The mass of a star is an important factor in the object's stellar evolution because it determines the star's core temperature and how long and hot the star will burn. The Transiting Exoplanet Survey Satellite (TESS) was launched to study the exoplanets of bright stars. Eventually, Earth's sun will cycle to the white dwarf stage as well. Scientists study white dwarfs like Sirius B in hopes of gaining a better understanding of the stellar cycle. White dwarfs get dimmer and dimmer until they eventually stop burning and go dark, thus becoming black dwarf stars- the theoretical final stage of a star's evolution. Sirius B is a white dwarf star, which is the last observable stage of a low- to medium-mass star. astronomer and telescope maker, confirmed Bessel's hypothesis in 1862 when he spotted Sirius B through Clark's newly developed great refractor telescope. Bessel hypothesized that an unseen companion star affected Sirius' motion. More than 100 years after Halley's finding, in 1844, German astronomer Friedrich Wilhelm Bessel published a scientific note in the Monthly Notices of the Royal Astronomical Society describing how Sirius had been deviating from its predicted movement in the sky since 1755. This means that stars, including Sirius, move across our sky with a predictable angular motion with respect to more distant stars. In 1718, English astronomer Edmond Halley discovered that stars have "proper motion" relative to one another, according to the Quarterly Journal of the Royal Astronomical Society. The brightest star (top center) is Sirius. This illustration displays the shape of the Canis Major constellation. The ancients felt that the combination of the sun during the day and the star at night was responsible for the extreme heat during mid-summer. 11, when Sirius rises in conjunction with the sun, previously reported. Today, Sirius is nicknamed the "Dog Star" because it is part of the constellation Canis Major, Latin for "the greater dog." The expression "dog days" refers to the period from July 3 through Aug. There is no accepted explanation of how this could have happened. Historical records from the Alexandrian astronomer Claudius Ptolemy (around the year 150 AD) suggest that Sirius was a red star in the past (it is very hot and white today). Are there any scientific mysteries surrounding Sirius that researchers would like to solve? That companion, referred to as Sirius B, has a mass equal to that of our sun, but it's 100 times smaller and thus a million times denser than our sun. ![]() Just as important, Sirius has the closest-known "white dwarf," a stellar "corpse," as a binary companion. Sirius is the closest star that's more massive and a lot more luminous than our sun. Why is Sirius of interest to the astronomy community? ![]() This is most easily seen by our eyes in the case of Sirius because it's so bright. The air in our atmosphere spreads out (or "disperses") different colors of light by different amounts, creating a rainbow effect for all stars. ![]() Out in airless space, stars never twinkle. Tiny differences in the amount of air every fraction of a second between us and Sirius cause the twinkling. We see Sirius through our atmosphere, which is turbulent. This combination of high intrinsic luminosity and closeness explains Sirius' brightness. Sirius is 25 times more luminous than our sun and just 8.6 light years distant. We asked Michael Shara, a curator in the American Museum of Natural History's Department of Astrophysics, a few frequently asked questions about Sirius. Curator and Professor, Department of Astrophysics, Division of Physical Sciences, at the American Museum of Natural History.
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