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Monstrous Cloud Boomerangs Back to Our Galaxy

Astronomy News - 29 January 2016 - 9:32am

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The old adage "what goes up must come down" even applies to an immense cloud of hydrogen gas outside our Milky Way galaxy. First discovered in the 1960s, the comet-shaped cloud is 11,000 light-years long and 2,500 light-years across. If the cloud could be seen in visible light, it would span the sky with an apparent diameter 30 times greater than the size of the full moon. The cloud, which is invisible at optical wavelengths, is plummeting toward our galaxy at nearly 700,000 miles per hour. Hubble was used to measure the chemical composition of the cloud as a means of assessing where it came from. Hubble astronomers were surprised to find that the cloud, which is largely composed of hydrogen, also has heavier elements that could only come from stars. This means the cloud came from the star-rich disk of our galaxy. The Smith Cloud is following a ballistic trajectory and will plow back into the Milky Way's disk in about 30 million years. When it does, astronomers believe it will ignite a spectacular burst of star formation, perhaps providing enough gas to make 2 million suns.

Please join the scientists in a live discussion about the origin and conclusions of this research during the Hubble Hangout at 3pm EST today (Thurs., Jan. 28, 2016): .

The Milky Way’s Clean and Tidy Galactic Neighbour

Astronomy News - 28 January 2016 - 9:34am
Many galaxies are chock-full of dust, while others have occasional dark streaks of opaque cosmic soot swirling in amongst their gas and stars. However, the subject of this new image, snapped with the OmegaCAM camera on ESO’s VLT Survey Telescope in Chile, is unusual — the small galaxy, named IC 1613, is a veritable clean freak! IC 1613 contains very little cosmic dust, allowing astronomers to explore its contents with great clarity. This is not just a matter of appearances; the galaxy’s cleanliness is vital to our understanding of the Universe around us.

Record-breaking double star may be cannibalising itself

Astronomy News - 28 January 2016 - 9:32am

A binary star with the longest and most infrequent eclipses ever may bust the records because one star is stealing material from the other

Stellar astrophysics: The mystery of globular clusters

Astronomy News - 28 January 2016 - 9:24am

Stellar astrophysics: The mystery of globular clusters

Nature 529, 7587 (2016). doi:10.1038/529473a

Authors: Antonella Nota & Corinne Charbonnel

The discovery of multiple stellar populations — formed at different times — in several young star clusters adds to the debate on the nature and origin of such populations in globular clusters from the early Universe. See Letter p.502

Formation of new stellar populations from gas accreted by massive young star clusters

Astronomy News - 28 January 2016 - 9:23am

Formation of new stellar populations from gas accreted by massive young star clusters

Nature 529, 7587 (2016). doi:10.1038/nature16493

Authors: Chengyuan Li, Richard de Grijs, Licai Deng, Aaron M. Geller, Yu Xin, Yi Hu & Claude-André Faucher-Giguère

Stars in clusters are thought to form in a single burst from a common progenitor cloud of molecular gas. However, massive, old ‘globular’ clusters—those with ages greater than ten billion years and masses several hundred thousand times that of the Sun—often harbour multiple stellar populations, indicating that more than one star-forming event occurred during their lifetimes. Colliding stellar winds from late-stage, asymptotic-giant-branch stars are often suggested to be triggers of second-generation star formation. For this to occur, the initial cluster masses need to be greater than a few million solar masses. Here we report observations of three massive relatively young star clusters (1–2 billion years old) in the Magellanic Clouds that show clear evidence of burst-like star formation that occurred a few hundred million years after their initial formation era. We show that such clusters could have accreted sufficient gas to form new stars if they had orbited in their host galaxies’ gaseous disks throughout the period between their initial formation and the more recent bursts of star formation. This process may eventually give rise to the ubiquitous multiple stellar populations in globular clusters.

Hawking’s latest black-hole paper splits physicists

Astronomy News - 28 January 2016 - 9:23am

Hawking’s latest black-hole paper splits physicists

Nature 529, 7587 (2016).

Author: Davide Castelvecchi

Some welcome his latest report as a fresh way to solve a black-hole conundrum; others are unsure of its merits.

Astronomy: Turbulence roils luminous galaxy

Astronomy News - 28 January 2016 - 9:23am

Astronomy: Turbulence roils luminous galaxy

Nature 529, 7587 (2016). doi:10.1038/529440c

The brightest-known galaxy is blasting gas out into space — and providing astronomers with a rare glimpse of how extreme galaxies evolve.Known as W2246-0526, the galaxy is as bright as 350 trillion Suns and is powered by a supermassive black hole at its heart.

Largest solar system discovered

Astronomy News - 28 January 2016 - 9:21am

Astronomers discover the largest known solar system, consisting of a large planet that takes a million years to orbit its star.

INTEGRAL X-rays Earth's aurora

Astronomy News - 27 January 2016 - 9:23am

Normally busy with observing high-energy black holes, supernovas and neutron stars, ESA's INTEGRAL space observatory recently had the chance to look back at our own planet's aurora.

Lonely exoplanet orbits its star at greatest distance yet seen

Astronomy News - 27 January 2016 - 9:12am

A closer look at the motions of a small star and a misfit planet shows the two are linked by gravity - and can teach us about planets and stars alike

Stephen Hawking’s Reith Lecture: Annotated transcript

Astronomy News - 27 January 2016 - 9:07am

A transcript of Stephen Hawking's first Reith Lecture, annotated by BBC science editor David Shukman

Hubble successor maintains course

Astronomy News - 26 January 2016 - 9:16am

James Webb, the space telescope that will take over from Hubble, is reaching some key milestones in its preparation for launch in 2018.

Dazzling diamonds [heic1601]

Astronomy News - 25 January 2016 - 9:32am

Single stars are often overlooked in favour of their larger cosmic cousins – but when they join forces, they create truly breathtaking scenes to rival even the most glowing of nebulae or swirling of galaxies. This NASA/ESA Hubble Space Telescope image features the star cluster Trumpler 14. One of the largest gatherings of hot, massive and bright stars in the Milky Way, this cluster houses some of the most luminous stars in our entire galaxy.

LISA Pathfinder arrives at its worksite

Astronomy News - 25 January 2016 - 9:32am

After a six-week journey, LISA Pathfinder arrived at its destination today, an orbit around a point of balance in space where it will soon start testing technologies crucial for exploring the gravitational Universe.

Galaxy-mapping Gaia space telescope gets an eye test from Pluto

Astronomy News - 25 January 2016 - 9:26am

The European Space Agency craft designed to map a billion stars in the Milky Way has also been keeping an eye out for everyone's favourite dwarf planet

Mystery supernova could be fast-spinning magnetic star

Astronomy News - 22 January 2016 - 9:07am

The brightest ever supernova was confirmed last week, but no one could explain it. Now a culprit has been found: a magnetar driven by an extremely massive star

Hubble Unveils a Tapestry of Dazzling Diamond-Like Stars

Astronomy News - 22 January 2016 - 9:06am

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Some of the Milky Way's "celebrity stars" opulent, attention-getting, and short-lived can be found in this Hubble Space Telescope image of the glittering star cluster called Trumpler 14. It is located 8,000 light-years away in the Carina Nebula, a huge star-formation region in our galaxy. Because the cluster is only 500,000 years old, it has one of the highest concentrations of massive, luminous stars in the entire Milky Way. Like some Hollywood celebrities, the stars will go out in a flash. Within just a few million years they will burn out and explode as supernovae. But the story's not over. The blast waves will trigger the formation of a new generation of stars inside the nebula in an ongoing cycle of star birth and death.

Come in #PlanetNine

Astronomy News - 22 January 2016 - 9:03am

US astronomers claim to have strong evidence that there is a ninth planet in our Solar System. We asked you to send us your suggested names for this new arrival.

VIDEO: Does the ninth planet really exist?

Astronomy News - 22 January 2016 - 9:02am

Why do astronomers in the US think there they have discovered a ninth planet in the solar system?

A prevalence of dynamo-generated magnetic fields in the cores of intermediate-mass stars

Astronomy News - 21 January 2016 - 10:07am

A prevalence of dynamo-generated magnetic fields in the cores of intermediate-mass stars

Nature 529, 7586 (2016). doi:10.1038/nature16171

Authors: Dennis Stello, Matteo Cantiello, Jim Fuller, Daniel Huber, Rafael A. García, Timothy R. Bedding, Lars Bildsten & Victor Silva Aguirre

Magnetic fields play a part in almost all stages of stellar evolution. Most low-mass stars, including the Sun, show surface fields that are generated by dynamo processes in their convective envelopes. Intermediate-mass stars do not have deep convective envelopes, although 10 per cent exhibit strong surface fields that are presumed to be residuals from the star formation process. These stars do have convective cores that might produce internal magnetic fields, and these fields might survive into later stages of stellar evolution, but information has been limited by our inability to measure the fields below the stellar surface. Here we report the strength of dipolar oscillation modes for a sample of 3,600 red giant stars. About 20 per cent of our sample show mode suppression, by strong magnetic fields in the cores, but this fraction is a strong function of mass. Strong core fields occur only in red giants heavier than 1.1 solar masses, and the occurrence rate is at least 50 per cent for intermediate-mass stars (1.6–2.0 solar masses), indicating that powerful dynamos were very common in the previously convective cores of these stars.