astronomy

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New images from European Space Agency’s Herschel Space Observatory show new insights into how matter is distributed in our galaxy – it’s threaded with filamentary structures. The filaments are enormous formations of gas and dust with complex structures as seen above. It is estimated that G49, the filament on the first image, has a total mass of around 80,000 times that of our Sun!
Thanks to Herschel, several of these unbelievably massive filaments have now been discovered in our own Milky Way. 
Copyright: ESA/Herschel/PACS/SPIRE/Ke Wang et al. 2015

Hubble Mystic Mountain

This craggy fantasy mountaintop enshrouded by wispy clouds looks like a bizarre landscape from Tolkien’s The Lord of the Rings. The NASA/ESA Hubble Space Telescope photograph, which is stranger than fiction, captures the chaotic activity atop a pillar of gas and dust, three light-years high, which is being eaten away by the brilliant light from nearby bright stars. The pillar is also being assaulted from within, as infant stars buried inside it fire off jets of gas that can be seen streaming from towering peaks.

This turbulent cosmic pinnacle lies within a tempestuous stellar nursery called the Carina Nebula, located 7500 light-years away in the southern constellation of Carina. The image marks the 20th anniversary of Hubble’s launch and deployment into Earth orbit.

Scorching radiation and fast winds (streams of charged particles) from hot newborn stars in the nebula are shaping and compressing the pillar, causing new stars to form within it. Streamers of hot ionised gas can be seen flowing off the ridges of the structure, and wispy veils of dust, illuminated by starlight, float around its peaks. The pillar is resisting being eroded by radiation.

Nestled inside this dense mountain are fledgling stars. Long streamers of gas can be seen shooting in opposite directions from the pedestal at the top of the image. Another pair of jets is visible at another peak near the centre of the image. These jets are the signpost for new starbirth. The jets are launched by swirling discs around the stars, as these discs allow material to slowly accrete onto the stellar surfaces.

Credit: NASA, ESA and M. Livio and the Hubble 20th Anniversary Team (STScI)

Galactic ‘whodunit’ may have been solved

Scientists have been aware for many years that there are two types of galaxies: gas-rich star-forming galaxies and galaxies deficient in gas that no longer form stars. It has been a mystery as to why some galaxies are ‘alive’ and continue stellar formation, whilst others are ‘dead’ and no longer give rise to any new stars.

Star formation is fuelled by cold gas, and if this supply is cut off the galaxy can no longer form stars. There are two different theories to explain how this might happen. The first is that the gas supply is slowly stifled until it is completely cut off - the galaxy is essentially strangled to death. The alternative theory to this slow death is a quick and painless one: the gas is stripped from the galaxy quickly and violently, possibly by the gravity of another galaxy.

Researchers from Cambridge’s Cavendish Laboratory have studied the evidence from more than 26,000 galaxies and have found that the clues point towards strangulation being the most likely modus operandi for these galactic murders. Stars are mostly comprised of hydrogen and helium, which are fused into heavier elements within a star. Researchers focused on looking for these heavier elements and found that the ‘dead’ non-star forming galaxies had a higher amount of heavy elements than the ‘live’ galaxies did. This result implied that the dead galaxies had lost their hydrogen and helium since both galaxy types should be creating heavy elements at about the same rate. Galaxies that undergo a quick death by the sudden removal of gas would also see abrupt end to their star formation. Galaxies that are slowly strangled still retain enough gas to sustain star formation for a while, which leads to there being heavier elements present. The larger quantity of heavy elements in the dead galaxies implies that they were killed slowly rather than quickly.

The exact method of strangulation is not yet known, but it is thought that the galaxies can take around 4 billion years to die.

-LC

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New research at the University of Arkansas suggests that methanogens – among the simplest and oldest organisms on Earth – could survive on Mars.

Methanogens, microorganisms in the domain Archaea, use hydrogen as their energy source and carbon dioxide as their carbon source, to metabolize and produce methane, also known as natural gas. Methanogens live in swamps and marshes, but can also be found in the gut of cattle, termites and other herbivores as well as in dead and decaying matter.

Methanogens are anaerobic, so they don’t require oxygen. They don’t require organic nutrients, either, and are non-photosynthetic, indicating they could exist in sub-surface environments and therefore are ideal candidates for life on Mars.

Rebecca Mickol, a doctoral student in space and planetary sciences, found that in the laboratory, four species of methanogens survived low-pressure conditions that simulated a subsurface liquid aquifer on Mars.

“These organisms are ideal candidates for life on Mars,” Mickol said. “All methanogen species displayed survival after exposure to low pressure, indicated by methane production in both original and transfer cultures following each experiment. This work represents a stepping-stone toward determining if methanogens can exist on Mars.”

Mickol, who has previously found that two species of methanogens survived Martian freeze-thaw cycles, conducted both studies with Timothy Kral, professor of biological sciences in the Arkansas Center for Space and Planetary Sciences and lead scientist on the project. She is presenting her work at the 2015 General Meeting of the American Society for Microbiology, being held May 30-June 2 in New Orleans.

The four species of methanogens Mickol studied were: Methanothermobacter wolfeii, Methanosarcina barkeri, Methanobacterium formicicum, Methanococcus maripaludis.