Pulsar
PSR B0021-72E (J0024-7204E)
Millisecond pulsar · in the globular cluster 47Tuc(NGC104)
A millisecond pulsar spinning 283 times per second: an old neutron star spun up again (“recycled”) by matter transferred from a companion. It shares a 2.257 days orbit with a helium white dwarf. Period, spin-down, distance and orbit come from the ATNF Pulsar Catalogue; the beam geometry is illustrative.
| Type | Pulsar |
|---|---|
| Constellation | Tucana |
| Period | 3.536 ms (283 Hz) |
| Period derivative | 9.9×10⁻²⁰ s/s |
| Characteristic age | 569 million years |
| Magnetic field | 6.0×10⁸ G |
| Spin-down luminosity | 8.8×10³⁴ erg/s |
| Dispersion measure | 24.2 pc/cm³ |
| Distance | 4,520 pc (14.7 thousand ly) |
| Location | in the globular cluster 47Tuc(NGC104) |
| Companion | helium white dwarf (estimated), ~0.18 M☉ |
| Orbital period | 2.257 days |
| Eccentricity | 0.000316 |
| Discovery | 1991 · pksgc |
| Source | ATNF Pulsar Catalogue |
| Right ascension (J2000) | 0h 24m 11.1s |
| Declination (J2000) | −72° 05′ 20″ |
In the sky
Visible from the whole Southern Hemisphere and north to latitude 18° N. South of latitude 18° S it never sets. It stands highest at midnight in September, the best time to observe it.
Through a telescope from Earth
Light's journey
The light you see tonight set out 15 thousand years ago. At that time Homo sapiens was spreading out of Africa; there was no farming yet. At the speed of Voyager 1, the fastest craft leaving the Solar System (16.9 km per second), the trip would take 262 million years.