Skrundas Secondary School

THE MILKY WAY AND ANDROMEDA COLLISION

The authors:

Dace Metēja;

Kristīne Kaltiniece;

Beāte Perševica;

The teacher:

Inese Pickaine

Latvia, Skrunda, 2011

The Milky Way and Andromeda collision

We choosed this theme because it is an astronomical topic in which we can discover many things

about the galaxies, the stars and the U

and do a scientifical work in a tem

So why the the Milky Way and Andromeda galaxy?

that the Universe is expanding.

possible to make a calculations how big the U

scientists can explain many topics in astronomy.

intensity of gravity holds them together

expansion of the Universe, the Local Group is gravitationally bound together

interact with each other. Gravity is a force for all objects with mass, so the galaxies are attracted to

each other, we can say that the local gravity o

with mass. The massive object attracts

that the gravitation force depends on mass of the first and second body, universal gravitational

constant and distance between two masses.

Sun is heavy, so this star attracts other planets.

is fundamental interactions of nature

1.Photo (YES I Can! Science)1

We used calculations to find out the force of gravity between two galaxies

Way.

F = (G x M1 x M2 ) / r2

G = 6.67 x 10-11 ( Nm2/kg2

1 YES I Can! Science [online]. [cited October 27,2011].

science.ca/orbits1/trans_gravity_eq1.html

The Milky Way and Andromeda collision

because it is an astronomical topic in which we can discover many things

he galaxies, the stars and the Universe. It is a great opportunity to make our own decisions

ork in a tem.

So why the the Milky Way and Andromeda galaxy? It is an astronomical ph

niverse is expanding. The Enstein had this theory. And it is true. Of course it is not

ake a calculations how big the Universe actually is.

scientists can explain many topics in astronomy. But the two galaxies are getting closer

of gravity holds them together. While most of galaxies are hurtling away from

expansion of the Universe, the Local Group is gravitationally bound together

Gravity is a force for all objects with mass, so the galaxies are attracted to

r, we can say that the local gravity overpowers the expansion

object attracts. This you can see in 1.photo. In this photo you can

that the gravitation force depends on mass of the first and second body, universal gravitational

constant and distance between two masses. It is like the Sun keeps planets in orbits.

Sun is heavy, so this star attracts other planets. And Earth with the Moon like 1.

fundamental interactions of nature.

We used calculations to find out the force of gravity between two galaxies

2 )

[online]. [cited October 27,2011]. Available: http://resources.yesican-science.ca/orbits1/trans_gravity_eq1.html

The Milky Way and Andromeda collision.

because it is an astronomical topic in which we can discover many things

niverse. It is a great opportunity to make our own decisions

t is an astronomical phenomenon. It is known

The Enstein had this theory. And it is true. Of course it is not

niverse actually is. But due to this theory the

But the two galaxies are getting closer and the

galaxies are hurtling away from due to the

expansion of the Universe, the Local Group is gravitationally bound together, and will continue to

Gravity is a force for all objects with mass, so the galaxies are attracted to

verpowers the expansion. And the gravity relates

This you can see in 1.photo. In this photo you can also see

that the gravitation force depends on mass of the first and second body, universal gravitational

It is like the Sun keeps planets in orbits. Because the

arth with the Moon like 1. photo. Gravitation

We used calculations to find out the force of gravity between two galaxies- Andromeda and Milky

G = universal gravitational constant;

M1 = mass of the first body;

M2= mass of the second body;

r = distance between the two masses in ^2.

r = 2.3652 x 1022 m

M1 = Milky Way (5.8 x 10 11 )2 Solar masses

M2 = Andromeda galaxy( 7.1 x 10-11 )3 Solar masses

mass of the Sun - (1.9891 x 1030 kg)4

Milky Way (mass) = 1.9891 x 5.8 x 1011 x 1030 =

1.9891 x 1041kg.

Andromeda galaxy= 1.9891 x 7.1 x 1011 x 10 30=

1.9891 x 7.1 x 1041kg

So:

F= (G x M1 x M2 ) / r2

F= (6.67 x 10-11 x 1.9891 x 5.8 x 1.9891 x 7.1 x 1082) / (2.3652 2 x

10 44 ) =

F= 1,04 x 1029 N ( The gravitation force between Andromeda galaxy and Milky Way)

So there is a question why the force of gravity depends on mass of two objects and distance

between then. The gravitation works because of tiny particles who are emited, so they are called

gravitons. So there we can see: if object has got bigger mass, there are more gravitons. And force

of gravitation depends on distance too because most of gravitons exist in a clouds, and the clouds

are around the object. So if the distance is bigger, there is a less of density, which means that there

are not so many gravitons and gravitation attraction too. Because the gravitation attraction depends

on gravitons in a clouds around objects. So if we calculated that the force between the two galaxies

is 1,04 x 1029 N then we can see that there are a lot of gravitons. And if these galaxies are getting

further the force of gravitation is increasing. And the gravitional force is doubled if the one of

bodies mass is doubled, and if we double the distance between two bodies the force is reduced .

And how does the gravitation works you can see in 2.photo.

2 Piena Ceļš [online]. [cited October 24,2011] Available: http://lv.wikipedia.org/wiki/Piena_Ce%C4%BC%C5%A1

3 Andromedas galaktika [online]. [cited 24, 2011] Available: http://lv.wikipedia.org/wiki/Andromedas_galaktika

4 Saule [online]. [cited October 24,2011] Available: http://lv.wikipedia.org/wiki/Saule

2. Photo (Graphic: LIGO)5

So the gravity is an imprtant force in Universe. It holds planets in orbits, everything depends on

gravititation. Galaxies, stars and because of gravity asteroids can crash into planets.

„The Andromeda Galaxy is a spiral galaxy approximately 2.5 million light-years from Earth in the

constellation Andromeda.”6 Andromeda is the nearest galaxy, called M31, but not the closest to

Milky Way. Also Andromeda is the largest of galaxies in Local Group, in Local Group are more

than 30 galaxies. And the Andromeda is very similar to Milky Way. Andromeda galaxy is one of

the brightest objects and it makes it visible to the naked eye. And plays an inmportant role to study

galaxies.

„The Milky Way includes the Solar System. The Milky Way is a spiral galaxy 100,000 light years

in diameter containing 200 – 400 billion stars.”7 So the Solar system is a small part of this galaxy.

The both galaxies are composed with billions stars. In Milky Way there are not so many stars like

it is in Andromeda galaxy-it is impressive.

The two galaxies are getting closer. And after many billion years they will merge. It is a theory, to

make it real we used some calculations to understand. It is possible or not:

v = S / t

t = 315 360 000s

v = 120000 m/s

S = t x v

The distance to Andromeda galaxy 2,5 million light years = 2,5 x 106 years

5 Graphic: LIGO [online]. [cited October 27,2011].

Available:http://blog.hasslberger.com/2007/05/atemporal_gravitation.html 6 Andromeda Galaxy [online]. [cited October 26,2011]. Available: http://en.wikipedia.org/wiki/Andromeda_Galaxy

7 Milky Way [online]. [cited October 26, 2011]. Availabe: http://en.wikipedia.org/wiki/Milky_Way

The speed of light c = 3 x 108 m/s

In one year the speed of light (distance) s = c x t ( c = speed of light, t - years in seconds)

The speed of light is a distance of light in one year. If we know the distance in 1 s, then c = 3 x 108

m/s. If we know this, we can calculate the distance of light in one year.

So S = 3 x 108 m/s x 315 360 00 s = 9,4608 x 1015

If the distance is 2,5 million light years, then the distance to Andromeda-

S = 2,5 x 106 x 9,4608 x 1015 = 23,652 x 1021 m = 2,3652 x 1022 m

t = S/v

t = ( 2,3652 x 1022) / 120 000 = (2,3652 x 1022) / 1,2 x 105 = 1,971 x 1017 s

t = 1,991 x 1017 s

1 minute = 60s

1 h = 3600s

1 day = 3600 x 24 = 86400s

1year = 86400 x 365=

in 1 year = 31536000s

t = (1,991 x 1017) / 31536000 = 6313419583 = 6,31 billion years

So after 6,31 billion years there will be the collision. And the galaxies will start to merge. In the

calculations the speed was lesser than the speed of light. If it was not so, if the speed had been

similar to the speed of light, we would have to use the Einstein theory of relativity. The mass

would have been indefinitely big. And the length infinitesimal.

We also calculated :

S = distance

S = v x t

To calculate the distance we get further to Andromeda galaxy, need to use:

S =120000 x 31536000 = 37843200000000 m = 3784320000 km

So in 1 year we get further about 3784320000 km. We had proved that the collision is inevitable.

There are no possibilities to change it. The gravity is stronger. And the galaxies collides

occasionaly. As a result of the collission there „born”many new stars. It is because the galaxies

contain giant clouds of gas and dust.So there will be theraw materials who are necessary to build a

stars because the gas becomes dense and therefore stars are forming. And if the galaxies collide,

they smash. „Collisions between galaxies are therefore relatively common. It is estimated there is a

crash every few hundred million years in each cluster of galaxies.”8

3. Photo.9 (Photograph courtesy NASA, ESA, and the Hubble Heritage Team (STScI/AURA)-ESA/Hubble Collaboration)

In 3. Photo you can see an image taken by Hubble Telescope. In this photo you can see Antennae

galaxies. These galaxies merged about 200 - 300 billion years ago. And it might be similar to

Andromeda and Milky Way too. In this image can see the new stars colored pink in blue-white

areas in the collision. And sometimes it is not so critical when the two galaxies merge with the

smaller ones. But the Andromeda and the Milky Way are huge galaxies with black holes. So the

merging will take a long time and eventually make an enourmous galaxy.And the Andromeda and

Milky Way will be around each other, spinning in circles around gravitational center,and it will not

be like one big crash it will take a very long time when they will get closer, until they eventually

8 Gerard. Milky Way and Andromeda Galaxy will collide [online]. [cited October 26,2011]. Available:

http://www.bajona.com/2010/09/15/milky-way-and-andromeda-galaxy-will-collide/ 9 Photograph courtesy NASA, ESA, and the Hubble Heritage Team (STScI/AURA)-ESA/Hubble Collaboration

[online]. [cited October 27,2011]. Available: http://science.nationalgeographic.com/science/photos/galaxies-gallery/

become one galaxy- the galaxies first collide and then they separate but the speeds will be so

insufficient that in the the end they merge into one galaxy because it is hard to escape from the pull

of gravitation. And the gravitation pull between these both galaxies is very powerful. The merging

due to the gravity you

4. Photo (C. Ishida)10

can see in 4. Photo. In this photo you can see process of merging, at first there are two galaxies

who are getting closer, then they start to collide, many stars are pulled out, and many new stars had

„born”. And in this photo you can also see that the in the end the center of two galaxies hold stars

together in new galaxy. And the new galaxy-with all the stars hold together due to the gravitation.

But in the collision the stars will be pulled out, many years the stars will be spinning due to the

gravity. When they eventulay will be together.And the new galaxy will be bigger than the

Andromeda and Milky Way together. The both galaxies are big spiral galaxies with supermassive

black holes, and if these galaxies merge there will be an enourmous galaxy, definitely the biggest

galaxy in the Local Group. „Gerry Gilmore, at the Institute of Astronomy at Cambridge

University, who was not involved in the study, said: "The galaxies will be dramatically stirred up,

but they are very squidgy, so they will stick together and eventually all the stars will die out, and it

will become one huge, dead galaxy."11 So if it possible or not, we don’t know because other

scientists have different point of view. And it is impossible to make perfect simulations.

What will happen in the merging time and after it. The first question is about stars, will they

crash? It is unlikely that any two stars will collide because of the big distance between them. They

10

C. Ishida [online]. [cited October 27,2011]. Available: http://www2.ifa.hawaii.edu/newsletters/article.cfm?a=187&n=1 11

Chris Irvine, Milky Way and Andromeda will collide sooner than expected [online]. [cited October 27, 2011].

Available: http://www.telegraph.co.uk/science/science-news/4128018/Milky-Way-and-Andromeda-will-collide-

sooner-than-expected.html

will pass. And many of them will be pulld out in the Universe. So there is a question what will

happen with Solar System and Earth. It is clear that in this time the Sun will be a hydrogen-burning

main-sequence star. Since the Sun will be increasing its radiation, life might not be able to survive

on our planet. After 6, 31 billion years, the climat will change radically. But after the merging the

Sun will be a red giant, and the other stars will be pushed out in the Universe. So if the Sun will be

a red giant, there will not be life on Earth, there will be only cinders.And the Sun will inflate it’s

atmosphere.And if it will be so, that it is not important to us what will happen with the Milky Way

and the Andromeda-our home will be destroyed, but if it won’t be so, then we have to look at other

versions about the merging time and what will happen to our Solar System. And there is a

possibility that the Solar System will left the Milky Way to Andromeda for a short time during the

collision or will be flung out of the galactic disk in interstellar space. But the merging will be a

very long time, so it is inpossible to predict due to all factors and it is quite difficult to analize. But

there are no possibilities to change the collision because of the fact that in Universe it happens

occasionaly. The smaller galaxies merge with the bigger ones. Just like Milky Way. Milky Way

had merged with smaller glaxies like Canis Major Dwarf Galaxy. Of course we hadn’t noticed that

because of the enourmous distances between the stars.

And there are many versions about the name of the new galaxy, it may be:

� Milkomeda;

� Mylkomeda;

� Andromeda Way;

� Milkdromeda.

Of course, maybe after 1000 years or more, maybe less, there will be another versions about the

name. But the most dominant is Milkomeda. And the new galaxy will be elliptical. So we can

infere that due to the collisions in Universe, the galaxies have different tipes- ellipticals, spirals and

irregulars.

The stars and planets will pass each other, clouds of dust and gas will smash into one another,

creating new stars. The collision will create a new galaxy, which some astronomers have

nicknamed. So we calculated that it will happen about 6.31 billion years from now. And it will not

happens it one day; the galaxies will be “dancing” around each other for many years. And it is due

to the gravity. We also calculated that every year we get closer about 3784320000 km. And we

also calculataded that the gravitational force between two galaxies is 1,04 x 1029 N. In our opinion

it is impossible to survive because of the Sun. There will be a radiation and the Sun will become a

red giant. But we think that in the future maybe the scientists will have a opportunuty to reatard the

proceses from the very beginning.

So there are the conclusions:

� The collision between Andromeda and Milky Way is an astronomical phenomenon;

� The Universe is expanding but the two galaxies are getting further due to the gravity

between them;

� Gravity is a force for all objects with mass;

� The gravitation force of two galaxies is 1,04 x 1029 N;

� After 6, 31 billion years will be the collision;

� Every single year we are getting further about 3784320000 km;

� The collision is inevitable;

� The galaxies collides occasionaly;

� Milky Way had merged with Canis Major Dwarf Galaxy;

� Due to collision will „born” many new stars;

� The gravitational pull between two galaxies is powerful;

� The collision will be a very long process;

� The stars will be pulled out in the Universe;

� After the merging they will connect in new galaxy.

� The galaxy will be enourmous big;

� The galaxy will be elliptical;

� After the merging the Sun will be a red giant;

� If the Sun will be red giant there won’t be life on Earth;

� It is possible that Solar System will left the Milky Way to Andromeda galaxy;

� The stars won’t collide because of the enourmous distance between them;

The references

1. YES I Can! Science [online]. [cited October 27,2011]. Available: http://resources.yesican-science.ca/orbits1/trans_gravity_eq1.html

2. Piena Ceļš [online]. [cited October 24,2011] Available: http://lv.wikipedia.org/wiki/Piena_Ce%C4%BC%C5%A1

3. Andromedas galaktika [online]. [cited 24, 2011] Available: http://lv.wikipedia.org/wiki/Andromedas_galaktika

4. Saule [online]. [cited October 24,2011] Available: http://lv.wikipedia.org/wiki/Saule 5. Graphic: LIGO [online]. [cited October 27,2011].

Available:http://blog.hasslberger.com/2007/05/atemporal_gravitation.html 6. Andromeda Galaxy [online]. [cited October 26,2011]. Available:

http://en.wikipedia.org/wiki/Andromeda_Galaxy 7. Milky Way [online]. [cited October 26, 2011]. Availabe:

http://en.wikipedia.org/wiki/Milky_Way 8. Gerard. Milky Way and Andromeda Galaxy will collide [online]. [cited October 26,2011].

Available: http://www.bajona.com/2010/09/15/milky-way-and-andromeda-galaxy-will-collide/

9. Photograph courtesy NASA, ESA, and the Hubble Heritage Team (STScI/AURA)-ESA/Hubble Collaboration [online]. [cited October 27,2011]. Available: http://science.nationalgeographic.com/science/photos/galaxies-gallery/

10. C. Ishida [online]. [cited October 27,2011]. Available: http://www2.ifa.hawaii.edu/newsletters/article.cfm?a=187&n=1

11. Chris Irvine, Milky Way and Andromeda will collide sooner than expected [online]. [cited October 27, 2011].Available:http://www.telegraph.co.uk/science/science-news/4128018/Milky-Way-and-Andromeda-will-collide-sooner-than-expected.html