The Andromeda Galaxy  is a spiral galaxy approximately 2.5 million light-years (2.4×10¹⁹ km) from Earth in the Andromeda constellation. Also known as Messier 31, M31, or NGC 224, it is often referred to as the Great Andromeda Nebula in older texts. The Andromeda Galaxy is the nearest spiral galaxy to our Milky Way galaxy, but not the nearest galaxy overall. It gets its name from the area of the sky in which it appears, the constellation of Andromeda, which was named after the mythological princess Andromeda. The Andromeda Galaxy is the largest galaxy of the Local Group, which also contains the Milky Way, the Triangulum Galaxy, and about 30 other smaller galaxies.

Imaging telescopes or lenses: Takahashi TOA-130
Imaging cameras: SBIG STL-11000
Mounts: Losmandy G11
Guiding telescopes or lenses: Orion ShortTube 80 f/5
Guiding cameras: Orion Star Shoot Planetary Imager & Autoguider
Software: photoshop, Maxim DL
Filters: L, Astrodon Red, Astrodon G, Astrodon Filter: Blue, Astrodon h-Alpha

Author: Maurizio Cabibbo
AstroPhotography of the day by SPONLI 14 Sep 2014

Observation history

The Persian astronomer Abd al-Rahman al-Sufi wrote a line about the chained constellation in his Book of Fixed Stars around 964, describing it as a “small cloud”. Star charts of that period have it labeled as the Little Cloud. The first description of the object based on telescopic observation was given by German astronomer Simon Marius on December 15, 1612. Charles Messier catalogued it as object M31 in 1764 and incorrectly credited Marius as the discoverer, unaware of Al Sufi’s earlier work. In 1785, the astronomer William Herschel noted a faint reddish hue in the core region of M31. He believed it to be the nearest of all the “great nebulae” and based on the color and magnitude of the nebula, he incorrectly guessed that it was no more than 2,000 times the distance of Sirius.

William Huggins in 1864 observed the spectrum of M31 and noted that it differed from a gaseous nebula. The spectra of M31 displayed a continuum of frequencies, superimposed with dark absorption lines that help identify the chemical composition of an object. The Andromeda nebula was very similar to the spectra of individual stars, and from this it was deduced that M31 had a stellar nature. In 1885, asupernova (known as S Andromedae) was seen in M31, the first and so far only one observed in that galaxy. At the time M31 was considered to be a nearby object, so the cause was thought to be a much less luminous and unrelated event called a nova, and was named accordingly “Nova 1885”.
The first photographs of M31 were taken in 1887 by Isaac Roberts from his private observatory in Sussex, England. The long-duration exposure allowed the spiral structure of the galaxy to be seen for the first time. However, at the time this object was still commonly believed to be a nebula within our galaxy, and Roberts mistakenly believed that M31 and similar spiral nebulae were actually solar systems being formed, with the satellites nascent planets. The radial velocity of this object with respect to our solar system was measured in 1912 by Vesto Slipher at the Lowell Observatory, using spectroscopy. The result was the largest velocity recorded at that time, at 300 kilometres per second (190 mi/s), moving in the direction of the Sun.

Imaging telescopes or lenses: Canon EF 70-200mm f/4L USM
Imaging cameras: Canon EOS 550D / Rebel T2i
Mounts: Skywatcher Neq6 pro synscan
Guiding cameras: QHY5
Software: DeepSkyStacker, PHD guiding
Dates: Oct. 11, 2013
Frames: 10×420″
Integration: 1.2 hours

Author: Ivan Jevremovic
AstroPhotography of the day by SPONLI 08 July 2014

The Andromeda Galaxy is approaching the Milky Way at about 110 kilometres per second (68 mi/s). We measure it approaching relative to our sun at around 300 kilometres per second (190 mi/s) as the sun orbits around the center of our galaxy at a speed of approximately 225 kilometres per second (140 mi/s). This makes Andromeda one of the few blueshifted galaxies that we observe. Andromeda’s tangential or side-ways velocity with respect to the Milky Way is relatively much smaller than the approaching velocity and therefore we expect it to directly collide with the Milky Way in about 4 billion years. A likely outcome of the collision is that the galaxies will merge to form a giant elliptical galaxy.  Such events are frequent among the galaxies in galaxy groups. The fate of the Earth and the Solar System in the event of a collision is currently unknown. Before the galaxies merge, there is a small chance that the Solar System could be ejected from the Milky Way or join M31.

Imaging telescopes or lenses: Orion 8″ f/3.9 Newtonian Astrograph
Imaging cameras: Canon T3i
Mounts: Celestron AVX
Focal reducers: Baader MPCC
Software: PixInsight
Filters: Orion SkyGlow 2″ Imaging Filter
Dates: Nov. 30, 2013
Frames: 20×360″
Integration: 2.0 hours

Author: Charles Ward
AstroPhotography of the day by SPONLI 02 June 2014

According to a team of astronomers reporting in 2010, M31 was formed out of the collision of two smaller galaxies between 5 and 9 billion years ago.

A paper published in 2012 has outlined M31’s basic history since its birth. According to it, Andromeda was born roughly 10 billion years ago from the merger of many smaller protogalaxies, leading to a galaxy smaller than the one we see today.

The most important event in M31’s past history was the merger mentioned above that took place 8 billion years ago. This violent collision formed most of its (metal-rich) galactic halo and extended disk and during that epoch Andromeda’s star formation would have been very high, to the point of becoming a luminous infrared galaxy for roughly 100 million years.

M31 and the Triangulum Galaxy (M33) had a very close passage 2–4 billion years ago. This event produced high levels of star formation across the Andromeda Galaxy’s disk – even some globular clusters – and disturbed M33’s outer disk.

While there has been activity during the last 2 billion years, this has been much lower than during the past. During this epoch, star formation throughout M31’s disk decreased to the point of nearly shutting down, then increased again relatively recently. There have been interactions with satellite galaxies like M32, M110, or others that have already been absorbed by M31. These interactions have formed structures like Andromeda’s Giant Stellar Stream. A merger roughly 100 million years ago is believed to be responsible for a counter-rotating disk of gas found in the center of M31 as well as the presence there of a relatively young (100 million years old) stellar population.

Imaging telescopes or lenses: Orion ED80T-CF
Imaging cameras: Nikon D7100
Mounts: Skywatcher AZ-EQ6 GT
Guiding telescopes or lenses: Orion 50mm mini guidescope
Guiding cameras: Orion Star Shoot autoguider (SSAG)
Focal reducers: TeleVue 0.8x Photo Reducer/Flattener TRF-2008
Software: Adobe Lightroom 5, StarTools64, Photoshop CS6, PHD Guiding, Luc Coiffier DeepSkyStacker
Dates: Nov. 8, 2013, Nov. 9, 2013
Frames:
15×180″ ISO800
12×300″ ISO800
Integration: 1.8 hours
Darks: ~9
Flats: ~9
Bias: ~9

Author: Vincent_Bellandi
AstroPhotography of the day by SPONLI 26 May 2014

The Andromeda Galaxy is a spiral galaxy approximately 2.5 million light-years (2.4×10¹⁹ km) from Earth in the Andromeda constellation. Also known as Messier 31, M31, or NGC 224, it is often referred to as the Great Andromeda Nebula in older texts.
M31 is known to harbor a dense and compact star cluster at its very center. In a large telescope it creates a visual impression of a star embedded in the more diffuse surrounding bulge. The luminosity of the nucleus is in excess of the most luminous globular clusters.

Imaging telescopes or lenses: Skywatcher Esprit 150ED
Mounts: 10 Micron GM1000 HPS
Software: Stark Labs Nebulosity 3.1, PHD
Accessories: Celestron OAG, Starlight Xpress Lodestar
Dates: Sept. 29, 2013
Frames: 20×600″
Integration: 3.3 hours

Author: Tim Jardine

AstroPhotography of the day by SPONLI

27 March 2014