The Bursting Pulsar: A New Type of Celestial Object

It is indeed rare when a totally new class of object is discovered in the sky. On December 2, 1995, scientists at the Space Sciences Laboratory of NASA's Marshall Space Flight Center did just that. Data analyzed from the Burst and Transient Source Experiment (BATSE) revealed a "bursting pulsar" near the center of our Milky Way Galaxy. BATSE detects high-energy X-rays and gamma-rays from objects in the Universe, and many different kinds of cosmic objects are known to emit these types of radiation. Gamma-ray bursts, for example, are non-repeating blasts of radiation that last a few seconds and come from random directions in the sky. Their origin still remains a mystery. Another example are the soft-gamma repeater objects (SGRs), different from gamma-ray bursts in that they produce lower energy bursts of radiation, are observed to repeatedly blast gamma-rays and X-rays into space, and are located within our own Galaxy. Pulsars are yet another kind of celestial object that emits X and gamma radiation. These objects vary in brightness in a regular, periodic fashion, increasing and decreasing their brightness from several times per second to every few seconds. Never before had an object been observed that displayed both the bursting behavior combined with the periodic behavior of a pulsar.

That was before December 2, 1995, when BATSE first detected the "Bursting Pulsar". More than 2,000 bursts from this one object have now been detected, each having remarkably similar properties. In addition to these frequent explosions of energy, the object is also observed to have a steady pulsar-like periodic variation in its brightness. This "one man band" is the only known object of its type in the Universe, and displays behaviors seen individually in several different objects, yet never before seen in the same object.