Alpha Trianguli

α Trianguli
Triangulum is just above Aries; with alpha and beta Arietis in your field of view move two binocular fields north: Alpha Trianguli.

Despite its seeming insignificance, because of its distinctive shape Triangulum has been around a long time. The Greeks called the three stars alpha, beta, and 12 Trianguli ‘Deloton’ (Δελοτον).

In the seventeenth century Hevelius invented the constellation Triangulum Minor, taking 12 Trianguli away to form a smaller triangle (formed from 6, 10, and 12 Tri). which in fact do make a nice asterism).
     At the same time the original triangle was scaled down to a thinner version: alpha, beta, and gamma which some sky charts show as the constellation's asterism.

These various configurations are compared here.

A particular star of interest here is 6 Trianguli (sometimes called iota). This pleasant binary goes under the name Struve 227 — a bright yellow primary with a blue companion: 5.3, 6.7, 69º, 3.8".

About a half a degree to the east of 6 Tri is Struve 232: 7.8, 7.9; 66º, 6.6".

M33 is the noted Pinwheel Galaxy. Click on M33 on the map for its details.


One binocular field north of alpha brings in beta, which is the brightest star in the constellation at 3.0 magnitude.

In this field to the southwest is epsilon Trianguli, a binary (Struve 201) with a very faint companion: 5.4, 11.4; 119º, 4.2".

Move half a binocular field east for R Trianguli, a Mira-type variable which may attain naked-eye visibility (around 5.4) every 266 days before dipping down around 12.6.
     Its last recorded maximum was 5 February 2014; just subtract three months for every year thereafter to estimate its future maxima.

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