Much has been written about the discovery of a pulsar 50 million light-years away but too little about the instrument that did it — a space observatory known as XMM-Newton.

Solving the deep mysteries of the cosmos — black holes and galaxies — takes more than the usual space observatory. XMM-Newton does that from a vantage point of view in its orbit, which is a third of the way to the moon, where astronomers can have a good look at celestial objects.

Brightest, Most Distant Pulsar

XMM-Newton has seen NGC 5907 X-1 for several times for the past 13 years which was considered only as a massive black hole.

The European Space Agency, however, announced that the object is a very dense and rapidly spinning pulsar. Its luminosity is a thousand times brighter than what was thought before.

"Before, it was believed that only black holes at least 10 times more massive than our sun feeding off their stellar companions," said Gian Luca Israel of INAF-Osservatorio Astronomica di Roma, Italy.

Luca, the lead author of a paper published in Science journal on Feb. 20, said the source has displayed the fingerprints of a neutron star with its "rapid and regular pulsations" distinguishing itself from black holes.

"Only a neutron star is compact enough to keep itself together while rotating so fast," he explained.

The object as it turns out is the most distant pulsar detected so far. It is 50 million light-years away from the Earth.

Neutron Stars And XMM-Newton

XMM-Newton holds the record of detecting more X-ray sources than any other previous satellite. The biggest science satellite developed in Europe, it has the distinction of having the ultra-sensitive telescope mirrors in the world.

The high-technology space observatory is built to give astronomers better insight on neutron star by measuring its gravitational field from the light it emits.

A neutron star about the size of a sugar cube weighs more than a thousand million tons. Among the densest cosmic objects, they are the remnants of massive stars when they breathe their last in a supernova explosion.

During such explosion, most of the stellar matter is sent into space to become the building blocks of all that are in the universe.

Identifying the nature of matter in pulsars has been a challenge to scientists in the past. The key problem then was the absence of an instrument which can possibly look into star's mass-to-radius ratio to obtain its density.

With XMM-Newton, this ratio has been obtained by astronomers for the first time. Subsequently, clues on what pulsars are made of are made available in what scientists believed as a "key first step" in determining its compactness.

No other science satellite had achieved what XMM-Newton has achieved by far.

"[The discovery] sets a new record for XMM-Newton, and is changing our ideas of how such objects really work," ESA's XMM-Newton project scientist Norbert Schartel said.

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