Observers
from the Netherlands, Germany, and the
US using a spectrograph
on the Spitzer Infrared
Telescope (formerly called SIRFT) have recently observed (see
Fig. 2 in Lahuis et al. Astrophys.J.636:L145-(2006))
for IRS 46 ([AMD2002]
J162729-243917). IRS 46, a Young Stellar Object, is 125 parsecs
from the sun in the dusty constellation Ophiuchus.
Their spectrogram shows absorption lines for acetylene (C2H2),
hydrogen cyanide (HCN), and carbon dioxide.
These molecules are among the essential pre-biotic ingredients
for life. NASA issued a press
release on this discovery December 20, 2005.
The Dyson Sphere search described
here has been using the IRAS Low
Resolution Spectrograph (LRS)
legacy data to look for Dyson Sphere-like
signatures. The Spitzer spectrogaph resolution is more than twenty
times better than the LRS. On the other hand the Calgary
LRS legacy
data bank contains spectra for more than 11000 sources scatterd over
the sky. In addition the IRS 46 carbon dioxide line including the ice
portion is fairly broad. There is not an IRAS spectrum for IRS 46.
However there is another intense nearby Young Stellar Object [AMD2002]
J162728-243934A associated with the region of IRS 44, that may be
associated with an IRAS LRS spectrum. This
only appears in the Kwok-Volk-Bidelman Calgary LRS data set (Ap.J. SS112, 557 [1997]), not in the 5425
sources
in the original IRAS release. The source is IRAS 16244-2432. The
spectrum below for IRAS 16244-2432 shows a hint of an absorption
region centered at
15.2 microns and has an amplitude (in my units) of 0.06 magnitudes or
about 20% of an underlying blackbody fit. I stress that this is a hint.
I have not tried to do a statistical analysis. Kwok and Volk classify
this source as U, an unusual candidate. The Spitzer team may not have
investigated this source spectroscopically because it is so intense. It
may be interesting to look at it and compare it to IRS 46.
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