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Milky Way Galaxy Facts with Pictures
The Milky Way Galaxy is the name of the Galaxy where our own solar system is located. In shape Milky is kind of a spiral and it is the building block of our universe. That means our universe is nothing but the conglomeration of numerous galaxies. The name Milky Way came from a Latin word called Via Lactea, which has a root in Greek, means a pale band of light.
The Size of Milky Way Galaxy
In 1917, Harlow Shapley made an estimation of the size of Milky Way and it is still valid. He determined that our galaxy will be around 100,000 light years in diameter and our Sun is almost 30,000 light years from the center of the center of this galaxy. The most distant stars of the galaxy found to be almost 72,000 light years from the galactic center (center of milky way), which means if you start our journey at the speed of light from the center of milky way towards its most distant stars, that will take us 72,000 light years and it we start our journey from the our planet towards, at the same speed, toward the center of Milky way that would take approximately 30,000 light years.
The Mass of Milky Way
Estimating the total mass of a galaxy is extremely complicated matter, which takes into account of the velocity and position of hydrogen gas, its distance from the center, gravitational pull etc. the mass is found by constructing a mathematical model of the galaxy considering all the components within it. In 1960 an estimate predicted that value of total mass of our galaxy is 200,000,000,000 times the mass of the Sun. however, in 1980, another estimate was made, which included the mass of invisible matter like dark matter, and the prediction was that the total mass of milky way is around 1,000,000,000,000 times the mass of our Sun, which is almost 10 times higher than the previous estimation of Milky Way Mass.
Actually the nature of undetected matters like dark matter, sub-atomatic particles still remains the matter of questions and this contributed significant change is the 1980’s estimation of our galaxy. It will be extremely difficult to identify the mass of the total nondirective matters in our universe, which might change the latest predicted mass of Milky Way.
Mass of the Sun- 1.98892 × 1030 kilograms
Major components of Milky Way
A galaxy is mainly composed of numerous Stars and stellar populations. All stars are not of the same character tics and values, just like Hollywood stars of our planet, they mainly differ by masses, luminosities and orbiting characteristics. That is why not all stars become black holes, when they die. Only the stars having 1.44 times of the mass of Sun can turn into black holes-this critical mass of becoming black hole is also known as Chandrasekhar limit. Though most of the stars in our Milky Way exists as either a single star (the Sun), but there are a number of well defined groups and clusters of stars, which has thousands of member stars. This type of formation of stars in a galaxy can be subdivided into three main categories-globular, open and stellar associations-age and numbers are the main distinguished parts of star sub division system. Apart from grouping of stars, there are some other important objects like emission nebulas, planetary nebulas act. More or less, the followings are the major components of Milky Way galaxy
- Star clusters and stellar associations
- Emission nebulas
- Planetary nebulas
- Supernova remnants
- Dust clouds
- Interstellar medium
1 Star clusters and stellar associations
Though most of the stars in our Milky Way exists as either a single star (the Sun), but there are a number of well defined groups and clusters of stars, which has thousands of member stars. This type of formation of stars in a galaxy can be subdivided into three main categories-globular, open and stellar associations, moving groups-age and numbers are the main distinguished parts of star sub division system.
1.1 Globular clusters
They are the largest star clusters with the most massive size stars. There are 130 globular clusters in Milky Way, mostly are spherically spread around the Milky Way. This 'type of clusters are the most luminous too, globular clusters brightness is comparable to around 25,000 suns. The masses of these objects are roughly 1,000,000 of the mass of Sun. almost all the clusters are extremely dense at the center and having radius of 10 to 300 light years.
1.2 Open clusters
They are smaller in numbers and less massive to globular type clusters. They are called open clusters because they have loose appearance in comparison to globular clusters. They are very concentrated at the center and gradually decrease at the edge from their center. They are less luminous than globular clusters; the most brightest open cluster is equivalent to 5000 times greater than the luminosity of the Sun. the average mass of an open clusters can be around 50 solar mass and the number of starts can be anywhere between tens to thousands. About 20 light years an average open clusters diameter. Most of open clusters are at the age of 1,000,000 or 2,000,000 years and only a few percentages have reached over 1,000,000,000 of age. So, far only 1,000 open clusters have been found in our galaxy.
1.3 Stellar associations
In terms of age, they are younger than open clusters and consist of very loosely grouped stars. They appear in the region of the galaxy where start formation take place, mostly at the spiral arms of the Milky Way. They very luminous objects, even brighter than the globular clusters. Their luminosity is about 1,000,000 times the Sun. but the lifetime of stars in stellar associations of clusters is very short-only a few million years. The size of stellar association is very high, their average diameter is over 700 light years and. Only a several hundred solar mass can be the mass of an average stellar body. All stellar associations are so loosely structured that their gravitational pull is not enough to hold them together, most of them after a few million years get disperse in the galaxy and become like unconnected stars of Milky Way.
Supermassive Black Hole in the Milky Way Galaxy
2. Emission Nebulous
Emission Nebulous are mainly a kind of cloud-like objects consists or bright and diffusive gases and stars. In a nebula gas exists in the form of ionized gas- this state of gas is due to the emission of ultra violet lights by hot stars inside a nebula. Since emission type nebulas are mostly of ionized hydrogen- they are also known as H II regions. Many of the emission nebulas are located 10,000 light years away from the center of Milky Way.
3. Planetary nebulas
Planetary nebulas are gaseous clouds. They are so called because they almost resemble disk shaped planets when you look at them with telescope. This type of nebula represents the end stage of stellar life cycle. So, far over 1,000 planetary nebulas have been identified in our Galaxy.
4. Supernova Remnants
They are another form of nebulous objects found in our galaxy, in the form of gas. The main reason of their existence is because of the forming of super massive stars or supernova. Though they almost look like planetary nebulas, but they have three distinguished characteristics that make them differ from other types of nebulas-they have larger mass, higher velocity, short life-time. Example of an observed supernova remnant is AD 1054. Inside these types of stellar objects particles move in spiral direction with the speed of light and their emitted radiation patterns form flat spectrum of radio waves-this pattern of radiation also know as synchrotron radiation.
5. Dust clouds
They are located, mainly, to the Milky Way Plane and they are very conspicuous in the region of spiral arms of our galaxy. Dust clouds over 2000 light years distant from our Sun are not detectable with any optical telescope. Dust clouds can have masses over several hundred of solar masses and their maximum size can be about 200 light years.
Milky Way in 3D
Structure of Milky Way
If we look at our Milky Way with 3D view, it can be considered as a large spiral system with 6 separate parts.
- Central bulge
- Spiral arms
- Spherical component
- Massive hallow
What is in the center of Milky Way
At the center point of our galaxy, there is a super massive black hole, which is only detectable by radio waves only. Near the center of this black hole, the activities like infrared radiation, X-ray emission, rapidly moving gases can be observed if you ever have the opportunity to visit this place. All the radio evidence gathered indicates that this black hole pulling material outside the nucleus of the Milky Way. When gases clouds near this black hole, its gravitational force turn it into a fast moving rotating disk, which extends 5-30 light years! And can you guess about the