Rogue planets: hunting the galaxy's most mysterious worlds

[Admin]

These planets, including Earth, benefit from the star’s warmth and light.

Rogue planets: hunting the galaxy's most mysterious worlds : Read more

 

[rod]

The article reported "One such “micro-lensing” event was attributed to the new rogue planet, called OGLE-2016-BLG-1928. The sighting of the amplification of the light from an inconspicuous star in the dense inner regions of the Milky Way galaxy only lasted 42 minutes."

Here is a paper on the object reported, 'A Terrestrial-mass Rogue Planet Candidate Detected in the Shortest-timescale Microlensing Event', https://iopscience.iop.org/article/10.3847/2041-8213/abbfad, "Abstract Some low-mass planets are expected to be ejected from their parent planetary systems during early stages of planetary system formation. According to planet formation theories, such as the core accretion theory, typical masses of ejected planets should be between 0.3 and 1.0 M ⊕..."

My observation. The mass of this lens event is not well determined, including the distance measurement from Earth. The arXiv paper says "If the lens is located in the Galactic disk (pirel ~ 0.1 mas), then M ~ 0.3Mearth (which is approximately three Mars masses). The lens located in the Galactic bulge (typically pirel ~ 0.016 mas) would be more massive (M ~ 2 Mearth)...The discovery of OGLE-2016-BLG-1928 demonstrates that current microlensing surveys are capable of finding extremely -short-timescale events. Although the mass of the lens cannot be unambiguously measured, properties of the event are consistent with the lens being a sub-Earth-mass object with no stellar companion up to the projected distance of ~ 8 au from the planet. Thus, the
lens is one of the best candidates for a terrestrial-mass rogue planet detected to date. This population of low-
mass free-floating (or wide-orbit) planets may be further explored by the upcoming microlensing experiments."

Rogue planets floating around lose in the Milky Way is very interesting and indicates the model(s) for planet formation via gas cloud collapse and protoplanetary disk accretion is a messy paradigm for creation. Recent reports supporting SETI promoting 300 million or more habitable earth like worlds in the Milky Way, need some rethinking in light of free-floating rogue planets, likely reduces the quantity *created* https://skyandtelescope.org/astronomy-news/kepler-retrospective-earth-like-planets-common/