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The Traveling Star

by Perry Pezzolanella

The stars look like tiny points of light glued to the night sky. The patterns they create never change and stars are so far away that their proper motion cannot be readily detected. There is one star however that breaks the rule and with patience its motion among the stars can be observed within a few years.

Barnard’s Star is a red dwarf 5.98 light years away and can be found in the summer constellation of Ophiuchus. It is the 4th nearest star to the Sun after the trio of Alpha, Beta, and Proxima Centauri and is the closest star in the north celestial hemisphere. It is about 14% of the Sun’s mass and rather dim at magnitude 9.5, therefore it cannot be seen without optical aid. The star is named after the American astronomer E.E. Barnard who measured its large proper motion of 10.3 arcseconds per year relative to the Sun in 1916, the highest known for any star. Images of the star were also recorded by Harvard in 1888 and 1890 aiding in the calculation of its proper motion. It is the most studied red dwarf because it is so close; its characteristics are well known. On February 1, 2017 the International Astronomical Union (IAU) approved the name for this red dwarf and now Barnard’s Star is officially recognized as a proper name in the List of IAU-approved Star Names.

Barnard’s Star is an ancient star being 7-12 billion years old compared to the Sun at 4.5 billion years and might be the oldest star in the Milky Way galaxy. It is a variable star and a flare star with a slow rotation of 130 days compared to about 27 days for the Sun. It is an active star in spite of its old age; an intense stellar flare was observed in 1998. Two more stellar flares were observed in 2019, one of which was an x-ray flare. A planet orbiting Barnard’s Star would have no chance for life with such intense bursts of radiation.

Barnard’s Star does move noticeably in the sky when near other stars and can be noted if plotted or photographed during the course of several years. It will be slight, but the 10.3 arcseconds of annual motion adds up to about ¼º in a lifetime, roughly half the angular diameter of the Moon. Barnard’s Star will make its closest approach to the Sun, 3.75 light years away, around AD 11,800, but still will not be the closest star as Proxima Centauri will be even closer. It will shine a little brighter at magnitude 8.5. Barnard’s Star is a cool star at 5000ºF compared to the Sun at 11,000ºF. It has roughly 150 times the mass of Jupiter even though it is only about twice as large. This means that Barnard’s Star has a higher density and consists of 10%-32% metal in proportion to hydrogen and helium. This is typical of old red dwarf stars.

A super-Earth was discovered orbiting Barnard’s Star in November 2018. It orbits about 37 million miles from the star every 233 days and is approximately 3.2 times the mass of Earth. It is most likely frigid with a surface temperature as cold as Titan at -277ºF and lies outside the habitable zone. The surface and atmospheric conditions of this world will have to wait until future telescopes become available with more sensitive instruments. Additional perturbations of Barnard’s Star hint at a second planet orbiting further out.

It is not hard to imagine what it would be like exploring or living at Barnard’s Star. It is literally within the Sun’s neighborhood which is composed mainly of red dwarfs. It is only 5.41 light years away from another red dwarf, Ross, and is the closest star to it. The Sun and Alpha Centauri are the next closest. The Sun shines bright as seen from Barnard’s Star, shining as a first magnitude star similar to Pollux from Earth. The Sun would be located in the eastern part of the winter constellation Monoceros, a welcoming beacon to all travelers.

This article is dedicated in memory of Al Mlinar (1915-2020)