Featured Research

from universities, journals, and other organizations

How pulsars slow down with age

Date:
October 8, 2012
Source:
University of Southampton
Summary:
Researchers have developed a model which explains how the spin of a pulsar slows down as the star gets older. A pulsar is a highly magnetized rotating neutron star which was formed from the remains of a supernova - an explosion which happens after a massive star runs out of nuclear fuel. A pulsar emits a rotating beam of electromagnetic radiation, rather like that of a lighthouse. This beam can be detected by powerful telescopes when it points towards and sweeps past the Earth.

Researchers at the University of Southampton have developed a model which explains how the spin of a pulsar slows down as the star gets older.

A pulsar is a highly magnetised rotating neutron star which was formed from the remains of a supernova -- an explosion which happens after a massive star runs out of nuclear fuel. A pulsar emits a rotating beam of electromagnetic radiation, rather like that of a lighthouse. This beam can be detected by powerful telescopes when it points towards and sweeps past Earth.

Pulsars rotate at very stable speeds, but slow down as they emit radiation and lose their energy. Professor Nils Andersson and Dr Wynn Ho, from the University of Southampton, have now found a way to predict how this 'slowing' process will develop in individual pulsars.1

Nils Andersson comments: "A pulsar's spin rate can be a very precise measurement of time which rivals the best atomic clocks, but in the end it will slow down. Until now, the nature of this slowing hasn't been well understood, despite 40 years of research. However, our model will open the door on this process -- extending our knowledge of how pulsars' operate and helping to predict how they will behave in the future."

As a hot pulsar cools, its interior increasingly begins to turn superfluid -- a state of matter which behaves like a fluid, but without a fluid's friction or 'viscosity'. It is this change of state which gradually affects the way that the star's rotation slows down.

"The effect on the star's rotation is like a figure skater extending their arms to slow their spin," says Wynn Ho. "Our model can explain the observed behaviour of young pulsars, such as the 958-year-old pulsar in the Crab nebula, which spins at 33 times a second."

The Southampton scientist's findings have important implications for the next generation of radio telescopes being developed by large international collaborations, like the Square Kilometre Array (SKA) and the Low Frequency Array (LOFAR), of which Southampton is a UK partner university. The discovery and monitoring of many more pulsars is one of the key scientific goals of these projects. Professor Andersson and Dr Ho's mathematical model can be used in conjunction with these observations to predict how a pulsar's rotation will change over time and enable scientists to peer inside these stars and explore their exotic composition.

"Our results provide a new method of linking the study of distant astronomical objects to laboratory work on Earth in both high-energy and low-temperature physics," says Professor Andersson. "It is an exciting example of interdisciplinary science."

1 Pulsars are rotating neutron stars that are seen to slow down, and the spin-down rate is thought to be due to magnetic dipole radiation. This leads to a prediction for the braking index n, which is a combination of the spin period and its first and second time derivatives. However, all observed values of n are below the predicted value of 3. We provide a simple model that can explain the rotational evolution of young pulsars, including the n=2.51 of the 958-year-old pulsar in the Crab nebula. The model is based on a decrease in the effective moment of inertia due to an increase in the fraction of the stellar core that becomes superfluid as the star cools through neutrino emission. The results suggest that future large radio monitoring campaigns of pulsars will yield measurements of the neutron star mass, nuclear equation of state, and superfluid properties.


Story Source:

The above story is based on materials provided by University of Southampton. Note: Materials may be edited for content and length.


Journal Reference:

  1. Wynn C. G. Ho, Nils Andersson. Rotational evolution of young pulsars due to superfluid decoupling. Nature Physics, 2012; DOI: 10.1038/nphys2424

Cite This Page:

University of Southampton. "How pulsars slow down with age." ScienceDaily. ScienceDaily, 8 October 2012. <www.sciencedaily.com/releases/2012/10/121008091556.htm>.
University of Southampton. (2012, October 8). How pulsars slow down with age. ScienceDaily. Retrieved September 20, 2014 from www.sciencedaily.com/releases/2012/10/121008091556.htm
University of Southampton. "How pulsars slow down with age." ScienceDaily. www.sciencedaily.com/releases/2012/10/121008091556.htm (accessed September 20, 2014).

Share This



More Space & Time News

Saturday, September 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

MIT BioSuit A New Take On Traditional Spacesuits

MIT BioSuit A New Take On Traditional Spacesuits

Newsy (Sep. 19, 2014) The MIT BioSuit could be an alternative to big, bulky traditional spacesuits, but the concept needs some work. Video provided by Newsy
Powered by NewsLook.com
Boeing, SpaceX to Send Astronauts to Space Station

Boeing, SpaceX to Send Astronauts to Space Station

AFP (Sep. 17, 2014) NASA selected Boeing and SpaceX on Tuesday to build America's next spacecraft to carry astronauts to the International Space Station (ISS) by 2017, opening the way to a new chapter in human spaceflight. Duration: 01:13 Video provided by AFP
Powered by NewsLook.com
East Coast Treated To Rare Meteor Sighting

East Coast Treated To Rare Meteor Sighting

Newsy (Sep. 16, 2014) Numerous residents along the East Coast reported seeing a bright meteor flash through the sky Sunday night. Video provided by Newsy
Powered by NewsLook.com
Space Race Pits Bezos Vs Musk

Space Race Pits Bezos Vs Musk

Reuters - Business Video Online (Sep. 16, 2014) Amazon CEO Jeff Bezos' startup will team up with Boeing and Lockheed to develop rocket engines as Elon Musk races to have his rockets certified. Fred Katayama reports. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins