The Absolute Cosmos: Astronomers detected a rogue Earth mass planet in the Milky Way

In the last few decades scientists have learned a lot about exoplanets. They have detected thousands of them and expect that almost every star hosts planets around it.

With more accurate data coming day by day, scientists have been constantly updating and refreshing the theories and models of planetary system formation (and evolution).

The updated models show that there could be huge number of rogue planets that got ejected from their planetary systems.

There could be billions of rogue planets floating freely through the interstellar space in our Milky Way galaxy. These objects are not gravitationally bound to any star. Rogue planets are hard to detect as they do not emit their own light.

Two organisations, OGLE (Optical Gravitational Lensing Experiment) and KMTN (Korean Microlensing Telescope Network) are working on detecting these nomad planets.

And now, a research team including scientists from both the organisations have detected a low mass rogue planet. The distance of the planet from Earth is not confirmed and there seems no star near it.

The newly discovered celestial wanderer has been named “OGLE-2016-BLG-1928” and it was detected using microlensing technique.

During the early days of a planetary system formation things are pretty chaotic. Gravitational interactions between the planets and star can sometimes toss small planets out into the deep space.

Scientists states that, “planet formation theories, for instance core accretion theory demonstrates that — ejected planet’s mass should be between 0.3/1.0 Earth masses”.

Since the planet emits no light of its own, so scientists used gravitational microlensing to detect it. Basically microlensing allows the scientists to study the objects which emits little to no light.

Microlensing essentially requires two things — a faraway light source (generally a star) and a nearby object massive enough to react like a lens and bend the light from the light source.

In this situation, the low mass rogue planet acts as the lens. Scientists can study a lot by observing how much light from the faraway light source is getting affected by the foreground object.

A moderately small object/body like a low mass planet does not bend lot of light and also the duration is short.

In their research, scientists records the various ways on how these planets can become a rogue -

  • Planet-planet scattering.
  • Interactions between giant planets which contributes to orbital disruption of smaller planets.
  • Interactions between the binary/trinary systems and star clusters.
  • Stellar fly-bys.
  • Evolution of the parent star past the main sequence.

The Cosmos is all that is or ever was or ever will be…

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