- The first planets discovered in 1993 were not orbiting a Sun-like star but a Neutron Star, a Pulsar. When a massive star goes supernova the explosion is expected to evaporate any existing solar system. How do we explain Pulsar Planets?
- Attachments : Supernova explosion.
- This Pulsar is a Neutron Star spinning at 161 revolutions per second. ( 9,660 rpm). The discovery was made using a radio telescope that detected the flashes from the electromagnetic jets streaming away from the Pulsar’s magnetic poles. The Neutron Star itself is only 20 miles in diameter. It’s spin was somewhat irregular. Its period was delayed and then advance on a recurring basis. Something was shifting the Neutron Star back and forth in a predictable sequence.
- When the best mathematicians were tasked as to what scenario would fit the observed data, they came up with two small nearby planet, a 3rd definite planet, and a 4th ultra- small planet orbiting the star.
- Of the 3 larger planets their orbits are 25 days, 67 days, and 98 days.
- Their sizes were 1/50th Earth size ( Moon-size), for one and 4 times Earth-size for the other two.
- A Pulsar is a collapsed core of a massive star that has gone supernova. Astronomers are surprised that a “ solar system” could survive such an explosion. By their calculations all of the Pulsar’s planets should have been obliterated.
- However, there they are, planets in circular orbits, remnants of a solar system belonging to a massive star. Maybe these remnants are the rocky cores of Jupiter-size planets that had their mantles blown away.
- It is hard to make sense of a scenario that these planets formed after the supernova explosion and after the Neutron Star was formed. One far fetched scenario is that a roving Neutron Star came too close to this Neutron Star and got pulled to pieces by the tidal forces. The debris formed a proto-planetary disk that eventually coalesced into the three planets. This is pure speculation, but, how else can you explain it?
- To make the mystery even more interesting another planetary system has sense been discovered in the year 2000 orbiting another Pulsar. PSR B1620-26 is a Pulsar binary system in the Constellation Scorpius, very near the bright star Antares, 12,400 lightyears away. The binaries are a Pulsar 16 miles in diameter and a White Dwarf 6,000 miles in diameter ( Earth-size).
- This system is the oldest planets discovered to date. Estimated to be 8 billion years old. Our Solar System planets are only 4.5 billion years old.
- Pulsars are not good solar parents. They deliver lethal X-rays and Gamma Rays to all their surroundings. This radiation would make mortal life impossible.
- Actually, the Earth was the first planet to be discovered and it just happens to be the right size and the right temperature orbiting the right star. How lucky can you get.
- What happens to a solar system, or even a companion star when a supernova explodes? Recently astronomers found a supernova remnant. A giant bubble of expanding gas and debris with everything inside consumed in the conflagration. The remnant is SNR-0509-67.5 in our neighboring galaxy the Large Megellanic Cloud. The remnant is judged to only 400 years old.
- The data makes astronomers believe that this Type 1a supernova was two White Dwarf stars orbiting each other until they got close enough to collide. Kaboom!!! But, this is different than astronomers thought Type 1a supernovae worked. It was always thought that there was one White Dwarf and a companion star in orbit. The White Dwarf was drawing gas from the companion until it reached exactly 1.4 Solar Mass. At that mass and gravitational force the electrons collapse into the nuclei. The atoms collapse. The star implodes. The implosion bounces off the core in a giant explosion. A Type 1a supernova.
- Since the mass of the explosion is always the same, 1.4 Solar Mass, the brightness of the explosion would always be the same. A peak luminosity of 10^10 Solar Luminosity with a linear decay in brightness over 300 days. This was a “ standard candle” that could be used to calculate distances accurately. In turn, astronomers could calculate the rate of expansion of the Universe.
- This discover of two White Dwarfs colliding, obliterating everything, with a different mass and Luminosity screws up all the calculations. They need to know which scenario applies before they can use the Chandrasekhar Limit of 1.4 Solar Mass in their calculation for Luminosity.
- Here is how the distance measurements are supposed to work once you have a light source of know Luminosity:
----------------------- Apparent Brightness = Luminosity // 4 * pi * r^2
-------------------- r = distance to the light source, the star
-------------------- Luminosity is known to be 3.8 *10^26 watts.
-------------------- Apparent Brightness is measured to be 10^-12 watts / meter^2
--------------------- 10^-12 = 3.8 * 10^26 watts / 4 * pi * r^2
--------------------- r^2 = 0.3 *10^38 meters^2
--------------------- r = 0.55 * 10^19 meters.
--------------------- One lightyear is 9.5*10^16 meters.
------------------- r = 580 lightyears distance to the star
- If the actual Luminosity is different than the distance calculation is different. The calculations for the rate of expansion of the Universe will be different. The astronomers are back to the drawing boards.
- Astronomy is a dynamic science. An announcement will be made shortly, stay tuned.
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707-536-3272, Tuesday, January 17, 2012
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