Triangle (constellation)

History

The Triangle appeared already in the list of the 48 constellations indexed by Ptolémée in its Almageste , one of the rare ancient constellations (with the Balance) not to come from a myth and the only one which is described by a geometrical figure .

At the time Greek, this constellation bore the name of Deltotron , the Delta (probably that of the Nile), identified by the Greek letter Δ. The Roman preserved this name by naming it Deltotum .

The Astronome Johannes Hevelius also created a Petit Triangle just beside this one (which it logically called the Grand Triangle ). They were molten in only one by Friedrich Argelander in 1843 during the publication of sound Uranometria Nova .

Observation of stars

The Triangle is a weak constellation (mag 4) but collected well, and its location does not pose a particular problem since the conditions of visibility are sufficient.

It is located under the diagonal of Andromède, between the leg of Andromède and stars of the Bélier.

It is of hardly interest other than its curious form.

Principal stars

α Trianguli

α Trianguli (also known under various traditional names like Metallah, Mothallah, Close-cropped Al Muthallah, Elmuthalleth, Caput Trianguli and Atria) is not the most brilliant star of the constellation, but its position at the top of the Triangle (its name means that in precisely Arab) with conduit Johann Bayer to give him the designation α.

Of Magnitude connect 3,41, it is a under-giantess white-yellow distant of 64 light-years, 13 times more luminous than the Sun and 1,5 times more massive than this one.

Alpha Trianguli is a star doubles: his/her companion, indistinguishable to the Telescope, turns around it in only 1,74 days and must be distant only of approximately 0,04 ua.

β Trianguli

β Trianguli, with a magnitude connects of 3,00, is the most brilliant star of the constellation of the Triangle. It is a under-giantess, 4 times larger than the Sun, 70 times more brilliant, surrounded by a disc of dust.

It is also a double star, his/her companion (similar to the Sun) orbiting with 0,3 ua on average in 31,8 days.

γ Trianguli

γ Trianguli, the third star of the constellation (magnitude 4,03), closes the Triangle. It is a white star, approximately 2 times larger than the Sun, which extremely quickly turns, in 12:00, at least with 200 km/s with the equator.

γ Trianguli, δ Trianguli (magnitude 4,84) and 7 Trianguli (magnitude 5,25) appear very close on the vault of heaven. Actually, δ Trianguli is located at 35 years light of us (thus rather near), γ Trianguli with 118 and 7 Trianguli with 293. They do not have thus anything to see one with the other.

Other stars

δ Trianguli is a double star are the two components resemble the Sun much. They are separated by only 0,1 ua.

ι Trianguli is also a double star, formed by a yellow star and the other blue one. Each one of them is again double.

R Trianguli is a variable star of type Mira (ο Ceti) and oscillates between the magnitudes 5,30 and 12,6 over one 266,9 days period.

Celestial objects

The constellation of the Triangle extremely precisely contains the Spiral galaxy M33, named Galaxie of the Triangle . It is about the third larger galaxy of our local Groupe (two others being the Milky Way and the Galaxie of Andromède).

This constellation also lodges the Nébuleuse NGC 604 (located in M33), the greatest area of Hydrogène Ion ized which one knows, of a 1.500 years diameter light, the open cluster C 0147+270, the spiral galaxy NGC 925 like NGC 672 and IC 1727, two Galaxie S distant of approximately 18 million years light, but separated by only 88.000 years light. The Quasar 3C 48, in the north of the constellation, was one of the first to have been discovered.

See too

List of stars of the Triangle

Random links: