STIS measures a velocity of 880,000 miles per hour (400 kilometers per
second) within 26 light-years of the galaxy's center, where the black
hole dwells. This motion allowed astronomers to calculate that
the black
hole contains at least 300 million solar masses.
MASSIVE BLACK HOLES IN GALAXIES NGC 3377, NGC 3379 AND NGC 4486B
The three galaxies above are believed to contain central, supermassive
black
holes. The galaxy NGC 4486B (lower-left) shows a double nucleus
(lower-right).
The images of NGC 3377 and NGC 4486B are 2.7 arcseconds on a side,
and for
NGC 3379 the size is 5.4 arcseconds; the lower-right is a blow-up of
the
central 0.5 arcseconds of NGC 4486B.
FIREWORKS NEAR A BLACK HOLE IN THE CORE OF
SEYFERT GALAXY NGC 4151
The Space Telescope Imaging Spectrograph (STIS) simultaneously records,
in
unprecedented detail, the velocities of hundreds of gas knots streaming
at
hundreds of thousands of miles per hour from the nucleus of NGC 4151,
thought to house a supermassive black hole.
This is the first time the velocity structure in the heart of this object,
or
similar objects, has been mapped so vividly this close to its central
black
hole.
The twin cones of gas emission are powered by the energy released from
the
supermassive black hole believed to reside at the heart of this Seyfert
galaxy. The STIS data clearly show that the gas knots illuminated by
one of
these cones is rapidly moving towards us, while the gas knots illuminated
by
the other cone are rapidly receding.
The images have been rotated to show the same orientation of NGC 4151.
The
figures show:
WFPC2 (upper left) -- A Hubble Wide Field Planetary Camera 2 image of
the
oxygen emission (5007 Angstroms) from the gas at the heart of NGC 4151.
Though the twin cone structure can be seen, the image does not provide
any
information about the motion of the oxygen gas.
STIS OPTICAL (upper right) -- In this STIS spectral image of the oxygen
gas,
the velocities of the knots are determined by comparing the knots of
gas in
the stationary WFPC2 image to the horizontal location of the knots
in the
STIS
image.
STIS OPTICAL (lower right) -- In this false color image the two emission
lines
of oxygen gas (the weaker one at 4959 Angstroms and the stronger one
at 5007
Angstroms) are clearly visible. The horizontal line passing through
the
image
is from the light generated by the powerful black hole at the center
of NGC
4151.
STIS ULTRAVIOLET (lower left) -- This STIS spectral image shows the
velocity
distribution of the carbon emission from the gas in the core of NGC
4151. It
requires more energy to make the carbon gas glow (CIV at 1549
Angstroms)
than
it does to ionize the oxygen gas seen in the other images. This means
we
expect that the carbon emitting gas is closer to the heart of the energy
source.
NASA's Hubble Space Telescope has provided a never-before-seen view
of
a warped disk flooded with a torrent of ultraviolet light from
hot gas trapped around a suspected massive black hole.
[Right]
This composite image of the core of the galaxy was constructed by
combining a visible light image taken with Hubble's Wide Field
Planetary Camera 2 (WFPC2), with a separate image taken in
ultraviolet light with the Faint Object Camera (FOC). While the
visible light image shows a dark dust disk, the ultraviolet image
(color-coded blue) shows a bright feature along one side of the
disk. Because Hubble sees ultraviolet light reflected from only
one side of the disk, astronomers conclude the disk must be
warped like the brim of a hat. The bright white spot at the
image's center is light from the vicinity of the black hole which
is illuminating the disk.
[Left]
A ground-based telescopic view of the core of the elliptical
galaxy NGC 6251. The inset box shows Hubble Space Telescope's
field of view. The galaxy is 300 million light-years away in the
constellation Ursa Minor
Resembling a gigantic hubcap in space, a 3,700 light-year-diameter
dust disk encircles a 300 million solar-mass black hole in the center of
the elliptical galaxy NGC 7052.
NASA's Hubble Space Telescope offers a stunning unprecedented
close-up view of a turbulent firestorm of starbirth along a nearly edge-on
dust disk girdling Centaurus A, the nearest active galaxy to Earth.
[UPPER LEFT] - A close-up high resolution Wide Field Planetary Camera
2
image of the dramatic dust disk which is thought to be the remnant
of a
smaller spiral galaxy that merged with the large elliptical galaxy.
The shock
of the collision compressed interstellar gas, precipitating a flurry
of star
formation and giving the material a fleecy pattern. Dark filaments
of dust
mixed with cold hydrogen gas are silhouetted against the incandescent
yellow-orange glow from stars behind it.
[LOWER RIGHT] - Hubble's Near Infrared Camera and Multi-Object
Spectrometer was used to peer past the dust to discover a tilted disk
of
hot gas at the galaxy's center (white bar running diagonally across
image center). This 130 light-year diameter disk encircles a suspected
black hole which may be one billion times the mass of our Sun. The
disk
feeds material to presumably an inner, unresolved accretion disk that
is made up of gas entrapped by the black hole. The red blobs near the
disk are glowing gas clouds which have been heated up and ionized by
the powerful radiation from the active nucleus.
The false-color NICMOS image was taken on Aug. 11, 1997 at a
wavelength of 1.87 microns ("Paschen alpha"), characteristic
of
ionized Hydrogen.
Confirming the presence of yet another super-massive black hole in the
universe, astronomers using the Hubble Space Telescope have found
unexpected new mysteries. The black hole, and a 800 light-year-wide
spiral-shaped disk of dust fueling it, are slightly offset from the
center of their host galaxy, NGC 4261, located 100 million light-years
away in the direction of the constellation Virgo.
The strikingly geometric disk -- which contains enough mass to
make
100,000 stars like our Sun -- was first identified in Hubble
observations made in 1992. These new Hubble images reveal for
the
first time structure in the disk, which may be produced by waves or
instabilities in the disk.
Prior to Hubble observations, astronomers did not think dust was common
in elliptical galaxies like NGC 4261, which were thought to have
stopped making stars long ago due to the absence of the requisite raw
materials: interstellar gas and dust. However, Hubble is showing
that
dust and beautiful disks are common in the centers of elliptical
galaxies. The most conventional explanation is that the disk
is the
remnant of a smaller galaxy that fell into the core of NGC 4261.
The
black hole will swallow the gas from the intruder over the next 100
million years, and in the process produce spectacular fireworks,
researchers predict.