Death valley flower show, nervy fossil and Hubble's blue bubble
Peer through the Hubble telescope to the exploding majesty of a giant hydrogen bubble or turn your gaze to the Death Valley in full bloom: Cosmos art director Robyn Adderly has it all in her top five images of the week.
Hubble's blue bubble
Sparkling at the centre of this beautiful image captured by the Hubble Space Telescope is a star known as WR 31a, located about 30,000 light-years away in the constellation Carina (The Keel).
The blue bubble that appears to encircle WR 31a is a Wolf-Rayet nebula – an interstellar cloud of dust, hydrogen, helium and other gases. Created when speedy stellar winds interact with the outer layers of hydrogen ejected by Wolf–Rayet stars, these nebulae are frequently ring-shaped or spherical. The bubble – estimated to have formed around 20,000 years ago – is expanding at around 220,000 kilometres per hour!
Unfortunately, the lifecycle of a Wolf–Rayet star is only a few hundred thousand years – the blink of an eye in cosmic terms. Despite beginning life with a mass at least 20 times that of the Sun, Wolf–Rayet stars typically lose half their mass in less than 100,000 years.
WR 31a is no exception. Eventually it will end its life as a spectacular supernova. But the stellar material expelled from the explosion will go on to nourishi a new generation of stars and planets.
One-year crew returns to Earth
The one-year International Space Station crew landed safely on Earth this week on Wednesday (Australian time).
The Soyuz TMA-18M spacecraft is seen here as it lands near the town of Zhezkazgan, Kazakhstan with Expedition 46 Commander Scott Kelly of NASA and Russian cosmonauts Mikhail Kornienko and Sergey Volkov on board.
Volkov returned after spending six months on the International Space Station, but Kelly and Kornienko completed a record year-long mission to collect valuable data on the effects of long-term weightlessness. The data will be used to formulate a human mission to Mars.
520-million-year-old fossilised nervous system found
Researchers have found one of the oldest and most detailed fossils of the central nervous system, from a crustacean-like animal that lived more than 500 million years ago. The fossil, from southern China, has been so well preserved that individual nerves are visible.
Finding any fossilised soft tissue is rare, but this particular find, by researchers in the UK, China and Germany and published in the Proceedings of the National Academy of Sciences, is helping researchers understand how the nervous system of arthropods – creepy crawlies with jointed legs – evolved.
The realm of buried giants
Clouds of crimson gas are illuminated by rare, massive stars that have only recently ignited and are still buried deep in thick dust clouds in this huge new image captured in fine detail by ESO’s VLT Survey Telescope at the Paranal Observatory in Chile.
These scorching-hot, very young stars are only fleeting characters on the cosmic stage and their origins remain mysterious.
The red cloud above centre in this new image is the vast nebula where these giants were born, known as RCW 106. It’s located only about 12,000 light-years away in part the southern constellation of Norma (The Carpenter’s Square).
Many other unrelated objects are also visible in this wide-field image. For example, the filaments to the right of the image are the remnants of an ancient supernova, and the glowing red filaments at the lower left surround an unusual and very hot star. Patches of dark, obscuring dust are also seen across the entire cosmic landscape.
Astronomers have been studying RCW 106 for some time, although it is not the crimson clouds that draw their attention, but rather the mysterious origin of the massive and powerful stars buried within. Although they are very bright, these stars cannot be seen in visible-light images such as this one as the surrounding dust is too thick, but they make their presence clear in images of the region at longer wavelengths.
Death Valley in bloom
Death Valley is the hottest place on Earth and the driest in North America, averaging about 50 millimetres (two inches) of rain per year. These extreme conditions make it all but impossible for plants to survive. Most of the time, the lower elevations in the park appear stark: a landscape of salt flats, sand dunes and rocky mountains vegetated by a few hardy shrubs and small trees.
But we’re currently treated to an unusually dense display of wildflowers in Death Valley National Park. It is the best the park has experienced in a decade and was triggered by a series of storms in October.
Matching previous patterns super blooms of 1998 and 2005 occurred in El Nino years. El Nino can affect Death Valley by shifting the track of winter and spring storms into the area, increasing rainfall during flower season.