DNA precursors in inner disk of YSO  updated March 3, 2016  D. Carrigan carrigan@fnal.gov (subject line must be sensible)

Channeling Adv. Accel. Infrared/IA
SETI Biography Bibliography Infrared
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.