Barnard’s Star
Barnard’s Star is a red dwarf about six light-years away from Earth in the constellation of Ophiuchus. It is the fourth-nearest-known individual star to the Sun after the three components of the Alpha Centauri system, and the closest star in the northern celestial hemisphere. 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.
About Barnard’s Star in brief
Barnard’s Star is a red dwarf about six light-years away from Earth in the constellation of Ophiuchus. It is the fourth-nearest-known individual star to the Sun after the three components of the Alpha Centauri system, and the closest star in the northern celestial hemisphere. 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. The star is named after the American astronomer E. E. Barnard, who in 1916 measured its proper motion as 10. 3 arcseconds per year relative to the sun. In 2016, the International Astronomical Union organized a Working Group on Star Names to catalogue and standardize proper names for stars. In November 2018, a candidate super-Earth planetary companion known as Barnard’s star b was reported to orbit the star at 0. 4AU. It has the variable star designation V2500 Ophiuchi, and it is now included in the List of IAU-approved Star Names. It will make its closest approach to theSun around 11,800 CE, when it will approach to within about 3. 75 light- years. Proxima Centauri is the closestStar to Sun at a position currently 4. 24 light- Years distant from it. Despite the star’s even closer pass to Sun in 11,000 CE, it will still not then be the nearest star, since by that time ProXima Centauri will have moved to a aarer-nearer position.
At 7–12 billion years of age, Barnard’s Star is considerably older than the Sun, which is 4. 5 billion years old. It might be among the oldest stars in the Milky Way galaxy. It was long assumed to be quiescent in terms of stellar activity, but in 1998, astronomers observed an intense stellar flare, showing it is a flare star. The proper motion of Barnards Star corresponds to a relative lateral speed of 90 kms. The 10.3 seconds of arc it travels annually amount to a quarter of a degree in a human lifetime, roughly half the angular diameter of the full Moon. The effective temperature is 3,100 kelvin and it has a visual luminosity of 0. 0004 solar luminosities. Its mass is about 150 times the mass of Jupiter, although its radius is only about 1 5 to 2 times larger, due to its much higher density. The Sun will still be seen with the naked eye yet, since its apparent magnitude will only have increased by one magnitude to about 8. 5 by then, still being short by 2 magnitudes of visibility by then by then. The Star has a mass of 14 solar masses and a radius of 15% to 20% of that of the Sun. It rotates once in 130 days, and its rotational energy is about 1.5 times the radius of Jupiter, although its mass is only 1.2 times that of Jupiter.
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This page is based on the article Barnard’s Star published in Wikipedia (as of Nov. 22, 2020) and was automatically summarized using artificial intelligence.
