Yet another subclass is those at the low-[B.sub.d] and short-P end, a mixture of millisecond pulsars (MSPs; isolated or in wide binaries) and Low-Mass X-ray Binaries (LMXBs).
4, BXPs and LMXBs accrete gas from their binary companions, and emit X-rays powered by gravitational energies released by the accreting matter.
Given the large number of the latter and their known spin-down ages (averaging 3 billion years), one would expect to find 20 or 30
LMXBs just to support the current millisecond-pulsar population if they are forming continuously.
Intriguingly, when the donor in an
LMXB fills (or nearly fills) its Roche lobe, it absorbs as much as 10 percent of the X-rays given off by the accretor.
According to the scientists, in most
LMXBs, the gas in the disk spirals inward heats up as it heads toward the black hole and produces a steady stream of X-rays.