Astrophys. J., 636, L145-L148 (2006/January-2)
Hot organic molecules toward a young low-mass star: a look at inner disk chemistry.
LAHUIS F., VAN DISHOECK E.F., BOOGERT A.C.A., PONTOPPIDAN K.M., BLAKE G.A., DULLEMOND C.P., EVANS II N.J., HOGERHEIJDE M.R., JORGENSEN J.K., KESSLER-SILACCI J.E. and KNEZ C.
Abstract (from CDS):
Spitzer Space Telescope spectra of the low-mass young stellar object (YSO) IRS 46 (Lbol~0.6 L☉) in Ophiuchus reveal strong vibration-rotation absorption bands of gaseous C2H2, HCN, and CO2. This is the only source out of a sample of ∼100 YSOs that shows these features, and this is the first time that they are seen in the spectrum of a solar-mass YSO. Analysis of the Spitzer data combined with Keck L- and M-band spectra reveals excitation temperatures of ≳350 K and abundances of 10–6 to 10–5 with respect to H2, orders of magnitude higher than those found in cold clouds. In spite of this high abundance, the HCN J=4-3 line is barely detected with the James Clerk Maxwell Telescope (JCMT), indicating a source diameter less than 13 AU. The (sub)millimeter continuum emission and the absence of scattered light in near-infrared images limit the mass and temperature of any remnant collapsing envelope to less than 0.01 M☉and 100 K, respectively. This excludes a hot-core-type region as found in high-mass YSOs. The most plausible origin of this hot gas rich in organic molecules is in the inner (<6 AU radius) region of the disk around IRS 46, either the disk itself or a disk wind. A nearly edge-on two-dimensional disk model fits the spectral energy distribution (SED) and gives a column of dense warm gas along the line of sight that is consistent with the absorption data. These data illustrate the unique potential of high-resolution infrared spectroscopy to probe the organic chemistry, gas temperatures, and gas kinematics in the planet-forming zones close to a young star.
Infrared: ISM - ISM: individual (IRS 46) - ISM: Jets and Outflows - ISM: Molecules - Stars: Planetary Systems: Protoplanetary Disks - Stars: Formation
View the reference in ADS
To bookmark this query, right click on this link: simbad:2006ApJ...636L.145L and select 'bookmark this link' or equivalent in the popup menu