Journey to the Center of the Galaxy

//

Because of increasing light pollution, the most spectacular

structure in the sky is seen by fewer and fewer people these days – the Milky

Way. During the summer months you are in fact peering in the direction of the downtown

hub of our pinwheel galaxy. The central

region straddles the constellations Scorpius and Sagittarius that are low on

the southern horizon when viewed from northern latitudes.

But even on the most pitch-black night you still can’t see

much of the real core because foreground spiral lanes of stars and black dust

obscure it. In visible light, we really see a just few percent of all the stars in the galaxy. It

is definitely a backyard-only view.

Nothing less than the penetrating power of all three

operating NASA Great Observatories was brought to bear on the mysterious galactic

core that lies 27,000 light-years away. Their stunning panoramic image released

today by NASA combines views taken in mid and near infrared light by the Hubble

and Spitzer space telescopes, and seething X-rays captured by the Chandra X-ray

Observatory.

The Spitzer (red) and Hubble (yellow) views reveal a firestorm

of star birth throughout the region. Three known clusters of massive stars dominate it: the

Central cluster, the Arches cluster, and the Quintuplet cluster. Large arcs of

glowing gas form linear filaments that might follow strong magnetic fields.

A smattering of lone superhot stars may have formed in

isolation, or they may have originated in clusters but then tossed out due to

strong gravitational tidal forces. The brightest of these stellar loners,

weighing in at 150 solar masses, is 10 million times the brilliance of our sun.

X-ray observations from Chandra complement this view by

showing the super-hot massive stars as brilliant point-like X-ray sources. The X-rays

reveal that the core is also peppered with the hot remains of supernovae

exploding like hot buttered popcorn. The energy in turn heats the material

between the stars.

The location of the exact center of the galaxy is just off the

tip of  Sagittarius’ “teapot

spout.” Infrared observations with ground-based telescopes, painstaking

collected over the past two decades, have gathered incontrovertible evidence

for the presence of a 3 million solar mass black hole at the core of the

galaxy.

The black hole has been “weighed” by measuring the slingshot

motions of stars caught in the black hole’s gravitational pull. In one stunning

observation a star whipped within 17 light-hours of the black hole and traveled

the distance between the Earth and Pluto in less that a day!

Planets and stars actually form in the disk encircling the

black hole. But their fate is terribly uncertain. Gravitational “pinball game”

interactions among the stars might plunge entire planetary systems into the

black hole pit. Alternatively, stars could get a slingshot kick out of the disk

of the galaxy altogether.

The super-telescope trio unveils the most torturous

neighborhood in the galaxy. Life as we know it would have a very tough time

originating, much less surviving in this cosmic version of Vice City that is bathed in deadly radiation.

DISCOVERYnewsletter
 
Invalid Email