Bulge (astronomy)

In astronomy, a bulge is a tightly packed group of stars within a larger formation. The term almost exclusively refers to the central group of stars found in most spiral galaxies (see galactic spheroid). Bulges were historically thought to be elliptical galaxies that happened to have a disk of stars around them, but high-resolution images using the Hubble Space Telescope have revealed that many bulges lie at the heart of a spiral galaxy. It is now thought that there are at least two types of bulges: bulges that are like ellipticals and bulges that are like spiral galaxies.

Classical bulges

Bulges that have properties similar to those of elliptical galaxies are often called classical bulges due to their similarity to the historic view of bulges. These bulges are composed primarily of stars that are older, Population II stars, and hence have a reddish hue (see stellar evolution). These stars are also in orbits that are essentially random compared to the plane of the galaxy, giving the bulge a distinct spherical form. Due to the lack of dust and gasses, bulges tend to have almost no star formation. The distribution of light is described by de Vaucouleurs' law.

Bulge

Bulge may refer to:

Astronomy and geography

Military

People

Other

Equatorial bulge

An equatorial bulge is a difference between the equatorial and polar diameters of a planet, due to the centrifugal force of its rotation. A rotating body tends to form an oblate spheroid rather than a sphere. The Earth has an equatorial bulge of 42.77 km (26.58 mi): that is, its diameter measured across the equatorial plane (12,756.27 km (7,926.38 mi)) is 42.77 km more than that measured between the poles (12,713.56 km (7,899.84 mi)). An observer standing at sea level on either pole, therefore, is 21.36 km closer to Earth's centrepoint than if standing at sea level on the equator. The value of Earth's radius may be approximated by the average of these radii.

An often-cited result of Earth's equatorial bulge is that the highest point on Earth, measured from the center outwards, is the peak of Mount Chimborazo in Ecuador, rather than Mount Everest. But since the ocean, like the Earth and the atmosphere, bulges, Chimborazo is not as high above sea level as Everest is.

Astronomy

Astronomy, a natural science, is the study of celestial objects (such as stars, galaxies, planets, moons, asteroids, comets and nebulae) and processes (such as supernovae explosions, gamma ray bursts, and cosmic microwave background radiation), the physics, chemistry, and evolution of such objects and processes, and more generally all phenomena that originate outside the atmosphere of Earth. A related but distinct subject, physical cosmology, is concerned with studying the Universe as a whole.

Astronomy is one of the oldest sciences. The early civilizations in recorded history, such as the Babylonians, Greeks, Indians, Egyptians, Nubians, Iranians, Chinese, and Maya performed methodical observations of the night sky. However, the invention of the telescope was required before astronomy was able to develop into a modern science. Historically, astronomy has included disciplines as diverse as astrometry, celestial navigation, observational astronomy and the making of calendars, but professional astronomy is nowadays often considered to be synonymous with astrophysics.

Astronomy (Dragonland album)

Astronomy is the fourth studio album by Swedish power metal band Dragonland, released in Europe on November 13, 2006 and in North America on November 28, 2006. While their third album Starfall focused heavily on keyboards and had a more upbeat lyrical tone, according to guitarist Olof Mörck, Astronomy is "gloomier, more stygian and packed with crunching guitars; both furiously fast and bone-grindingly heavy."

Track listing

All songs written and composed by Olof Mörck, except "Intuition", by Tony Harnell, Ronni Le Tekrø. 

Lyrical references

In a February 2007 interview with Metal Reviews, guitarist Olof Mörck went into details about some of musical and lyrical influences in Astronomy:

Astronomy (song)

"Astronomy" is a rock song by Blue Öyster Cult that has appeared on several of the band's albums. It was first published on their 1974 album Secret Treaties. Their second live album, Some Enchanted Evening, included a version with an extended guitar solo and a third version was included on the Imaginos album. It was also re-recorded for the band's Cult Classic collection in connection with the TV miniseries of Stephen King's The Stand. Most recently the song was included on the A Long Day's Night album.

Lyrics

The song's lyrics are selected verses from a poem by Sandy Pearlman, the band's producer and mastermind behind their image, called "The Soft Doctrines of Immaginos". In the poem, which was later partially released under the BÖC moniker in the album Imaginos, aliens known as Les Invisibles guide an altered human named Imaginos, also called Desdinova, through history, playing key roles that eventually lead to the outbreak of World War I.

In "Astronomy", the character of Imaginos comes to realize his heritage and his role as the altered human. References are made to celestial objects throughout the song: "The light that never warms" being the moon, "The Queenly flux" the constellation Cassiopeia, "My dog, fixed and consequent" being Sirius, the dog star. The "Four Winds Bar" may be a reference to the Tropic of Cancer. All in all, it has Imaginos explaining his position as part of Les Invisibles.