IMAGES: New Technology Yields Closest-ever View of the Dusty Donut Around a Young Star and a Surprise Companion

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This picture is a close-up
view of the donut-shaped dust cloud around the massive star LkHa101. It was
taken in September, 1998 using an interferometer aperture mask on the secondary
mirror in front of the Near Infrared Camera (NIRC) instrument on the Keck telescope,
Mauna Kea, Hawaii. It reveals the hottest, innermost regions of the cloud using
near-infrared light (at 2.27 microns for this image), which is invisible to
the human eye. The false colors represent intensity; white is the most intense,
red the least. The star, which can’t be seen, is in the reddish “hole” in the
middle. The hole is a void in the cloud caused by the star’s heat, which vaporizes
the dust. This void extends about 316 million miles from the star. Although
the star is intensely hot, it can’t be seen in this image because it is too
small, and most of its radiation is of a different type which can’t be detected
by the NIRC.

We are seeing the cloud
at a slight angle (no more than 35 degrees) to the star’s axis of rotation;
if we were viewing directly down the rotation axis, the image would appear ring-shaped.
Instead, we see a crescent shape because one side of the “donut” is tipped towards
us. The large, bright region on the right side of the hole is the side of the
donut-shaped cloud closest to us, which blocks light from the far side (left
side of the hole), forming a crescent-shaped image.

This picture reveals
regions in a surrounding dust cloud that are closer to the central star than
anything previously seen, and images for the first time the central void in
these clouds caused by the star’s heat and radiation. The ability to see fine
structure in these dust clouds is of interest to astronomers because the clouds
are thought to provide the material for planet formation. The dust cloud around
LkHa101 is larger than the NIRC images indicate, because there is a great deal
of outlying material that is cooler than what NIRC can see. The bar on the bottom
axis is for scale, ten Astronomical Units (AU) is about 930 million miles, or
ten times the Earth’s distance from the Sun. The picture on the right has Earth’s
orbit added for scale.

Image credit:
The National Science Foundation, NASA and the Harvard-Smithsonian Center for
Astrophysics

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This picture is a wide
field-of-view shot of the dust cloud around LkHa101 that shows its previously
unknown companion star. It was also taken in September, 1998 using the interferometer
aperture mask with the Near Infrared Camera (NIRC) instrument on the Keck telescope,
Mauna Kea, Hawaii. Like the close-up image, it was made using near infrared
light, but at a slightly different energy level (1.65 microns). The dust cloud
around LkHa101 is the large, bright area on the right, and the newly-discovered
companion star with surrounding hot dust is the faint region in the upper left.
Prior observations did not have sufficient resolution to detect the companion
star, which orbits around LkHa101 at a distance of about 2.6 billion miles.
The bar on the bottom axis is for scale, 20 Astronomical Units (AU) is about
1.86 billion miles, or 20 times the Earth’s distance from the Sun. The right
picture has the orbits of Earth and Uranus added for scale.

Image credit:
The National Science Foundation, NASA and the Harvard-Smithsonian Center for
Astrophysics

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These images are an
artist’s concept of the dust cloud around LkHa101. We are seeing the cloud at
a slight angle (no more than 35 degrees) to the star’s axis of rotation; if
we were viewing directly down the rotation axis, the image would appear ring-shaped
(left picture). Instead, we see a crescent shape because one side of the “donut”
is tipped towards us (right picture).
The bar on the bottom axis is for scale, 20 Astronomical Units (AU) is about
1.86 billion miles, or 20 times the Earth’s distance from the Sun. The
right picture has Jupiter’s orbit added for scale.

Image credit:
NASA, Joseph Miller