Blanet Explained

A blanet is a member of a hypothetical class of exoplanets that directly orbit black holes.^[1]

Blanets are fundamentally similar to other planets; they have enough mass to be rounded by their own gravity, but are not massive enough to start thermonuclear fusion and become stars. In 2019, a team of astronomers and exoplanetologists showed that there is a safe zone around a supermassive black hole that could harbor thousands of blanets in orbit around it.^{[2] [3]}

Etymology

The team led by Keiichi Wada of Kagoshima University in Japan has given this name to black hole planets.^[4] The word is a portmanteau of black hole and planet.

Formation

Blanets are suspected to form in the accretion disk that orbits a sufficiently large black hole.^{[3] [5]}

Possible candidates

• The unconfirmed extragalactic planet M51-ULS-1b.^[6]
• The unconfirmed planet or brown dwarf, IGR J12580+0134 b, being disrupted by a supermassive black hole.^{[7] [8]}

In fiction

• In the two episodes "The Impossible Planet" and "The Satan Pit" (both 2006) of the British television series Doctor Who, the plot of the episode takes place on the titular “impossible planet”, a barren blanet called Krop Tor orbiting a black hole called K37 Gem 5.
• In Interstellar (2014), two of the 3 terrestrial planets orbiting supermassive black hole Gargantua are proper blanets. The other one orbits a main-sequence star named Pantagruel.

References

1. Web site: Letzter. R.. 6 August 2020. Thousands of Earthlike 'blanets' might circle the Milky Way's central black hole. 2020-08-08. Space.com.
2. Wada. K.. Tsukamoto. Y.. Kokubo. E.. Planet Formation around Supermassive Black Holes in the Active Galactic Nuclei . The Astrophysical Journal. 886. 2. 26 November 2019. 107. 10.3847/1538-4357/ab4cf0. 1909.06748. 2019ApJ...886..107W. free.
3. Wada. K.. Tsukamoto. Y.. Kokubo. E.. Formation of "Blanets" from Dust Grains around the Supermassive Black Holes in Galaxies. The Astrophysical Journal. 2021. 909. 1. 96. 10.3847/1538-4357/abd40a. 2007.15198. 2021ApJ...909...96W. 220870610. free.
4. Web site: Starr. M.. We Have Ploonets. We Have Moonmoons. Now Hold Onto Your Hats For... Blanets. 3 August 2020. 2020-08-08. ScienceAlert.
5. Web site: Greene. T.. 2020-08-04. Scientists: What if black holes had a safe zone where little planets could live? Let's call them 'blanets'. 2020-08-08. The Next Web.
6. Web site: Chandra Sees Evidence for Possible Planet in Another Galaxy - NASA . 2024-08-07 . en-US.
7. Web site: Martin . Pierre-Yves . 2016 . Planet IGR J12580+0134 b . 2024-11-03 . exoplanet.eu . en.
8. Lei . Wei-Hua . Yuan . Qiang . Zhang . Bing . Wang . Daniel . 2016-01-01 . Igr J12580+0134: The First Tidal Disruption Event with an Off-Beam Relativistic Jet . The Astrophysical Journal . 816 . 1 . 20 . 10.3847/0004-637X/816/1/20 . free . 0004-637X. 1511.01206 .