Why So Sirius? Trivia Quiz

Answer: scorching

Sirius was considered a scorching star. It rose for the first time each year in the pre-dawn sky in July and August, the hottest times of the year in the Mediterranean region. The Greek word for sun is helios or ilios, photra is fire, and phloga is flame.

Answer: False

The Moon, Jupiter, Venus, and Mars at closest approach are all brighter than Sirius.

Answer: 1

Sirius B is a white dwarf. Its age has been calculated at 120 million years, and the two stars, forming a binary system, are calculated to be between 200 million and 300 million years old. It was discovered on January 31, 1862 through the lens of an 18.5-inch refractor, by Alvan Graham Clark and his father, telescope makers in Cambridgeport, Massachusetts.

They reported their finding right away to George Bond, head of the Harvard College Observatory. Professor Bond confirmed their discovery with Harvard's 15-inch refractor a week later, and reported the find to scientific societies in the United States and Europe. (Thanks to the University of Arizona's article about this discovery.)

Answer: Procyon and Betelgeuse

Procyon, in Canis Minor, the Little Dog, and Betelgeuse, the red giant in the right shoulder of Orion, form the Winter Triangle with Sirius. While all the others are nearby, they are too far away to form a distinctive, obvious triangle with Sirius.

Answer: 40 days

In Homer's time, when the "dog days" were first identified, they extended 40 days from the last week of July till the end of the first week of September. This long spell of very hot weather was rumored to drive dogs crazy. Nowadays, the dog days are considered just the hottest days of August, whenever they might occur in any particular year.

Answer: A0-1V

Sirius is an A-type star, temperature class 0, the hottest of the light blue or blue-white A stars. The 1V refers to its size, a subgiant.

Answer: Size

Sirius is a mere 8.6 light years from our sun, it has a hot surface temperature and its apparent magnitude is -1.45, so all of these reasons contribute to its being recognized as the brightest star in our sky. Its size classification is subgiant, so it is much smaller than other very bright stars such as Betelgeuse and Antares, which are both M-class red supergiants.

Answer: 2 times our sun's mass

Surprisingly for such a bright, hot star, Sirius has just over twice the mass of our sun. It is expected to expend its hydrogen and convert to burning helium long before our sun, a steadily burning G-type star, exhausts its fuel supply.

Answer: In about 700 million years

Sirius will remain in our sky as a bright blue-white A-type star for only about another 700 million years. Then it will start burning its helium for a short time.

Answer: White dwarf like Sirius B

Even though Sirius is currently two solar masses in size, above the Chandrasekhar limit for the formation of white dwarfs, astronomers are reasonably sure it will lose about sixty per cent or more of that mass as it goes through helium fusion, and becomes for a short time, a red giant.

As it cools it will then shrink and become a white dwarf like its companion. Sirius would need a current mass of 8 or more solar masses to become a neutron star or a black hole rather than a white dwarf. Stars significantly smaller than Sirius end their existence as brown dwarf stars.