Pulsar
PSR J1640+2224
Millisecond pulsar · binary system
A millisecond pulsar spinning 316 times per second: an old neutron star spun up again (“recycled”) by matter transferred from a companion. It shares a 175 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 | Hercules |
| Period | 3.163 ms (316 Hz) |
| Period derivative | 2.8×10⁻²¹ s/s |
| Characteristic age | 17.8 billion years |
| Magnetic field | 9.6×10⁷ G |
| Spin-down luminosity | 3.5×10³³ erg/s |
| Dispersion measure | 18.4 pc/cm³ |
| Distance | 1,370 pc (4.5 thousand ly) |
| Companion | helium white dwarf (estimated), ~0.29 M☉ |
| Orbital period | 175 days |
| Eccentricity | 0.000797 |
| Discovery | 1995 · ar4, FermiBlind, ar327 |
| Source | ATNF Pulsar Catalogue |
| Right ascension (J2000) | 16h 40m 16.8s |
| Declination (J2000) | +22° 24′ 09″ |
In the sky
Visible from the whole Northern Hemisphere and south to latitude 68° S. North of latitude 68° N it never sets. It stands highest at midnight in May, the best time to observe it.
Through a telescope from Earth
Light's journey
The light you see tonight set out 4,468 years ago. At that time the first farming villages were being founded; there was no writing yet. At the speed of Voyager 1, the fastest craft leaving the Solar System (16.9 km per second), the trip would take 79 million years.