The universe is an infinite sea of galaxies, which are majestic star-cities. When galaxies group together in massive clusters, some of them can be ripped apart by the gravitational tug of other galaxies. It's a giant cosmic mosh pit. Astronomers using the Hubble Space Telescope to probe the massive galaxy cluster Abell 2744 nicknamed Pandora's Cluster have found forensic evidence of galaxies torn apart long ago. It's in the form of a phantom-like faint glow filling the space between the galaxies. This glow comes from stars scattered into intergalactic space as a result of a galaxy's disintegration.
Planetary science: Mercury's ice is a recent arrival
Nature 514, 7524 (2014). doi:10.1038/514538b
Ice at Mercury's poles is a relatively new arrival — a finding that could help to resolve a debate about whether ice may have survived for billions of years on the planet closest to the Sun.Using data from NASA's MESSENGER spacecraft, Nancy Chabot of
Astronomy: Mysterious signals may be from Earth
Nature 514, 7524 (2014). doi:10.1038/514538d
Radio pulses that look like they came from deep space could actually have earthly origins.A team led by Pascal Saint-Hilaire at the University of California, Berkeley, detected five short but intense radio bursts at the Bleien Radio Observatory in Switzerland. This is only the
Astrophysics: Secret ingredient exposed
Nature 514, 7524 (2014). doi:10.1038/nature13932
Authors: Christopher M. Johns-Krull
Astronomers have suspected for some time that magnetic fields are a key ingredient in the accretion of material that surrounds young stars. New observations have just begun to reveal these fields in action. See Letter p.597
Spatially resolved magnetic field structure in the disk of a T Tauri star
Nature 514, 7524 (2014). doi:10.1038/nature13850
Authors: Ian W. Stephens, Leslie W. Looney, Woojin Kwon, Manuel Fernández-López, A. Meredith Hughes, Lee G. Mundy, Richard M. Crutcher, Zhi-Yun Li & Ramprasad Rao
Magnetic fields in accretion disks play a dominant part during the star formation process but have hitherto been observationally poorly constrained. Field strengths have been inferred on T Tauri stars and possibly in the innermost part of their accretion disks, but the strength and morphology of the field in the bulk of a disk have not been observed. Spatially unresolved measurements of polarized emission (arising from elongated dust grains aligned perpendicularly to the field) imply average fields aligned with the disks. Theoretically, the fields are expected to be largely toroidal, poloidal or a mixture of the two, which imply different mechanisms for transporting angular momentum in the disks of actively accreting young stars such as HL Tau (ref. 11). Here we report resolved measurements of the polarized 1.25-millimetre continuum emission from the disk of HL Tau. The magnetic field on a scale of 80 astronomical units is coincident with the major axis (about 210 astronomical units long) of the disk. From this we conclude that the magnetic field inside the disk at this scale cannot be dominated by a vertical component, though a purely toroidal field also does not fit the data well. The unexpected morphology suggests that the role of the magnetic field in the accretion of a T Tauri star is more complex than our current theoretical understanding.
Possible planet formation in the young, low-mass, multiple stellar system GG Tau A
Nature 514, 7524 (2014). doi:10.1038/nature13822
Authors: Anne Dutrey, Emmanuel Di Folco, Stéphane Guilloteau, Yann Boehler, Jeff Bary, Tracy Beck, Hervé Beust, Edwige Chapillon, Fredéric Gueth, Jean-Marc Huré, Arnaud Pierens, Vincent Piétu, Michal Simon & Ya-Wen Tang
The formation of planets around binary stars may be more difficult than around single stars. In a close binary star (with a separation of less than a hundred astronomical units), theory predicts the presence of circumstellar disks around each star, and an outer circumbinary disk surrounding a gravitationally cleared inner cavity around the stars. Given that the inner disks are depleted by accretion onto the stars on timescales of a few thousand years, any replenishing material must be transferred from the outer reservoir to fuel planet formation (which occurs on timescales of about one million years). Gas flowing through disk cavities has been detected in single star systems. A circumbinary disk was discovered around the young low-mass binary system GG Tau A (ref. 7), which has recently been shown to be a hierarchical triple system. It has one large inner disk around the single star, GG Tau Aa, and shows small amounts of shocked hydrogen gas residing within the central cavity, but other than a single weak detection, the distribution of cold gas in this cavity or in any other binary or multiple star system has not hitherto been determined. Here we report imaging of gas fragments emitting radiation characteristic of carbon monoxide within the GG Tau A cavity. From the kinematics we conclude that the flow appears capable of sustaining the inner disk (around GG Tau Aa) beyond the accretion lifetime, leaving time for planet formation to occur there. These results show the complexity of planet formation around multiple stars and confirm the general picture predicted by numerical simulations.
The Hubble Space Telescope treats astronomers to gorgeous close-up views of the eerie outer planets. But it's a bit of a trick when it seems like the planet's looking back at you! In this view, the shadow of the Jovian moon Ganymede swept across the center of the Great Red Spot a giant storm on the planet. This gave Jupiter the uncanny appearance of having a pupil in the center of a 10,000-mile-diameter "eye." Now if it blinks, we may really have to worry!
This is a photo composite of the encounter of Comet Siding Spring with Mars on October 19, 2014. Separate Hubble Space Telescope images of Mars and the comet have been combined together into a single picture. This is a composite image because a single exposure of the stellar background, Comet Siding Spring, and Mars would be problematic because the objects are all moving with respect to each other and the background stars. Hubble can only track one planetary target at a time. Also, Mars is actually 10,000 times brighter than the comet, and the exposure here has been adjusted so that details on the Red Planet can be seen.
Solar physics: Solar atmosphere is a hotbed of activity
Nature 514, 7523 (2014). doi:10.1038/514406a
Explosions of plasma in the Sun's atmosphere can reach temperatures of nearly 100,000 °C, much hotter than scientists had expected.The finding is one of several about the region between the solar surface and the uppermost edge of the Sun's atmosphere, or corona, revealed by
Sun’s stroke keeps Kepler online
Nature 514, 7523 (2014). http://www.nature.com/doifinder/10.1038/514414a
Author: Mark Zastrow
Space telescope beats mechanical failures to begin a second mission that will trace new celestial targets.