Astronomy Current Affairs - 2019
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Scientists have discovered an asteroid named Oumuamua (or (514107) 2015 BZ509) nestling in Jupiter’s orbit that had migrated from another star system. It makes it first known permanent immigrant to our solar system. It confirms suspicions of scientists’ that asteroids from other stars have arrived in our solar system. The asteroid Oumuamua was actually first discovered in 2014, but after four years of tracking it, scientists were able to determine that it had arrived in our solar system some 4.5 billion years ago – just as Earth was beginning to form.
All planets in our solar system travel around Sun. But this asteroid moves in opposite direction, referred to as retrograde orbit and is in same path as Jupiter. This shows that it is from different solar system. If it was native of our solar system, it might have same original direction as all of other planets and asteroids, inherited from cloud of gas and dust that formed them.
Asteroid immigration from other star systems occurs because Sun initially formed in tightly-packed star cluster, where every star had its own system of planets and asteroids. The close proximity of stars, aided by gravitational forces of planets, help these systems attract, remove and capture asteroids from one another solar system.
Scientists using Kepler 2 telescope have discovered hot, metallic, Earth-sized planet named K2-229b orbiting dwarf star located 260 million light years away. They had employed Doppler spectroscopy technique also known as ‘wobble method‘ to discover and characterise this faraway planet.
K2-229b planet is almost 20% larger than Earth but has mass which is over two-and-a-half times greater. It is located very close to its host star (0.012 AU, around a hundredth of the distance between Earth and Sun), which itself is medium-sized active K dwarf in Virgo Constellation.
K2-229b orbits its star every fourteen hours. Its day side temperature reaches over 2000 degrees Celsius. Scientists calculated size, position and mass of K2-229b by measuring radial velocity of star and finding out starlight ‘wobbles’ during orbit, due to gravitational tug from planet, which changes depending on planet’s size.
K2-229b has same high density that of Mercury-like planets. It is also innermost planet in system of at least three planets, though all three orbit much closer to their star than Mercury.
The dense, metallic nature of K2-229b has numerous potential origins. The one hypothesis is that its atmosphere might have been eroded by intense stellar wind and flares, as it is so close to its star. Another possibility is that K2-229b was formed after huge impact between two giant astronomical bodies in space billions of years ago – much like theory that Moon was formed after Earth collided with body size of Mars. K2-229b is similar to Mercury, knowing more about it can potentially give more clues of formation our planets in our own solar system.