An X-ray image of the Sirius star system. The bright source in this image is the white dwarf star Sirius B. The fainter x-ray source is Sirius A, the brightest visible star in the northern sky.
Click on image for full size
NASA/CXC/SAO

Sirius B - Bizarre White Dwarf Companion of Sirius A

What's in a Name: Nicknamed the "Pup" because it is the companion to Sirius, "the Dog Star"
Claim to Fame: Highly compressed white dwarf remnant. Density about 50,000 times that of water. It has approximately the mass of the sun compressed into an object the size of the Earth. Swings around Sirius A every 50 years. First observed in 1862 by Alvin Clark.
Type of Star: White dwarf
How Far Away: 8.7 light years away (2.7 parsecs)
How Big: Only three quarters as big as the Earth (2/100 of the sun's diameter, 0.9 times the solar mass)
How Bright: 360 times fainter than the sun
Where to View: In the constellation Canis Major (Star Map).
When to View: Not visible with the unaided eye. Canis Major best viewed January through March
Last modified January 31, 2005 by Travis Metcalfe.

You might also be interested in:

Traveling Nitrogen Classroom Activity Kit

Check out our online store - minerals, fossils, books, activities, jewelry, and household items!...more

Gamma Ray Bursts - The Most Powerful Objects in the Universe?

In the 1960's, the United States launched some satellites to look for very high energy light, called Gamma Rays. Gamma Rays are produced whenever a nuclear bomb explodes. The satellites found many bursts...more

Galaxies

During the early 1900's, which is not very long ago, astronomers were unaware that there were other galaxies outside our own Milky Way Galaxy. When they saw a small fuzzy patch in the sky through their...more

Neutron Stars

Neutron Stars are the end point of a massive star's life. When a really massive star runs out of nuclear fuel in its core the core begins to collapse under gravity. When the core collapses the entire star...more

Spiral Galaxies

Spiral galaxies may remind you of a pinwheel. They are rotating disks of mostly hydrogen gas, dust and stars. Through a telescope or binoculars, the bright nucleus of the galaxy may be visible but the...more

White Dwarfs

When stars like our own sun die they will become white dwarfs. As a star like our sun is running out of fuel in its core it begins to bloat into a red giant. This will happen to our sun in 5 Billion years....more

Algol

What's in a Name: Arabic for "head of the demon" Claim to Fame: Represents Medusa's eye in Perseus. A special variable star that "winks" every 3 days. Type of Star: Blue-white Main Sequence Star, and...more

Sirius B - Bizarre White Dwarf Companion of Sirius A

What's in a Name: Nicknamed the "Pup" because it is the companion to Sirius, "the Dog Star" Claim to Fame: Highly compressed white dwarf remnant. Density about 50,000 times that of water. It has approximately...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA