Triangle (constellation)
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Constellation triangle |
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| Latin name | Triangulum |
| Latin genitive | Trianguli |
| Abbreviation | Tri |
| Right ascension | 01 h 31 m 28 s to 02 h 50 m 40 s |
| declination | + 25 ° 36 ′ 18 ″ to + 37 ° 20 ′ 50 ″ |
| surface | 131.847 deg² rank 78 |
| Completely visible | 90 ° N to 53 ° S |
| Observation time for Central Europe | June - (Oct.) - March |
| Number of stars brighter than 3 mag | 1 |
| Brightest star (size) | β triangles (3.00) |
| Meteor streams |
no |
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Neighboring constellations ( clockwise from north ) |
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| swell | IAU , |
The constellation triangle ( Latin triangulum ) is a small constellation in the northern fixed star sky. In the evening it can be seen south of the constellation Andromeda from September to March.
description
The triangle is an inconspicuous constellation made up of three stars. Only two reach the 3rd size class .
The triangle lies between the Andromeda and the Aries (Aries). Its most famous celestial object is the Triangle Nebula (M33), which, as a companion to the Andromeda Nebula, is one of the closest spiral galaxies to us.
In the southern hemisphere there is a counterpart of the triangle - the southern triangle (Triangulum Australe).
history
The triangle is one of the classic 48 constellations of antiquity described by Ptolemy . The Greeks called it Trigonon or Deltoton or Delta. The Greeks also saw the Nile Delta in this constellation, from which the name Gift of the River is derived. The triangle also stood for Sicily , which was also called "Trinacria" because of its shape. Sicily was dedicated to Demeter and Persephone was kidnapped from here to Hades .
The Danzig astronomer Johannes Hevelius created the constellation "Triangulum Minor" (Small Triangle) from other faint stars in the vicinity of the triangle , which however did not prevail.
Celestial objects
Stars
| B. | F. | Names or other designations | Apparent brightness (mag) | Lj | Spectral class |
|---|---|---|---|---|---|
| β | 4th | 3.00 | 124 | A5 III | |
| α | 2 | Elmuthalleth , Metallah, Mothallah, Caput Trianguli | 3.42 | 64 | F6 IV |
| γ | 9 | 4.03 | 118 | A1 Vnn | |
| δ | 8th | 4.84 | 35 | G0 V | |
| ι | 6th | 4.94 | 305 | F4 V | |
| 14th | 5.15 | 392 | K5 III | ||
| 7th | 5.25 | 293 | A0 V | ||
| 10 | 5.29 | 350 | A2 V | ||
| 12 | 5.29 | 155 | F0 III | ||
| R trianguli | 5.3 to 12.6 | 1300 | M4 IIIe-M8e / A5 | ||
| 15th | 5.38 | 204 | M3 III | ||
| ε | 3 | 5.50 | 370 | A2 V | |
| 13 | 5.89 | ||||
| 5 | 6.24 | 480 |
Beta Trianguli , the brightest star in the triangle, is 124 light years distant binary star . The main star has four times the diameter and 70 times the mass of our sun. The companion star is about the size of our sun. Both stars are 0.3 AU apart and orbit each other in just 31.8 days. Due to the small angular distance, they cannot be observed in the telescope.
α Trianguli , the second brightest star in the constellation, is a star 64 light-years away. It is also a close binary star system that cannot be observed in the telescope. The main star has 1.5 times the mass and 13 times the luminosity of our sun. The distance between the stars is only 0.04 AU, they orbit each other in 1.74 days.
The name Elmuthalleth is of Arabic origin and means "triangle". The Latin name "Caput Trianguli" means "point of the triangle".
Gamma Trianguli is a bluish-white star 118 light-years away and twice the diameter of the Sun. The star rotates around its own axis in just 12 hours.
Double stars
| system | Apparent brightness (mag) | distance |
|---|---|---|
| ι | 5.2 / 7.0 | 3.6 " |
| 15th | 5.4 / 6.8 | 143 " |
ιTrianguli ( mostly only referred to as 6 Tri in newer star catalogs ) is a binary star system 305 light years away. The two yellow and whitish shining stars can already be observed with a small telescope.
15 Trianguli is a binary star system 150 light years away. The main star is a deep red giant star of the rare spectral class M4. His companion is a whitish star of the spectral class A5. The two stars are very far apart with a distance of 143 arc seconds and can be separated with a small telescope.
Variable stars
| object | Apparent brightness (mag) | period | Type |
|---|---|---|---|
| R. | 5.3 to 12.6 | 266.9 days | Mira star |
R Trianguli is a variable star of the Mira type, 1300 light-years away , which changes its brightness strongly over a period of 266.9 days. During the maximum brightness it can be seen with the naked eye, at a minimum you need a medium telescope.
Messier and NGC objects
| Messier (M) | NGC | other | Apparent brightness | Type | Surname |
|---|---|---|---|---|---|
| 33 | 598 | 11 | Galaxy | Triangle Nebula, Triangulum Galaxy | |
| 604 | Emission nebula | ||||
| 672 | Galaxy | ||||
| 925 | Galaxy | ||||
| IC 1727 | Galaxy | ||||
| 3C 48 | quasar |
In the triangle is the Triangle Nebula (M33), at a distance of 2.3 million light years after the Andromeda Nebula, the second closest large galaxy . The Triangle Nebula, the Andromeda Nebula and our Milky Way together with a number of smaller companion galaxies form the Local Group . The Triangular Nebula, discovered by Charles Messier in 1764 , is difficult to observe due to its low surface brightness. On a moonless night, away from artificial light sources, it can already be seen as a misty spot in prism binoculars . Spiral arms are visible in larger telescopes.
