Pulsar
PSR J1748-2021D
Millisecond pulsar · in the globular cluster NGC6440
A millisecond pulsar spinning 74 times per second: an old neutron star spun up again (“recycled”) by matter transferred from a companion. It shares a 6.87 h 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 | Sagittarius |
| Period | 13.496 ms (74 Hz) |
| Period derivative | 5.9×10⁻¹⁹ s/s |
| Characteristic age | 364 million years |
| Magnetic field | 2.9×10⁹ G |
| Spin-down luminosity | 9.4×10³³ erg/s |
| Dispersion measure | 225.0 pc/cm³ |
| Distance | 8,200 pc (26.7 thousand ly) |
| Location | in the globular cluster NGC6440 |
| Companion | helium white dwarf (estimated), ~0.14 M☉ |
| Orbital period | 6.87 h |
| Discovery | 2008 · misc |
| Source | ATNF Pulsar Catalogue |
| Right ascension (J2000) | 17h 48m 51.6s |
| Declination (J2000) | −20° 21′ 08″ |
In the sky
Visible from the whole Southern Hemisphere and north to latitude 70° N. South of latitude 70° S it never sets. 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.