galactic center

Also found in: Wikipedia.

galactic center

The innermost region of our Galaxy, or its exact center. Interstellar extinction obscures this region by up to 30 magnitudes at optical wavelengths and information on the very complex phenomena in the galactic center has been derived mainly from radio, infrared, and X-ray observations. The central region (with radius around 200 parsecs) is bright in radio and infrared continuum emission, particularly in lines of molecular CO and atomic C. This central molecular zone accounts for about 10% of the Galaxy's total molecular mass and has a high density and temperatures (30–200K). Star formation at rates of 0.5 solar masses a year is occurring at many places within this central molecular zone, probably triggered by external events, such as shocks. In particular the central parsec shows evidence for recent massive star formation, with many emission-line stars centered on the core of the central stellar cluster. The peak of this infrared emission and the stellar density coincide with the radio emission from an H II region in Sagittarius A (West). This is generally considered to be the dynamic center of the galaxy. There is also extended X-ray line emission centered on the Galactic nucleus, with a size roughly half that of the central molecular zone, indicating that some of the gas not consumed by star formation is present as a hot plasma. The X-rays also reveal a point source at the position of Sgr A West.

The density of dust at the center is very low but probably increases beyond a radius of 1 parsec to give rise to a double-lobed structure, with a 100 μm luminosity of about 107 L O. This may be heated by ultraviolet radiation from a central object located at the position of Sgr A West. The source of this heating radiation is thought to be emission from a massive black hole.

Farther away from the center, radio observations indicate that there is a thin rapidly rotating disk of hydrogen extending out to a radius of about 750 parsecs and also gas moving rapidly away from the center. In particular there are two expanding arms of gas both roughly at a radius of 3 kiloparsecs. The arm on the sunward side of the center is approaching us with a speed of 50 km s–1 and the one on the other side is receding at 135 km s–1.

Galactic Center

(religion, spiritualism, and occult)

Earth is located in a spiral-shaped galaxy approximately 100,000 light-years in diameter. Our solar system lies on the outskirts of the galaxy, about 30,000 light-years away from the galactic center (GC). From Earth’s perspective, the GC is located in the latter degrees of the sign Sagittarius. (Owing to the tropical or moving zodiac that most Western astrologers use, the exact position of the GC appears to be is gradually shifting.) The GC is such an intense source of infrared emissions and microwaves that astrophysicists have speculated that an explosion took place there 10 million years ago. Because our solar system is actually rotating around the GC, the GC can be thought of as a bit like the sun of our solar system. The 250 million years that it takes for our solar system to complete one rotation is called a cosmic year.

Astrologers who have studied the effects of the galactic center in horoscopes have found that it exerts a powerful influence within a narrow orb of 2°, with some effect out to 4°. Individuals with inner planets or one of the angles conjunct the GC have, as noted in Philip Sedgwick’ book The Astrology of Deep Space, a potential link “with whatever it is behind all this.” When this transpersonal link is ignored, the individual can experience stress and confusion; when it is consciously appropriated, information can be grasped that the individual may seem to have no outward way of knowing. The GC is not significant in such natural events as earthquakes, but it does appear to be prominent in important events involving technology. It also seems to play a major role in human inventiveness, especially technological inventiveness.

Given the many points occupying contemporary astrological space—heliocentric planets, multiple midpoints, thousands of asteroids, and so forth—everyone surely has some such point in the latter degrees of Sagittarius. On this basis, some astrologers find it useful to examine the position of the galactic center in every chart, and, by its house placement, determine to which area of the native’s life the cosmos is “speaking.” The GC was located at 26°09’ Sagittarius in 1950, at 26°34’ in 1980, and at 26°51’ in 2000.


Brau, Jean-Louis, Helen Weaver, and Allan Edmands. Larousse Encyclopedia of Astrology. New York: New American Library, 1980.
Sedgwick, Philip. The Astrology of Deep Space. Birmingham, MI: Seek-It Publications, 1984.

galactic center

[gə′lak·tik ′sen·tər]
The gravitational center of the Milky Way Galaxy; the sun and other stars of the Galaxy revolve about this center.
References in periodicals archive ?
When the team looked at the pattern of element abundances in detail, they found that much of the data could be explained by a model in which stars migrate radially, moving closer or farther from the galactic center with time.
The 27,000 light years to the galactic center on our BB-sized solar system scale is more than 40 miles.
The enormous structure, dubbed the Fermi Bubbles, was discovered five years ago as a gamma-ray glow on the sky in the direction of the galactic center.
And I knew that my colleagues from Warsaw monitor the galactic center.
Using publicly available data from NASA's Fermi Gamma-ray Space Telescope, independent scientists at the Fermi National Accelerator Laboratory (Fermilab), the Harvard-Smithsonian Center for Astrophysics (CfA), the Massachusetts Institute of Technology (MIT) and the University of Chicago developed new maps showing that the galactic center produces more high-energy gamma rays than can be explained by known sources and that this excess emission is consistent with some forms of dark matter.
There are some excess gamma rays observed in the Galactic Center but these are probably due to an unresolved population of millisecond pulsars.
Given its size, this supermassive black hole is about a billion times fainter than it could be," said Nathalie Degenaar, principal investigator on the Swift galactic center campaign and an astronomer at the University of Michigan in Ann Arbor.
The star labelled S0-2 has the smallest semi-major axis of about 1020 AU and has been monitored for one complete revolution of its orbit, thereby allowing a determination of the position of the Galactic center Sgr A* at a distance of 8.
This was the fourth international workshop organized by the galactic center community, a disparate group of observers working at all accessible energy ranges from [micro]eV to TeV and theoreticians studying stellar and gas dynamics, star formation, magnetic fields, cosmic rays, astrochemistry, accretion phenomena, and general relativity.
The actual galactic center is best observed with radio telescopes.
To begin with, astronomers agree, there is nothing special about the Sun and galactic center aligning in the sky.
It's hard to study stars at the galactic center," Bonanos says.