William B. Latter's
Pictures and Research Page
What's this? (OH231.8+4.2) |
And this? (NGC 7027) |
It is
new data from the Hubble Space Telescope and the Near-Infrared Camera/Multiobject
Spectrometer (NICMOS). Click on it to learn more, and to see a comparison
with ground-based data.
 |
Hubble 12: Click here to see the young planetary nebula Hubble 12 in the 2.121 micron emission of molecular hydrogen (H2). A butterfly in the making! This near-infrared molecular emission comes from a process called fluorescence, which is triggered by pumping from ultraviolet photons coming from the hot central star. Click on the images to see a brief discussion. (Hora, J.H., and Latter, W.B. 1996, ApJ, 461, 288) |  |
The Cygnus Egg Nebula: The images below (taken using a telescope
on the summit of Mauna Kea in 1992) are of the very evolved star (``proto''
planetary nebula) AFGL 2688 (the ``Egg Nebula'') in the constellation Cygnus.
Most of the light seen in these images is light from the completely obscured
central star that has been scattered by tiny dust particles. This dust
has formed out of the carbon-rich material cast off by the star as its
nuclear fuel runs out. The image at 0.8 microns (top) shows spectacular
concentric rings of emission and bright beams shining out of the polar
regions. The rings suggest this star has had a time-varying mass loss rate
(``puffs'') on a time scale of about 470 to 650 years. In the image at
2.2 microns (bottom) we see emission from molecular hydrogen in what might
be a ring in the equatorial region. This emission is caused by shocks within
interacting winds, but how it arises in the observed location is not understood
(Latter et al. 1993, AJ,
106, 260; Hora, J.H.,
and Latter, W.B. 1994, ApJ,
437, 281). Similar objects are AFGL
618 and M
1-92. It is possible that these objects will evolve to take on the
form of a butterfly, like NGC
2346 (Latter et al. 1995, ApJS,
100, 159).
AFGL 2688 at 0.8 microns (I band) |
AFGL 2688 at 2.2 microns (K band) |
| I reported the first ever detection of the carbon monoxide ion (CO+) in the interstellar medium and a planetary nebula. These detections were based on three millimeter and submillimeter transitions in M17SW (right) and two in NGC 7027 (See some ground-based near-IR images here.) using the NRAO 12 meter and the Caltech Submillimeter Observatory. Chemical models suggest that CO+ should be most abundant where complex molecules are least likely to be present. In my search for CO+, I therefore minimized the chance of confusion while maximizing the probability of detection by observing regions whose chemistry is dominated by the effects of ultraviolet radiation (Latter, Walker, and Maloney 1993, ApJ Letters, 419, L97). Most likely present in regions were molecules are being destroyed by the UV photons from nearby very young stars, CO+ has now been found in several other interstellar regions, including in a part of the Great Nebula in Orion. The information it provides is helping us to understand the evolution of the interstellar medium and the star formation process. |  |
First detection spectra of the carbon monoxide ion.
Is this methanol (CH3OH) in the very carbon-rich circumstellar envelope around the star IRC+10216? No, it is not. But, we thought thought it might have been! If it were methanol, then the implications to our understanding of circumstellar chemistry would have been far reaching. Learn more by clicking here.
(Not!) Spectra of methanol in IRC+10216.
The Serpens Molecular Cloud in the millimeter-wave (146.97 GHz) emission of the carbon monosulfide (CS) molecule. These data were taken with the new on-the-fly observing technique at the NRAO 12 meter telescope on Kitt Peak. The CS emission probes dense gas found in regions of star formation (Mangum, Latter, and McMullin, 1998, ApJ, in preparation).
Watch this spot for soon to be revealed images and other data of:
Last update: Fri Oct 8 21:21:11 PDT 1999 by Dr. William B. Latter
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