Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


The Manifold Path to Millisecond Pulsars

Two astronomers from Bonn have proposed a new path for the formation of a newly discovered class of millisecond pulsars with similar orbital periods and eccentricities.

In the scenario of Paulo Freire and Thomas Tauris, a massive white dwarf star accretes matter and angular momentum from a normal companion star and grows beyond the critical Chandrasekhar mass limit.

MPIfR’s 100-m radio telescope near Bad Effelsberg seen from the visitors’ pavilion. The milli-second pulsar PSR J1946+3417 is one of 14 new pulsars recently discovered with this telescope

MPIfR/Norbert Junkes

The final path of close binary stellar evolution according to the new scenario, starting with an X-ray binary with an accreting white dwarf and leading to a millisecond pulsar with a low-mass

Paulo Freire & Thomas Tauris

The new hypothesis makes several testable predictions about this recently discovered sub-class of millisecond pulsars. If confirmed, it opens up new avenues of research into the physics of stars, in particular the momentum kicks and mass loss associated with accretion induced collapse of massive white dwarfs.

Neutron stars can spin very fast – with a record value of 716 rotations per second. Such extreme objects are known as millisecond pulsars. Ever since their first discovery in 1982, it has been thought that they are old dead neutron stars that are lucky enough to be in binary star system.

As the companion evolves, it starts transferring matter onto the neutron star, spinning it up. This sort of system is known as an X-ray binary. Eventually the companion evolves into a white dwarf star, accretion stops and the neutron star becomes a millisecond pulsar, detectable through its radio pulsations. The orbits of these systems have very low eccentricities, meaning their orbits are extremely close to being perfect circles.

This is a consequence of the tidal circularization that happens during the mass transfer stage. Such a scenario has been confirmed both in theoretical work and in the discovery of several systems in different stages of their evolution from X-ray binaries to millisecond pulsars.

However, recent discoveries like PSR J1946+3417 are hinting at the possibility of different formation paths to millisecond pulsars. This source is among 14 new pulsars recently discovered with the Effelsberg 100-m radio telescope. Spinning 315 times per second, this is clearly a millisecond pulsar; however, its orbital eccentricity is 4 orders of magnitude larger than other systems with a similar orbital period. Its companion mass is about 0.24 solar masses, most likely a helium white dwarf. Interestingly enough, at about the same time, two systems with similar parameters were discovered using the Arecibo 305 m radio telescope.

It is quite possible that these binary systems started their evolution as triple systems which became dynamically unstable, as in the case of PSR J1903+0327, the first millisecond pulsar with an eccentric orbit. However, this process generates a wide variety of orbital periods, eccentricities and companion masses, quite unlike the three new discoveries, which are in everything very similar.

The new hypothesis includes the collapse of a massive white dwarf after accretion has terminated. It explains not only the similarity of eccentricities and companion masses, but also their values. "I was surprised when we looked at the calculated orbital periods and eccentricities predicted by our model", says Thomas Tauris, affiliated with both, Argelander-Institut für Astronomie & Max-Planck-Institut für Radioastronomie (MPIfR) in Bonn. "It gives an exact match with the observations! Thus I knew then we were on to something, although small number statistics could still be at work."

The new theory builds on previous extensive computational work lead by Tauris. It makes a prediction for the new type of systems: they should have orbital periods between 10 and 60 days, but with a concentration towards the middle of that range, almost exactly as observed for the new systems.

"Our new approach is very elegant", says the lead author, Paulo Freire from MPIfR. "But whether Nature is really making millisecond pulsars this way is not known yet.''

For the next few years, the pulsar team at the Fundamental Physics In Radio Astronomy Group at MPIfR will be involved in testing the predictions of this scenario, particularly by doing optical follow-up studies and by making precise mass measurements of the pulsars and their companions, a key feature of this study. They will also attempt to find more of these pulsar systems using the Effelsberg radio telescope.

"The neat thing is that if the theory passes these tests, it will allow us to learn much more about the kicks and mass loss associated with accretion induced supernovae, and even about the interiors of neutron stars. It might thus be an extremely useful piece of understanding", concludes Paulo Freire.

The paper appears as a Letter in Monthly Notices of the Royal Astronomical Society.


Dr. Paulo Freire
Max-Planck-Institut für Radioastronomie, Bonn, Germany.
Fon: +49(0)228-525-496
Dr. Thomas Tauris,
Argelander-Institut für Astronomie &
Max-Planck-Institut für Radioastronomie, Bonn, Germany.
Fon: +49(0)228-73-3660
Dr. Norbert Junkes,
Press and Public Outreach,
Max-Planck-Institut für Radioastronomie, Bonn, Germany.
Fon: +49(0)228-525-399

Norbert Junkes | Max-Planck-Institut
Further information:

More articles from Physics and Astronomy:

nachricht Scientists discover particles similar to Majorana fermions
25.10.2016 | Chinese Academy of Sciences Headquarters

nachricht Light-driven atomic rotations excite magnetic waves
24.10.2016 | Max-Planck-Institut für Struktur und Dynamik der Materie

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Etching Microstructures with Lasers

Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.

This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...

Im Focus: Light-driven atomic rotations excite magnetic waves

Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion

Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Ice shelf vibrations cause unusual waves in Antarctic atmosphere

25.10.2016 | Earth Sciences

Fluorescent holography: Upending the world of biological imaging

25.10.2016 | Power and Electrical Engineering

Etching Microstructures with Lasers

25.10.2016 | Process Engineering

More VideoLinks >>>