Smallest speed jump of pulsar caused by billions of superfluid vortices

Artist’s impression of a pulsar. Pulsars are rotating neutron stars -- remnants of massive stars that end their lives in supernova explosions. They act like cosmic lighthouses whose beams sweep through the universe. 

Credit: NASA

A team of astronomers, including Danai Antonopoulou and Anna Watts from the University of Amsterdam, has discovered that sudden speed jumps in the rotational velocity of pulsars have a minimum size, and that they are caused not by the unpinning and displacement of just one sub-surface superfluid vortex, but by billions.

This result is important to our understanding of the behaviour of matter under extreme conditions, and has been published this week in the journal Monthly Notices of the Royal Astronomical Society.

Pulsars are rotating neutron stars - remnants of massive stars that end their lives in supernova explosions. They act like cosmic lighthouses whose beams sweep through the Universe.

Their rotational velocity decreases in time, but can suddenly increase in rare events called glitches.

These glitches are caused by the unpinning and displacement of vortices that connect the crust with the mixture of particles containing superfluid neutrons beneath the crust.

The team of astronomers discovered that the glitches of the Crab Pulsar always involve a decrease in the rotational period of at least 0.055 nanoseconds.

The Crab Pulsar was one of the first pulsars to be discovered and has been observed almost daily with the 42-ft Telescope at the Jodrell Bank Observatory over the last 29 years.

The huge amount of data makes this object the best choice to study glitches.

The smallest glitch is likely to be caused by the unpinning and movement of billions of vortices. "Surprisingly, no one tried to determine a lower limit to glitch size before. Many assumed that the smallest glitch would be caused by a single vortex unpinning.

The smallest glitch is clearly much larger than we expected", says Danai Antonopoulou from the University of Amsterdam (UvA).

"Astronomers would of course like to know whether the smallest glitches of other pulsars are also caused by billions of vortices. The next step is to sift through the data of other pulsars and to continue observing", says first author Cristobal Espinoza (IA-PUC, Chile).

Antonopoulou's supervisor Anna Watts (UvA) adds: "By comparing the observations with theoretical predictions we learn about the behavior of matter in these exotic objects. The precise cause of glitches is still a mystery to us, and this result offers a new challenge to theorists."

More information: "Neutron star glitches have a substantial minimum size," C. M. Espinoza, D. Antonopoulou, B. W. Stappers, A. Watts, A. G. Lyne, Monthly Notices of the Royal Astronomical Society, MNRAS (2014) 440 (3): 2755 dx.doi.org/10.1093/mnras/stu395, preprint: arxiv.org/abs/1402.7219

BRITE: World's smallest space telescope launched

BRITE, the smallest astronomical satellite was launched Monday as part of a mission to prove that even a very small telescope can push the boundaries of astronomy.

The satellite was designed and assembled at the Space Flight Laboratory (SFL) of the University of Toronto Institute for Aerospace Studies (UTIAS).

It will be launched from the Satish Dhawan Space Centre in Sriharikota, India, along with its twin, also designed in Canada, but assembled in Austria.

Each nano-satellite in the BRIght Target Explorer (BRITE) mission is a cube 20 cms per side, and weighing less than 7 kilograms.

The BRITE satellites are part of the new wave of nano-satellites that can be designed, assembled and deployed fast and relatively cheaply.

"SFL has demonstrated that nano-satellites can be developed quickly, by a small team and at a cost that is within reach of many universities, small companies and other organizations," says Cordell Grant, Manager of Satellite Systems for the Space Flight Laboratory at UTIAS.

"A nano-satellite can take anywhere from six months to a few years to develop and test, but we typically aim for two years or less."

Up to now, such nano-satellites had been used only to monitor the earth and experiment with new technologies.

"Researchers, scientists and companies worldwide, who have great ideas for space-borne experiments, but do not have the means to fund a large spacecraft, can now see their ideas realized," said Grant.

"BRITE has the potential to open an entirely new market for low-cost high-performance satellites."

BRITE is the first nano-satellite mission intended for astronomy, and the first-ever astronomy constellation -more than one satellite working toward a common objective- of any size.

The previous world-record holder for small astronomy satellites was the MOST satellite, designed and assembled in part by SFL at UTIAS.

Launched in 2003 and still operating, MOST was the first entirely Canadian satellite for astronomy, weighing in at 53 kilograms. Compared to the 11 metric tons of the Hubble Space Telescope, MOST was aptly called a micro-satellite.

"BRITE is expected to demonstrate that nano-satellites are now capable of performance that was once thought impossible for such small spacecraft," says Grant. But only small telescopes can fit within a 20 centimetre cube.

Therefore, BRITE is not intended to take pretty pictures, but will simply observe stars and record changes in their brightness over time.

Such changes could be caused by spots on the star, a planet or other star orbiting the star, or by oscillations and reverberations within the star itself -the analogue of earthquakes on stars.

The study of these so-called "starquakes" is called astero-seismology.

Worlds smallest One-man Helicopter GEN H-4 - YouTube video

Meet 75-year-old Gennai Yanagisawa, who runs an electronics equipment company in Matsumoto, central Japan, has created a 75kg (165-pound) one-man aircraft which sets the world record for the smallest helicopter.

The Smallest Vertebrate on Earth: Paedophryne amauensis

Paedophryne amauensis

The smallest vertebrate on Earth - a frog just a quarter of an inch long - has been discovered by scientists.

The tiny frog has been named Paedophryne amauensis after Amau Village in Papua New Guinea in the Pacific Ocean where it was found.

Its adult body size ranges from just 7 to 8 mm - just over a quarter of an inch long.

Paedocypris progenetica

It has snatched the "world's smallest vertebrate" title from a fish called Paedocypris progenetica which measures 7.9 to 10.3 mm when fully grown.

The creature was identified along with another new and slightly larger frog of the same genus, Paedophryne swiftorum, which is between 8.3 and 8.9 mm.

Picture: NATIONAL PICTURES

Smallest Dinosaur footprints

ONLY just hatched and new to the world, the little guy who left these prints in the riverbed was probably running for its life. Barely 10 centimetres tall, the hatchling would have been the length of a wren and easy prey for pterosaurs and other hungry dinosaurs.

The prints are the tiniest dinosaur footprints ever found. They were left between 125 and 110 million years ago, are just 1.27 cm and 1.51 cm long, and clearly show soft foot pads and three pointed claws.

Kyung Soo Kim of Chinju National University of Education in Jinju, South Korea, says the baby track-maker was a cousin of the fearsome T. Rex and belonged to the theropod sub-order, which includes tyrannosaurs.

"It was running to hide right after hatching," Kim speculates. It had plenty of reasons to do so: nearby tracks show it shared its home with fleet-footed, meat-eating dromeosaurs, such as Velociraptor, together with other dinosaurs, pterosaurs and shorebirds.

The prints were discovered in 2008 during the construction of a reservoir on Changseon Island, located 320 kilometres from the South Korean capital of Seoul.