Images to accompany Throop, Bally, Esposito, McCaughrean paper in Science, 27-Apr-2000,
'Large Grains in Young Circumstellar Disks'

General info: Most of the images here are Hubble Space Telescope (HST)
images.  The two instruments we've used are WFPC2 (Wide Field and
Planetary Camera) and NICMOS (Near-InfraRed Camera and Multi-Object
Spectrograph).  All these images are courtesy NASA / STScI / J. Bally,
C. R. O'Dell, M. McCaughrean unless otherwise noted.  In general, the
color images are false-color composites of three monochrome images,
where the R, G, and B channels each correspond to one emission line of
the nebula.

Size-scales: 
             The Orion nebula is about 1 ly across.
             The 114-426 disk is about 1000 AU across.  1 Astronomical Unit is the 
                distance between the Sun and the Earth.
             Most of the circumstellar disks in Orion are 50-200 AU across.

The most relevant to our current work are the following:
  wfpc2mosaicw.jpg	- overview of the Orion nebula
  SW.jpg		- new color image
  SW_IR.jpg		- new color image
  mosaic114clip.jpg	- new b&w image
  Bally.fig7aw.jpg	- composite b&w image of many circumstellar disks in Orion

In alphabetical order, here are descriptions of the images:
  
mosaic114clip.jpg - These are the two processed, monochrome images
shown in the Science paper.  They both show the 114-426 disk and are
HST images.  At left, taken with WFPC2, in H-alpha, 656 nm (credit:
NASA / STScI / J. Bally, C. R. O'Dell, M. McCaughrean).  At right,
taken with NICMOS, in Paschen-apha, 1870 nm (credit: NASA / STScI / M.
McCaughraen).

Bally.fig7aw.jpg - A collection of all the dark silhouette disks that
we have seen in Orion, including 114-426 at the lower right corner.
Taken from Bally et al 2000, Astronomical Journal 119, 2919-2959.

bally.fig7bw.jpg - A collection of many of the 'comet tails' of ionozed
material being evaporated from the disk surfaces.  The bright regions
are gas which used to be in the disk, but has been heated an has now
escaped.  Taken from Bally et al 2000, Astronomical Journal 119,
2919-2959.

Figure_10w.jpg - A cartoon image of disk photoevaporation.
Taken from Bally et al 2000, Astronomical Journal 119, 2919-2959.

HST6_prop_galleryw.jg - A mosaic of six objects in Orion.  #2 has a
dark tail, and appears to be dust that has been blown off of the
(hidden) circumstellar disk.  #3 (HST10) has a visibile disk edge-on at
its center.  #5 is the 114-426 disk, with its central star visible
indirectly.  #6 (HST16) is the prototypical Orion circumstellar disk,
with teh central star easily visible.  Both #5 and #6 are in regions of
the nebula where they are not being photo-evaporated right now.

LV3Haoiiioi.jpg - The core Trapezium region of the Orion nebula.  These
four stars are responsible for lighting the entire region, and causing
the photo-evaporation.  Theta 1C, at the lower right-hand corner, is
the brightest, approx. 100,000 times the brightness of our sun.  The
'tails' from all the objects seen are proto-planetary disks currently
being destroyed.

hst10haniioi.jpg - The HST10 and HST16 disks.

SW.jpg - A color composite showing the 114-426 disk in the 656 nm light
of hydrogen (blue), and a broad band filter centered at 814 nm.  This
image was obtained with WFPC2 on HST.

SW_IR.jpg - A close-up color composite if 114-426 in which the blue
light corresponds to the 656 nm hydrogen line, the green shows the 1870
nm line of hydrogen, and the red show the continuum at 1100 nm.  The
background Orion nebula looks turquoise since there is about the same
amount of light filtering through both the blue and green channels.
The Orion Nebula (background) is relatively dark in the 1100 nm
continuum.  However, the young  star embedded in the disk (and which is
completely obscured by it) generates light that is reflected by dust
above and below the disk in the 1100 nm continuum image, and to some
extent in the 1870 nm image, hence it looks orange.  

io113w.jpg - A cartoon of processes in the Orion disks.  Created by
STScI and not to be released.

orionfujiw.jpg - The Orion constellation.  The Orion nebula is the
middle star of the sword.  Photograph by Akira Fujii.  Not to be
released.

wfpc2mosaicw.jpg - WFPC2 mosaic of the Orion region.  The Trapezium
cluster is visible at the center.  The center also has a high density
of stars, most of which are surrounded by disks and/or ionized
material.  The 114-426 disk is located about halfway out, and not
easily visible in this image.  The Orion nebula has given birth to
about 20,000 young stars in the last 12 million years.

	-Henry Throop, Southwest Research Institute
	26-Apr-2001
	throop@REMOVE_ME.colorado.edu