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FastestThings

Space

PSR J1748−2446ad

Spin frequency of 716 Hz, the fastest pulsar in the Hessels et al. discovery. Science, the arXiv preprint and NRAO all print 716 Hz.

Also known as Terzan 5 ad
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Rotation rate

716Hz

Spin frequency of PSR J1748−2446ad. The date is the Science Express publication, 12 January 2006, not an observation timestamp. The papers lead with 716 Hz.

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Mechanism

Why it's so fast

PSR J1748−2446ad is a neutron star spinning hundreds of times a second. The core of a dead massive star collapsed and kept its spin, and this one was spun still faster by taking gas from a companion. The radio beam crosses us once each turn.

  1. Collapse

    A neutron star packs a stellar core into a city-sized sphere. Angular momentum conserved through that shrink is why the spin is furious even before any companion is involved.

  2. Spun up

    The fastest pulsars are recycled. Gas pulled from a companion adds spin until the star is a millisecond pulsar. Hessels and colleagues measured this one at the frequency the entry ranks. This note does not add a second frequency.

  3. A lighthouse, counted

    The telescope does not see the surface move. It counts the pulses. The frequency is how often the beam sweeps past, which is the spin.

The previous record holder on this list is PSR B1937+21. A fast orbit of a different kind is Mercury.

Provenance

Every measurement

Claimed, measured and official figures side by side, each with its source. The ranked figure is marked.

  1. 716HzRanked figure

    Spin frequency of PSR J1748−2446ad. The date is the Science Express publication, 12 January 2006, not an observation timestamp. The papers lead with 716 Hz.

    Verified
    Science (opens source in a new tab)

Reference

Specs

Object
PSR J1748−2446ad
Cluster
Terzan 5
Frequency
716 Hz
Telescope
Green Bank

Context

Background

The Science paper, the arXiv preprint and the National Radio Astronomy Observatory's announcement all say the Terzan 5 pulsar PSR J1748−2446ad spins at 716 Hz. Science calls it the fastest spinning neutron star then found. NRAO says 716 times per second. The ranked unit is hertz.

The Science Express date is 12 January 2006. That is the publication day stored on the row, not the night of the observation. A more precise frequency inside the paper is not the number the three accounts lead with, so 716 Hz is the rank. The previous record, B1937+21 at 642 Hz, is its own row.

Spot a wrong number?

Every report is read by a person, and corrections are dated on the page.