Breakthrough...

Jocelyn Bell Burnell discovered pulsars as a PhD student.Credit: David Hartley/Shutterstock

Topics: Astrophysics, Diversity, Diversity in Science, Nobel Prize, Pulsar, Women in Science

Fifty years after discovering pulsars — compact rotating stars that emit beams of radiation — astrophysicist Jocelyn Bell Burnell has been awarded one of the most lucrative prizes in science: a US$3-million Breakthrough prize. Thought by many to have been snubbed for a Nobel prize for the discovery1, Bell Burnell, 75, has been recognized by the Breakthrough committee with a special award in fundamental physics for both her scientific achievements and her “inspiring leadership” over the past five decades.

“I cannot think of a more deserving scientist to win this prize,” says Chiara Mingarelli, an astrophysicist at the Flatiron Institute in New York City. “In addition to being both a pioneer and a giant in the field, Bell Burnell is the highest calibre role model — a champion for women in science, who speaks out against the many inequities faced by women in STEM [science, technology, engineering and mathematics] fields.”

The Breakthrough prizes were launched in 2012 and are funded by entrepreneurs including Google co-founder Sergey Brin and Facebook chief Mark Zuckerberg. Awarded in fundamental physics, life sciences and mathematics and each worth $3 million, they are usually handed out in December, based on selections made after an open nomination process. But the selection committee can decide to make special awards, bypassing the standard nomination procedure, to those they deem particularly deserving. Previous special awards have been given to Stephen Hawking, the Laser Interferometer Gravitational-Wave Observatory (LIGO) collaboration for the discovery of gravitational waves, and seven CERN scientists who co-ordinated the hunt for the Higgs boson.

Pulsar discoverer Jocelyn Bell Burnell wins $3-million Breakthrough Prize
Zeeya Merali, Nature

Related link:

Scientist Robbed of Nobel in 1974 Finally Wins $3 Million Physics Prize — And Gives It Away
Rafi Letzter, Live Science

Nuclear Pasta...

Credit: Columbia University

Pulsars are neutron stars—remnants from supernova explosions. Neutron stars have immensely huge magnetic fields (think ~10¹² times Earth's magnetic field). These fields accelerate charged particles, and in the course of that acceleration, light is emitted. But because of the nature of the fields, the light is emitted in a rather narrow cone. Because neutron stars rotate, this cone is scanned like a search light across the sky. So we only observe pulsars if the powerful beam happens to sweep across the face of the Earth.

This pasta has a distinctive property: it changes the way energy is dissipated and transported within the star. The magnetic field generates currents in the pasta region, which provides an intermediate step in converting magnetic energy to rotational energy. Hence, the crust changes the way the star spins down. In a series of models that take different neutron star masses, different crust diameters, and differently pasta region sizes, researchers from Spain showed that without a pasta region of some kind, a neutron star continues to spin down indefinitely, and we should observe X-Ray pulsars with periods that extend out past one minute.

The pasta, however, disrupts the magnetic field, stealing energy from it. In the end, that energy is transferred to rotational energy, keeping the spin period up. This is not such an efficient process, though, so for the early stages of the neutron star's life, it rapidly spins down. This continues until the additional energy from the magnetic field counters the losses due to other processes, stabilizing the rotational period at the cost of the magnetic field. The exact period at which this occurs depends on the mass of the star, the thickness of the crust, and the fraction of impurities in the crust.

Ars Technica: X-Ray pulsars boil “nuclear pasta” to keep spinning

Celestial Janus...

Science Daily: Jan. 24, 2013 — Using a satellite X-ray telescope combined with terrestrial radio telescopes the pulsar was found to flip on a roughly half-hour timescale between two extreme states; one dominated by X-ray pulses, the other by a highly-organised pattern of radio pulses.

The research was led by Professor Wim Hermsen from The Netherlands Institute for Space Research and the University of Amsterdam and will appear in the journal Science on the 25th January 2013.

Researchers from Jodrell Bank Observatory, as well as institutions around the world, used simultaneous observations with the X-ray satellite XMM-Newton and two radio telescopes; the LOw Frequency Array (LOFAR) in the Netherlands and the Giant Meter Wave Telescope (GMRT) in India to reveal this so far unique behaviour.

Pulsars are small spinning stars that are about the size of a city, around 20 km in diameter. They emit oppositely directed beams of radiation from their magnetic poles. Just like a lighthouse, as the star spins and the beam sweeps repeatedly past Earth we see a brief flash.

Science Daily: Chameleon pulsar dramatically changes the way it shines

Black Widow Pulsar...

Artist's impression of a black widow pulsar: a rapidly spinning stellar remant that strips matter off a companion star and evaporates it by intense radiation.

NASA/ESA/M.J. Jee and H. Ford (Johns Hopkins University)/Hubble Field), AEI/Milde Marketing Science Communication

Pulsars are the dense, rapidly spinning remains of stars much more massive than the Sun. To really get a pulsar revolving quickly, it needs a companion star: matter stripped from the partner falls onto the pulsar, speeding it up until it can rotate hundreds of times every second. Astronomers discovered these millisecond pulsars by their radio emissions, but many of them are also very strong gamma ray sources.

Astronomers have now used the Fermi Gamma-Ray Space Telescope to identify a "black widow" pulsar that's stripping mass off a close companion star while simultaneously evaporating it by emitting intense radiation. It's having these dramatic effects because the pulsar and its companion orbit each other so closely that they complete an orbit once every 93 minutes, making this the tightest black widow binary yet discovered.

Ars Technica: First black widow pulsar found from gamma ray observations