The Magnificent Seven is the informal name of a group of isolated young cooling neutron stars at a distance of 120 to 500 parsecs from Earth.
[1] These objects are also known under the names XDINS (X-ray Dim Isolated Neutron Stars) or simply XINS.
[2] The first to fit this classification was RX J1856.5-3754, which was discovered by Walter et al. in 1992, and confirmed as a neutron star in 1996.
[8] The Magnificent Seven represent a large class of young neutron stars with many properties different from normal radio pulsars.
There are other types of young isolated neutron stars which are different from standard radio pulsars, such as soft gamma repeaters, anomalous X-ray pulsars, rotating radio transients, and central compact objects in supernova remnants.
Distance estimates to other sources can be found in Posselt et al. (2007)[11] Population synthesis studies[12] show that the Magnificent Seven are related to the Gould Belt, a local group of stars with an age of about 30–50 million years formed by massive stars.
This means that the Magnificent Seven-like objects may be one of the most typical young neutron stars with a galactic birth rate larger than that of normal radio pulsars.
Although their origin is not clear yet (see Haberl (2006)[13] for references and more detailed description of the results), it is almost certain that the stars' strong magnetic field plays a fundamental role in their formation.
At present, two main explanations for their origin have been suggested: either proton cyclotron resonances or atomic transitions in light elements.
The holy grail of neutron star astrophysics is the determination of the equation of state (EOS) of matter at supra-nuclear densities.
The most direct way of constraining the EOS is to measure simultaneously the neutron star mass and radius.
Reality is somewhat more complicated, but this oversimplified analysis captures the essence of what is needed in order to measure the neutron star radius: distance, flux and surface temperature.
Their clean thermal emission, unmarred by contamination from magnetospheric activity, a surrounding nebula or supernova remnant, makes these sources ideal targets for such a study.