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Exoplanetary Scratchpad

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Ain, also called Epsilon Tauri, is the brightest star in the Hyades Cluster (one of four giant stars in the cluster) and the first found to have a planet. Its name means "Eye" as in the Eye of the Bull, dimmer than Taurus' other eye, Aldebaron, and is 147ly away. The star is a 12.7 RS Red Clump Orange Giant and is the most massive one (2.7 MS) found at the time to host a planet. It used to be a class A main sequence star. The 7.8 MJ super Jovian, Amateru, orbits at 2 AU in a somewhat eccentric orbit. Since no other giant planets were detected in any of the other dwarf stars, that suggests giant planets are more common around giant stars. The age of the system was better known than any others at 625 MY, since it was a member of the cluster, and this put a precise upper limit for giant planet formation times. The harsh environment of the cluster would make planet building by core accretion difficult. One nearby star would appear as bright as Venus, while Ain would be as bright as the full moon from it. The star would appear 7 times as large as the Sun does from the planet. One of the first 20 exoplanet systems allowed to be given common names by the IAU. The planet is named after a Japanese sun goddess, or a shrine dedicated to her.

My Thoughts[]

I wish I could find out how bright those other giant stars in the cluster appear from Ain's planet. A virtual reality look through the sky there would be cool. If Ain appears as bright as a full moon from its nearest neighbor, the other ones have got to appear at least a decent of a fraction from it.


It is in the Hyades cluster, which is associated with "weeping sisters", so something related to tears would be appropriate. It is also associated with rain. It is also the "eye" of the bull, so something related to eyes or bulls would be appropriate. It was also discovered by a Japanese team, so Japanese name would be appropriate.

  • Namida - The meaning of "Namida" is a tear in Japanese. And also,we think it has a meaning of beautiful thing which come from the host star-Ain. Ain is a exoplanet discovered by Japanese, which means "eye".

A simple Japanese word, how boring, but it's probably not already an asteroid name.

  • Kanenone - Hyades Cluster is called “Tsurigane Boshi” in Japan. “Tsurigane” means “temple bell,” and “Boshi” means “star.” Just like church bell in the West, temple bell is indispensable to everyday life in the East for a long time...Essentially means ring of bell

Cool twist to Japanese lore, but it has nothing to do with eyes, so it doesn't quite seem right

  • Amaterasu - Amaterasu is a goddess of the sun in Japanese myth. She was born from left-eye of god Izanagi, when he was washing up his eyes. We propose this name because the system is left-eye of Taurus and found at Japan.

I like it, but it's already an asteroid name, so probably wouldn't work

Ain System Web Pages[]

Ain System In the News[]

Discovery (2007)[]

One of the Top 20 Exoplanetary Systems First Up For Naming (May 2015)[]

See Also[]