A Black Hole? Quite Likely!
An Example of the Value of Indirect Evidence

Elliptical Galaxy NGC 4261

As Seen by
The Hubbel Space Telescope's Wide Field/Planetary Camera

and The National Radio Astronomy Observatory


Many school texts state that black holes are "purely theoretical," but scientists are busy finding and studying them. For example, views from ground-based visual and radio telescopes combined with views from the Hubbel Space Telescope give evidence of a black hole in the giant elliptical galaxy NGC 4261.

Ground-Based Composite
Optical / Radio Image
Hubbel Space Telescope
Image of a Gas and Dust Disk
380 Arc Seconds
( 88,000 Light Years )
--17 Arc Seconds
--( 400 Light Years )

Ring Around a Suspected Black Hole

Left: Ground Based Composite Visual/Radio View: The giant elliptical galaxy NGC 4261 is one of the twelve brightest galaxies in the Virgo cluster, located 45 million light-years away. Photographed in visible light (white) the galaxy appears as a fuzzy disk of hundreds of billions of stars. A radio image (orange) shows a pair of opposed jets emanating from the nucleus and spanning a distance of 88,000 light-years.

Right: HST Image of NGC 4261: A giant disk of cold gas and dust fuels a possible black hole at the core of this galaxy. Estimated to be 300 light-years across, the disk is tipped enough (about 60 degrees) to provide astronomers with a clear view of the bright hub, which presumably harbors the black hole. The dark, dusty disk represents a cold outer region which extends inwards to an ultra-hot accretion disk with a few hundred million miles from the suspected black hole. This disk feeds matter into the black hole, where gravity compresses and heats the material. Hot gas rushes from the vicinity of the black hole's creating the radio jets. The jets are aligned perpendicular to the disk, like an axel through a wheel. This provides strong circumstantial evidence for the existence of black hole "central engine" in NGC 4261.

Resources on Black Holes

booksweb resources

Web Resources

Britannica search: "black hole"

Black Holes and Neutron Stars -- Cambridge Relativity: Black Holes

Black Holes FAQ

Observational Evidence for Black Holes

How We Detect Black Holes and Neutron Stars

Evidence That Black Holes Exist

Space Telescope Science Institute: Black Holes

Images of Black Holes

NCSA Spacetime Wrinkles Exhibit: Site Map
Black Holes and Beyond

Virtual Trips to Black Holes and Neutron Stars 

Simulation of a Black Hole by Ray Tracing

Hubble Space Telescope Images Hubble Heritage Project

More Science Pages from Dharma Haven


Hubble Revisited: New Images From the Discovery Machine
-- Infant galaxies, distant quasars, exploding stars, black holes, supernovae, star deaths -- astonishing clarity.

An Earthling's Guide to Deep Space
Huble images and commentary for young people.

The Mystery of Black Holes -- written for ages 9-11.

Black Holes and Time Warps: Einstein's Outrageous Legacy

Black Holes: A Traveler's Guide

All images and "Ring Around a Suspected Black Hole" text from

Hubbel Space Telescope's Greatest Hits 1990-1995:
A Photo Gallery of the Universe

Responsibility for conducting and coordinating the science operations of the Hubble Space Telescope rests with the Space Telescope Science Institute (STScI) on the Johns Hopkins University Homewood Campus in Baltimore, Maryland. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc. (AURA).

All HST images and pertinent text on these pages were created with support to Space Telescope Science Institute, operated by the Association of Universities for Research in Astronomy, Inc., from NASA contract NAS5-26555 and is reproduced with permission from AURA/STScI. Digital renditions of images produced by AURA/STScI are obtainable royalty-free.

Dharma Haven

Last updated April 3, 2001 

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