Planetary Environment Around a Pulsar

1. Planetary Environment Around a Pulsar David Dunkum, Jacob Houdyschell, Caleb Houdyschell, and Abigail Chaffins Spring Valley High School Huntington, WV Abstract: Pulsars are densely-packed, spinning neutron stars that are the remaining cores of massive stars that ended in a catastrophic supernova. Due to the extreme processes that these stellar objects are formed, it was believed that any planets orbiting it would have been annihilated by the explosive events of their creation or survive the intense conditions around a pulsar. In 1992, it was discovered that not only were planetary bodies possible around pulsars, an actual pulsar system (PSR 1257+12) was found by AleksanderWolszczan and Dale Frail with two bodies orbiting the pulsar. 162 pointings were analyzed to collect the necessary data, which is about 5670 plots. Out of the 5670 plots, three known pulsars were found. Finally, an orbiting body must survive the extreme magnetic fields a pulsar constantly emits. Many pulsars have such powerful magnetic fields that it warps the electron clouds of atoms into needle-like shapes less than 1% of their original size, rendering much of the chemistry of life impossible in close proximity to the star. To calculate the magnetic field strength (measured in Gauss) of a pulsar, the radius of the pulsar (R), the angle between the pulsar’s magnetic poles and it’s rotational axis (α), and the pulsar’s moment of inertia (I) must be determined. Since, like before, these values are not easily accessible, a “typical” pulsar’s values are used, which are 10 km, 900, and 1045 g cm2 respectively. These values, along with the pulsar’s period (P) and P-dot, which are how long in seconds it takes for one revolution and the rate of deceleration of the pulsar's angular velocity in revolutions per second per second, are then used to calculate the characteristic magnetic field using the following equation: Results: Conditions Around a Pulsar: Data Analysis: There are several aspects of a pulsar that make the environment around it particularly dangerous for orbiting bodies. One of the more obvious dangers to anything orbiting a pulsar is the intense radiation that it emits, especially along the two iconic jets that pulsars produce. This radiation, being so powerful, would have the effect of blasting away any atmosphere the orbiting planets could have possibly formed. Another danger to any orbiting body is the strong gravitational field that such a dense and massive object generates. Such a gravitational field has a specific area where the gravitational pull to the closest end of an orbiting body is much stronger than the farthest end, which tears the body apart. This zone is called the “Roche Limit” (d) which can be calculated with the primary object’s radius (RM), the primary object’s density (pM), and the orbiting satellite’s density (pm). Since there is no easily accessible data on the exact mass and radius of a pulsar to calculate density, the values of a “typical” pulsar, which are 1.4 solar masses (2.785 x 1030 kg) and 10 km respectively, are used. As for the theoretical orbiting body, the values of an Earth-like planet (mass = 5.972 x 1026 kg, radius = 6,371 km) are used. After calculating densities, the following equation is then used to calculate the Roche Limit: The three pulsars used for the calculations are: J1801-1417; J1719-1438; J1738+0333 Since many of the values used for the equations are based off of a “typical” pulsar and not each pulsar’s unique values, the results will end up being an approximation for each pulsar. Also, since the P-dot for each pulsar can only be determined exactly through years of observation, the value given on each pulsar’s prepfold plot is merely an estimate, leading to an approximate value as the final result. These results, although accurate, provide only a rough estimate of what these pulsars’ individual Roche Limits and magnetic fields actually are due to using generalized data. Overall, this shows how hostile pulsar’s can be for both orbiting bodies and for life as we know it possibly existing on the planets. With the intense solar radiation emissions, strong gravitational pull, and powerful magnetic field of these pulsars, any Earth-like planets orbiting them would be little more than barren terrestrials, with very little chance of life as we know it existing on their surfaces. Despite these extreme conditions, there is a possibility that some form of life could exist in an ocean deep inside of a planet that is warmed by tidal friction, similar to Jupiter’s moon Europa, thereby providing heat for life and shielding the ocean from the pulsar’s intense radiation. Such a possibility is remote though, since so many different variables must be exactly right to achieve this. Example of the Roche Limit