As our nearest cosmic neighbor to the earth is the moon, the closest shining cosmic object to our solar system is Alpha Centauri, the second closest star after our sun.
What
we call Alpha Centauri is actually a combination of three stars, Alpha
Centauri-A, Alpha Centauri-B and Alpha Centauri-C, respectively. Of these,
Alpha Centauri-A is the largest in size, volume and brightness, and Alpha
Centauri-C is the smallest in all respects. Alpha Centauri-A and Alpha Centauri-B
have been orbiting each other with a common center of gravity (Barycenter), and
at some distance Alpha Centauri-C has been orbiting this pair of dual stars.
The
name Alpha Centauri was given by the German lawyer Johann Bayer. However,
another name for this star is Regil Kentaurus which means the legs of a
fictional creature like a human horse. In short, this star is also known by
many as Regil Kent or Regil. At an average of 4.37 light-years or 1.34 parsec (Light-year:
The distance that light travels in a year. Parsec: The largest
unit of distance in space research. The value of 1 parsec is equal to 3.26
light-years) away from the Sun, the third brightest star visible from Earth
(after Sirius and Canopus) is 1.14 times the mass of the Sun and 1.2 times the
radius of the Sun. This star is about the same size as our Sun but 1.5 times
brighter than the Sun. Alpha Centauri has a surface temperature of 5,790 Kelvin
or 5,516.9 degree Celsius. At present, the brightness value of this star is
+0.01 (The smaller or negative the brightness value in astronomy, the
brighter the cosmic object). Alpha Centauri takes 36 days to orbit its axis
once and has a speed of 2-3.4 km per second or 7,200-12,240 km per hour.
Studies so far have shown that the age of this G2V class star is 5-5.6 billion
years, or 500-560 crore years, which means that the star may be slightly older
than the Sun in terms of age.
This
is followed by Alpha Centauri-B, a slightly smaller star from Alpha Centauri-A.
Its other name is Toliman which means two male ostriches. Its mass is 0.92
times the mass of the Sun and its radius is 0.86 times the radius of the Sun,
which means that this star is slightly smaller in size and volume than our Sun.
Alpha Centauri-B has a brightness value of +1.33, an orange star with a surface
temperature of 5,260 Kelvin or 4,986.9 degree Celsius. Like Alpha Centauri-A,
it takes 36 days to orbit its axis once. However, its speed is slightly lower
than that of Alpha Centauri-A and it is 0.93-1.9 km per second or 3,348-6,840
km per hour. Alpha Centauri-A and Alpha Centauri-B, the dual star system, are
of same age. Since this K1V class star is one of the dual stars, it, like Alpha
Centauri-A, is 4.37 light-years or 1.34 parsec from Earth. However, in some
respects Alpha Centauri has some differences with the star, such as the
magnetism of Alpha Centauri-A and the magnetism of the Sun are almost same, but
the magnetism of Alpha Centauri-B is greater than all of them. In addition, the
X-ray emission rate of this star is also very high.
These
two stars have been orbiting each other for 79.91 years with their barycenter.
The maximum distance between them at this time is 35.6 AU (AU or
Astronomical Unit: The average distance between the earth and the sun)
or 5.33 billion km or 533 crore km which is approximately equal to the distance
of Pluto from the Sun and the minimum distance is 11.2 AU or 1.68 billion km or
168 crore km which is approximately equal to the distance of Saturn from the
Sun. The last time these two stars were farthest apart was in May 1995. This
situation will happen again in 2075. The last time these two stars came close
was in August 1955 and the next time they will be close again in 2035, that is,
every 40 years they come closer and farther away. The last time this double
star went too far from earth was in February 1976, and it will be the farthest
from earth again in January 2056. These two stars came closest to earth last
time in 2016 and will come closer again in 2096.
This
time we will talk about the star that we discus about the most. Alpha
Centauri-C is the red dwarf star of the M6Ve class located at an average of
0.21 light-years or 13,000 AU or 1.9 trillion km or 19,000 crore km away from
Alpha Centauri-AB. The star, discovered by Scottish astronomer Robert Innes in
1915, was named Proxima Centauri, which later became popular around the world.
The reason for this naming is that this star is closest to the Sun. The star
Proxima Centauri is 4.24 light-years, or 1.3 parsec away from the Sun. This
second closest star to the earth, which is 0.122 times the mass of the Sun and
0.15 times the radius of the Sun, is also seen as the one of the faintest stars
from the earth. It has a brightness value of +11.05 and a surface temperature
of 3,042 Kelvin or 2,768 degree Celsius. The Proxima Centauri takes 82.5-82.7
days to orbit its axis once with a very low speed which is less than 0.1 km per
second or 360 km per hour. In terms of age, Alpha Centauri-C is 4.85 billion
years, or 485 million years, slightly smaller than the Sun.
The
speed with which Alpha Centauri is changing its position can be understood
through an event. Ptolemy, in his writings, spoke of observing this star. He
was in Alexandria, Egypt when he observed this star. The Egyptian city is
located at 31 degree north latitude, but at present the star no longer rises
above the maximum of 29 degree north latitude. Even at this latitude, the star
is visible only 45 days a year, from April 24 to June 7. After crossing the earth's equator, at 29 degree south latitude, the star's position is fixed
relative to the earth, meaning that the Alpha Centauri is visible throughout
the year without any rise or set. Alpha Centauri-C or Proxima Centauri, the
nearest stellar neighbor to our Sun, is the faint star that can be seen with
the help of a telescope 2.2 degree south-west of its position in the sky after
seeing the visible Alpha Centauri from Earth.
Mention
of Alpha Centauri is probably found first in the description of Ptolemy. Long
after, the British mathematician and geographer Robert Hues wrote about the
star in 1592. In 1689, while observing a comet from the then Pondicherry or
present-day Puducherry in India, the French scientist Jean Richer suddenly saw
this star. Although the star was initially thought to be stationary, Sir Edmund
Haley's research on the star in 1718 revealed that the position of the star was
changing little by little. Manuel John Johnson, a British astronomer from St. Helena
Island, tried to measure the velocity of the star and sent the data about his
observations and research to Scottish scientist Thomas Henderson, who worked at
the Royal Observatory in South Africa. From April 1832 to May 1833, Thomas
Henderson gathered a great deal of information on this subject and published it
in 1839, the most notable of which was the determination of the distance of
Alpha Centauri from Earth. In 1834, the famous British scientist Sir John
Herschel researched the subject and presented many unknown facts. On the series
of these events, one of important event was the discovery of Proxima Centauri,
the closest star to the Sun, in 1915 by the Scottish astronomer Robert Innes.
In 1928, South African astronomer William Finsen determined the approximate
orbit of the star, which was later proven and recognized.
Next
let's come to some interesting facts about Alpha Centauri. Based on the
information expressed by Sir Edmund Haley about the changing location of the
star, scientists have studied that the star is moving 1.02 degree north-west of
the sky every thousand years. During this shift, the velocity of the star in
the west is 23 km per second or 72,600 km per hour and in the north it is 4.4
km per second or 15,640 km per hour. In May 2026, a ring of blue light will
form around Alpha Centauri which we know as the Einstein Ring in the language
of space science. The cause of this ring of light is the passage of another
star through place between the earth and any other large star. This will happen
many more times in the next decade. Just as the actual motion of a star can be discovered
for this rotation, so too can we know many more unknown facts. In the year 6200
Alpha Centauri will cross the Beta Centauri and it will be visible from Earth.
At that time, the night sky of the southern hemisphere of the earth will be covered
with the light of two stars. Just after that, Alpha Centauri will cross the
Crux constellation and move further north. Currently the closest star to Alpha
Centauri is Luhmani. The distance between them is now 3.6 light years or 1.9
parsec. This will change further in 26,000 AD, and Hydra will be the closest constellation.
Then the distance between them will be 2.9 light years or 1.5 parsec.
An
event around this star was noticed in 2015. As the star faded, it began to
shine again, and on 13th August of that year, it became 8.3 times brighter than
the normal brightness of the star. Alpha Centauri will become brighter in the
future, but not more than Sirius in the near future. It will continue to
increase in brightness for the next 60,000 years, and then for the next
2,10,000 years, Alpha Centauri will become the second brightest star after the
Sun visible from earth.
So
far the existence of two planets has been confirmed. Both planets revolve
around Alpha Centauri-C or Proxima Centauri. The first is Proxima Centauri-B.
Discovered in 2016, this rocky planet is located at a habitable zone of 0.049
AU or 73,30,367 km away from its star. The mass of this planet is 1.17 times
the mass of the earth which is almost equal to the mass of the earth. The
second definitive planet to be mentioned is Proxima Centauri-C, discovered in
2020, which is similar in shape to Neptune; hence it is called Mini Neptune or
Super Earth. The mass of this planet is 7 times the mass of the earth. The planet
is located 1.49 AU or 22,29,01,129 km away from its star. The planet orbits its
star Proxima Centauri in 1,928 days or 5.28 years of Earth time. The presence
of a ring around this planet has been found.
In
February 2021, the presence of the planet is estimated to be 1.1 AU or
16,45,56,60 km away from Alpha Centauri-A. The name of this planet is Alpha
Centauri-Ab or Candidate-1 or C-1. This planet, half the mass of Neptune and
Saturn, is probably orbiting Alpha Centauri in 360 days of Earth time. There
may be a ring of dust around this planet. In 2013, the presence of a planet
orbiting Alpha Centauri-B is estimated to be called Alpha Centauri Bc. The
planet is orbiting Alpha Centauri-B in 20.4 days as Earth time. Alpha
Centauri-Bb is another planet that orbited Alpha Centauri-B in December 2012.
All these planets are only approximate. They have not yet been accepted as
definitive planets as no definitive evidence has been found. Since Alpha
Centauri is a sun-sized star, it is certain to have Earth-like planets in its
habitable space. The habitable zone of Alpha Centauri A is between 1.2 - 2.1 AU
or 17,95,17,688 - 31,41,55,953 km and that of Alpha Centauri-B is 0.7-1.2 AU or
10,47,18,651 - 17,95,17,688 km. In addition, various models of computers have
confirmed this based on various other practical facts. So scientists are
relentlessly searching for planets in this region.
The
first target of man's first interstellar mission is, of course, the world of
Alpha Centauri. The flyby mission (Flyby: According to the space
science, the shortest distance, at the
time of observation, without landing, between observation space vehicle and the
planet or satellite) by robotic technology will dominate there. It may take
centuries to carry out this mission using the most advanced technology, but
scientists are now thinking of some other technologies that could shorten the
journey to that world by at least a few decades.
However,
it is not possible to make any predictions right now. But it is certain that
we, the human, will one day carry out the Alpha Centauri mission and establish
ourselves in the universe. Now it's time to develop us from every respect.
DECLARATION: All The Images Have Been Sourced From Google.