Andromeda Galaxy and Star Birth

In a recent study, Astronomers took over 8,000 images of 2,753 star clusters, covering 61,600 light years across and containing 117,000,000 stars in the Andromeda Galaxy (M31).

Needless to say, it was a pretty big picture. The width of the picture spanned across 362,123,322,988,110,236 miles.

However, that’s not an entirely comprehensive picture of the Andromeda Galaxy. It’s pretty darn impressive though, but the Andromeda Galaxy is 220,000 light years across, so this sample is only a little more than 25% of the entire galaxy. For this study’s purposes, it was more than enough.

What Was The Purpose of This Study?

Astronomers wanted to look at another galaxy and perform an Initial Mass Function (IMF) analysis. The only other IMF study that has been performed to identify star mass and ages in star clusters was done in the Milky Way Galaxy, taking photos and analyzing stars from within our own galaxy.

What Were Their Findings?

The findings of the Initial Mass Function study was pretty interesting, the percentage of newborn stars in the Andromeda Galaxy that have a particular mass within a cluster, is extremely similar to that percentage of newborn stars in the Milky Way Galaxy.

What Will They do With This Information?

Once Scientists and Astronomers are able to determine the percentage of stars within a star cluster that have a specific mass, they can better understand the data when looking into the amount of light projected from stars and star clusters in distant galaxies.

This will help them read the data that will tell the story of how stars are formed throughout the Universe and if that’s changed over time.

How Did They do the Study?

The study looked at over 414 mosaic images of the Andromeda Galaxy taken by the Hubble Space Telescope.

Due to the vast amount of information contained in these images, remember, 117,000,000 stars, Scientists and Astronomers needed help.



Photo by NASA,


In an effort to “crowd source” the solution, this study utilized 30,000 “citizen scientists” to assist in the collection, analysis and findings of this insanely large amount of data.

Dude, that’s PHAT!

It sure was, the Panchromatic Hubble Andromeda Treasury (PHAT) program is the panoramic collection of images of the Andromeda Galaxy that Scientists, Astronomers and citizen scientists were looking into.

Most of the 8,000 images of the 117,000,000 stars were in 3 different types of wavelengths collected; near-ultraviolet, visible and near-infrared.

New Stars in a 9 Billion Year Old Galaxy?

Yeah, the Andromeda Galaxy is pretty old, over 9,000,000,000 years old, in fact. But this didn’t stop Scientists and Astronomers from looking at the nearly endless amount of stars in its Galaxy.

Stars are born in Giant Molecular Clouds, also known as Nebula, which as massive collections of galactic dust and gas. They’re mostly composed of hydrogen, dust particles and other smaller but important elements which help in the birthing of stars.



Photo by NASA,


Prior to this IMF study of the Andromeda Galaxy, Scientists and Astronomers had only performed an IMF measurement on a cluster of stars in a section of the Milky Way Galaxy, referred to as our local stellar neighborhood.

Milky Way or Andromeda Galaxy, Who Cares?

Well, performing this study and getting the data was really important. We’ve only had collections of this data from our own Galaxy, which isn’t a very large sample size.

Knowing what star masses are in star cluster and the amount of light they project will help us better understand light from star clusters in Galaxies far, far away.

The data collected from the Andromeda Galaxy was signficantly greater than the amount of data collected from the Milky Way Galaxy. We have the ability to see the entire Andromeda Galaxy with the Hubble Space Telescope, rather than looking outwards from within the Milky Way which only provides a small sample.

Collecting data samples from the entire width of a galaxy enables us to see the diversity of star formations. As you can image, the diversity of star clusters across the Andromeda’s 220,000 light year arm span is pretty impressive.

Galactic Menopause:

Well, to the best of our knowledge galaxies don’t go through menopause of galactic proportions. Nonetheless, this 9 billion year old galaxy is still giving birth to baby stars all these years later.

The Hubble Space Telescope was able to look 2.5 million light years away at the Andromeda’s 220,000 light year span and see extremely different and diverse samples of new stars being born.



Photo by NASA,


Some of the stars differ in solar mass by a factor of 10, which is huge! These star clusters can be as young as 4 million years old to 24 million years old, pretty wild!

Our local star, the Sun, is 4.5 billion years old. These newborn stars in the Andromeda galaxy are just infants compared to our Solar System’s star.

What Results Did They See?

Scientists and Astronomers were able to conclude from the countless images and stars examined that the brightest and most massive stars in these star clusters are about 25% less abundant than previously predicted.

The light projected and estimated solar masses (the mass of a star relative to our Sun, 1 solar mass) from these star clusters help Scientists and Astronomers determine how fast these stars are forming.

The results suggest that Scientists and Astronomers underestimated the amount of solar mass in these star clusters, and that there are actually more low-mass and younger stars forming in these star clusters along with older, brighter and greater solar mass stars.

Any Findings About the Universe?

Carl Sagan would be rolling over in his grave if there wasn’t.

This study provides sufficient evidence that there was actually less heavy elements in the Universe in its early days. Due to fewer supernovas from massive stars, we can also deduce that there weren’t enough heavy elements in the early Universe to begin planet formation until much later.

Scientists and Astronomers want to understand how, and the rate of early star formation because it will help us better understand the early Universe. Most “early stars” began their formation about 10 billion years ago, which is roughly 3 billion years after the Universe was formed.

More About the Andromeda Galaxy:

The Andromeda Galaxy, which is also called the Messier 31, NGC 224 or M31. Is a spiral galaxy about 780 kilo parsecs (2.5 million light years) away from the Milky Way Galaxy.

The Andromeda Galaxy is the closest galaxy to the Milky Way and can be viewed from the Earth with the naked eye.



Photo by NASA,


The Andromeda Galaxy, the closest galaxy to us, is on path to collide with the Milky Way Galaxy in roughly 3.75 billion years. This collision will create a spectacular elliptical galaxy, but you won’t be around to witness it.

How Many Stars are in the Andromeda Galaxy?

In 2006, observations made by the Spitzer Space Telescope showed that Andromeda Galaxy is composed of nearly 1,000,000,000,000 (trillion) stars.

To put this into perspective, the Milky Way only has about 100,000,000,000 (billion) stars. The Andromeda Galaxy is the big dog in our local group, which has more than 54 galaxies, most of which are dwarf galaxies.

Other Facts About the Andromeda Galaxy:

While the Andromeda Galaxy is considered to be one of the largest galaxies in our local cluster of galaxies, it might not be the most massive in size. Hypothetically, the Milky Way contains a vast amount of dark matter, which can add mass when we can begin measuring it. Until we have the proper scientific measurement instruments, we’ll let the Andromeda Galaxy hang on to the Biggest Galaxy Trophy a little longer.

Astronomers also study the Andromeda Galaxy to better understand the evolution of gases in both a galactic and universal scale.



Photo by NASA,


The Andromeda Galaxy is on path to collide with us and it’s racing towards the Milky Way Galaxy at 68 miles per second, or 4,080 miles per hour. Spoiler alert, Keanu Reeves is stuck on the Andromeda Galaxy in Speed 3: the Race to the Milky Way.

The Andromeda Galaxy has a crowded double nucleus at its core. There’s both a massive star cluster at its center as well as a single supermassive black hole which is hidden at the center.

A Few Facts on the Hubble Telescope:

The Hubble Space Telescope was launched into lower Earth orbit in 1990. It has four major instruments which Scientists and Astronomers use to observe visible light waves, near-infrared light waves and near-ultraviolet light waves.

The Hubble Space Telescope uses the low Earth orbit to take its incredible and breath-taking high-resolution images to escape background light pollution as experienced here on Earth.



Photo by NASA,


This telescope has recorded some of the most delicate visible light images ever captured and some of the deepest views into space. The Hubble Telescope was one of the main telescopes used in determining the rate at which the Universe expands.

The Hubble Telescope was developed by NASA, along with some contributions from the European Space Agency (ESA), its main hub for operation is at the Space Telescope Science Institute.

The idea for a low orbit telescope isn’t new, initial discussions and concepts date as far back as 1923. The Hubble Telescope was initially funded in the early 1970’s with a project launch date set for 1983. Unfortunately, the launch of the telescope was delayed by technical difficulties and quickly began running over budget.

Finally! The Hubble Telescope was launched in 1990 and has been providing some of the best imagery taken throughout the Universe. With a handful of service missions, the Hubble Space Telescope continues to operate today and it’s estimated that the Hubble will continue operating through 2030 or even 2040.



Photo by NASA,


For more information about the Hubble Space Telescope, check out our 10 Hubble Space Telescope Facts infographic.




Featured image by NASA,

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