CASSIOPEIA

The Queen

Cassiopeia - Alexander Jamieson - 1822

After the Big Dipper, the most recognizable grouping of stars in the northern sky is the big "W" of Cassiopeia. Nestled securely in the heart of the Milky Way, Cassiopeia is the queen who started a lot of trouble by boasting about her daughter Andromeda's beauty, which you can read all about in the Andromeda Story. The queen is usually depicted sitting on a throne, and to early Arabs, she was the lady in the chair.

Like most queens, Cassiopeia is surrounded by jewels. In this case the jewels are the myriad of star clusters and nebulae that fill the middle of the Milky Way, where she sits on her throne. On her left hand, like a sparkling setting of diamonds, is the open star cluster M103, and on her right, the colorful cluster M52.

The alpha star in the constellation is named Shedir, from the Arabic for breast. It is spectral class K0, magnitude 2.24, 230 light years away. The beta star is Caph, from the Arabic for palm. It is an F2 type star, magnitude 2.28, 55 light years away. The third named star in Cassiopeia is Ruchbah, from the Arabic for knee. Spectral type A5, the star has a magnitude of 2.68, and is 100 light years away.

Supernovae

There have been four officially observed and recorded supernovae in our Milky Way galaxy. The first was SN 1006, observed in the constellation Lupus, in 1006 AD. The second was SN 1054, observed in the constellation of Taurus, which gave rise to Messier's first catalogued "nebula", M1, otherwise known as the Crab Nebula (NGC 1952). Before the fourth and last supernova, SN 1604 (also known as Kepler's Star), was observed in the constellation Ophiuchus in 1604, Milky Way supernova number three, SN 1572, occurred right here, in the constellation of Cassiopeia, in 1572. The famous astronomer, Tycho Brahe, describes his discovery of the "new" star:

"On the 11th day of November in the evening after sunset, I was contemplating the stars in a clear sky. I noticed that a new and unusual star, surpassing the other stars in brilliancy, was shining almost directly above my head; and since I had, from boyhood, known all the stars of the heavens perfectly, it was quite evident to me that there had never been any star in that place of the sky, even the smallest, to say nothing of a star so conspicuous and bright as this. I was so astonished of this sight that I was not ashamed to doubt the trustworthiness of my own eyes. But when I observed that others, on having the place pointed out to them, could see that there was really a star there, I had no further doubts. A miracle indeed, one that has never been previously seen before our time, in any age since the beginning of the world."

Tycho initiated an in-depth study of the star, before the days of telescopes, publishing his results in his famous De Nova Stella, which included his hand drawn map of the star's position, and resulted in the star being given his name: Tycho's Star.

Tycho's star-de nova stella-1572-sm (102K)

Tycho's Star - De Nova Stella - Tycho Brahe - 1572

It would take another 400 years before modern telescopes were able to detect the gaseous remnant of the SN 1572 explosion. The photo below is a x-ray infrared composite of the expanding gas cloud caused by the explosion. It is about 10,000 light years away, and expanding at a speed of about 20 million miles per hour.

SN 1572 - Tycho's Star Supernova Remnant - NASA Spitzer Space Telescope - December, 2008

Cassiopeia also contains the youngest supernova remnant so far discovered in our galaxy. Named Cassiopeia A, it is estimated to be 340 years old, but there is no record of anyone observing the supernova explosion that caused it. It is possible the initial material shed from the dying star obscured the final explosion.

Cassiopeia A Supernova Remnant - Hubble Space Telescope - Optical Light - December, 2004

NGC 7635, also known as The Bubble Nebula, is not a supernova remnant. The shell or bubble of expanding gas is not caused by a dying star, but from a freshly formed star. Embedded in a vast cloud of star formation known as an emission nebula, the stellar wind from this very large, very hot young star has created a bubble of gas around it that is expanding at four million miles per hour.

NGC 7635 - The Bubble Nebula - Adam Block - November, 2011

Exoplanets

There have been two planetary systems discovered so far in the constellation Cassiopeia. Both of the stars are beyond naked eye visibility, and the planets are all gas giants.

Alphabetical Links to the Constellations

ANDROMEDA AQUARIUS AQUILA ARIES AURIGA BOOTES CAMELOPARDALIS CANCER CANES VENATICI CANIS MAJOR CANIS MINOR CAPRICORNUS CARINA CASSIOPEIA CENTAURUS CEPHEUS CETUS COLUMBA COMA BERENICES CORONA AUSTRALIS CORONA BOREALIS CORVUS CRATER CRUX CYGNUS DELPHINUS DORADO DRACO EQUULEUS ERIDANUS FORNAX GEMINI HERCULES HYDRA LACERTA LEO LEO MINOR LEPUS LIBRA LUPUS LYNX LYRA MONOCEROS OPHIUCHUS ORION PEGASUS PERSEUS PISCES PISCIS AUSTRALIS PUPPIS SAGITTA SAGITTARIUS SCORPIUS SCULPTOR SCUTUM SERPENS SEXTANS TAURUS TUCANA URSA MAJOR URSA MINOR VIRGO VULPECULA