![]() Pulsar planets are not good places to raise a family. ![]() It was celebrating itsĨ billionth birthday when our Sun first clicked on and while Earth was still a ball of fiery goo. Is also the oldest planet ever discovered. Since globular cluster M4 is ancient, with all its stars and planets born together more than 12 billion years ago, scarcely a billion years after the Big Bang, this pulsar-orbiting world The planet circles them both! To clear them in a stable fashion, its orbit is large, and its “year” is a period of exactly one Earth century. The system consists of two collapsed stars in a tight orbit - a pulsar 16 miles (26 km) wide and a white dwarf the size of Earth. Pulsar PSR B1620–26 is a binary star in the beautiful globular cluster M4 right near Antares, 12,400 light-years away. In 2000, astronomers found an even more remarkable pulsar planet, but this time in the constellation Scorpius. If so, their survival and continued existence is indeed a puzzle. The neat ordering of these coplanar worlds (they all lie in the same pancake-like flat plane) strongly suggests they were created from scratch in an original protoplanetary disk, like the genesis of our solar system. Some theorists argue that these planets must have formed after the supernova blast, but there are major troubles making sense of that. They simply don’t build them like that anymore. Frankly, how even those withstood a nearby supernova blast is no small mystery to try and explain. They each must have started out as giant Jupiter-class gas objects, and the intense explosion blew most of their bodies away until only their rocky cores remained. No doubt these planets are remnants - on-sale damaged goods. Yet here they are, orbiting in well-behaved near-circular paths. There should be nothing left, not even dust. A supernova should obliterate any planets around it. ![]() After all, a pulsar is the collapsed core of a massive sun that went kablooey in an awesome supernova - after becoming bright enough to outshine its entire parent galaxy. The existence of pulsar planets took everyone by surprise. (We can’t count Pluto anymore now that it’s considered a dwarf planet. And there you have the first-ever planets found since Neptune’s discovery in 1846. The “years” it takes this trio to orbit their pulsar sun last 25, 67, and 98 Earth days. Of the three definite pulsar planets, one weighs 1/50 Earth mass (not too dissimilar to our Moon), while the other two have about 4 Earth masses apiece. What size object, and at what orbital distance and period, would do the job? In this case, the exact fit could be achieved if this pulsar is orbited by two small nearby planets later refinements added a third definite planet, as well as a potential ultra-teensy fourth. Obviously something was yanking the tiny star back and forth in a predictable fashion. In 1991, astronomers detected just such a changing period in PSR B1257+12’s spin and got to work deciphering why the signals were alternately delayed and then advanced. If the rate changes, something interesting must be going on. What’s valuable for astrophysicists isn’t the ultra-fast spin but the Teutonic regularity. These super-collapsed neutron stars are always less than 20 miles (32 kilometers) wide, with wild amusement park spins of dozens or even hundreds of rotations per second. Electromagnetic energy streaming away from their magnetic poles sweeps around like a lighthouse beam, producing flashes with each rotation. Instead, the radio telescope in Arecibo, Puerto Rico, with its 1,000-foot (305 meters) collecting area, carefully monitored radio signals from pulsars. No telescope was used in the discovery - at least not one that gathers visible light. We’re excited to announce Astronomy magazine’s new Space and Beyond subscription box – a quarterly adventure, curated with an astronomy-themed collection in every box. It spins 161 times a second and, like all pulsars, is a neutron star, the smallest and densest visible object in the universe.īringing the universe to your door. Its name is PSR B1257+12, and it lies in the constellation Virgo the Virgin at a distance of 980 light-years. Three years earlier, astronomers Aleksander Wolszczan and Dale Frail announced they had found not one but two planets - and these orbited the oddest kind of star in the universe, a millisecond pulsar. What was the first planet found beyond our solar system? Astro-geeks usually cite the discovery of the Jupiter-mass planet circling the naked-eye star 51 Pegasi in 1995.
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