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111 Tauri

V1119 Tauri, Gliese 201 (B component)

111 Tauri is a bright yellow star in eastern Taurus, lying directly northward of Bellatrix in Orion. This is a main sequence star, somewhat more luminous and larger than the Sun, and with the higher temperature of an F-type bright yellow star. This is a binary system, with the primary star having a less massive orange companion, designated Gliese 201, orbiting at a distance of some 1,500 AU (or more than fifty times Neptune's distance from the Sun).

Imagery provided by Aladin sky atlas

The F-type primary star is a variable of the BY Draconis type, rotating rapidly on its axis over a period of 3.5 days (some seven times more rapidly than the Sun). Its variability is caused by patterning on the chromosphere of the star itself, and so the star's brightness changes as it rotates. The effect is not perfectly periodic, but increases in brightness are seen over periods of three to four days, approximately matching the star's rotation period.

The motion of 111 Tauri through the Galaxy suggests that it belongs to the Hyades Moving Group, sharing an origin in the distant past with the Hyades cluster that forms the 'face' of Taurus the Bull, though it now lies some way from the main cluster in the sky. It is also rather closer to the Sun than most the stars in the Hyades, at a distance of some 48 light years.


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