By: Bhavani Shankar
August 5th, 2022
Photograph by European Space Agency
Astronomers have for the first time discovered the heaviest known neutron star, an object that forms when the core of a massive star undergoes gravitational collapse at the end of its life. The star is spinning so fast that it has shredded and consumed nearly the entire mass of its companion star to emerge as the heaviest known.
The newly discovered neutron star weighs roughly 2.35 times the mass of the sun, and if it gets heavier could collapse and form a black hole. The star has been named black widow an analogy to the tendency of female black widow spiders to consume the much smaller male after mating.
The one described by the researchers was supposedly born with the usual mass of a neutron star, about 1.4 times that of our sun, and is a highly magnetized type of neutron star called a pulsar that unleashes beams of electromagnetic radiation from its poles. As it spins, these beams appear from the perspective of an observer on Earth to pulse - akin to a lighthouse's rotating light.
"Since we don't yet know how matter works at these densities, the existence of this neutron star is an important probe of these physical extremes," Mr. Romani said.
The neutron star, residing in our Milky Way galaxy in the direction of the constellation Sextans and formally named PSR J0952-0607, is located roughly 20,000 light years from Earth, Romani said. A light year is the distance light travels in a year, 5.9 trillion miles (9.5 trillion km). The researchers studied it using the Keck I telescope in Hawaii.
Its companion star has been stripped almost bare, losing perhaps 98% of its mass to the black widow, leaving it at about 20 times the mass of our solar system's largest planet Jupiter — a far cry from its original size.
"It has swallowed nearly a full sun's worth of mass without yet becoming a black hole. So it should be just on the edge of black hole collapse," said Roger Romani, director of Stanford University's Center for Space Science and Astrophysics.
This black widow system also has a third companion orbiting much farther out, at a distance of roughly 600 astronomical units, or AUs (an AU is the distance between Earth and the sun). While the primary pulsar and brown dwarf orbit each other every 62 minutes, the third partner star orbits the tight pair every 10,000 years.The scientists also point out that this is the first black widow system discovered using optical light. "The population of black widows we've been finding so far with other wavelengths of light, such as X-rays, gamma rays, and radio waves, is probably biased because we haven't been catching all of them," says Kevin Burdge, a postdoctoral scholar at MIT who performed the research while at Caltech. "Now we have a new lens through which we can identify these systems,” says Burdge.
What is black widow pulsar?
When the dead star continuously pulls in matter from the living star, the resultant reaction is a release of energy. On Earth, we receive these energies from far away stars as radio waves. But instead of being continuous energy, they pulsate at a specific frequency. For instance, the black widow in discussion here, named J0610-2100, sends a radio frequency every 4 milliseconds. This specific characteristic is only seen in this specific star system and is called black widow pulsar.
So what could it mean to us and the research of space?
Our universe is filled with unsolved mysteries and this particular black widow star system has emerged as one of the biggest mysteries to solve. A dead star is sending pulsars (radio signals from a star that cannot be seen) to Earth. These pulsars are being sent every 4 milliseconds. But the pulsars do not mean any harm to our planet. On the contrary, they can reveal secrets about the space-time continuum and unanswered questions about our own star. What is a black widow star system? And how exactly can a pulsar be so crucial to us?
There are two interesting factors with this black widow star system. Researchers have not seen any star system with this level of predictability. As the other star eclipses the dead star, the pulsars become irregular and show weird glitches. There are almost none present in this one. Further, with just a 4-millisecond gap, it is also very frequent. These two factors make it very easy to study one of the rarest phenomena in the world. Something that directly ties into not only our Sun but the entire space-time continuum - gravitational waves. Researchers believe that these steady black widow pulsars will help them in understanding these rare waves that can dictate the possibility of opening the gates to another dimension.
References:
“A Black Widow Star Can Unlock the Secrets of Our Sun.” HT Tech, 1 Apr. 2022, tech.hindustantimes.com/tech/news/a-black-widow-star-can-unlock-the-secrets-of-our-sun-71648787855669.html.
Desk, India Today Web. “Meet 'Black Widow': The Heaviest Neutron Star Eating Its Own Mate.” India Today, 29 July 2022, www.indiatoday.in/science/story/meet-black-widow-the-heaviest-neutron-star-eating-its-own-mate-1981488-2022-07-29.
Garner, Rob. “'Spidery' Pulsars Consume Their Mates.” NASA, NASA, 24 Feb. 2015, www.nasa.gov/content/goddard/with-a-deadly-embrace-spidery-pulsars-consume-their-mates.
Reuters. “Gluttonous Cosmic 'Black Widow' Is Heaviest-Known Neutron Star.” Return to Frontpage, The Hindu, 29 July 2022, www.thehindu.com/sci-tech/science/gluttonous-cosmic-black-widow-is-heaviest-known-neutron-star/article65699744.ece.
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