Our Top Ten Closest Relatives in Space

Our Top Ten Closest Relatives in Space

Stars are astronomical objects consisting of a luminous spheroid of plasma held together by its own gravity. Many stars are visible with naked eyes at night. Most protuberant stars are grouped together to form constellations and asterisms. Stars can form orbital systems with other astronomical objects, as in the case of planetary systems and star systems with two or more stars. When two such stars have a relatively close orbit, their gravitational interaction can have a significant impact on their evolution. Stars can form part of a much larger gravitationally bound structure, such as a star cluster or a galaxy. All stars spend the majority of their existence as main sequence stars, fueled primarily by the nuclear fusion of hydrogen into helium within their cores. However, stars of different masses have markedly different properties at various stages of their development. The ultimate fate of more massive stars differs from that of less massive stars, as do their luminosities and the impact they have on their environment. The currently known 76 objects are bound in 54 stellar systems. The closest system is Alpha Centauri, with Proxima Centauri as the closest system star at 4.25 light-years from Earth. The brightest among these systems, as well as the brightest in Earth’s night sky, is Sirius.

1.Proxima Centauri

Proxima Centauri is just 4.2465 light years away from the sun. It was discovered by Robert Innes in 1915. This star is a part of Alpha Centauri star system. Being a flare star, it undergoes dramatic increases in brightness because of magnetic activity.  It is a red dwarf, because it is a part of the main sequence on the Hertzsprung-Russell diagram and is of spectral class M5.5 means that it falls in the low-mass end of M-type dwarf stars. Proxima Centauri will consume nearly all of its fuel before the fusion of hydrogen comes to an end after about 4 trillion years. Due to very small weight as compared to Sun, the mass loss per unit surface area from Proxima Centauri may be eight times that from the solar surface. From the star, Sun would be a bright 0.4 magnitude star in the constellation Cassiopeia, similar to that of Achernar from Earth.

2.Barnard’s Star

Six light years away from Earth, Barnard’s Star is also a red dwarf. Despite its proximity, the star has a dim apparent magnitude of +9.5 and is invisible to the unaided eye. It is much brighter in the infrared than in visible light. Star gets it name from an American astronomer E.E Barnard. Photographic plates of Harvard University observed the star in 1888 and 1890. Barnard’s Star is older than Sun and it might be the oldest in the Milky Way galaxy. The star has already lost tremendous deal of rotational energy, and the periodic slight changes in its brightness indicate that it once in 130 days. Barnard’s Star indeed does not host Earth-mass planets, or larger, in hot and temperate orbits, unlike other M-dwarf stars that commonly have these types of planets in close-in orbits.

3.Wolf 359

Wolf 259 is located in the Leo constellation. It is 7.9 light years away from Earth. Its proximity to Earth has led to its mention in several works of fiction. It is one of the faintest and lowest mass stars known. At the light-emitting layer called the photosphere, it has a temperature of about 2,800 K, which is low enough for chemical compounds to form and survive. Magnetic field of the star is much stronger than that of the Sun. As a result, it can undergo abrupt increases in brightness for several minutes. It a comparatively young star with an age of less than a billion years. In combination with a lower rate of hydrogen consumption due to its low mass, the convection will allow Wolf 359 to remain a main-sequence star for about eight trillion years.

4.Alpha Centauri

Name, Alpha Centauri is Latinized from α Centauri, and abbreviated Alpha Cen or α Cen. It is a triple star system, consisting of the three stars: α Centauri A, α Centauri B, and the closest star α Centauri C (officially Proxima Centauri). Alpha Centauri A along with Alpha Centauri B are Sun-like stars and together they form the binary star Alpha Centauri AB. Naked eyes can see only two main components which appear like a single-star. It the brightest in the Southern constellation of Centaurus and the third-brightest in the night sky. The Alpha Centauri system as a whole has two confirmed planets, both of them around Proxima Centauri. While other planets have been claimed to exist around all of the stars, none of these discoveries have been confirmed.

5.Lalande 21185

Lalande 21184 in the South of Ursa Major, is the brightest red dwarf in northern hemisphere. It is visible through telescope or binoculars. Close distance makes it a good subject for astronomical surveys and other researches. Most the energy emitted by this star is in the form of infrared rays. It is the brightest star between variable CO Ursae Maj and the comparably bright star HD 95129 to its west (specifically by south) and is a little closer to the latter.

6.Sirius

Sirius is the brightest star in the night star. Sirius is almost twice as bright as Canopus, the next brightest star. Sirius is a binary star consisting of a main-sequence star of spectral type A0 or A1, termed Sirius A, and a faint white dwarf companion of spectral type DA2, termed Sirius B. The distance between the two varies between 8.2 and 31.5 astronomical units as they orbit every 50 years. Also known as Dog Star reflecting the significance in its constellation, Canis Major. Sirius is also visible in daylight with the naked eyes under the right conditions. It appears brighter because of its intrinsic luminosity and its proximity to the Solar system. From earth Sirius appears to be dimmer in comparison to Jupiter, Venus, Mercury and Mars.

7.Rose 154

Rose 154 is a part of southern Sagittarius constellation. It is the nearest to the Sun in that constellation. It was discovered by American astronomer Frank Elmore Ross in 1925 and it became a part of his fourth list of new variable stars. He also added another of stars showing measurable proper motion after comparing its position with photogenic plates by his fellow American astronomer E.E Barnard in 1926. At a minimum, viewing Ross 154 requires a telescope with an aperture of 6.5 cm (3 in) under ideal conditions. The distance to this star can be estimated from parallax measurements, which places it at 9.69 light-years (2.97 parsecs) away from Earth. This star is placed at the sixth position of the then-known nearby stars (during 19th century).

8.Alpha Centauri A

Alpha Centauri A has 1.1 times the mass and 1.519 times the luminosity of the Sun, while Alpha Centauri B is smaller and cooler, at 0.907 times the Sun’s mass and 0.445 times its luminosity. The pair orbit around a common centre with an orbital period of 79.91 years. Their elliptical orbit is eccentric, so that the distance between A and B varies from 35.6 AU (astronomical units), or about the distance between Pluto and the Sun, to 11.2 AU, or about the distance between Saturn and the Sun.

9.Sirius A

Sirius, also known as the Dog Star or Sirius A, is the brightest star in Earth’s night sky. The name means “glowing” in Greek. Because Sirius is so bright, it was well-known to the ancients. But the discovery of a companion star, Sirius B, in 1862 surprised astronomers. In 1718, English astronomer Edmond Halley discovered that stars have “proper motion” relative to one another. This means that stars, including Sirius, move across our sky with a predictable angular motion with respect to more-distant stars. Being a young star, it doesn’t have any planet orbiting around it.

10.Luyten 726-8

8.7 light years away from Earth, Luyten 726-8 is also known as Gliese 65. It was found to be a variable star and was given the designation of BL Ceti. It is a red dwarf and a flare star, classified under UV Ceti variable type, but it is not nearly as remarkable or extreme in its behavior as its companion star UV Ceti. Although UV Ceti was not the first flare star discovered, it is the most prominent example of such a star, so similar flare stars are now classified as UV Ceti type variable stars. This star goes through fairly extreme changes of brightness.

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