Pulsar
PSR B1855+09 (J1857+0943)
Millisecond pulsar · binary system
A millisecond pulsar spinning 186 times per second: an old neutron star spun up again (“recycled”) by matter transferred from a companion. It shares a 12.327 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 | Aquila |
| Period | 5.362 ms (186 Hz) |
| Period derivative | 1.8×10⁻²⁰ s/s |
| Characteristic age | 4.8 billion years |
| Magnetic field | 3.1×10⁸ G |
| Spin-down luminosity | 4.6×10³³ erg/s |
| Dispersion measure | 13.3 pc/cm³ |
| Distance | 1,200 pc (3.9 thousand ly) |
| Companion | helium white dwarf (estimated), ~0.28 M☉ |
| Orbital period | 12.327 days |
| Eccentricity | 0.000022 |
| Discovery | 1986 · ar2, ar3, pksmb, fast_gpps |
| Source | ATNF Pulsar Catalogue |
| Right ascension (J2000) | 18h 57m 36.4s |
| Declination (J2000) | +9° 43′ 17″ |
In the sky
Visible from the whole Northern Hemisphere and south to latitude 80° S. It stands highest at midnight in July, the best time to observe it.
Through a telescope from Earth
Light's journey
The light you see tonight set out around 1889 BC. At the speed of Voyager 1, the fastest craft leaving the Solar System (16.9 km per second), the trip would take 69 million years.