In 2012, the Voyager mission team announced that the Voyager 1 spacecraft had passed into interstellar space, traveling further from Earth than any other manmade object.
But, in the nearly two years since that historic announcement, and despite subsequent observations backing it up, uncertainty about whether Voyager 1 really crossed the threshold continues. There are some scientists who say that the spacecraft is still within the heliosphere – the region of space dominated by the Sun and its wind of energetic particles – and has not yet reached the space between the stars.
Now, two Voyager team scientists have developed a test that they say could prove once and for all if Voyager 1 has crossed the boundary. The new test is outlined in a study accepted for publication in Geophysical Research Letters, a journal of the American Geophysical Union.
A new home-grown instrument based on bundles of optical fibres is giving Australian astronomers the first ‘Google street view’ of the cosmos — incredibly detailed views of huge numbers of galaxies.
Developed by researchers at the University of Sydney and the Australian Astronomical Observatory, the optical-fibre bundles can sample the light from up to 60 parts of a galaxy, for a dozen galaxies at a time.
By analysing the light’s spectrum astronomers can learn how gas and stars move within each galaxy, where the young stars are forming and where the old stars live. This will allow them to better understand how galaxies change over time and what drives that change.
“It’s a giant step,” said Dr James Allen of the ARC Centre of Excellence for All-sky Astrophysics(CAASTRO) at the University of Sydney.
“Before, we could study one galaxy at a time in detail, or lots of galaxies at once but in much less detail. Now we have both the numbers and the detail.”
Astronomers using the NASA/ESA Hubble Space Telescope have probed the extreme outskirts of the stunning elliptical galaxy Centaurus A. The galaxy’s halo of stars has been found to extend much further from the galaxy’s centre than expected and the stars within this halo seem to be surprisingly rich in heavy elements. This is the most remote portion of an elliptical galaxy ever to have been explored.
There is more to a galaxy than first meets the eye. Extending far beyond the bright glow of a galaxy’s centre, the swirling spiral arms, or the elliptical fuzz, is an extra component: a dim halo of stars sprawling into space.
These expansive haloes are important components of a galaxy. The halo of our own galaxy, the Milky Way, preserves signatures of both its formation and evolution. Yet, we know very little about the haloes of galaxies beyond our own as their faint and spread-out nature makes exploring them more difficult. Astronomers have so far managed to detect very few starry haloes around other galaxies.
In this striking new image from ESO’s La Silla Observatory in Chile young stars huddle together against a backdrop of clouds of glowing gas and lanes of dust. The star cluster, known as NGC 3293, would have been just a cloud of gas and dust itself about ten million years ago, but as stars began to form it became the bright group of stars we see here. Clusters like this are celestial laboratories that allow astronomers to learn more about how stars evolve.
This beautiful star cluster, NGC 3293, is found 8000 light-years from Earth in the constellation of Carina (The Keel). This cluster was first spotted by the French astronomer Nicolas-Louis de Lacaille in 1751, during his stay in what is now South Africa, using a tiny telescope with an aperture of just 12 millimetres. It is one of the brightest clusters in the southern sky and can be easily seen with the naked eye on a dark clear night.
Star clusters like NGC 3293 contain stars that all formed at the same time, at the same distance from Earth and out of the same cloud of gas and dust, giving them the same chemical composition. As a result clusters like this are ideal objects for testing stellar evolution theory.
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One of the main models to form giant planets is called “core accretion”. In this scenario, a rocky core forms first by aggregation of solid particles until it reaches a few Earth masses when it becomes massive enough to accrete a gaseous envelope. For the first time, astronomers have detected evidence of this rocky core, the first step in the formation of a giant planet like our own Jupiter.
The astronomers used the Canada-France-Hawaii Telescope (CFHT) to analyze the starlight of the binary stars 16 Cygni A and 16 Cygni B. The system is a perfect laboratory to study the formation of giant planets because the stars were born together and are therefore very similar, and both resemble the Sun. However, observations during the last decades show that only one of the two stars, 16 Cygni B, hosts a giant planet which is about 2.4 times as massive as Jupiter. By decomposing the light from the two stars into their basic components and looking at the difference between the two stars, the astronomers were able to detect signatures left from the planet formation process on 16 Cygni B.
A new analysis of data from the ESA/NASA Solar and Heliospheric Observatory (SOHO) spacecraft has revealed that comet 2012/S1 (ISON) stopped producing dust and gas shortly before it raced past the Sun and disintegrated.
When comet ISON was discovered in the autumn of 2012, astronomers hoped that it would eventually light up the night sky to become a “comet of the century”. Orbital analysis showed that the sungrazing intruder from the outer reaches of the Solar System would pass only 1.2 million kilometres above the Sun’s visible surface on 28 November 2013.
Based on its early brightness, the comet promised to be a unique research object and, should it survive its flyby of the Sun, a stunning celestial phenomenon in the weeks preceding Christmas. However, it soon became clear that these hopes and expectations would not be met.