Astronomy

Astronomy News

Our Sun Came Late to the Milky Way's Star-Birth Party

10 April 2015 - 9:36am

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Our Sun missed the stellar "baby boom" that erupted in our young Milky Way galaxy 10 billion years ago. During that time the Milky Way was churning out stars 30 times faster than it does today. Our galaxy was ablaze with a firestorm of star birth as its rich reservoir of hydrogen gas compressed under gravity, creating myriad stars. But our Sun was not one of them. It was a late "boomer," arising 5 billion years later, when star birth had plunged to a trickle.

Citizen Scientists Discover Yellow "Space Balls"

10 April 2015 - 9:35am
Citizen scientists scanning images from a NASA observatory have found "yellow balls" in space that may hold important clues to the mysteries of starbirth.

Complex Organic Molecules Discovered in Infant Star System

9 April 2015 - 9:42am
For the first time, astronomers have detected the presence of complex organic molecules, the building blocks of life, in a protoplanetary disc surrounding a young star. The discovery, made with the Atacama Large Millimeter/submillimeter Array (ALMA), reaffirms that the conditions that spawned the Earth and Sun are not unique in the Universe. The results are published in the 9 April 2015 issue of the journal Nature.

A primordial origin for the compositional similarity between the Earth and the Moon

9 April 2015 - 9:40am

A primordial origin for the compositional similarity between the Earth and the Moon

Nature 520, 7546 (2015). doi:10.1038/nature14333

Authors: Alessandra Mastrobuono-Battisti, Hagai B. Perets & Sean N. Raymond

Most of the properties of the Earth–Moon system can be explained by a collision between a planetary embryo (giant impactor) and the growing Earth late in the accretion process. Simulations show that most of the material that eventually aggregates to form the Moon originates from the impactor. However, analysis of the terrestrial and lunar isotopic compositions show them to be highly similar. In contrast, the compositions of other Solar System bodies are significantly different from those of the Earth and Moon, suggesting that different Solar System bodies have distinct compositions. This challenges the giant impact scenario, because the Moon-forming impactor must then also be thought to have a composition different from that of the proto-Earth. Here we track the feeding zones of growing planets in a suite of simulations of planetary accretion, to measure the composition of Moon-forming impactors. We find that different planets formed in the same simulation have distinct compositions, but the compositions of giant impactors are statistically more similar to the planets they impact. A large fraction of planet–impactor pairs have almost identical compositions. Thus, the similarity in composition between the Earth and Moon could be a natural consequence of a late giant impact.

Saturn’s fast spin determined from its gravitational field and oblateness

9 April 2015 - 9:39am

Saturn’s fast spin determined from its gravitational field and oblateness

Nature 520, 7546 (2015). doi:10.1038/nature14278

Authors: Ravit Helled, Eli Galanti & Yohai Kaspi

The alignment of Saturn’s magnetic pole with its rotation axis precludes the use of magnetic field measurements to determine its rotation period. The period was previously determined from radio measurements by the Voyager spacecraft to be 10 h 39 min 22.4 s (ref. 2). When the Cassini spacecraft measured a period of 10 h 47 min 6 s, which was additionally found to change between sequential measurements, it became clear that the radio period could not be used to determine the bulk planetary rotation period. Estimates based upon Saturn’s measured wind fields have increased the uncertainty even more, giving numbers smaller than the Voyager rotation period, and at present Saturn’s rotation period is thought to be between 10 h 32 min and 10 h 47 min, which is unsatisfactory for such a fundamental property. Here we report a period of 10 h 32 min 45 s ± 46 s, based upon an optimization approach using Saturn’s measured gravitational field and limits on the observed shape and possible internal density profiles. Moreover, even when solely using the constraints from its gravitational field, the rotation period can be inferred with a precision of several minutes. To validate our method, we applied the same procedure to Jupiter and correctly recovered its well-known rotation period.

The comet-like composition of a protoplanetary disk as revealed by complex cyanides

9 April 2015 - 9:39am

The comet-like composition of a protoplanetary disk as revealed by complex cyanides

Nature 520, 7546 (2015). doi:10.1038/nature14276

Authors: Karin I. Öberg, Viviana V. Guzmán, Kenji Furuya, Chunhua Qi, Yuri Aikawa, Sean M. Andrews, Ryan Loomis & David J. Wilner

Observations of comets and asteroids show that the solar nebula that spawned our planetary system was rich in water and organic molecules. Bombardment brought these organics to the young Earth’s surface. Unlike asteroids, comets preserve a nearly pristine record of the solar nebula composition. The presence of cyanides in comets, including 0.01 per cent of methyl cyanide (CH3CN) with respect to water, is of special interest because of the importance of C–N bonds for abiotic amino acid synthesis. Comet-like compositions of simple and complex volatiles are found in protostars, and can readily be explained by a combination of gas-phase chemistry (to form, for example, HCN) and an active ice-phase chemistry on grain surfaces that advances complexity. Simple volatiles, including water and HCN, have been detected previously in solar nebula analogues, indicating that they survive disk formation or are re-formed in situ. It has hitherto been unclear whether the same holds for more complex organic molecules outside the solar nebula, given that recent observations show a marked change in the chemistry at the boundary between nascent envelopes and young disks due to accretion shocks. Here we report the detection of the complex cyanides CH3CN and HC3N (and HCN) in the protoplanetary disk around the young star MWC 480. We find that the abundance ratios of these nitrogen-bearing organics in the gas phase are similar to those in comets, which suggests an even higher relative abundance of complex cyanides in the disk ice. This implies that complex organics accompany simpler volatiles in protoplanetary disks, and that the rich organic chemistry of our solar nebula was not unique.

Solar System: An incredible likeness of being

9 April 2015 - 9:39am

Solar System: An incredible likeness of being

Nature 520, 7546 (2015). doi:10.1038/520169a

Authors: Robin M. Canup

Earth and the Moon share many puzzling chemical similarities. New analyses show that the last planet-sized body to hit Earth could have been similar enough to Earth to yield a Moon with an Earth-like composition. See Letter p.212

Planetary science: Prebiotic chemistry on the rocks

9 April 2015 - 9:39am

Planetary science: Prebiotic chemistry on the rocks

Nature 520, 7546 (2015). doi:10.1038/520161a

Authors: Geoffrey A. Blake & Edwin A. Bergin

Organic compounds called nitriles have been detected in material surrounding a young star. The finding hints at a vast reservoir of ice and volatile species that can seed the surfaces of young rocky planets or moons. See Letter p.198

Lunar affairs

9 April 2015 - 9:32am

Lunar affairs

Nature 520, 7546 (2015). doi:10.1038/520132a

A study in Nature adds a dramatic twist to the backstory of a neighbour we thought we knew.

Riddles of Moon's origin resolved

9 April 2015 - 9:15am

Three new studies resolve some of the inconsistencies in our understanding of the Moon's birth, including the violent impact that started the process.

Einstein puts a ring on distant galaxy

8 April 2015 - 9:13am

The effects of general relativity, which celebrates its centenary this year, distorted light to create this beautiful ring-like image of a distant galaxy







NASA Extends Campaign for Public to Name Features on Pluto

7 April 2015 - 9:51am

The public has until Friday, April 24 to help name new features on Pluto and its orbiting satellites as they are discovered by NASA’s New Horizons mission.

Hubble Finds Phantom Objects Near Dead Quasars

3 April 2015 - 8:12am

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In 2007, Dutch schoolteacher Hanny van Arkel discovered a never-before-seen ghostly structure near a galaxy, while she was participating in an online amateur scientist project called Galaxy Zoo. The galaxy hosts a bright quasar that may have illuminated the apparition by hitting it with a beam of light from hot gas around a central black hole. Astronomers eagerly used the Hubble Space Telescope to do follow-up observations, which revealed knots of dust and gas in the "greenish blob." Assuming that this feature could offer insights into the puzzling behavior of active galaxies, Bill Keel of the University of Alabama, Tuscaloosa, initiated a search for other similar phenomenon. After all, where there's one strange blob there could be more. Keel had 200 volunteers look at archival data of 15,000 galaxies hosting quasars. In the end, he found eight other galaxies with bright active nuclei that have illuminated material far outside the radius of the galaxy. The eerie structures have looping, spiral, and braided shapes. Hubble's images show that they are like the remnants of galaxy collisions.

Join Hubble scientists for a live Hubble Hangout discussion at 3pm EDT on Thurs., April 2, to learn even more. Visit: http://hbbl.us/y6c .

Hubble finds ghosts of quasars past [heic1507]

3 April 2015 - 8:09am

The NASA/ESA Hubble Space Telescope has imaged a set of enigmatic quasar ghosts – ethereal green objects which mark the graves of these objects that flickered to life and then faded. The eight unusual looped structures orbit their host galaxies and glow in a bright and eerie goblin-green hue. They offer new insights into the turbulent pasts of these galaxies.

Mars beckons for European satellite

3 April 2015 - 8:02am

The satellite Europe will be sending to Mars early next year enters its final test programme.

Star's birth glimpsed 'in real time'

3 April 2015 - 8:00am

Astronomers witness a key stage in the birth of a very heavy star, using two radio telescope views of the process taken 18 years apart.