Pulsar
PSR B1802-07 (J1804-0735)
Millisecond pulsar · in the globular cluster NGC6539
A millisecond pulsar spinning 43 times per second: an old neutron star spun up again (“recycled”) by matter transferred from a companion. It shares a 2.617 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 | Serpens |
| Period | 23.101 ms (43 Hz) |
| Period derivative | 4.7×10⁻¹⁹ s/s |
| Characteristic age | 784 million years |
| Magnetic field | 3.3×10⁹ G |
| Spin-down luminosity | 1.5×10³³ erg/s |
| Dispersion measure | 186.3 pc/cm³ |
| Distance | 8,200 pc (26.7 thousand ly) |
| Location | in the globular cluster NGC6539 |
| Companion | helium white dwarf (estimated), ~0.35 M☉ |
| Orbital period | 2.617 days |
| Eccentricity | 0.2120 |
| Discovery | 1993 · misc, htru_pks |
| Source | ATNF Pulsar Catalogue |
| Right ascension (J2000) | 18h 04m 49.9s |
| Declination (J2000) | −7° 35′ 25″ |
In the sky
Visible from the whole Southern Hemisphere and north to latitude 82° N. It stands highest at midnight in June, the best time to observe it.
Through a telescope from Earth
Light's journey
The light you see tonight set out 27 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 474 million years.