Walk 1: Andromeda and Triangulum – astronomia-iniciacion.com

Walk through the sky of Andromeda and Triangulum

This walk can be observed from both hemispheres. There are many interesting objects in this area, among which the Andromeda and the Molinillo galaxy stand out. The Andromeda galaxy is the furthest object visible to the naked eye. Of course, for this, we need to leave the city.

The darker the sky, the better. But you do not need as much darkness, but rather, know where it is located and look out of the corner of your eye and not in front, because with this area you can see weaker objects better. Of course, it looks much better with the help of binoculars and much better with a telescope, even if it is small. This galaxy is known since ancient times.

By placing the pointer over the image you can magnify it with the magnifying glass. With the mouse wheel you can enlarge or decrease the size of the magnifying glass field.

Let’s see some of the objects visible in this area.

1 Alpheratz (α Andromedae). This star marks one of the corners of the Pegasus square, so it is sometimes also called Delta Pegasi. It is a bluish-white double star of magnitude between 2.02 and 2.06. It is α Andromedae, making it the brightest star in the Andromeda constellation. It is 97 light years from the Solar System. With a telescope of 200 mm or more, it is possible to see his companion, of magnitude 11.3.

2 Andromeda Galaxy (M31). To locate it we can use as reference the stars β Andromedae and μ Andromedae. As I said before, it is the farthest object that can be seen with the naked eye. When we observe it, we are looking at 2,200,000 light years. It is a large and bright object. We need dark sky to see it with the naked eye. It appears like a cottony cloud. With telescope, low power eyepieces are preferable, to be able to see it whole. Otherwise, we can only see its core. In the year 1924 Hubble showed that M31 was not part of the Milky Way. To do this, he compared the luminosity of the Cepheid variables in M31 and the Milky Way, and found that they were much weaker in M31 because they are much farther away.

3 M110 (NGC 205). It is a satellite elliptical galaxy of M31 and belongs to the Local Group. It is about 2,690,000 light years from Earth and it has a magnitude of 8, so it can not be observed with the naked eye. In a 100 mm telescope it appears as an elongated spot brighter by its nucleus. It is the last object on the list of Charles Messier .

4 M32 (NGC 221). It is an elliptical galaxy near M110. In 100 mm telescopes it appears as an oval spot of light. With larger telescopes it looks even better.

5 R Andromedae. It is located southwest of M32. It is a long-term Mira type variable, ranging from magnitude 5.3 to 15 in 409 years. Sometimes it is visible with binoculars, but when it is in its minimum magnitude it is still difficult to see it with 200 mm telescopes. To the west of R are the stars θ Andromedae, σ Andromedae and ρ Andromedae forming a triangle that helps locate the star when its magnitude is minimal.

6 Almach (γ Andromedae). It is one of the best doubles to observe with small telescopes for its contrast of colors. The primary star of magnitude 2.3 is an orange giant and its companion, which is in turn a binary, of magnitude 5.1 is greenish. The companion of the binary is, in turn, double too, so it is a quadruple system.

7 NGC 752. It is located south of Almach. It is an open cluster of about 70 stars that can be seen with the naked eye with dark skies. Seen with binoculars you can see the chains and knots of the stars that form a twisted X inside this magnificent cluster.

8 Galaxy of the Mill (M33). It is located southwest of NGC 752. Although it is a bright object of magnitude 5.5, it is difficult to see as it appears from the front and is very widespread. In dark sky and with binoculars it appears as a diffuse glow, but with a 200 mm telescope and a wide-field eyepiece you can see its diffuse arms.

9 ι Tri. It is a double with an amazing color contrast. The primary is yellow of magnitude 5 and the secondary is blue of magnitude 6.5.